Summary of the invention
Main purpose of the present invention is to provide a kind of fuel cell power supply and electric power system, is easily subject to the problem of load effect to solve the generating efficiency of fuel cell in prior art.
To achieve these goals, according to an aspect of the present invention, provide a kind of fuel cell power supply, having comprised: fuel cell; Inverter; The first converter unit, input is connected with fuel cell, and output is connected with the input of inverter; The second converter unit, the first delivery of electrical energy end is connected to first node, and wherein, first node is the node between fuel cell and the first converter unit; Discharge and recharge energy-storage units, be connected with the second delivery of electrical energy end of the second converter unit; The first output, is arranged on Section Point, and for connecting DC load, wherein, Section Point is the second converter unit and discharges and recharges the node between energy-storage units; The second output, is arranged on the output of inverter, for connecting AC load; And control unit, be connected with the control end of the second converter unit, for according to the variation of AC load or DC load demand power, control changing direction of the second converter unit.
Further, control unit is also for controlling the power conversion amplitude of the second converter unit according to the variation of DC load demand power, control unit comprises: power monitoring module, for AC load, DC load and the power that discharges and recharges energy-storage units are carried out to Real-time Obtaining, and the power sum arriving according to Real-time Obtaining is controlled the power output of fuel cell; And control module, be all connected with the control end of the second converter unit with power monitoring module, for the variation of fuel cell power output, control the power conversion amplitude of the second converter unit and change direction.
Further, control module comprises: first controls submodule, is connected with the control end of the second converter unit, for the variation of fuel cell output current, controls the power conversion amplitude of the second converter unit and changes direction; And second control submodule, be connected with the control end of the second converter unit, for the variation of fuel cell output voltage, control the power conversion amplitude of the second converter unit and change direction.
Further, fuel cell power supply also comprises: switch unit, wherein, the first control submodule and second is controlled submodule and all by switch unit, is connected with the control end of the second converter unit, switch unit is used for choosing the first control module to the power conversion amplitude of the second converter unit and changes direction and control, or chooses the second control submodule to the power conversion amplitude of the second converter unit and change direction and control.
Further, first controls submodule comprises the first error amplifier, the positive input of the first error amplifier receives the default output current of fuel cell, the reverse input end of the first error amplifier receives the actual output current of fuel cell, second controls submodule comprises the second error amplifier, the positive input of the second error amplifier receives the output voltage of fuel cell, and the reverse input end of the second error amplifier receives default output voltage.
Further, power monitoring module comprises: calculating sub module, default output current and the default output voltage of the power sum computing fuel battery getting for basis, wherein, the positive input of the first error amplifier is for receiving the current output signal from calculating sub module, and the negative input of the second error amplifier is for receiving the Voltage-output signal from calculating sub module.
Further, fuel cell power supply also comprises: filter unit, is connected with the input of inverter.
To achieve these goals, according to a further aspect in the invention, provide a kind of electric power system, comprised any fuel cell power supply that foregoing of the present invention provides.
By the present invention, adopt the fuel cell power supply that comprises following structure: fuel cell; Inverter; The first converter unit, input is connected with fuel cell, and output is connected with the input of inverter; The second converter unit, the first delivery of electrical energy end is connected to first node, and wherein, first node is the node between fuel cell and the first converter unit; Discharge and recharge energy-storage units, be connected with the second delivery of electrical energy end of the second converter unit; The first output, is arranged on Section Point, and for connecting DC load, wherein, Section Point is the second converter unit and discharges and recharges the node between energy-storage units; The second output, is arranged on the output of inverter, for connecting AC load; And control unit, be connected with the control end of the second converter unit, for according to the variation of DC load or AC load demand power, control changing direction of the second converter unit.By arranging and be connected to first node and discharge and recharge the second converter unit between energy-storage units in the electric supply installation of fuel cell, and control changing direction of the second converter unit according to the demand power of load, realized when the demand power of AC load is uprushed, can pass through the second converter unit to AC load makeup energy by discharging and recharging energy-storage units, when the demand power anticlimax of AC load, can by the second converter unit, will have more than needed stored energy in discharging and recharging energy-storage units by fuel cell, when the demand power of DC load is uprushed, by discharging and recharging energy-storage units directly to DC load makeup energy, when the demand power anticlimax of DC load, can by the second converter unit, will have more than needed stored energy in discharging and recharging energy-storage units by fuel cell, avoid fuel cell because transient response is poor, to occur the drawback that generated output is affected by bearing power easily, and then reached the generating efficiency that improves fuel.Solve the generating efficiency of fuel cell in prior art and be easily subject to the problem of load effect, and then reached generating efficiency and the useful life of improving fuel cell.
