JP6183465B2 - Power storage system - Google Patents

Description

  The present invention relates to a power storage system that supplies power to an electrical load, and more particularly to a capacity type battery and a power storage system that uses a secondary battery having different characteristics.

  As an example of an energy management system, in recent automobiles, in addition to the idling stop function, regenerative energy during deceleration is converted into electrical energy by a generator and charged to a lead battery, and this lead battery is used as a head that is an electrical load. Micro hybrid vehicles (hereinafter referred to as “micro HEVs”) that are used as power sources for auxiliary devices such as lights and heaters are becoming popular.

  Here, a conventional micro-HEV secondary battery is, for example, a lead battery (so-called capacity type) in order to recover (regenerate) a large amount of deceleration energy, as disclosed in, for example, re-published patent WO2009-013891 (Patent Document 1). Battery) and an output type battery such as a lithium ion battery in parallel. Basically, a secondary battery for automobiles is assumed to be equipped with a lead battery. The reason for this is that, in automobiles, it is necessary to supply weak power such as a security device used during parking for several months, so a lead battery with a larger capacity satisfies this requirement. .

  Furthermore, in energy management systems (hereinafter referred to as XEMS) in homes, buildings, factories, etc., voltages from DC 48V to 400V may be used for indoor wiring, and external power sources (AC power from external power transmission lines may be converted to DC). When a secondary battery is charged with a battery converted into electric power or a solar battery, etc., and the power demand in the building or factory increases, peak cutting is performed using the power stored in the secondary battery. Furthermore, it is also considered to use power stored in the secondary battery when an instantaneous power failure due to lightning occurs.

  In order to increase the peak cut amount and reduce the electricity contract fee (that is, reduce the contract amperage), it is necessary to increase the output of the power storage system as in the case of the micro HEV described above. In addition, it is necessary to increase the output of the power storage system in order to cover power during an instantaneous power failure. In addition, a small capacity output type battery is sufficient for instantaneous peak cut or instantaneous power failure itself, but the output type battery tends to have a high cost for capacity (Ah). For this reason, in XEMS that requires a large capacity, it is a fact that a low-cost lead battery must be used. Therefore, a power storage system in which a lead battery and an output type battery are combined in parallel has also been proposed for industrial use.

  Here, in a power storage system that uses a secondary battery with different characteristics such as an output type battery and a lead battery, the output type battery is charged and discharged with a larger current than the lead type battery, and the lead type battery has a higher capacity than the output type battery. Charging and discharging are performed with a small current. Lead batteries have a larger storage capacity than output batteries.

Republished patent WO2009-013891

  In Patent Document 1, a lead battery and a capacitor are connected in parallel, and a DC voltage converter is connected to the capacitor side having a large voltage fluctuation.

  Generally, when the charging voltage of a lead battery is increased to the rated voltage of the lead battery, lead sulfate generated in the lead battery is finely decomposed. Furthermore, in the case of a liquid lead battery, it is known that the capacity of the liquid lead battery is restored and the life is extended by stirring the electrolyte. That is, in a liquid lead battery, a phenomenon called a stratification phenomenon, in which high-concentration sulfuric acid accumulates at the bottom of the battery, occurs, and corrosion of components such as electrodes proceeds due to high-concentration sulfuric acid. is there.

  Therefore, in order to extend the battery life, the charging voltage of the liquid lead battery is increased to increase the charging current, and the increased amount of gas such as hydrogen and oxygen generated by the reaction of the electrolyte increases with the increased charging current. The life of the liquid lead battery is increased by stirring the electrolyte in the liquid lead battery and making the sulfuric acid concentration uniform. In addition, when eliminating the stratification phenomenon that sulfuric acid with high concentration accumulates in the lower part of the battery and extending the life, it is more suitable for the battery than the deterioration of the electrolyte due to the generation of gas such as hydrogen and oxygen. The gain is large.

  However, in Patent Document 1, the lead battery is connected to the electric load, and the charging voltage of the lead battery remains low due to the relationship with the rated voltage of the electric load, so that there is a problem that the life of the lead battery cannot be greatly extended. It was. Therefore, in order to extend the life of the lead battery, even in the configuration of Patent Document 1, if a DC voltage converter is connected to the lead battery side to increase the charge voltage of the lead battery, both the capacitor and the lead battery are used. A DC voltage converter is required, and there are problems in that the production cost increases and the occupied volume of the circuit increases.

  In addition, although the above description has demonstrated the lead battery, when there exists the same phenomenon also in capacity type batteries other than this, this invention shown below can be applied.

  An object of the present invention is to provide an improved power storage system capable of solving the above-described problems and increasing the charging voltage of the capacity type battery while extending the life of the capacity type battery while maintaining the rated voltage of the electric load. It is to provide.

  A feature of the first invention is that an output type battery that discharges current to an electric load and charges current from a generator, and a capacity type that discharges current to the output type battery and charges current from the output type battery. A direct current voltage capable of boosting and stepping down the capacity battery, wherein the first specified current that can be passed through the output battery has a larger current value than the second specified current that can be passed through the capacity battery It is in place where it is connected in series with the output type battery via a converter.

  The second aspect of the invention is characterized in that an output type battery that discharges current to an electric load and charges current from a generator, and a capacity type that discharges current to the output type battery and charges current from the output type battery. A direct current voltage capable of boosting and stepping down the capacity battery, wherein the first specified current that can be passed through the output battery has a larger current value than the second specified current that can be passed through the capacity battery The output type battery is connected in series with the output type battery via the converter, and the output type battery is equal to or higher than the first predetermined charging rate, higher than the first predetermined voltage, lower than the second predetermined charging rate, or second. The current is discharged to the electric load by the capacity type battery when the voltage falls below the predetermined voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power of a DC voltage converter can be suppressed by lowering the share voltage of a DC voltage converter with the output type battery connected in series with the DC voltage converter at the time of charge of a capacity type battery. Moreover, the lifetime of a capacity type battery can be extended by raising the charging voltage of a capacity type battery, maintaining the rated voltage of an electrical load.

