CN113141040B

CN113141040B - Satellite power supply system

Info

Publication number: CN113141040B
Application number: CN202110450805.6A
Authority: CN
Inventors: 桑晓茹; 杨峰; 任维佳
Original assignee: Spacety Co ltd Changsha
Current assignee: Spacety Co ltd Changsha
Priority date: 2020-05-07
Filing date: 2020-05-07
Publication date: 2024-07-26
Anticipated expiration: 2040-05-07
Also published as: CN111293759A; CN113141039A; CN113141039B; CN113141040A; CN111293759B

Abstract

The invention relates to a satellite power supply system, which comprises an energy storage module, wherein the energy storage module comprises at least one unique energy storage device configured to store all electric energy generated by an energy generation module and a super capacitor group of the unique energy storage device for supplying power to an on-board load in a voltage value changing mode in response to the control of an energy management module, wherein the maximum state of charge (SOC) of the super capacitor group is transmitted into a current closed loop through an equalizer connected with the current closed loop and a direct current bus in the form of a direct current signal through the direct current bus, so that the maximum value of the state of charge is directly transmitted to all the super capacitor groups in the direct current bus, and the current closed loop of each super capacitor group automatically acquires a second difference value in a second balance coefficient. Based on modeling analysis of a plurality of groups of super capacitors in the satellite power supply system, a more effective equivalent circuit model is designed.

Description

Satellite power supply system

The invention relates to a split application of a satellite power supply system with the application number of CN202010375070.0, the application date of 2020, 05 and 07, the application type of the invention and the application name of integrated energy generation, energy storage and energy management.

Technical Field

The invention relates to the technical field of satellite on-orbit power supply, in particular to a satellite power supply system.

Background

The super capacitor (ELECTRICAL DOUBLE LAYER CAPACITOR, EDLC) is a new energy storage device between a conventional capacitor and a rechargeable battery, which has both the fast charge and discharge characteristics of the capacitor and the energy storage characteristics of the battery. The super capacitor has high-power output characteristics, can meet the requirements of a high-pulse power system, and can be used for systems requiring high-power pulse power sources such as satellite communication systems, radio systems, electromagnetic gun emission, unmanned aerial vehicle electromagnetic emission and the like. However, the energy density of the existing super capacitor still cannot meet the requirements of part of satellite devices, so in the prior art, for example, chinese patent document with publication No. CN103414235A discloses a low-cost and ultra-long-life artificial satellite electric storage system using solar energy as primary energy, the electric storage system adopts a dual electric storage module formed by a buffer electric storage unit with small capacity for frequent charge and discharge and a main electric storage unit with large capacity for long-time interval charge and discharge, and the capacities of the buffer electric storage unit and the main electric storage unit are set according to a certain principle, and the main electric storage unit adopts a step buffer gradual change design. The invention takes the super capacitor with no memory and high cycle life (the charge-discharge cycle times are 3-10 ten thousand times) as a small-capacity buffer electric storage unit. The lithium ion (the charge-discharge cycle number is 1-2 thousands) or nickel-hydrogen or nickel-cadmium (the cycle number of the nickel-hydrogen or nickel-cadmium battery is 500-700) accumulator with memory effect and low cycle life is used as a large-capacity main accumulator. The invention makes up the problem of low energy density of the super capacitor by utilizing the characteristic of high energy density of the lithium ion or nickel-hydrogen storage battery pack, thereby constructing the satellite electric power storage system with high energy density and high power density. However, in the satellite power supply system using the lithium battery pack and the super capacitor, because the characteristics of the two devices are different, the design and the use of the system need to be considered simultaneously, so that the scheme is very complex, and the improvement of the complexity of the system not only can lead to the improvement of the product cost, but also can lead to the increase of the failure probability, thereby reducing the reliability of the satellite power supply system.

The national academy of sciences vinca application chemistry institute developed a novel colloidal supercapacitor, 100% utilization of active cations was achieved under kinetic permission, and a variety of series of colloidal supercapacitor batteries were developed in 2013. The energy density of the Ni-Fe colloid ion super capacitor battery developed by the Saint GmbH of the applied chemistry institute Xue Dongfeng of Chinese sciences in 2018 can reach 350Wh/kg, the power density is 2kW/kg, and the energy density can reach 100Wh/kg, and the power density is 10kW/kg. The performance is superior to the current super capacitor battery, for example, the energy density of the super capacitor product of MaxWell in the United states is 6Wh/kg, the power density of the super capacitor product of 12kW/kg, the energy density of the super capacitor product of the CORNING company in the United states is 9Wh/kg, the power density of the super capacitor product of 7kW/kg, and the energy density of the super capacitor product of NESSCA in Korea is 10Wh/kg, and the power density of the super capacitor product of 10kW/kg. The super capacitor developed by the application chemistry research of the vinca of the Chinese academy of sciences can basically reach the energy density of 150Wh/kg of the lithium battery, the working temperature range of the colloid super capacitor is-60 ℃ to 80 ℃, the temperature requirement of satellite on-orbit working is met, the vacuum environment basically has no influence on the super capacitor, the vibration test result meets the requirement, the colloid super capacitor can be applied to a satellite power supply system after being packaged, and the satellite power supply system with high power density and high energy density can be realized without mixing a lithium battery pack. However, although the super capacitor with high energy density and high power density is already provided in the prior art, the withstand voltage of the single super capacitor is low, and the satellite power supply needs a plurality of super capacitors to be connected in series and parallel to improve the voltage and the energy storage capacity, but due to the manufacturing process difference, different charging rates and the difference of working environment temperatures, the internal resistance, capacitance, leakage current and other parameters of each super capacitor are different, and therefore, as the satellite platform operates for a long time, in the process of charging and discharging the super capacitors in series, the voltages of the super capacitors are inconsistent, the super capacitor with lower voltage can be overcharged, or the super capacitor with lower voltage is overdischarged in the discharging process, the service life of the super capacitor is seriously damaged, and the safe operation of the satellite is influenced. The prior art therefore typically provides an energy management system in a satellite power system to balance the supercapacitor bank. The balance control of the super capacitor energy storage system can be generally divided into single energy balance control and module energy balance control, and the two have no substantial difference except voltage class and capacitance value.

Literature [1]Mishra R,Saxena R.Comprehensive Review of Control Schemes for Battery and Super-capacitor Energy Storage System[C].2017 7th International Conference on Power Systems(ICPS),2017,702–707. discloses a common equalization control strategy for supercapacitors. The existing equalization control strategies can be divided into an active equalization strategy, a passive equalization strategy and a dynamic equalization control strategy based on a cascading power converter. The passive equalization strategy, which requires using an external circuit to consume excess energy in the form of heat, is an energy consumption strategy, and is mainly implemented by equalization resistors or zener diodes. However, although the passive equalization strategy is easy to implement, the equalization efficiency is not high, the equalization speed is slow, and the system heating is easy to be serious, so that the passive equalization strategy is suitable for a low-power energy storage system or an occasion with low requirement on the equalization speed and is not suitable for a satellite energy storage system. Active equalization strategies require the use of external equalization circuitry to transfer energy in high energy devices into low energy devices. The implementation of the external equalization circuit may be divided according to whether or not there is an isolation transformer. The active equalization strategy without the transformer is to utilize the Boost converter to transfer energy step by step from bottom to top, but the equalization speed of the energy equalization strategy is slower, the equalization speed of the voltage doubling equalization circuit can be effectively improved by adopting a parallel equalization capacitor mode, or the time of energy transfer is shortened by changing the input time of the low-voltage energy storage module on the basis of the traditional equalization circuit, and the equalization speed is improved. The transformer-free active equalization strategy can reduce the loss of equalization energy, and the cost and the volume of the energy equalization system are smaller. However, as the number of super capacitors in series increases, the equalization efficiency cannot be ensured. The active equalization strategy based on the isolation transformer can improve the efficiency of energy conversion between non-adjacent super-capacitors, and is generally based on the equalization strategy of a multi-winding transformer to realize active equalization, but with the increase of the number of super-capacitors connected in series, the isolation transformer with a plurality of windings is difficult to manufacture, so that the active equalization strategy based on the isolation transformer is only suitable for a system with a small number of super-capacitors connected in series. The energy balance control strategy based on the cascade power converter is to directly utilize the system current to realize the energy balance control among the energy storage modules in the system charge-discharge dynamic process so as to simplify the balance system structure. Specifically, the energy storage and the energy balance control are normalized, and the Charge State of Charge (SOC) of the energy storage module is controlled to Charge and discharge. However, the equalization control strategy uses cascaded modularized direct current converters, structurally belongs to a series output and series (Input-Serious Output-Serious, ISOS) system, and the equalization of submodules generally adopts a multi-closed loop control strategy in a current differential mode, and the strategy has high requirements on system parameters and is easily influenced by the current of a main power circuit.