Embodiment
It should be noted that, in the situation that not conflicting, embodiment and the feature in embodiment in the application can combine mutually.Describe below with reference to the accompanying drawings and in conjunction with the embodiments the present invention in detail.
The embodiment of the present invention provides a kind of fuel cell power supply, below fuel cell power supply that the embodiment of the present invention is provided be specifically introduced:
Fig. 1 is according to the schematic diagram of the fuel cell power supply of the embodiment of the present invention, as shown in Figure 1, the fuel cell power supply of this embodiment comprises fuel cell 1, inverter 6, the first converter unit 1(, DC/DC2), the second converter unit 2(, DC/DC3), discharge and recharge energy-storage units 3, the first output O1, the second output O2 and control unit.
Particularly, the first converter unit 1 and the second converter unit 2 are direct current power converter unit, and the second converter unit 2 is bidirectional, dc power conversion unit, the input of direct current power converter unit DC/DC2 is connected with the output of fuel cell 1, and the output of direct current power converter unit DC/DC2 is connected with the input of inverter 6; A delivery of electrical energy end of bidirectional, dc power conversion cells D C/DC3 is connected with first node, another delivery of electrical energy end with discharge and recharge energy-storage units 3 and be connected, first node is the node between fuel cell 1 and direct current power converter unit DC/DC2; The first output O1 is arranged on Section Point, and Section Point is bidirectional, dc power conversion cells D C/DC3 and discharges and recharges the node between energy-storage units 3, for connecting DC load; The second output O2 is arranged on the output of inverter, for connecting AC load; Control unit is connected with the control end of bidirectional, dc power conversion cells D C/DC4, for according to the variation of DC load or AC load demand power, controls changing direction of bidirectional, dc power conversion cells D C/DC3.Wherein, the energy that a kind of power transfer direction of bidirectional, dc power conversion cells D C/DC3 is fuel cell is to DC load and discharge and recharge energy-storage module, and another kind of power transfer direction is that the energy of release energy-storage module is direct current power converter unit DC/DC2 power supply; Direct current power converter unit DC/DC2 is for by the output voltage of fuel cell or by the output voltage of fuel cell be converted to the front step voltage of inverter from the output voltage of bidirectional, dc power conversion cells D C/DC3, wherein, direct current power converter unit DC/DC2 includes but not limited to push-pull circuit, half-bridge circuit and full-bridge circuit constant power topology.
The embodiment of the present invention by arranging and be connected to first node and discharge and recharge the second converter unit between energy-storage units in the electric supply installation of fuel cell, and control changing direction of the second converter unit according to the demand power of load, realized when the demand power of AC load is uprushed, can pass through the second converter unit to AC load makeup energy by discharging and recharging energy-storage units, when the demand power anticlimax of AC load, can by the second converter unit, will have more than needed stored energy in discharging and recharging energy-storage units by fuel cell, when the demand power of DC load is uprushed, by discharging and recharging energy-storage units directly to DC load makeup energy, when the demand power anticlimax of DC load, can by the second converter unit, will have more than needed stored energy in discharging and recharging energy-storage units by fuel cell, avoid fuel cell because transient response is poor, to occur the drawback that generated output is affected by bearing power easily, and then reached the generating efficiency that improves fuel.Solve the generating efficiency of fuel cell in prior art and be easily subject to the problem of load effect, and then reached generating efficiency and the useful life of improving fuel cell.
Further, control unit is also controlled for bidirectional, dc power conversion unit being carried out to the power conversion amplitude of energy while transmitting, so-called power conversion amplitude that is to say that energy transmits size, particularly, control unit can comprise power monitoring module 7 and control module, wherein, power monitoring module 7 is for to being connected to the power P of the AC load of the second output O2
aC, be connected to the power P of the DC load of the first output O1
dCwith the power P that discharges and recharges energy-storage units 3
bATcarry out Real-time Obtaining, and the power sum arriving according to Real-time Obtaining is controlled the power output of fuel cell,, produce the power demand instruction corresponding with the power sum of obtaining, and finally produce electric energy according to power demand instruction supply fuel, wherein, the power output of power monitoring module controls fuel cell
≈ P
aC+ P
dC+ P
bAT, accurately, can control P
fC=P
aC+ P
dC+ P
bAT; Control module, for the variation of the power output of the fuel cell determined according to power monitoring module, is controlled changing direction and power conversion amplitude of bidirectional, dc power conversion cells D C/DC3, wherein, discharges and recharges the power P of energy-storage units
bATinclude but not limited to by monitoring discharge and recharge energy-storage units voltage, discharge and recharge energy-storage units state-of-charge (State Of Charge, be called for short SOC) and obtain.