  If it is determined that the charge state of the output type battery is not normal, connect the capacity type battery (eg, lead battery), generator, and electrical load to prevent overcharge and overdischarge of the output type battery. be able to.

It is the block diagram which showed the outline of the micro HEV carrying the electrical storage system with which this invention is applied. It is the block diagram which showed the outline of XEMS carrying the electrical storage system with which this invention is applied. 1 is a configuration diagram illustrating an outline of a power storage system according to a first embodiment of the present invention. It is a block diagram which shows the structure of the DC voltage converter circuit used in the 1st Embodiment of this invention. It is a block diagram explaining the principle of the voltage controller used for the DC voltage converter shown in FIG. It is a block diagram which shows the structure of the voltage controller used for the direct-current voltage converter shown in FIG. It is a block diagram which shows another structure of the voltage controller used for the DC voltage converter shown in FIG. It is the block diagram which showed the outline of the electrical storage system which becomes the 2nd Embodiment of this invention. It is the block diagram which showed the outline of the electrical storage system which becomes the 3rd Embodiment of this invention. FIG. 10 is a configuration diagram illustrating an outline of a power storage system that further embodies the power storage system illustrated in FIG. 9. It is a flowchart figure which shows the specific process flow of the switch switching control part shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is included in the range.

  Before describing the embodiment of the present invention, the configuration of the micro HEV and the XEMS will be briefly described. FIG. 1 shows the configuration of the micro HEV, and FIG. 2 shows the configuration of the XEMS.

  In FIG. 1, a micro HEV 11 equipped with a power storage system 14 includes an engine 12, a generator 13 (for example, an alternator) mechanically connected to the engine 12, a power storage system 14, a light, an electric air conditioner, a starter, and the like. An electric load 15 is included.

  Here, the electric power of the electric load 15 of the micro HEV 11 is supplied from the power storage system 15 when idling is stopped. Then, when the vehicle is decelerated, the generator 13 is rotated and operated by the rotational force (deceleration energy) from the tire generated by the coasting of the vehicle, and the electric energy generated by the generator 13 is supplied to the electric load 15 as electric power, The secondary battery provided in the power storage system 14 is configured to be charged. Here, the voltage of the generator 13 is the rated voltage (for example, 14 V) of the electric load 15.

  In FIG. 2, an XEMS 21 equipped with a power storage system 14 includes an external distribution line 22, a distribution facility 23, an AC / DC converter 24, a generator (for example, a fuel cell) 25, a converter 26, a DC distribution line 27 in XEMS, a solar cell 28, a solar cell DC / DC converter 29, a power storage system 14, an electric load (such as a light, an electric motor, etc.) 15 for homes, buildings, and the like.

  Here, the DC distribution line 27 in the XEMS has a rated voltage of 48 V to 400 V and is maintained at a specified voltage. Further, the generator 25 is configured to be periodically stopped for maintenance. The solar cell 28 also does not generate power at night, and the power output is not constant on a cloudy day. In the case of a power failure, the power supply is also stopped. Thus, the power supplied to XEMS is not constant, and the generated power is not constant. Furthermore, the electric load 15 is not constant depending on the on / off state of the indoor light and the load of the air conditioner. In this case, electric power is supplied by the power storage system 14 so as to keep the voltage of the DC power distribution in the XEMS constant. Here, since the instantaneous peak and instantaneous power failure of XEMS do not last for a long time, the time required for the power of the power storage system 14 is generally not long. That is, the power supply time to XEMS is short.

  In the energy management system as described above, an embodiment of the present invention will be described next. In the embodiment described below, a case where the present invention is applied to the power storage system 14 constituting the power source of the micro HEV 11 is shown. The embodiment described below can also be applied to the XEMS power storage system 14 shown in FIG.

  A first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 3 shows the overall configuration of the power storage system 14 in the present embodiment. In the following embodiments, a lead battery is desirably used as the capacity type battery, and a lithium ion capacitor in which a lithium ion battery and an electric double layer capacitor are combined is used as a representative of the output type battery.

  However, as described above, the capacity type battery is not limited to the lead battery, and may have the same characteristics as the lead battery. For example, a nickel metal hydride battery or a nickel zinc battery can be used. The output type battery is not limited to a lithium ion capacitor, and other batteries or power storage elements can be used. For example, an electric double layer capacitor, a lithium ion battery, or the like can be used as the output type battery.

  In FIG. 3, the power storage system 14 includes a lead battery 31, a DC voltage converter 32, an output type battery 33, a lead battery side voltage detection line 34, a power storage system side output voltage detection line 35, and a voltage controller 36 for the DC voltage converter 32. The DC voltage converter 32 is connected in series between the output type battery 33 and the lead battery 31. The output battery 33 is connected to an electric load 15 of auxiliary equipment such as a headlight and an electric air conditioner, and a generator 13 such as an alternator.

  Therefore, the output type battery 33 is discharged so as to supply electric power to the electric load 15 in a certain state, and is charged with electric energy generated by the generator 13 when the automobile is decelerated. Note that the output type battery 33 uses a battery or a storage element that can flow more current than the lead battery 31. That is, the current that can be passed through the battery of the output battery 33 (hereinafter referred to as the first specified current) has a larger value than the current that can be passed through the battery of the lead battery 31 (hereinafter referred to as the second specified current). ing. For example, the maximum current value is selected as the specified current. An appropriate value may be selected depending on the design of the system. Further, the lead battery 31 discharges current to the output type battery 33 via the DC voltage converter 32, and conversely, it is charged with the current from the output type battery 33.