Furthermore, there are differences in one aspect due to understanding to those skilled in the art; on the other hand, as the inventors studied numerous documents and patents while the present invention was made, the text is not limited to details and contents of all that are listed, but it is by no means the present invention does not have these prior art features, the present invention has all the prior art features, and the applicant remains in the background art to which the rights of the related prior art are added.

Disclosure of Invention

In the prior art, a satellite power supply system with a lithium battery pack and a super capacitor being mixed is used, and because the characteristics of the two devices are different, the design and the use of the system need to be considered simultaneously, so that the complexity of the system is improved, the product cost is high, the failure probability of the system is increased, and the reliability of the satellite system is seriously reduced. While the super capacitor group formed by a plurality of super capacitors with high power density and high energy density is used for supplying power to the satellite platform, the improvement of the complexity of the system can be avoided, for example, the super capacitors developed by using the applied chemistry of the department of academy of science are used, and the parameters of each super capacitor are different due to the difference of manufacturing process, different charging rates and the difference of working environment temperatures, so that the super capacitors are inconsistent in voltage in the process of serial charging and discharging of the super capacitors as the satellite platform operates for a long time, or the super capacitors with lower voltage are overcharged in the process of discharging, the service life of the super capacitors is seriously damaged, and the safe operation of the satellite is influenced. Therefore, the prior art adopts a super capacitor voltage balancing mode to ensure that the voltages of a plurality of super capacitors are kept consistent in the charging and discharging process, so that overcharge or overdischarge is avoided. The existing balancing technology of the super capacitor generally adopts an active balancing or energy balancing control strategy based on a cascade power converter, but no matter the active balancing strategy or the energy balancing control strategy based on the cascade power converter is adopted, the voltage balancing is realized by using a multi-closed-loop control strategy in a current or voltage differential form, and the multi-closed-loop control strategy relates to an external balancing circuit, so that the energy balancing of an energy storage system and the system power control are kept independent of each other, the energy loss of the system is increased, the operability of the control system is weakened, the overall reliability of the system is reduced, and the balancing efficiency cannot be ensured along with the increase of the number of the series super capacitors.

In view of the above problems, the present invention provides a modularized satellite power system integrating energy generation, energy storage and energy management, which at least comprises an energy generation module, an energy storage module and an energy management module. The energy storage module stores the electric energy generated by the energy generation module and supplies power to the on-board load based on the control of the energy management module. The energy storage module at least comprises at least one super capacitor group formed by a plurality of super capacitors. The super capacitor bank is configured to store a unique energy storage device that generates all electric energy by the energy generation module and a unique energy supply device that supplies power to the on-board load in a manner of at least two changes in voltage value in response to control of the energy management module. The energy management module at least comprises a voltage closed loop which is used for transmitting signals in a direct current mode through a direct current bus and is shared by all the super capacitor groups, at least one current closed loop which is positioned in the voltage closed loop and is respectively closed with each super capacitor group, and an equalizer which is connected with the current closed loop and the direct current bus. The method is used for solving the problems of energy loss increase and weaker operability of a control system caused by adopting independent voltage and current closed-loop control strategies in the existing satellite power storage system. The technical effect that reaches is through the common voltage closed loop to simplify the structure to a certain extent and reduce the energy loss the communication line in the prior art is replaced through being connected with the direct current busbar on the basis, because common voltage closed loop and direct current busbar are connected and use the reference current signal that the state of charge value information and the voltage closed loop that the direct current signal transmission super capacitor group produced, consequently can guarantee that the system possesses the ability of stable satellite power supply system. The traditional multi-closed-loop control system uses a communication line to transmit a voltage signal or a current signal, because a direct current bus is used for transmitting the signal, and the carrier or the information quantity of the signal is the amplitude of direct current, so that the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signal is limited, and therefore, the traditional multi-closed-loop control system adopts a digital signal to transmit information. However, the digital signal needs another communication line for equalization to transmit the digital signal, which inevitably leads to the complexity of the whole satellite communication line with the increase of the number of super capacitor groups, and the huge communication data generated by the digital signal also causes the operation burden to the processor. The reference current signal required by the current closed loop is transmitted through the direct current bus in the voltage closed loop, the communication data volume and the processing cost can be greatly reduced in an analog current transmission information mode, and the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the short length of the direct current bus of the satellite power supply system, so that the complexity of a circuit and huge data information are avoided under the condition of sacrificing part of anti-interference capability.

Preferably, the energy management module is configured to output a reference current signal through the voltage closed loop based on the voltage value fed back by the direct current bus and the reference voltage signal. The energy management module is configured to adjust the equalization parameters of each super capacitor bank output by the equalizer in response to the difference between the reference current signal and the system current feedback value. The energy management module is configured to generate a driving signal for equalizing charge of the super capacitor group through the current closed loop based on the equalization parameter. The super capacitor bank energy balance device is used for solving the problem that the super capacitor bank is overcharged or overdischarged in the energy balance process of the super capacitor bank in the energy storage module. The method has the technical effects that the voltage fed back by the direct current bus and the reference voltage signal set based on the number and the specification of the super capacitor group are input into the voltage closed loop. A voltage regulator within the voltage closed loop generates a reference current signal. And combining the difference value generated by the reference current signal and the system current feedback value with the equalization parameter corresponding to each super capacitor group generated by the equalizer, and sending the result into the current closed loop of each super capacitor group. The current regulator in the current closed loop generates the duty ratio of the super capacitor group according to the input result, and the duty ratio is in proportional relation with the charge state value of the super capacitor group, so that the energy balance of each super capacitor group can be controlled through the duty ratio.

Preferably, in the case where the energy generation module charges the energy storage module, the equalizer is configured to: and acquiring the state of charge value of each super capacitor group in an on-line estimation mode based on the voltage value and the current value fed back by the voltage closed loop and the current closed loop, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient, and the sum of the equalization parameters is always kept at a fixed value. The first equalization coefficients are configured as the ratio of the corresponding first difference value of the super capacitor group to the sum of the first difference values of all the super capacitor groups, and the sum of the first equalization coefficients of all the super capacitor groups is the constant value. The first difference is defined by the difference between the state of charge value of the corresponding supercapacitor group and the fixed value. the second equalization coefficients include at least a second difference defined by a difference between a maximum and a minimum of the state of charge values of all of the super capacitor banks and a first dynamic coefficient for defining the second difference such that a sum of the second equalization coefficients of all of the super capacitor banks remains at a zero value. The technical scheme is used for solving the problem that the balance efficiency cannot be ensured along with the increase of the number of the super capacitor groups. In the process of balancing the super capacitor groups, along with continuous balancing of energy among the super capacitor groups, the state of charge values of the super capacitor groups gradually tend to be consistent. And the energy balance is performed based on the state of charge value of the super capacitor, and the balance is performed according to the difference of the state of charge value of the super capacitor. If the difference of the charge state values of the super capacitors is gradually reduced, the equalization speed of the energy management module is gradually reduced. And along with the increase of the number of the super capacitor groups, the number of the super capacitor groups with similar charge state values is increased, and the equalization speed of the energy management module is greatly reduced. The equalization parameters adopted in the prior art are generally the first equalization coefficient in the invention, namely the first equalization coefficient is defined according to the state of charge value among the super capacitor groups. The sum of the first equalization coefficients of each super capacitor group is generally set to be a constant value of 1, so that the equalizer is convenient to control and set and the current closed loop demodulates equalization parameters. The second equalization coefficient is a linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values of the super capacitor group, so that the equalization speed is increased under the condition that the state of charge values of the super capacitor group tend to be consistent. In addition, the equalizer connected with the current closed loop and the direct current bus respectively can transmit the maximum state of charge value of the super capacitor group into the current closed loop through the direct current bus in the form of direct current signals, so that the maximum value of the state of charge value of all the super capacitor groups can be directly transmitted in the direct current bus, and the current closed loop of each super capacitor group can automatically acquire a second difference value in the second equalization coefficient. Through the arrangement mode, the direct current bus is used for replacing a communication line to directly transmit the state of charge value of the super capacitor in a direct current signal mode, the information quantity processed by the equalizer is further simplified, and the state of charge value of a key parameter used for determining equalization control is put into the direct current bus and a current closed loop corresponding to each super capacitor group, so that the state of charge value is not required to be intensively processed by the equalizer, and the equalization capacity of the energy management module is not affected after any super capacitor group is disabled due to failure. and the direct current carrier transmits the signals with the charge state values, and the sum of the signals is a fixed value, so that the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Through the arrangement mode, in the process of performing multi-closed-loop energy balance control by using the energy storage module formed by the super capacitor only in the satellite power supply system, reference current signals required by a current closed loop are transmitted through the direct current bus in a voltage closed loop, communication data quantity and processing cost are greatly reduced in an information transmission mode through analog current, and the balance speed is accelerated by further amplifying the difference of the charge state values of the super capacitor group through the second balance coefficient. The sum of the second equalization coefficients is zero, the sum of the first equalization coefficients is a constant value 1, so that the energy management module can strictly track the current reference signal, in addition, the equalization speed based on the state of charge value is related to the number of the super capacitor groups along with the increase of the number of the super capacitor groups, but the first equalization coefficients and the second equalization coefficients are mainly determined by the state of charge value, which means that the number of the cascaded super capacitor groups cannot influence the equalization speed of the energy management module, and the influence on the equalization speed of the energy management module is only the state of charge value of the super capacitor groups, so that the equalization efficiency of the energy management module can still be ensured under the condition that the number of the super capacitor groups is increased through the setting of the second equalization coefficients.