Wherein, control module comprises the first control submodule and the second control submodule, and first controls submodule controls changing direction of bidirectional, dc power conversion unit and power conversion amplitude for the variation of fuel cell output current; Second controls submodule for control changing direction and power conversion amplitude of bidirectional, dc power conversion unit according to the variation of described fuel cell output voltage.The fuel cell power supply of the embodiment of the present invention also comprises switch unit 24, wherein, the first control submodule and second is controlled submodule and all by switch unit 24, is connected with the control end of bidirectional, dc power conversion cells D C/DC3, switch unit 24 for choose the first control submodule to bidirectional, dc power conversion cells D C/DC3 change direction and power conversion amplitude control, or choose the second control submodule to bidirectional, dc power conversion cells D C/DC3 change direction and power conversion amplitude control.
In the embodiment of the present invention, the first function of controlling submodule and the second control submodule can be passed through voltage-type operational amplifier, current mode trsanscondutance amplifier and digital PID control etc. realize, switch unit 24 can be realized selection switching by analog channel circuit, also can under digital PID be controlled, realize and select to switch, with each, control submodule below and all adopt error amplifier (voltage-type operational amplifier or current mode trsanscondutance amplifier), switch unit 24 adopts diode and the voltage source shown in Fig. 2, the mode that current-limiting resistance matches, further illustrate the fuel cell power supply of the embodiment of the present invention:
Particularly, first controls submodule can comprise the first error amplifier 21, the positive input of the first error amplifier 21 receives the default output current Iref of fuel cell, the reverse input end of the first error amplifier 21 receives the actual output current Ifc of fuel cell, the output of the first error amplifier 21 connects the negative electrode of diode 27, and 5V direct voltage source is connected to the anode of diode 27 through resistance R 1, light-coupled isolation chip U9; Second controls submodule can comprise the second error amplifier 23, the positive input of the second error amplifier 23 receives the output voltage V dc of fuel cell, the reverse input end of the second error amplifier 23 receives default output voltage V ref, the output of the second error amplifier 23 connects the negative electrode of diode 26, and 5V direct voltage source is connected to the anode of diode 26 through resistance R 1, light-coupled isolation chip U9; Light-coupled isolation chip U9, resistance R 1 and Rc, capacitor C c, voltage source V 5C and diode 26 and 27 form switch unit, output is connected to the control end of bidirectional, dc power conversion unit, input is the negative electrode of diode 26 and 27, error amplifier 21 shown in Fig. 2, resistance on 23 and electric capacity play the effect (that is, the pi regulator in closed-loop control) of closed loop compensation.Wherein, the actual output current Ifc of fuel cell can obtain by the current sample parts 20 that are arranged on fuel cell outlet line, the feedback signal of the given or fuel cell of the operating state that the default output current Iref of fuel cell and default output voltage V ref include but not limited to fuel cell given, in embodiments of the present invention, default output current Iref and the default output voltage V ref of the so-called operating state of fuel cell or the given fuel cell of feedback signal of fuel cell, refer to: the calculating sub module in power monitoring module 7 is according to power output
calculate default output current Iref and the default output voltage V ref of fuel cell, simply, in the situation that fuel cell has not started or do not put into operation, Ifc is 0, as long as Iref>0, the first error amplifier output high level, diode 26 cut-offs, the second error amplifier closed loop work, make DC/DC3 work in discharge condition, the voltage Vdc of first node equals Vref, approaches the access voltage of fuel cell, the current over pulse that can avoid fuel cell to cause due to voltage difference when putting into operation by setting Vref, after fuel cell puts into operation, according to power stage, set Iref, reduce Vref simultaneously, until Vref<Vdc, the second error amplifier output high level, diode 27 cut-offs, the first error amplifier closed loop work, now Vref can play the effect of the minimum discharge voltage restriction of fuel cell, the in the situation that of fuel cell generation voltage jump, and protection fuel cell.When controlling the power output of fuel cell
when large, the default output current calculating becomes large, otherwise, little.Wherein, fuel cell comprises that (Balance of Plant, is called for short BOP, is also subsidiary engine for fuel cell pack, fuel cell power generation control system, auxiliary equipment, may comprise electromagnetically operated valve, mass flowmenter, air pump etc.) unit etc., its power-generating control system can be according to the P of power monitoring module
fCinstruction, control the operation of fuel supply, BOP, the monitoring fuel cell pack that power-generating control system is simultaneously real-time is also mutual with power monitoring module information, the operating state of fuel cell pack is fed back to power monitoring module, and the calculating sub module in power monitoring module is according to feedback signal and power output
calculate default output current Iref and default output voltage V ref.