  Here, in the case of the micro HEV, the capacity (Ah) of the output type battery 33 is sufficient to ensure at least the capacity of “idling stop time × average load current”. Of course, it goes without saying that an output type battery 33 capable of securing a capacity larger than this may be used. Furthermore, in the case of XEMS, the capacity (Ah) of the output type battery should be at least “(instant peak power−contract power) × duration” or “instantaneous power interruption time × load power”. It ’s good. The lead battery 31 and the output type battery 33 may be connected to commercially available single cells in series and parallel. However, since the electric load 15 is supplied with power from the output type battery 33, the number of output type batteries 33 in series is not limited. It is necessary to set so that the voltage is equal to or lower than the rated voltage of the electric load 15.

  Here, the rated voltage of the electric load 15 is about 14 V when an alternator is used as the electric load. In general, the rated voltage when the lead battery 31 is used as a battery that generates a large amount of gas is about 16V.

  Next, the charging / discharging voltage and current behavior of the power storage system 14 according to the present embodiment will be described separately when the micro HEV is charged and discharged.

  First, the behavior of current and voltage during charging will be described. At the time of charging, the electric power of the generator 13 is generated by the deceleration energy (regeneration) of the automobile (micro HEV), but this generated voltage is maintained at the rated voltage (for example, 14V) of the electric load, and the power storage system 14 itself The charging voltage is also the rated voltage (for example, 14V). In recent years, there has been a tendency for the generator 13 of an automobile to increase in size (4 kW or more) in response to a request for improvement in electric power and fuel consumption, and for example, the charging current flowing through the power storage system 14 increases to about 300A. There is a request.

  The charging current flowing from the generator 13 into the power storage system 14 is charged in the output type battery 33. At this time, the voltage of the DC voltage converter 32 drops by the voltage of the output type battery 33. For example, when two lithium ion capacitors (nominal voltage 3V) are used in series as the output battery 33, the combined nominal voltage is about 6V. Therefore, when two lithium ion capacitors are connected in series as the output type battery 33, the input voltage of the DC voltage converter 32 is about 14V-6V = 8V, and the input current is about 300A. Note that the DC voltage converter 32 has a format capable of stepping up and down the voltage bidirectionally.

  The output voltage of the DC voltage converter 32 is boosted so that the voltage of the lead battery 31 is not less than the voltage of the power storage system 14 and not more than the maximum rating of the lead battery 31 (for example, about 15V). . For this purpose, based on the voltage of the lead battery 31 detected by the lead battery voltage detection line 34, the voltage controller 36 provided in the DC voltage converter 32 controls the voltage of 8V input to the DC voltage converter 32. To do. The details of the voltage controller 36 of the DC voltage converter 32 will be described later.

  By the action of the DC voltage converter 32, the charging voltage of the lead battery 31 is about 15V, and the charging current is about 155A because the efficiency of the DC voltage converter 32 is approximately 1. In the lead battery 31, the amount of gas such as oxygen and hydrogen generated in the electrolyte of the lead battery 31 during charging increases, and the electrolyte of the lead battery 31 is agitated by this large amount of gas to generate a concentration of sulfuric acid. Is made uniform. Thus, the battery life is improved by suppressing the stratification phenomenon which has occurred in the conventional lead battery. The lead battery in this case is a so-called liquid lead battery. Even in the case of a control valve type lead battery, the sulfation recovery action (rejuvenation) works due to an increase in the charging current, thus extending the life.

  Next, the current and voltage behavior during discharge will be described. At the time of discharging, the voltage of the lead battery 31 is a voltage of “open circuit voltage (about 12.8V) −internal resistance of the lead battery 31 × discharge current”, which is about 9V to 12V. Then, this voltage is input to the DC voltage converter 32, and the voltage is lowered to about 6 V by the step-down control of the DC voltage converter 32 during discharging. Since the output type battery 33 is connected to the DC voltage converter 32 in series, 6V stepped down by the DC voltage converter 32 and the above-mentioned combined nominal voltage 6V of the output type battery 33 are added, and 6V + 6V = 12V. These numerical values are only a guide.

  Here, the voltage controller 36 of the DC voltage converter 32 detects the output voltage of the power storage system 14 with the output voltage detection line 35 of the power storage system 14 so that the output voltage from the power storage system 14 becomes 12V. By controlling the output of the DC voltage converter 32, feedback control is performed so that the output voltage of the power storage system 14 becomes 12V. Accordingly, the power storage system 14 can have a function as a stable power source. Therefore, for example, at the time of restart after idling stop, there is little fluctuation or decrease in the voltage supplied to the starter motor.

  Further, the current at the time of discharge will be described. When the engine is restarted by the starter motor, it is necessary to continuously supply a current of 300 A for about 1 second. In the present embodiment, since the DC voltage converter 32 controls the voltage of the lead battery 31 to be stepped down, the discharge current of the lead battery 31 is reduced to about 150 A, which is about half, and the lead battery 31 having a large internal resistance is used. However, the voltage drop is not so large, and the frequency of troubles such as the engine not starting can be reduced.

  Next, the circuit configuration of the DC voltage converter 32 will be described with reference to FIG. The DC voltage converter 32 is a bidirectional type that can perform a step-up operation and a step-down operation. The output type battery 33 is connected to the output type battery side terminal 41 of the DC voltage converter 32, and the lead voltage side of the DC voltage converter 32. A lead battery 31 is connected to the terminal 42.