According to a preferred embodiment, said first dynamic coefficient comprises at least a first coefficient and a second coefficient proportional to said second difference. The equalizer is configured to: a first coefficient is constructed that maintains a sum at a zero value based on the difference between the average value of the first differences of the supercapacitor group and the first difference of the corresponding supercapacitor group. And constructing a second coefficient for linearly amplifying the second equalization coefficient based on the second difference.

According to a preferred embodiment, in case the energy storage module supplies power to the on-board load, the equalizer is configured to: and constructing an equalization parameter which at least comprises a third equalization coefficient and a fourth equalization coefficient and the sum of which is always kept at a constant value based on the obtained state of charge value of each super capacitor group. The third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group to the sum of the state of charge values of all supercapacitor groups. And the sum of the third equalization coefficients of all the super capacitor groups is the constant value. The fourth equalization coefficient includes at least a second difference defined by the difference between the maximum and minimum of the state of charge values of all of the supercapacitor groups. The fourth equalization coefficient further includes a second dynamic coefficient for defining the second difference such that a sum of fourth equalization coefficients of all of the super capacitor groups remains a zero value.

According to a preferred embodiment, said second dynamic coefficient comprises at least a third coefficient and a fourth coefficient proportional to said second difference. The equalizer is configured to: a third coefficient is constructed that maintains a sum of zero values based on the difference between the state of charge values of the respective supercapacitor group and the average of the states of charge of all the supercapacitor groups. A fourth coefficient is constructed that linearly amplifies the third equalization coefficient based on the second difference.

According to a preferred embodiment, in case the energy generation module charges the energy storage module or the energy storage module supplies power to the on-board load, the energy management module is configured to: the second equalization coefficient and the fourth equalization coefficient are controlled by the equalizer to gradually increase as the second difference decreases.

According to a preferred embodiment, in case the energy management module is responsive to a reference current signal delivered by the voltage closed loop, the energy management module is configured to: and controlling the equalizer to transmit the state of charge value of the super capacitor bank into the current closed loop through the direct current bus in the form of direct current signals. The current closed loop is configured to: the reference current signal transmitted by the voltage closed loop is redetermined based on the direct current signal of the highest state of charge value.

According to a preferred embodiment, in case the equalizer performs equalization control based on the duty cycle generated by the current closed loop, the equalizer is configured to: and under the condition that the energy generation module charges the energy storage module, controlling the super capacitor group with low charge state value to charge at a duty ratio larger than that of the super capacitor group with high charge state value. And under the condition that the energy storage module supplies power to the on-board load, the super capacitor group with low charge state value is controlled to discharge at a duty ratio smaller than that of the super capacitor group with high charge state value. And under the condition that the charge state values of all the super capacitor groups are consistent, controlling the current closed loop to charge or discharge the super capacitor groups at the same duty ratio.

The invention also provides a configuration method of the modularized satellite power supply system, which comprises the following steps: the energy storage module of at least one super capacitor group formed by a plurality of super capacitors stores the electric energy generated by the energy generation module and supplies power to the on-board load based on the control of the energy management module; the super capacitor group is used as a unique energy storage device and a unique energy supply device for storing all electric energy generated by the energy generation module, and the unique energy supply device responds to the control of the energy management module to supply power to the on-board load in a mode of at least two changes of voltage values.

Preferably, the energy management module performs the steps of:

outputting a reference current signal through a voltage closed loop based on a voltage value fed back by the direct current bus and a reference voltage signal;

Adjusting the equalizer to output the equalizing parameter of each super capacitor group in response to the difference value between the reference current signal and the feedback value of the system current;

and generating a driving signal for equalizing charge of the super capacitor group through a current closed loop based on the equalization parameters.

According to a preferred embodiment, the equalizer performs the following steps in case the energy generating module charges the energy storage module:

And acquiring the state of charge value of each super capacitor group in an on-line estimation mode based on the voltage value and the current value fed back by the voltage closed loop and the current closed loop, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient, and the sum of the equalization parameters is always kept at a fixed value. The first equalization coefficient is the ratio of the corresponding first difference value of the super capacitor group to the sum of the first difference values of all the super capacitor groups. And the sum of the first equalization coefficients of all the super capacitor groups is the constant value. The first difference is defined by the difference between the state of charge value of the corresponding supercapacitor group and the fixed value. The second equalization coefficient includes at least a second difference defined by the difference between the maximum and minimum of the state of charge values of all of the supercapacitor groups. The second equalization coefficients further include a first dynamic coefficient for defining the second difference such that a sum of second equalization coefficients of all of the super capacitor groups remains a zero value.

Drawings

FIG. 1 is a block diagram of a preferred embodiment of a satellite power system of the present invention;

FIG. 2 is a schematic diagram of the structure of a preferred embodiment of the energy management module of the present invention;

FIG. 3 is a classical model of a supercapacitor equivalent circuit;

FIG. 4 is a simplified model of a supercapacitor equivalent circuit;

FIG. 5 is a schematic circuit diagram of the working principle of the super capacitor bank of the present invention; and

Fig. 6 is a flowchart illustrating steps of a satellite power configuration method according to the present invention.

List of reference numerals

10: The energy generation module 20: energy storage module

30: Energy management module 40: on-board load

201: Super capacitor bank 202: the first bridge arm

203: Second leg 301: voltage closed loop

302: Current closed loop 303: equalizer

304: Boost module 305: step-down module

306: Ratio link 3011: voltage regulator

3012: Reference voltage signal 3013: voltage value fed back by DC bus

3021: Current regulator 3022: reference current signal

3023: System current feedback value 3024: waveform generator

SOC: state of charge value Req: equivalent parallel resistor

C: capacitance Res: equivalent series resistance

Detailed Description

The following detailed description refers to the accompanying drawings.

First, background knowledge of the embodiments and technical terms appearing will be explained.

Because the voltage of the single super capacitor is low, a plurality of super capacitors are connected in series to increase the voltage and the capacity of energy storage. For satellite power systems, depending on the size, weight, and loading of the satellite, a large satellite may require multiple supercapacitors to be grouped and connected in parallel or series to multiply the energy stored, thereby powering the satellite. The super capacitor is applied to a satellite power supply system, so that the super capacitor has a complex resistance-capacitance network, and the equivalent resistance and capacitance of each branch circuit have differences. In fact, the charge amount stored by the super capacitor is related to the charge state value SOC, the voltage level, the running time and other factors, so that modeling analysis is required to be performed on the energy storage system of the super capacitor, and the modeling of the super capacitor is mainly based on an RC impedance network at present. Modeling types include RC transmission line models and equivalent circuit models. Because of the short response time of the super capacitor energy storage system, the dynamic charge and discharge process is usually only tens of seconds. When the dynamic current of the system is directly utilized to carry out balance control on the super capacitor, the significance of the long-time parameters in the multistage RC branch circuit on the balance control is not great, so that the equivalent circuit model adopting lumped parameters is more effective. The simplified RC equivalent circuit model is shown in FIGS. 3 and 4.

The simplified circuit structure shown in fig. 3 is referred to as a classical model in a supercapacitor energy storage system. The model is formed by connecting an ideal capacitor C with an equivalent series resistor Res with a smaller resistance value in series and simultaneously connecting the ideal capacitor C with an equivalent parallel resistor Rep with a larger resistance value in parallel. The equivalent series resistance Res will make the dynamic efficiency of the supercapacitor less than 1, while it can be used to describe the dynamic loss of the supercapacitor. The equivalent parallel resistor Rep is used for describing the leakage current characteristic of the super capacitor in a long-time static energy storage state.

The classical model in fig. 3 can be further simplified to obtain a simplified model as shown in fig. 4. The model consists of only one ideal capacitance and equivalent series resistance Res. The equivalent series resistance Res characterizes the internal loss of the super capacitor, the voltage drop generated in the dynamic process and the constraint condition of the maximum working current of the super capacitor, and the model only considers the dynamic characteristics of the charge and discharge of the super capacitor. Therefore, a simplified model can be adopted for analysis when the short-time charge-discharge dynamic characteristics of the super capacitor are researched.