  The DC voltage converter 32 is used in a step-down manner so that the voltage of the output type battery side terminal 41 is equal to or lower than the voltage of the lead battery side terminal 42, and the voltage of the lead battery side terminal 42 is It is used in a step-up type so that the power generation voltage (for example, 14V) or higher.

  The DC voltage converter 32 includes smoothing capacitors 43 and 44, switching elements (for example, power MOS-FET, IGBT, thyristor, etc.) 45 and 46, a boosting diode 47, a step-down diode 48, a choke coil 49, The voltage controller 36 is configured. A lead battery side voltage detection line 34 for detecting the voltage of the lead battery 31 and a power storage system side output voltage detection line 35 for detecting the output voltage of the power storage system 14 are connected to the voltage controller 36 from the lead battery side terminal 42. Yes. The voltage controller 36 generates a control signal for turning on and off the switching elements 45 and 46 based on the voltage of the lead battery 31 and the output voltage of the power storage system 14 obtained from the respective detection lines 34 and 35. That is, the voltage controller 36 performs feedback control so that the voltage of the lead battery 31 and the voltage of the power storage system 14 are respectively predetermined voltages.

  For example, during charging in which a current flows from the output type battery side terminal 41 to the lead battery side terminal 42, the DC voltage converter 32 is used in a step-up type, the switching element 45 is always off, and the switching element 46 is a lead battery. Control is performed so that the side terminal 42 is repeatedly turned on and off so as to have a predetermined voltage (for example, 15 V). As a method for turning on / off the switching element 46, the ratio of the on / off of the switching element 46 (so-called duty ratio) is controlled according to the value of the difference between the target voltage and the voltage of the lead battery side terminal 42. By doing so, feedback control of the voltage of the lead battery side terminal 42 to the target voltage can be performed. Here, instead of the on / off ratio of the switching element 46, the on / off frequency may be controlled.

  On the other hand, during discharging in which current flows from the lead battery side terminal 42 to the output battery side terminal 41, the DC voltage converter 32 is used in a step-down type, the switching element 46 is always turned off, and the switching element 45 is turned off. The output voltage is controlled to be turned on and off repeatedly so that the output voltage becomes constant. As the on / off method, the on / off ratio of the switching element 45 (so-called duty ratio) is determined according to the value of the difference between the target output voltage and the output voltage of the power storage system 14 in the same manner as described above. ), Feedback control of the voltage of the lead battery side terminal 42 to the target voltage can be performed. Here, similarly, the on / off frequency may be controlled instead of the on / off ratio of the switching element 45.

  Here, in order to switch between discharging and charging, since the voltage of the generator 13 is controlled to 14 V, for example, at the time of charging, the voltage from the power storage system side output voltage detection line 35 that detects the output voltage of the power storage system 14 is 14 V. It can be determined by whether or not Therefore, if it is determined that the voltage from the power storage system side output voltage detection line 35 has reached 14 V, it is determined that the battery is in the charged state, and the DC voltage converter 32 is used as a boost type. Therefore, the DC voltage converter 32 is used as a step-down type.

  In addition to this, it is also possible to switch between discharging and charging by receiving a signal representing the operating state of the generator 13 through a communication line. In this case, a microcomputer is mounted on the DC voltage converter 32, the operation state of the generator 13 is determined by the microcomputer, and when the generator 13 is operated, it is determined that the battery is charged. For example, the operating state of the generator 13 can be determined by A / D converting the voltage of the generator 13 and comparing it with a predetermined voltage (for example, 14 V) stored in the memory of the microcomputer. Furthermore, the same operation as described above can also be performed by controlling the switching elements 45 and 46 to be switched simultaneously without performing charge / discharge determination. That is, the switching element 46 is turned off when the switching element 45 is on, and the switching element 46 is turned on when the switching element 45 is off.

  Instead of the DC voltage converter 32 as shown in FIG. 4, a DC voltage converter called a four-quadrant DC voltage converter may be used. In short, it functions as a step-up type when charging the lead battery 31 from the output type battery 33, and functions as a step-down type when discharging from the lead battery 31 to the output type battery 33.

In the embodiment shown in FIG. 4, the switching element 45 is always turned off during charging in which a current flows from the output type battery side terminal 41 to the lead battery side terminal 42, and the output battery side terminal 42 is switched from the lead battery side terminal 42 to the output battery side terminal. The switching element 46 is always turned off at the time of discharging in which a current flows through 41.
In addition to this, both the switching elements 45 and 46 may be operated in the state of charge and discharge, so that the DC voltage converter 32 performs step-up and step-down operations. However, in the case where both switching elements 45 and 46 are operated in the state of charging and discharging, the efficiency of the DC voltage converter 32 is reduced when both of the switching elements 45 and 46 are turned on. is important.

  Next, the configuration and control of the voltage controller 36 of the DC voltage converter 32 will be described with reference to FIG. As a control method, an analog circuit or a microcomputer incorporating or externally attaching an A / D converter may be used. Here, the voltage controller 36 that performs PWM control using an analog circuit will be described.

  The voltage controller 36 shown in FIG. 5 controls the voltage by PWM (Pulse Wide Modulation) that changes the on / off ratio of the switching elements 45 and 46. The voltage controller 36 basically includes an amplifier circuit 503, a triangular wave generation circuit 504, and a comparator 505. The voltage controller 36 has a voltage terminal 501 as an input and an on / off signal 502 for the switching elements 45 and 46 as an output. The voltage of the output type battery side terminal 41 (output voltage of the power storage system 14) and the voltage of the lead battery side terminal 42 (voltage of the lead battery 31) are input to the voltage terminal 501.