The state of charge value SOC of the supercapacitor is used to describe the amount of charge stored in the supercapacitor in the current state. The calculation method of the SOC of the super capacitor comprises two forms of charge and electric energy. The two calculation methods define the calculation form of the state of charge value SOC of the super capacitor from different angles, and can reflect the current storage electric quantity of the super capacitor. The following examples employ a charge-form-based state-of-charge value SOC calculation method, as shown in the following formula:

The SOC _g represents a state of charge value of the supercapacitor calculated based on the electric charge. Qc (·) represents the amount of charge currently stored by the supercapacitor. u _ocv represents the current open circuit voltage of the supercapacitor. u _rated denotes the rated voltage of the supercapacitor. It should be noted that the super capacitor referred to by the above formula may be a single super capacitor or a super capacitor group 201.

The super capacitor group 201 is formed by connecting a plurality of single super capacitors in series and parallel. The port voltage of the supercapacitor group 201 can be detected by the voltage detecting element, but in the case of high-current charge and discharge, the voltage drop of the equivalent series resistance Res of the supercapacitor group 201 will cause the port voltage of the supercapacitor group 201 to be greater than the voltage across the supercapacitor group 201, and in the case of discharge, the port voltage of the supercapacitor group 201 will cause the port voltage of the supercapacitor group 201 to be less than the voltage across the supercapacitor group 201, so that the voltage drop generated by the equivalent series resistance Res in the supercapacitor group 201 cannot be ignored. In order to accurately estimate the state of charge value SOC of the supercapacitor group 201, online estimation of relevant parameters of the supercapacitor group 201 is required.

The on-line estimation method of the SOC of the supercapacitor group 201 may be estimated by using a kalman filter (KALMAN FILTER, KF) algorithm commonly used in a control system. From this, an equivalent state equation of the discrete state supercapacitor group 201 can be obtained, as shown in the following formula:

u_sc(m)＝u_c(m)+i_sc(m)R_es(m)+v(m)

Where u _c (m+1) represents the voltage across the supercapacitor bank 201 at the (m+1) th sampling instant. u _c (m) represents the voltage across the supercapacitor bank 201 at the mth sampling instant. C (m) represents the capacitance value of the supercapacitor group 201 at the mth sampling time. i _sc (m) represents the port current of the supercapacitor bank 201 at the mth sampling time. T _c denotes the sampling time. u _sc (m) represents the port voltage of the supercapacitor group 201 at the mth sampling time. u _c (m) represents the voltage across the supercapacitor bank 201 at the mth sampling instant. R _es (m) represents the equivalent resistance of the supercapacitor group 201. w (m) and v (m) represent Gaussian white noise with the mean value of 0, and the self independence and mutual independence are satisfied. The voltage and related parameters of the super capacitor group 201 can be identified by constructing a dual observer based on the Kalman filtering algorithm through a state variable based on the Kalman filtering algorithm in a discrete state and an equivalent state equation of the discrete state super capacitor group 201. Because the super capacitor parameter changes slowly, the parameter observation and the model can adopt independent sampling time to reduce the calculated amount.

The principle of dynamic energy balance of the super capacitor is shown in fig. 5. The super capacitor group 201 in the energy storage module 20 is connected to the energy management module 30 through a first bridge arm 202 and a second bridge arm 203. The first leg 202 and the second leg 203 each include at least one transistor and one diode. In the case where the supercapacitor group 201 is charged and discharged, the current is connected to the supercapacitor group 201 through the first bridge arm 202, that is, the first bridge arm 202 is in a conductive state, and the second bridge arm 203 is in a disconnected state. In the case where the energy management module 30 controls the energy storage module 20 to charge, the current charges the supercapacitor bank 201 through the anti-parallel diode of the first bridge arm 202, and the current flows as shown by the dotted line in fig. 5. In the case where the energy management module 30 controls the energy storage module 20 to discharge, the first bridge arm 202 is in the on state, the second bridge arm 203 is in the off state, the supercapacitor group 201 discharges through the first bridge arm 202, and the flow direction of the circuit is shown as a solid line in fig. 5. When the first bridge arm 202 is in the off state and the second bridge arm 203 is in the on state, the second bridge arm 203 is directly connected with the energy management module 30, so that the super capacitor bank 201 is in the bypass state, and the voltage is kept unchanged. From the analysis of the above states, the relationship between the average current i _sci flowing through the supercapacitor group 201 and the system current i _L is shown as follows:

i_sci＝d_ii_L

Where d _i represents the duty cycle of the ith supercapacitor group 201. The duty cycle represents the proportion of the conducting time of the first bridge arm 202 corresponding to the supercapacitor group 201 relative to the control period in one control period. The energy management module 30 controls the on and off of the supercapacitor bank 201 by calculating the duty ratio generated. According to the above equation, the average current flowing through each supercapacitor group 201 in the system is as follows:

i_sc1：i_sc2：...：i_sck＝d₁：d₂：...：d_k

In fact, the coulomb law can be used to determine that the amount of charge stored in the capacitor is linearly related to the charge-discharge current and time, so that the relationship between the duty cycle of each supercapacitor group 201 and the state of charge value SOC can be obtained:

d₁：d₂：...：d_k＝ΔSOC₁：ΔSOC₂：...：ΔSOC_k

wherein Δsoc _k represents the amount of change in state of charge value SOC of kth supercapacitor group 201. Due to the adoption of the modularized structure, the system current flowing through each super capacitor group 201 is the same, so that the change of the SOC value of the super capacitor group can be controlled through the duty ratio of each super capacitor group 201, and the balance control among the super capacitor groups 201 can be realized through the adjustment of the duty ratio. In the mode in which the energy generating module 10 charges the energy storage module 20, the super capacitor group 201 with a higher SOC should be charged with a smaller average current, and the super capacitor group 201 with a lower SOC should be operated with a larger average current. In the discharging mode of the energy storage module 20, the energy management module 30 should control the duty ratio so that the super capacitor group 201 with a higher SOC value should discharge with a larger average current, and the super capacitor group 201 with a smaller SOC value should discharge with a smaller average current. In the state that the super capacitor bank 201 is in the bypass state, the triode of the second bridge arm 203 and the diode connected in anti-parallel with the triode can provide a conducting path for the system current, so that the energy management module 30 can adjust the working average current of each super capacitor bank 201 according to the state of charge value SOC of each super capacitor bank 201 on the premise of ensuring the stable DC bus voltage of the satellite power system, and the state of charge value SOC balance control of the super capacitor bank 201 is realized in the dynamic process of charging and discharging of the satellite power system.

The dynamic balancing of the energy of the supercapacitor bank 201 is achieved by the energy management module 30. The energy management module 30 includes at least a voltage closed loop 301 and a current closed loop 302. Voltage closed loop 301 generally includes a voltage regulator 3011, a reference voltage signal 3012, and a dc bus fed back voltage value 3013. The current closed loop 302 generally includes a current regulator 3021, a reference current signal 3022, and a system current feedback value 3023. Preferably, the current loop 302 further comprises a waveform generator 3024 connected to the current regulator 3021. The waveform generator 3024 may be a triangular waveform generator.

The power management module 30 operates on the principle that the voltage closed loop 301 is used to control the voltage of the dc bus. The voltage closed loop 301 is connected to the current closed loop 302, and the voltage closed loop 301 is outside the current closed loop 302, as shown in fig. 2. Preferably, in the voltage closed loop 301, the voltage regulator input includes at least a reference voltage signal 3012 and a voltage value 3013 fed back by the dc bus. The reference voltage signal 3012 is set according to the information of the energy storage module 20, and serves as a reference parameter to balance the supercapacitor group 201 in the energy storage module 20. Preferably, the difference between the reference voltage signal 3012 and the voltage value 3013 fed back by the dc bus is input to the voltage regulator 3011. The voltage regulator 3011 calculates an output reference current signal 3022 and transmits it into the current closed loop 302. The difference signal generated by the reference current signal 3022 and the fed-back system current 3023 is input to the current regulator 3021. The current regulator 3021 calculates and generates a corresponding duty ratio, and then compares the duty ratio with the waveform generator 3024 to generate a driving signal for driving the supercapacitor group 201. Or the duty cycle generated by the current regulator 3021 may be modulated by a pulse width modulation (Pulse Width Modulation, PMW) modulator to generate the modulated signal for the supercapacitor bank 201. Preferably, the voltage regulator 3011 may be a voltage PID regulator. The current regulator 3021 may be a current PID regulator.

Preferably, the energy management module 30 may be connected to the energy storage module 20 through a bi-directional DC-DC converter. The bidirectional DC-DC converter mainly realizes the transmission of energy among the super capacitor groups 201 and has the characteristics of low voltage and high current. In addition, the DC bus may also be connected to the on-board load 40 through a bi-directional DC-DC converter.

Example 1

As shown in fig. 1 and 2, the present embodiment provides a modular satellite power system integrating energy generation, energy storage and energy management. The satellite power system at least comprises an energy generation module 10, an energy storage module 20 and an energy management module 30. The energy storage module 20 stores the electric energy generated by the energy generation module 10. The energy storage module 20 supplies power to the on-board load 40 based on the control of the energy management module 30. Preferably, the energy storage module 20 comprises at least one supercapacitor group 201. The supercapacitor bank 201 is made up of a plurality of supercapacitors. The supercapacitor bank 201 is configured as the only energy storage device that the energy storage source generating module 10 generates all the electric energy. Preferably, the supercapacitor bank 201 is further configured as the only energy supply means for supplying power to the on-board load 40 in response to control of the energy management module 30. Preferably, the supercapacitor bank 201 supplies power to the on-board load 40 in at least two variations in voltage values. At least two ways of varying the voltage value may be to power the on-board load 40 in a step-up and step-down manner. Preferably, the energy management module 30 includes at least a boost module 304 and a buck module 305. The boost module 304 may be a boost type DC-DC converter. The buck module 305 may be a buck DC-DC converter. Preferably, the energy generating module 10 may be a solar panel.

Preferably, the energy management module 30 includes at least a voltage closed loop 301, at least one current closed loop 302, and an equalizer 303. Preferably, the voltage closed loop 301 transmits a signal in the form of a direct current through a direct current bus. The voltage closed loop 301 is a voltage closed loop 301 common to all the super capacitor banks 201, as shown in fig. 2. Current closed loop 302 is within voltage closed loop 301. The current closed loop 302 forms a closed loop with each supercapacitor group 201, respectively. Equalizer 303 is connected to current loop 302 and to the dc bus. The problems of increased energy consumption and weaker operability of the control system caused by adopting independent voltage and current closed-loop control strategies in the existing satellite power storage system. The present embodiment replaces the prior art communication lines by connection to the dc bus on the basis of somewhat simplified construction and reduced energy consumption by the common voltage closed loop 301. The common voltage closed loop 301 is connected with the direct current bus and uses the direct current signal to transmit the state of charge value of the super capacitor group 201 and the reference current signal 3022 generated by the voltage closed loop 301, so that the system can be ensured to have the capability of stabilizing the satellite power supply system. The traditional multi-closed-loop control system uses a communication line to transmit a voltage signal or a current signal, because a direct current bus is used for transmitting the signal, and the carrier or the information quantity of the signal is the amplitude of direct current, so that the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signal is limited, and therefore, the traditional multi-closed-loop control system adopts a digital signal to transmit information. However, the use of digital signals requires an additional communication line for equalization to transmit the digital signals, which inevitably complicates the entire satellite communication line as the number of super capacitor banks 201 increases, and the generation of huge communication data by the digital signals also places a computational burden on the processor. The reference current signal 3022 needed by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, so that the communication data volume and the processing cost can be greatly reduced in a mode of simulating current transmission information, and the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the short length of the direct current bus of the satellite power supply system, so that the complexity of a circuit and huge data information are avoided under the condition of sacrificing part of anti-interference capability.

Preferably, the energy management module 30 is configured to output the reference current signal 3022 through the voltage closed loop 301 based on the voltage value 3013 and the reference voltage signal 3012 fed back by the dc bus. The energy management module 30 is configured to adjust the equalizer 303 output equalization parameters for each super capacitor bank 201 in response to the difference between the reference current signal 3022 and the system current feedback value 3023. The energy management module 30 generates a driving signal for equalizing charge of the super capacitor bank 201 through the current closed loop 302 based on the equalization parameters. In the process of realizing the energy balance of the super capacitor bank 201 in the energy storage module 20, the problem of overcharge or overdischarge of the super capacitor bank 201 is easily generated. The present embodiment utilizes the voltage fed back by the dc bus and the reference voltage signal 3012 set based on the number and specifications of the super capacitor bank 201 to input to the voltage closed loop 301. Voltage regulator 3011 within voltage closed loop 301 generates reference current signal 3022. The difference between the reference current signal 3022 and the system current feedback value 3023 is combined with the equalization parameters generated by the equalizer 303 for each supercapacitor group 201 and the result is fed into the current closed loop 302 of each supercapacitor group 201. The current regulator 3021 in the current closed loop 302 generates a duty ratio of the supercapacitor group 201 according to the input result, the duty ratio being in a proportional relation to the state of charge value SOC of the supercapacitor group 201, and thus energy balance of each supercapacitor group 201 can be controlled by the duty ratio.

Preferably, in the case where the equalizer 303 performs the equalization control based on the duty ratio generated by the current closed loop 302, the equalizer 303 is configured to: in the case where the energy generation module 10 charges the energy storage module 20, the super capacitor group 201 having a low state of charge is controlled to charge at a duty ratio larger than that of the super capacitor group 201 having a high state of charge. Preferably, a supercapacitor group 201 with a low state of charge value refers to a supercapacitor group 201 with a higher state of charge value than the supercapacitor group 201. The super capacitor group 201 with low state of charge is controlled to discharge at a smaller duty cycle than the super capacitor group 201 with high state of charge when the energy storage module 20 supplies power to the on-board load 40. The current closed loop 302 is controlled to charge or discharge the supercapacitor bank 201 at the same duty cycle in the case that the state of charge values of all the supercapacitor banks 201 are identical.

Preferably, in the case where the energy generation module 10 charges the energy storage module 20, the equalizer 303 is configured to: the state of charge value of each super capacitor group 201 is obtained in an on-line estimation manner based on the voltage value and the current value fed back by the voltage closed loop 301 and the current closed loop 302, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient, and the sum is always kept at a constant value. Preferably, the first equalization coefficient is configured as a ratio of the first difference of the corresponding supercapacitor group 201 to the sum of the first differences of all supercapacitor groups 201. The sum of the first equalization coefficients of all the supercapacitor groups 201 is a constant value. The constant value may be 1. The first difference is defined by the difference between the state of charge value and the fixed value of the corresponding supercapacitor group 201. Preferably, the first equalization coefficient F ₁ may be expressed by the following formula:

Wherein, 1-SOC _i is the first difference. Is the sum of the first differences of all the supercapacitor groups 201. k is the number of supercapacitor groups 201. SOC _i is the state of charge value of the corresponding supercapacitor bank 201.

Preferably, the second equalization coefficient comprises at least a second difference value and a first dynamic coefficient. The second difference is defined by the difference between the maximum and minimum values of the state of charge values of all supercapacitor groups 201. The second difference represents the degree of non-uniformity of the state of charge value SOC between the supercapacitor bank 201. The first dynamic coefficient is used to define the second difference such that the sum of the second equalization coefficients of all the supercapacitor groups 201 remains at a zero value. Preferably, the first dynamic coefficient comprises at least a first coefficient and a second coefficient. The second coefficient is proportional to the second difference. Preferably, the equalizer 303 is configured to construct a first coefficient whose sum remains at a zero value based on the difference between the average value of the first differences of the supercapacitor bank 201 and the corresponding first difference of the supercapacitor bank 201. The equalizer 303 is configured to construct a second coefficient that linearly amplifies the second equalization coefficient based on the second difference. Preferably, the second equalization coefficient F ₂ may be expressed by the following formula:

wherein, SOC _d is the second difference. Is the first dynamic coefficient. Is the first coefficient. m ₁ is a second coefficient, and the value size is related to the second difference. m ₁ takes a positive integer, for example, in the case where the second difference is 0.4, m ₁ may take a value of 4.m ₂ is a gain factor, and generally takes a value of 2.

Preferably, the equalization parameters may be represented by the following formula:

According to a preferred embodiment, in the case where the energy storage module 20 supplies power to the on-board load 40, the equalizer 303 is configured to: equalization parameters are constructed based on the acquired state of charge values for each supercapacitor group 201. The equalization parameters include at least a third equalization coefficient and a fourth equalization coefficient. The sum of the equalization parameters for each supercapacitor group 201 remains constant at all times. Preferably, the third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group 201 to the sum of the state of charge values of all supercapacitor groups 201. The sum of the third equalization coefficients of all the supercapacitor groups 201 is a constant value. The third equalization coefficient may be represented by the following equation:

Preferably, the fourth equalization coefficient comprises at least the second difference and the second dynamic coefficient. The second difference is defined by the difference between the maximum and minimum values of the state of charge values of all supercapacitor groups 201. The second dynamic coefficient is used to define the second difference such that the sum of the fourth equalization coefficients of all the supercapacitor group 201 remains at a zero value. The second dynamic coefficient includes at least a third coefficient and a fourth system number. The fourth coefficient is proportional to the second difference. Preferably, the equalizer 303 is configured to construct a third coefficient whose sum remains zero based on the difference between the state of charge value of the respective supercapacitor group 201 and the average of the states of charge of all supercapacitor groups 201. The equalizer 303 is configured to construct a fourth coefficient that linearly amplifies the third equalization coefficient based on the second difference. Preferably, the fourth equalization coefficient may be represented by the following formula:

wherein, SOC _d is the second difference. Is the second dynamic coefficient. Preferably, the method comprises the steps of, Is the third coefficient. m ₃ is a fourth coefficient, and the value size is related to the second difference. m ₃ takes a positive integer, for example, in the case where the second difference is 0.4, m ₃ may take a value of 4.