  The amplifier circuit 503 has a function of amplifying the difference between the reference voltage Vref 506 and the output voltage of the power storage system 14 or the voltage of the lead battery 31 with the operational amplifier 507. The triangular wave generation circuit 504 has a function of comparing a voltage obtained by dividing the reference voltage Vcc 508 with a voltage integrated by the triangular wave generating capacitor 509 to generate a periodic triangular wave time series voltage signal. The reference voltage Vcc 508 may be the voltage of the lead battery 31 or may be a separately provided constant voltage source.

  When the periodic triangular wave voltage signal generated by the triangular wave generating circuit 504 is compared with the output voltage signal of the amplifier circuit 503 by the comparator 505, the output voltage signal of the amplifier circuit 503 becomes a voltage equal to or higher than the triangular wave voltage signal. On the other hand, the comparator 505 is turned on, and in the reverse case, the comparator 505 is turned off to generate an on-off signal for the switching elements 45 and 46.

  Since the period of the triangular wave voltage signal is constant, when the output voltage from the amplifier circuit 503 is lower than the voltage signal of the triangular wave, the comparison result by the comparator 505 has a longer on time / period. This long on-time / cycle controls the switching element 45 or the switching element 46 in the direction of increasing the voltage of the DC voltage converter 32. On the other hand, when the output voltage from the amplifier circuit 503 is higher than the triangular wave voltage signal, the comparison result by the comparator 505 has a shorter ON time / cycle. This short ON time / cycle controls the switching element 45 or the switching element 46 in the direction of decreasing the voltage of the DC voltage converter 32.

Therefore, when the switching element 46 is selected for charging, if the voltage of the lead battery 31 is lower than the target voltage, the ON time / cycle is lengthened to increase the degree of boosting, and the voltage of the lead battery 31 is higher than the target voltage. If it is high, shorten the ON time / cycle to reduce the degree of boosting.
When the switching element 45 is selected for discharging, when the output voltage on the power storage system 14 side is lower than the target voltage, the ON time / cycle is lengthened to reduce the step-down degree, and the output on the power storage system 14 side is reduced. If the voltage is higher than the target voltage, shorten the ON time / cycle to increase the degree of step-down. Of course, as described above, it is possible to perform the step-up operation or the step-down operation using both the switching elements 45 and 46.

  Next, the configuration and operation of such a voltage controller 36 applied to the bidirectional DC voltage converter 32 shown in FIG. 4 will be described with reference to FIG. In the following description, a case where a boosting operation or a step-down operation is performed using both switching elements 45 and 46 is shown.

  In FIG. 6, the voltage controller 36 of the DC voltage converter 32 includes a charge / discharge determination unit 601 that determines either a charge state or a discharge state, a detection line switching unit 602, and on / off of the step-down switching element 45 during discharge. Signal terminal 603, ON / OFF signal terminal 604 of step-up switching element 46 at the time of charging, switching element control circuit 605 comprising the circuit shown in FIG. 5, inverter 606 for inverting ON / OFF signal applied to step-down switching element 45, lead battery A side voltage input terminal 607, an output voltage input terminal 608 of the power storage system, and voltage buffers 609 and 610 are configured.

  The voltage of the lead battery 31 is input from the lead battery side voltage detection line 34 to the lead battery side voltage input terminal 607, and the power is stored from the power storage system side output voltage detection line 35 to the output voltage input terminal 608 of the power storage system. The output voltage of the system 14 is input.

  The inverter 606 of the step-down switching element 45 has a function for preventing both of the switching elements 45 and 46 from being turned on. In response to an on-off signal from the switching element control circuit 605, the switching element 45 In contrast to the on / off operation of 45, the switching element 46 always performs the opposite on / off operation.

  As described above, in the charge / discharge determination unit 601, a power generation control signal input to the generator 13 or a charge signal indicating that the battery 13 is in a charged state when the output voltage of the generator 13 becomes, for example, a voltage of 14V or higher. (Digital signal ON, in logic circuit, for example, 3.3V or 5V voltage) is output. The charge signal is input to the detection line switching unit 602, and if it is in the charged state, the voltage buffer 610 on the lead battery 31 side is selected, and if it is in the discharged state, the voltage buffer 609 on the power storage system 14 side is selected. The voltage of one of the voltage buffers 609 and 610 is input to the voltage terminal 501 shown in FIG. 5 as the input voltage of the switching element control circuit 605.

  The operation of the switching element control circuit 605 is as described with reference to FIG. 5, and the signal generated thereby is used as an on / off signal for the switching elements 45 and 46. That is, the output of the switching element control circuit 605 becomes an on / off signal of the on / off signal terminal 604 of the step-up switching element 46 during charging, and the logic is inverted by the inverter 606 to turn on the step-down switching element 45 during discharging. -It becomes an on-off signal of the off signal terminal 606. Thus, when the voltage from the power storage system side output voltage detection line 35 has reached 14V, it is determined that the battery is in the charged state, and the DC voltage converter 32 is used as a boost type. Thus, the DC voltage converter 32 is used as a step-down type.

  A modification of the voltage controller 36 is shown in FIG. The voltage controller 36 includes a charging switching element control circuit (voltage controller shown in FIG. 5) 71 during charging, a discharging switching element control circuit (voltage controller shown in FIG. 5) 72 during discharging, a switching element 45, It comprises a switching element driver 73 of a logic circuit that prevents the switching elements 46 from being turned on at the same time. The switching element driver unit 73 is configured as an XOR gate (exclusive OR).

  Therefore, when one of the signals of the charging switching element control circuit 71 and the discharging switching element control circuit 72 is input, the signal is output. Thus, the switching element control circuit 71 and the switching element control circuit 72 are output. The on / off signal 603 of the step-down switching element 45 is generated by XOR (exclusive OR) of the step-down switching element 45, and the on-off signal 604 of the step-up switching element 46 is generated by an inverted signal of the on-off signal 603 of the step-down switching element 45. You can make it.