Preferably, in the case where the supercapacitor bank 201 supplies power to the on-board load 40, the equalization parameters may be expressed by the following formula:

In the prior art, whether an average SOC equalization strategy or an active equalization strategy, the equalization efficiency of the super capacitor group 201 cannot be ensured as the number of the super capacitor group increases. In the process of balancing the supercapacitor group 201, the state of charge value SOC of the supercapacitor group 201 gradually tends to be consistent with continuous balancing of energy among the supercapacitor groups 201. And the energy balance is performed based on the state of charge value of the super capacitor, and the balance is performed according to the difference of the state of charge value SOC of the super capacitor. If the difference in state of charge values of the super-capacitor gradually decreases, the equalization rate of the energy management module 30 gradually decreases. Moreover, as the number of super capacitor banks 201 increases, the number of super capacitor banks 201 with similar state of charge values SOC increases, and the speed of equalization of the energy management module 30 may be greatly reduced. Whereas the equalization parameters used in the prior art are generally the first equalization coefficients in the present invention, i.e. the first equalization coefficients are defined according to the state of charge values between the individual supercapacitor groups 201. The sum of the first equalization coefficients of each supercapacitor group 201 is generally set to a constant value of 1, which facilitates control setting of the equalizer 303 and demodulation of equalization parameters by the current closed loop 302. The second equalization coefficient set in the invention is a linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values SOC of the super capacitor group 201, so that the equalization speed is increased under the condition that the state of charge values of the super capacitor group 201 tend to be consistent. More importantly, the second equalization coefficient adopted by the invention not only can accelerate the equalization speed, but also is insensitive to the number of the super capacitor groups 201, namely the equalization efficiency is not affected along with the increase of the number of the cascade super capacitor groups 201. Preferably, taking the mode that the supercapacitor group 201 supplies power to the on-board load 40 as an example, it is demonstrated that the first equalization coefficient and the second equalization coefficient adopted by the present invention are not affected by the number of supercapacitor groups 201 in cascade:

And (3) an equalization strategy based on the state of charge (SOC) of the super capacitor, wherein the equalization speed of the equalization strategy is related to a third equalization coefficient. Ideally, when all of the supercapacitor groups 201 are balanced, the third balancing coefficient is determined only by the number of supercapacitor groups 201. Therefore, the third equalization coefficient adjustment amount Δf _3(k) of the kth supercapacitor group 201 can be obtained as follows:

The larger Δf _3(k) indicates that the more energy the supercapacitor group 201 needs to adjust, the faster the equalization speed, and conversely, the slower the equalization speed if the less energy needs to adjust. From the above equation, the third equalizing coefficient adjustment amount Δf _3(k+1) of the (k+1) th supercapacitor group 201 can be obtained as follows:

Preferably, subtracting Δf _3(k) from Δf _3(k+1) yields the deviation Δj of the third equalization coefficient adjustment amount as the number of supercapacitor bank 201 increases. Δj may be represented by the following formula:

Since the state of charge SOC of the supercapacitor bank 201 takes a value between 0 and 1, Δj may take a positive or negative value. A positive value indicates a decrease in Δj and a decrease in the initial equalization rate of the satellite power system. Negative values indicate an increase in Δj and an increase in the initial equalization rate of the satellite power system. Therefore, under the same condition, Δj is mainly determined by the state of charge SOC of the added supercapacitor bank 201, and the fourth equalization coefficient is also determined by the state of charge SOC. In summary, the number of the super capacitor banks 201 in cascade will not affect Δj, and thus will not affect the equalization speed of the satellite power system. Only the state of charge value SOC of the supercapacitor bank 201 is affected by the equalization speed.

Preferably, the sum of the second equalization coefficients is zero and the sum of the first equalization coefficients is a constant value of 1, so that the energy management module 30 can strictly track the reference current signal 3022, i.e. the duty cycle generated by the current regulator 3021 in the current closed loop 302 is three parts under the setting of the first equalization coefficients and the second equalization coefficients. Preferably, the first portion is a base duty cycle, the duty cycle generated by the reference current signal 3022 generated by the voltage closed loop 301 of the system, and the duty cycle at which the system is actually operating is fluctuating around that value. The second part is the duty cycle of the first equalization coefficient generation with respect to the state of charge value SOC difference. The third part is the duty cycle of the second equalization coefficient generation. Since the sum of the first equalization coefficients is a constant value of 1 and the sum of the second equalization coefficients is zero, the duty ratio of each supercapacitor group 201 changes around the basic value duty ratio, and the magnitude of the change is determined by the first equalization coefficients and the second equalization coefficients, but the total average duty ratio of the system is unchanged. Accordingly, the equalization control of each supercapacitor group 201 is related only to the duty cycle generated by the first equalization coefficient and the second equalization coefficient, without affecting the current control of the system, and energy equalization between the supercapacitor groups 201 can be achieved by controlling the first equalization coefficient and the second equalization coefficient.

According to a preferred embodiment, in case the energy generating module 10 charges the energy storage module 20 or the energy storage module 20 supplies power to the on-board load 40,

The energy management module 30 is configured to: the second equalization coefficient and the fourth equalization coefficient are controlled by the equalizer 303 to gradually increase as the second difference decreases. In the case where energy management module 30 is responsive to reference current signal 3022 delivered by voltage closed loop 301, energy management module 30 is configured to: the equalizer 303 is controlled to transmit the state of charge value SOC of the supercapacitor bank 201 in the form of a dc signal into the current closed loop 302 through a dc bus. The current closed loop 302 is configured to: the reference current signal 3022 delivered by the voltage closed loop 301 is redetermined based on the dc signal of the highest state of charge value. Preferably, as shown in fig. 2, one voltage closed loop 301 is common to all of the supercapacitor groups 201. Through the arrangement mode, the satellite power supply system can be guaranteed to have the capacity of stabilizing the power grid voltage. As shown in fig. 2, each supercapacitor bank 201 has an independent current closed loop 302. The reference current signal 3022 and the system current feedback value 3023 are the same within each current loop 302. Preferably, as shown in fig. 2, equalizer 303 delivers the maximum state of charge value into each current loop 302 via a dc bus. By the arrangement mode, the super capacitor group 201 with low state of charge value SOC can perform balanced control according to the state of charge value SOC. Preferably, the difference between the state of charge value and the maximum state of charge value of the corresponding supercapacitor group 201 is transferred to the current regulator 3021 after being amplified by the scaling element. Preferably, the scaling element 306 is used to proportionally reproduce the change in the input signal, with no distortion, no delay in its output, i.e. no inertia in the signal transfer. The scaling element 306 of the present invention is used to transfer the second difference. Through the arrangement mode, the invention has the beneficial effects that:

The equalizer 303 respectively connected with the current closed loop 302 and the direct current buses can transmit the maximum state of charge value SOC of the super capacitor group 201 to the current closed loop 302 through the direct current buses in the form of direct current signals, so that the maximum value of the state of charge value transmitted to all the super capacitor groups 201 in the direct current buses can be directly transmitted, and the current closed loop 302 of each super capacitor group 201 automatically obtains a second difference value in the second equalization coefficient. The direct current bus is used for replacing a communication line to directly transmit the state of charge value SOC of the super capacitor bank 201 in a direct current signal mode, so that the information quantity processed by the equalizer 303 is further simplified, and the state of charge value SOC which is a key parameter for determining equalization control is lowered into a current closed loop 302 corresponding to each super capacitor bank 201 through the direct current bus, so that the state of charge value SOC does not need to be intensively processed by the equalizer 303, and the equalization capability of the energy management module 30 is not affected after any super capacitor bank 201 is disabled due to failure. And the direct current carrier transmits the signals of the state of charge value SOC, and the sum of the signals is a fixed value, so that the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Preferably, the equalizer 303 is further configured to generate a current compensation parameter based on the second difference value and to introduce the current compensation parameter into the current closed loop 302 in the form of a direct current signal. In the process of transmitting the state of charge value SOC in the form of a direct current signal, a problem of large deviation of the current output by the satellite power supply system may be caused. The use of a dc signal to transfer the state of charge value and the use of a second equalization coefficient enables the duty cycle between different supercapacitor sets 201 to be amplified, which, although increasing the duty cycle difference facilitates energy equalization between supercapacitor sets 201, also results in the problem of large deviations in the system current. In order to reduce the influence of the energy management module 30 on the output current generated by the balance control of the energy storage module 20, the output current needs to be adjusted, that is, the current compensation parameter generated based on the second difference is introduced into the current closed loop 302, and the reference current signal 3022 generated by the voltage closed loop 301 is compensated, so that the service life of the supercapacitor can be prolonged. Through the above arrangement, in the process of performing multi-closed-loop energy balance control by using the energy storage module 20 formed by the super capacitor only in the satellite power supply system, the reference current signal 3022 required by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, so that the communication data amount and the processing cost are greatly reduced in a mode of simulating current transmission information, and the balance speed is further increased by amplifying the difference of the state of charge values of the super capacitor group 201 through the second balance coefficient. The sum of the second equalization coefficients is zero, and the sum of the first equalization coefficients is a constant value 1, so that the energy management module 30 can strictly track the current reference signal, in addition, as the number of the super capacitor groups 201 increases, the equalization speed based on the state of charge value is also related to the number of the super capacitor groups 201, but the first equalization coefficients and the second equalization coefficients are mainly determined by the state of charge value SOC, which means that the number of the cascaded super capacitor groups 201 cannot affect the equalization speed of the energy management module 30, and the influence on the equalization speed of the energy management module 30 is only the state of charge value of the super capacitor groups 201, so that by setting the second equalization coefficients, the equalization efficiency of the energy management module 30 can still be ensured under the condition that the number of the super capacitor groups 201 increases.