  Further, the charging / discharging determination unit 601 shown in FIG. 6 is used to determine whether the charging state or the discharging state. Based on this determination, the charging switching element control circuit 71 and the discharging switching element control circuit 72 during discharging are used. Can also be switched. As a result, the on / off signal 603 of the step-down switching element 45 may be generated, and the on / off signal 604 of the step-up switching element 46 may be generated by the inverted signal of the on / off signal 603 of the step-down switching element 45.

  Moreover, the electric power of a DC voltage converter may be obtained from the lead battery 31, or a small battery may be installed separately.

  Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that the charging current is controlled when the lead battery 31 is charged. Although the voltage of the lead battery 31 is detected in the first embodiment, the current sensor 81 is characterized in that the current of the lead battery 31 is detected by the current sensor 81.

  The difference in control differs in that the charging voltage of the lead battery 31 is boosted to, for example, 15 V during charging in the first embodiment, whereas the charging current of the lead battery 31 during charging is constant in the second embodiment. Yes. However, it is important that the charging current is set to a value equal to or less than the second specified current that can flow through the lead battery 31. And the value of a charging current is input instead of the voltage 607 on the lead battery side in FIGS. The current sensor 81 can use a shunt resistor or a Hall element.

  In this embodiment, since the current is controlled, the voltage is not controlled. For this reason, in order to protect the lead battery by preventing an excessive voltage from being applied to the lead battery 31, when a voltage detection line for detecting the voltage of the lead battery 31 is added and the lead battery 31 reaches the rated voltage, It is also effective to perform voltage limiter control so that no more voltage is applied.

  Next, a third embodiment of the present invention will be described with reference to FIGS. The feature of the present embodiment is that the output type battery 33 is equal to or higher than a first predetermined charge amount, for example, when the output type battery 33 is fully charged, or when the output type battery 33 is equal to or lower than a second predetermined charge amount. An emergency measure is taken when the charge amount is substantially “0”. The range described above varies depending on the type of the output battery 33. In the case of a lithium ion battery, the charging rate is outside the range of 0% to 80%, for example. In the case of a lithium ion capacitor, the voltage is 2.2V, for example. In the case of an electric double layer capacitor outside the range of ˜3.8 V, the voltage is set outside the range of 0 V to 2 V, for example.

  The difference between the present embodiment and the first embodiment shown in FIG. 3 and the second embodiment shown in FIG. 8 is that the power source for supplying power from the power storage system 14 to the electric load 15 is either the output type battery 33 or the lead battery 31. The changeover switch 91 is added. Here, although the detection line 34 detects the voltage of the lead battery 31 in FIG. 9, the current may be detected as in the second embodiment shown in FIG. 8. FIG. 9 is a schematic diagram for emphasizing the provision of the changeover switch 91, and a specific configuration is shown in FIG.

  In FIG. 9, the changeover switch 91 is designated in advance when the power storage system 14 is turned off, or the charging rate of the output battery 33 (current charge amount / full charge amount × 100 (%)) or voltage is specified in advance. When it is outside the range, the connection state of the electric load 14 and the generator 13 is switched to the lead battery 31 side. Here, the changeover switch 91 shown in FIG. 9 indicates the position in the normal state, and is reversed to the opposite side in the case of an emergency. When the power storage system 14 itself is turned off, for example, in the micro HEV, it is necessary to supply weak power such as a security device used during parking for a long period of time, so the lead battery 31 having a large capacity is used. This is because it is effective.

  Further, the charging rate or voltage of the output type battery 33 is out of a predetermined range (in the case of a lithium ion battery, the charging rate is outside the range of 0% to 80%, for example, in the case of a lithium ion capacitor, the voltage is For example, in the case of an electric double layer capacitor outside the range of 2.2V to 3.8V, the voltage is outside the range of 0V to 2V, for example. For example, if discharging is continued when the charging rate or voltage is low, an overdischarged state may be caused, and sometimes the battery may cause irreparable deterioration. Further, if charging is continued when the charging rate or voltage is high, deterioration of the electrodes and the like is caused, and thus adverse effects on the battery are inevitable. Furthermore, in the case of a lithium ion battery, if it is overcharged, it may cause fire and smoke.

  Next, a specific configuration and operation of the third embodiment shown in the schematic diagram of FIG. 9 will be described with reference to FIG. The following description is an example in which a lithium ion battery is used as the output type battery 33, the charge rate is measured, and the changeover switch 91 is switched.

  10, in the embodiment shown in FIG. 3 or FIG. 8, the charge rate estimation unit 101 that estimates the charge rate of the output type battery 33, the switching control unit 102 that controls the changeover switch 91, and the voltage detection between the output type battery 33. It is characterized in that the lines 103 and 104 and the current detection line 105 between the changeover switch 91 and the output type battery 33 are added.

  Here, the switching control unit 102 is activated at the time of factory shipment or battery replacement, and can continue processing until battery replacement or system disposal. Further, the charging rate estimation unit 101 and the switching control unit 102 may be implemented as a program in one microcomputer, or when the microcomputer is used for the voltage controller 36 in the DC voltage converter 32. May also be used as the microcomputer. When using a microcomputer, the power source of the microcomputer may be obtained from the lead battery 31. Furthermore, the changeover switch 91 can use a power MOS-FET, IGBT, or the like.

  Hereinafter, the operation of the charging rate estimation unit 101 and the switching control of the selector switch 91 will be described.

  The charging rate estimation unit 101 reads the voltages and currents of the detection lines 103 and 104 for detecting the voltage of the output type battery 33 and the current detection line 105, calculates the charging rate of the output type battery 33, and calculates the calculated charging rate. Is sent to the switching control unit 102. Here, although there are various methods for calculating the charging rate of the output type battery 33, the charging rate may be estimated using a method suitable for the power storage system 14.