Preferably, the equalizer 303 in this embodiment may be an array of editable logic gates (Field Programmable GATE ARRAY, FPGA), such as an antifuse FPGA. Or may be an FPGA or complex programmable logic device (Complex Programmable Logic Device, CPLD) that is radiation-resistant.

Preferably, the energy management module 30 further comprises a storage unit. The Memory cells may be Static Random-Access memories (SRAMs).

Example 2

In this embodiment, the repeated contents are not repeated in addition to embodiment 1.

The embodiment also provides a configuration method of the modularized satellite power supply system, which comprises the following steps:

The energy storage module 20 of at least one super capacitor bank 201 composed of a plurality of super capacitors stores electric energy generated by the energy generation module 10 and supplies power to the on-board load 40 based on the control of the energy management module 30, and the super capacitor bank 201 as a unique energy storage device and a unique energy supply device that generate all electric energy by the energy generation module 10 supplies power to the on-board load 40 in a manner of at least two variations in voltage value in response to the control of the energy management module 30.

Preferably, as shown in fig. 6, the energy management module 30 performs the following steps:

S100: the voltage value 3013 and the reference voltage signal 3012 based on dc bus feedback output a reference current signal 3022 through the voltage closed loop 301. Preferably, the voltage closed loop 301 transmits a signal in the form of a direct current through a direct current bus. The voltage closed loop 301 is a voltage closed loop 301 common to all the super capacitor banks 201, as shown in fig. 2. Current closed loop 302 is within voltage closed loop 301. The current closed loop 302 forms a closed loop with each supercapacitor group 201, respectively. Equalizer 303 is connected to current loop 302 and to the dc bus. The present embodiment replaces the prior art communication lines by connection to the dc bus on the basis of somewhat simplified construction and reduced energy consumption by the common voltage closed loop 301. The common voltage closed loop 301 is connected with the direct current bus and uses the direct current signal to transmit the state of charge value of the super capacitor group 201 and the reference current signal 3022 generated by the voltage closed loop 301, so that the system can be ensured to have the capability of stabilizing the satellite power supply system. The traditional multi-closed-loop control system uses a communication line to transmit a voltage signal or a current signal, because a direct current bus is used for transmitting the signal, and the carrier or the information quantity of the signal is the amplitude of direct current, so that the direct current bus generates voltage drop, the voltage drop is easy to change along with the length of the direct current bus, and the transmission of the direct current signal is limited, and therefore, the traditional multi-closed-loop control system adopts a digital signal to transmit information. However, the use of digital signals requires an additional communication line for equalization to transmit the digital signals, which inevitably complicates the entire satellite communication line as the number of super capacitor banks 201 increases, and the generation of huge communication data by the digital signals also places a computational burden on the processor. The reference current signal 3022 needed by the current closed loop 302 is transmitted through the direct current bus in the voltage closed loop 301, so that the communication data volume and the processing cost can be greatly reduced in a mode of simulating current transmission information, and the problem of low anti-interference capability caused by transmission loss can be greatly reduced due to the short length of the direct current bus of the satellite power supply system, so that the complexity of a circuit and huge data information are avoided under the condition of sacrificing part of anti-interference capability.

Preferably, the energy management module 30 is configured to output the reference current signal 3022 through the voltage closed loop 301 based on the voltage value 3013 and the reference voltage signal 3012 fed back by the dc bus.

S200: the equalizer 303 is adjusted to output the equalization parameters for each supercapacitor bank 201 in response to the difference between the reference current signal 3022 and the system current feedback value 3023. Preferably, in the case where the energy generation module 10 charges the energy storage module 20, the equalizer 303 performs the steps of:

The state of charge value of each super capacitor group 201 is obtained in an on-line estimation manner based on the voltage value and the current value fed back by the voltage closed loop 301 and the current closed loop 302, so as to construct an equalization parameter which at least comprises a first equalization coefficient and a second equalization coefficient, and the sum is always kept at a constant value.

Preferably, in the case that the energy generation module 10 charges the energy storage module 20, the first equalization coefficient is a ratio of the first difference value of the corresponding super capacitor group 201 to the sum of the first difference values of all the super capacitor groups 201. The sum of the first equalization coefficients of all the supercapacitor groups 201 is a constant value. The constant value may be 1. The first difference is defined by the difference between the state of charge value and the fixed value of the corresponding supercapacitor group 201. Preferably, the first equalization coefficient F ₁ may be expressed by the following formula:

Preferably, the equalizer 303 builds equalization parameters based on the acquired state of charge values of each supercapacitor bank 201, with the energy storage module 20 supplying power to the on-board load 40. The equalization parameters include at least a third equalization coefficient and a fourth equalization coefficient. The sum of the equalization parameters for each supercapacitor group 201 remains constant at all times. Preferably, the third equalization coefficient is configured as a ratio of the state of charge value of the corresponding supercapacitor group 201 to the sum of the state of charge values of all supercapacitor groups 201. The sum of the third equalization coefficients of all the supercapacitor groups 201 is a constant value. The third equalization coefficient may be represented by the following equation:

Preferably, in the prior art, whether an average SOC balancing strategy or an active balancing strategy, as the number of super capacitor groups 201 increases, the balancing efficiency cannot be guaranteed. In the process of balancing the supercapacitor group 201, the state of charge value SOC of the supercapacitor group 201 gradually tends to be consistent with continuous balancing of energy among the supercapacitor groups 201. And the energy balance is performed based on the state of charge value of the super capacitor, and the balance is performed according to the difference of the state of charge value SOC of the super capacitor. If the difference in state of charge values of the super-capacitor gradually decreases, the equalization rate of the energy management module 30 gradually decreases. Moreover, as the number of super capacitor banks 201 increases, the number of super capacitor banks 201 with similar state of charge values SOC increases, and the speed of equalization of the energy management module 30 may be greatly reduced. Whereas the equalization parameters used in the prior art are generally the first equalization coefficients in the present invention, i.e. the first equalization coefficients are defined according to the state of charge values between the individual supercapacitor groups 201. The sum of the first equalization coefficients of each supercapacitor group 201 is generally set to a constant value of 1, which facilitates control setting of the equalizer 303 and demodulation of equalization parameters by the current closed loop 302. The second equalization coefficient set in the invention is a linear superposition of the first equalization coefficients, and the purpose to be achieved is to further amplify the difference between different first equalization coefficients according to the difference of the state of charge values SOC of the super capacitor group 201, so that the equalization speed is increased under the condition that the state of charge values of the super capacitor group 201 tend to be consistent. More importantly, the second equalization coefficient adopted by the invention not only can accelerate the equalization speed, but also is insensitive to the number of the super capacitor groups 201, namely the equalization efficiency is not affected along with the increase of the number of the cascade super capacitor groups 201. Preferably, taking the mode that the supercapacitor group 201 supplies power to the on-board load 40 as an example, it is demonstrated that the first equalization coefficient and the second equalization coefficient adopted by the present invention are not affected by the number of supercapacitor groups 201 in cascade:

The larger Δf _3(k) indicates that the more energy the supercapacitor group 201 needs to adjust, the faster the equalization speed, and conversely, the slower the equalization speed if the less energy needs to adjust. The third equalization coefficient adjustment amount Δf _3(k+1 of the (k+1) th supercapacitor group 201 can be obtained from the above formula:

Preferably, as shown in fig. 2, one voltage closed loop 301 is common to all of the supercapacitor groups 201. Through the arrangement mode, the satellite power supply system can be guaranteed to have the capacity of stabilizing the power grid voltage. As shown in fig. 2, each supercapacitor bank 201 has an independent current closed loop 302. The reference current signal 3022 and the system current feedback value 3023 are the same within each current loop 302. Preferably, as shown in fig. 2, equalizer 303 delivers the maximum state of charge value into each current loop 302 via a dc bus. By the arrangement mode, the super capacitor group 201 with low state of charge value SOC can perform balanced control according to the state of charge value SOC. Preferably, the difference between the state of charge value and the maximum state of charge value of the corresponding supercapacitor group 201 is transferred to the current regulator 3021 after being amplified by the scaling element. Preferably, the scaling element 306 is used to proportionally reproduce the change in the input signal, with no distortion, no delay in its output, i.e. no inertia in the signal transfer. The scaling element 306 of the present invention is used to transfer the second difference. Preferably, the equalizer 303 respectively connected to the current closed loop 302 and the dc bus can transmit the maximum state of charge value SOC of the supercapacitor group 201 to the current closed loop 302 through the dc bus in the form of a dc signal, so that the maximum value of the state of charge value transmitted to all the supercapacitor groups 201 in the dc bus can be directly transmitted to the current closed loop 302 of each supercapacitor group 201, and the current closed loop 302 of each supercapacitor group 201 automatically obtains the second difference value in the second equalization coefficient. The direct current bus is used for replacing a communication line to directly transmit the state of charge value SOC of the super capacitor bank 201 in a direct current signal mode, so that the information quantity processed by the equalizer 303 is further simplified, and the state of charge value SOC which is a key parameter for determining equalization control is lowered into a current closed loop 302 corresponding to each super capacitor bank 201 through the direct current bus, so that the state of charge value SOC does not need to be intensively processed by the equalizer 303, and the equalization capability of the energy management module 30 is not affected after any super capacitor bank 201 is disabled due to failure. And the direct current carrier transmits the signals of the state of charge value SOC, and the sum of the signals is a fixed value, so that the anti-interference capability of the direct current signals can be further improved by utilizing the proportional amplifier.

Preferably, the equalizer 303 generates a current compensation parameter based on the second difference value and introduces the current compensation parameter into the current closed loop 302 in the form of a direct current signal. In the process of transmitting the state of charge value SOC in the form of a direct current signal, a problem of large deviation of the current output by the satellite power supply system may be caused. The use of a dc signal to transfer the state of charge value and the use of a second equalization coefficient enables the duty cycle between different supercapacitor sets 201 to be amplified, which, although increasing the duty cycle difference facilitates energy equalization between supercapacitor sets 201, also results in the problem of large deviations in the system current. In order to reduce the influence of the energy management module 30 on the output current generated by the balance control of the energy storage module 20, the output current needs to be adjusted, that is, the current compensation parameter generated based on the second difference is introduced into the current closed loop 302, and the reference current signal 3022 generated by the voltage closed loop 301 is compensated, so that the service life of the supercapacitor can be prolonged.

S300: the driving signal for equalizing charge of the supercapacitor group 201 is generated through the current closed loop 302 based on the equalization parameters. Preferably, in the process of realizing the energy balance of the super capacitor bank 201 in the energy storage module 20, the problem of overcharge or overdischarge of the super capacitor bank 201 is easily generated. The present embodiment utilizes the voltage fed back by the dc bus and the reference voltage signal 3012 set based on the number and specifications of the super capacitor bank 201 to input to the voltage closed loop 301. Voltage regulator 3011 within voltage closed loop 301 generates reference current signal 3022. The difference between the reference current signal 3022 and the system current feedback value 3023 is combined with the equalization parameters generated by the equalizer 303 for each supercapacitor group 201 and the result is fed into the current closed loop 302 of each supercapacitor group 201. The current regulator 3021 in the current closed loop 302 generates a duty ratio of the supercapacitor group 201 according to the input result, the duty ratio being in a proportional relation to the state of charge value SOC of the supercapacitor group 201, and thus energy balance of each supercapacitor group 201 can be controlled by the duty ratio.

Preferably, in the case where the equalizer 303 performs the equalization control based on the duty ratio generated by the current closed loop 302, in the case where the energy generation module 10 charges the energy storage module 20, the equalizer 303 controls the super capacitor group 201 having a low state of charge value to charge at a duty ratio larger than that of the super capacitor group 201 having a high state of charge value. Preferably, a supercapacitor group 201 with a low state of charge value refers to a supercapacitor group 201 with a higher state of charge value than the supercapacitor group 201. The super capacitor group 201 with low state of charge is controlled to discharge at a smaller duty cycle than the super capacitor group 201 with high state of charge when the energy storage module 20 supplies power to the on-board load 40. The current closed loop 302 is controlled to charge or discharge the supercapacitor bank 201 at the same duty cycle in the case that the state of charge values of all the supercapacitor banks 201 are identical.

The term "module" as used herein describes any hardware, software, or combination of hardware and software capable of performing the functions associated with the "module".

It should be noted that the above-described embodiments are exemplary, and that a person skilled in the art, in light of the present disclosure, may devise various solutions that fall within the scope of the present disclosure and fall within the scope of the present disclosure. It should be understood by those skilled in the art that the present description and drawings are illustrative and not limiting to the claims. The scope of the invention is defined by the claims and their equivalents.

Claims

1. A satellite power supply system comprises at least an energy management module (30),

It is characterized in that the method comprises the steps of,

The energy storage module (20) comprises at least one unique energy storage device configured to store all electric energy generated by the energy generation module (10) and a super capacitor bank (201) of the unique energy storage device for supplying power to the on-board load (40) in a voltage value at least two changing modes in response to the control of the energy management module (30), wherein the maximum state of charge (SOC) of the super capacitor bank (201) is transmitted into the current closed loop (302) through an equalizer (303) connected with the current closed loop (302) and a direct current bus in the form of a direct current signal through the direct current bus, so that the maximum value of the state of charge is directly transmitted to all the super capacitor banks (201) in the direct current bus, and the current closed loop (302) of each super capacitor bank (201) automatically obtains a second difference value in a second balance coefficient, wherein the second difference value is a difference value between the maximum value and the minimum value of the state of charge of all the super capacitor banks (201),

Wherein the second equalization coefficient F ₂ is represented by the following formula:

wherein SOC _d is the second difference, As a result of the first dynamic coefficient,For the first coefficient, m ₁ is a second coefficient, the value is related to the second difference value, m ₁ is a positive integer, when the second difference value is 0.4, m ₁ is 4, m ₂ is a gain coefficient, the value is 2, and k is the number of the super capacitor group (201).

2. The satellite power supply system of claim 1, wherein the second equalization coefficients are linear stacks of first equalization coefficients configured as a ratio of a first difference of the respective supercapacitor group (201) to a sum of first differences of all the supercapacitor groups (201) to further amplify differences between different first equalization coefficients according to differences in state of charge values, SOCs, of the supercapacitor groups (201);

The first difference is defined by the difference between the state of charge value and the fixed value of the corresponding supercapacitor group (201), and the first equalization coefficient F ₁ is represented by the following formula:

Wherein, 1-SOC _i is the first difference, For the sum of the first differences of all the super capacitor groups (201), SOC _i is the state of charge value of the corresponding super capacitor group (201).

3. The satellite power supply system of claim 2, wherein the second equalization coefficients comprise at least the second difference and a first dynamic coefficient for defining the second difference such that a sum of second equalization coefficients of all of the super capacitor groups (201) remains at a zero value.

4. The satellite power system of claim 3, wherein the first dynamic coefficient comprises at least a first coefficient and a second coefficient proportional to the second difference, wherein,

Constructing a first coefficient whose sum remains zero based on the difference between the average value of the first differences of the supercapacitor group (201) and the first difference of the corresponding supercapacitor group (201);

And constructing a second coefficient for linearly amplifying the second equalization coefficient based on the second difference.

5. The satellite power supply system according to claim 4, characterized in that the energy management module (30) is connectable to the energy storage module (20) via a bi-directional DC-DC converter, the equalizer (303) constructing equalization parameters based on the acquired state of charge value of each of the super capacitor groups (201) in case the energy storage module (20) supplies power to the on-board load (40), the equalization parameters comprising at least a third equalization coefficient and a fourth equalization coefficient,

Wherein the third equalization coefficient is represented by the following formula:

The fourth equalization coefficient is represented by the following formula:

wherein SOC _d is the second difference, As a result of the second dynamic coefficient,For the third coefficient, m ₃ is a fourth coefficient, the value is related to the second difference value, m ₃ is a positive integer, and m ₃ is a value of 4 when the second difference value is 0.4.

6. The satellite power supply system of claim 5, wherein the energy management module (30) is configured to control, via the equalizer (303), a second equalization coefficient and a fourth equalization coefficient to gradually increase as the second difference decreases.

7. The satellite power supply system of claim 6, wherein all of the super capacitor banks (201) share a voltage closed loop (301) to ensure that the satellite power supply system has the ability to stabilize the grid voltage.

8. The satellite power supply system of claim 7, wherein the equalizer (303) is further configured to generate a current compensation parameter based on the second difference value and to introduce the current compensation parameter into the current closed loop (302) in the form of a direct current signal.

9. The satellite power supply system of claim 8, wherein the method of calculating the state of charge, SOC, of the supercapacitor bank (201) includes reflecting the current stored power of the supercapacitor bank (201) from different angles based on at least two forms of charge and power.