  For example, in this embodiment, the charging rate is estimated by the following method. That is, a resistance value is obtained by referring to a resistance table mapped in advance, and the calculation of “current × resistance + voltage difference (voltage difference between voltage detection line 103 and voltage detection line 104)” is performed using this resistance value. The battery voltage is estimated by the formula. Next, a charging rate (hereinafter, voltage estimated charging rate) is estimated from a battery voltage and charging rate table mapped in advance from the battery voltage.

  In addition, the charging rate estimated by the voltage difference when the power storage system 14 is at rest (voltage difference between the voltage detection line 103 and the voltage detection line 104) is set as an initial value, and the current detection line 105 is set to this initial value. You may use the charging rate (henceforth a current estimation charging rate) which added the value which divided the integral value of the measured electric current by battery capacity. Furthermore, a weighted average of the voltage estimated charging rate and the current estimated charging rate may be output as the charging rate. Further, since the charging rate also varies depending on the temperature, a temperature sensor may be attached to the output type battery 33 to correct the temperature of the resistance table. As the temperature sensor, a thermocouple or a thermistor can be used.

  Next, the operation of the switching control unit 102 of the changeover switch 91 will be described using the control flowchart shown in FIG.

<< Step S111 >>
In step S111, the charging rate of the output type battery 33 estimated by the charging rate estimation unit 102 is read. This charging rate is estimated using an appropriate estimation method as described above. Here, when the estimated charging rate is obtained, the process proceeds to the next step.

<< Step S112 >>
Next, in step S112, it is determined whether or not the estimated charging rate of the output type battery 23 is within the range between the preset upper limit value and lower limit value of the charging rate. That is, this step S112 determines whether or not the charging state of the output type battery 33 is normal. If the estimated charging rate is within the range between the preset upper limit value and lower limit value in step S112, the process proceeds to step S113. Otherwise, the process proceeds to step S114. Here, the range of the upper limit value and the lower limit value of the charging rate is, for example, 0% to 80% in the case of a lithium ion battery.

<< Step S113 >>
In step 113, the operating state of the power storage system 14 is determined. For example, in the micro HEV, it is determined whether an ignition signal is input, and in the XEMS, it is determined whether the signal is not in a maintenance state, that is, whether the signal is in operation. These determination signals are not limited to these, and other signals may be used as long as the operation state of the power storage system 14 can be determined. If power storage system 14 is in the operating state, the process proceeds to step S115, and if not, the process proceeds to step S114.

<< Step S114 >>
In step S114, since it is determined in step S112 that the charging state of the output type battery 33 is not normal, a switching designation signal for switching the switching switch 91 to the lead battery 31 side is sent, and the lead battery 31 and the generator 13. Connect the electrical load 15. Thereby, overcharging and overdischarging of the output type battery 33 can be prevented.

  In addition, even if the charging state of the output battery 33 is normal in step S112, if the power storage system 14 is suspended, the micro HEV supplies weak power such as a security device used during parking for a long period of time. Therefore, the lead battery 31, the generator 13, and the electric load 15 are connected. As a result, weak power such as a security device used during parking can be supplied over a long period of time.

<< Step S115 >>
In step S115, since the state of charge of the output type battery 33 is normal in step S112 and the power storage system 14 is determined to be operating in step S113, the changeover switch 91 is designated to be switched to the output type battery 33 side. The output type battery 33, the generator 13, and the electric load 15 are connected.

  As described above, in the present embodiment, the changeover switch 91 is connected to the lead battery 31 when the power storage system 14 itself is turned off or when the charging rate of the output type battery 23 is outside the range specified in advance. The connection state of the electrical load 14 and the generator 13 is switched to the side. For this reason, when it is determined that the charging state of the output type battery 33 is not normal, the lead battery 31, the generator 13, and the electric load 15 are connected to prevent overcharging and overdischarging of the output type battery 33. Will be able to. In addition, when the power storage system 14 is suspended, the micro HEV needs to supply weak power such as a security device used during parking for a long period of time, so the lead battery 31, the generator 13, By connecting the load 15, weak power such as a security device used during parking can be supplied over a long period of time.

  In this embodiment, a charging rate estimation unit that estimates the charging rate of a lithium ion battery is used. However, when estimating the voltage of a lithium ion capacitor or an electric double layer capacitor, a voltage estimation unit may be provided. Therefore, in the above description, “charging rate” may be read as “voltage”.

  As described above, according to the present invention, an output type battery that discharges a current to an electric load and is charged by a current from a generator, and a current that is discharged from the output type battery to the output type battery. The first specified current that can be supplied to the output type battery is set to a current value larger than the second specified current that can be supplied to the capacity type battery, and further boosts the capacity type battery. And it connected in series with the output type battery via the DC voltage converter which can step down.

  As a result, when the capacity type battery is charged, the power of the DC voltage converter can be suppressed by lowering the shared voltage of the DC voltage converter by the output type battery connected in series with the DC voltage converter. The calculation was able to reduce to 70%.

  Moreover, the lifetime of a capacity type battery can be extended by raising the charging voltage of a capacity type battery, maintaining the rated voltage of an electrical load. For example, when the charge voltage of a lead battery is increased to 14.4 V with a micro HEV, the life of the lead battery is 1.8 times longer.

  DESCRIPTION OF SYMBOLS 11 ... Micro HEV, 12 ... Engine, 13 ... Generator, 14 ... Power storage system, 15 ... Electric load, 21 ... XEMS, 31 ... Lead battery, 32 ... DC voltage converter, 33 ... Output type battery, 34 ... Lead battery Voltage detection line on the side, 35 ... Output voltage detection line on the power storage system side, 36 ... Voltage controller of the DC voltage converter, 41 ... DC voltage converter terminal on the output type battery side, 42 ... DC voltage conversion on the lead battery side Terminal 43, smoothing capacitor 1, 44 ... smoothing capacitor 2, 45 ... step-down switching element, 46 ... step-up switching element, 47 ... step-up diode, 48 ... step-down diode, 49 ... choke coil, 501 ... Voltage detection terminal, 502 ... On-off signal, 503 ... Amplifier circuit, 504 ... Triangular wave generation circuit, 505 ... Comparator, 506 ... Reference voltage, 507 ... Differential amplifier, 508 ... V CC, 509... Triangular wave generating capacitor, 601. Charge / discharge determination unit, 602... Switching switch, 603. Step-down switching element signal terminal, 604. Step-up switching element signal terminal, 605 ... switching element control circuit, 606 ... inverter, 607. Lead battery voltage input terminal, 608... Power storage system output voltage input terminal, 609... Voltage buffer, 610.

Claims (14)

In a power storage system comprising a secondary battery charged with electric power generated by a generator while supplying electric power to an electric load,
An output-type battery that discharges current to the electric load and is charged by a current from a generator; and a DC voltage converter capable of step-up and step-down provided with an output-type battery side terminal connected to the output-type battery; And a capacity type battery connected to a capacity type battery side terminal provided in the DC voltage converter, and a second specification that allows a first specified current that can flow to the output type battery to flow to the capacity type battery. The output type battery and the capacity type battery are connected in series via the DC voltage converter, and the DC voltage converter is connected to the voltage of the output type battery side terminal . And the DC voltage converter performs a discharging operation to step down the voltage of the capacitive battery and discharge it to the output battery side terminal. Characteristic power storage system Beam. The power storage system according to claim 1,
The power storage system according to claim 1, wherein the first specified current that can flow through the output type battery and the second specified current that can flow through the capacity type battery are charging currents. The power storage system according to claim 1,
The capacity type battery is a lead battery, and when the lead battery is charged, the charge voltage of the lead battery is greater than the power generation voltage of the generator and less than the rated charge voltage of the lead battery by the DC voltage converter. A power storage system characterized by adjusting to the above. The power storage system according to claim 1,
The capacity type battery is a lead battery, and when the lead battery is charged, the voltage is adjusted by the DC voltage converter so that the charge current of the lead battery is equal to or lower than a predetermined charge current. Power storage system. The power storage system according to claim 1,
The capacitive battery is a lead battery, and when the voltage of the lead battery at the time of charging reaches a rated voltage, the charging voltage is limited by the DC voltage converter so that the charging voltage becomes the rated voltage. A featured power storage system. The power storage system according to claim 1,
When discharging from the output type battery to the electric load, the combined discharge voltage of the output type battery and the DC voltage converter is adjusted by the DC voltage converter so as to become a rated voltage of the electric load. A power storage system characterized by that. The power storage system according to any one of claims 1 to 6,
The output type battery is a lithium ion battery or a lithium ion capacitor. In a power storage system comprising a secondary battery charged with electric power generated by a generator while supplying electric power to an electric load,
An output-type battery that discharges current to the electric load and is charged by a current from a generator; and a DC voltage converter capable of step-up and step-down provided with an output-type battery side terminal connected to the output-type battery; And a capacity type battery connected to a capacity type battery side terminal provided in the DC voltage converter, and a second specification that allows a first specified current that can flow to the output type battery to flow to the capacity type battery. The output type battery and the capacity type battery are connected in series via the DC voltage converter, and the DC voltage converter is connected to the voltage of the output type battery side terminal . The DC voltage converter performs a discharging operation to step down the voltage of the capacity type battery and discharge it to the output type battery side terminal . The output type battery When the voltage is equal to or higher than a predetermined charge rate of 1, or equal to or higher than a first predetermined voltage, equal to or lower than a second predetermined charge rate, or equal to or lower than a second predetermined voltage, the capacity is not the output type battery. A power storage system, wherein a current is discharged to the electric load by a battery. The power storage system according to claim 8, wherein
The power storage system according to claim 1, wherein the first specified current that can flow through the output type battery and the second specified current that can flow through the capacity type battery are charging currents. The power storage system according to claim 8, wherein
The capacity type battery is a lead battery, and the output type battery and the lead battery are connected to the electric load via a changeover switch, and are switched to either the output type battery or the lead battery by the changeover switch. A power storage system that discharges to the electrical load. The power storage system according to claim 8, wherein
The capacity type battery is a lead battery, and the output type battery and the lead battery are connected to the electric load via a changeover switch, and a charge rate estimating unit for estimating a charge rate of the output type battery, or the output A voltage estimation unit for estimating the voltage of the battery, and when the charging rate or voltage of the output battery is not within a predetermined range, the changeover switch connects the lead battery and the electric load. A power storage system characterized by this. The power storage system according to claim 11, wherein
The output type battery is a lithium ion battery, a lithium ion capacitor, or an electric double layer capacitor. In the lithium ion battery, the predetermined range of the charging rate is set to 0% to 80%. The power storage system is characterized in that the predetermined range is set to 2.2V to 3.8, and in the electric double layer capacitor, the predetermined range of voltage is set to 0V to 2V. In the electrical storage system of Claim 10 or Claim 11,
When the electric load or the generator is not operated, the changeover switch connects the lead battery and the electric load. The power storage system according to claim 13,
The electrical load or the generator is used for a micro HEV, and when the micro HEV is not operated, the changeover switch connects the lead battery and the electrical load. .

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