The operation principle of the fuel cell power supply of the above structure explanation embodiment of the present invention based on fuel cell power supply:
Bidirectional, dc power conversion cells D C/DC3 adopts Current Control or voltage control, abnormal at voltage on line side, but in the situation that fuel cell not yet starts, by voltage control loop, decide the power conversion amplitude of bidirectional, dc power conversion cells D C/DC3 and change direction, the energy that DC/DC3 obtains from discharge and recharge energy-storage units 3 is given by presetting the actual voltage Vdc that should export of output voltage V ref and fuel cell, , when voltage on line side is abnormal, the given default output voltage V ref in power monitoring unit, the voltage swing of first node of take is Vdc, the size of this Vdc should meet loading demand, but because fuel cell not yet puts into operation, error amplifier 23 closed loop work, diode 27 conductings, the in the situation that of diode 27 conducting, the control end of bidirectional, dc power conversion cells D C/DC3 receives control signal, under this control signal, bidirectional, dc power conversion cells D C/DC3 realizes the energy discharging and recharging in energy-storage units 3 is passed to direct current power converter unit DC/DC2, the size of transmission amplitude is by the electric capacity on error amplifier 23 and the closed loop compensation of resistance, the output of tracking error amplifier 23 reduces degree, with this, realize by Voltage loop control loop and control bidirectional, dc power conversion cells D C/DC3, after, fuel cell start-up abnormal at voltage on line side, fuel cell has electric current output, in such cases, by current controlled circuit, is decided the power conversion amplitude of bidirectional, dc power conversion cells D C/DC3 and is changed direction.
After fuel cell power supply starts to put into operation, a part of electric energy that fuel cell 1 produces is powered to AC load after by direct current power converter unit DC/DC2, inverter 6, and another part electric energy is given DC load and discharged and recharged energy-storage units 3 power supplies after by bidirectional, dc power conversion cells D C/DC3.AC load power P
aCwhile uprushing, need to get larger output current Ifc from fuel cell, power monitoring module will provide signal to fuel cell pack, makes it send more P
fC, now, in the situation that the power that fuel cell need to be exported becomes large, the default output current Iref of given fuel cell becomes large gradually, before fuel cell output power and actual output current are increased to corresponding desired value, the input current that direct current power converter unit DC/DC2 needs is greater than Iref, the output control signal step-down of the first error amplifier, diode 26 conductings, the in the situation that of diode 26 conducting, changing direction of bidirectional, dc power conversion cells D C/DC3 is satisfied: discharge and recharge energy-storage units 3 and discharge by bidirectional, dc power conversion cells D C/DC3, supplement AC load institute energy requirement, the size of the transmission amplitude of bidirectional, dc power conversion cells D C/DC3 is by the electric capacity on error amplifier 21 and the closed loop compensation of resistance, the output of tracking error amplifier 21 reduces degree, that is, lower in error amplifier 21 output control signals, illustrate that needs compensation is more,
AC load P
aCduring anticlimax, power monitoring module will provide signal to fuel cell pack, makes it send P still less
fC, need to get less output current Ifc from fuel cell, now, in the situation that the power that fuel cell need to be exported diminishes, the default output current Iref of given fuel cell diminishes gradually, before fuel cell output power and actual output current are reduced to corresponding desired value, the input current that direct current power converter unit DC/DC2 needs is less than Iref, the output control signal of the first error amplifier uprises, diode 26 cut-offs, the in the situation that of diode 26 cut-off, changing direction of bidirectional, dc power conversion cells D C/DC3 is satisfied: the energy more than needed that fuel cell sends is powered for discharging and recharging energy-storage units 3 by bidirectional, dc power conversion cells D C/DC3, simultaneously, the size of the transmission amplitude of bidirectional, dc power conversion cells D C/DC3 is by the electric capacity on error amplifier 21 and the closed loop compensation of resistance, the output rising degree of tracking error amplifier 21, , higher in error amplifier 21 output control signals, illustrate that needs storage is more.
DC load power P
dCwhile changing, the working condition of fuel cell stand-by power supply and control system thereof and AC load power P
aCsimilar while there is conversion.DC load P
dCwhile uprushing, energy-storage module supplements DC load institute energy requirement by electric discharge.DC load P
dCduring anticlimax, the energy more than needed that fuel cell sends will be that energy-storage module charges by bidirectional, dc power conversion cells D C/DC3.
From the description of above operation principle, can find out, at current value corresponding to the overall power requirement of system, become greatly (, it is large that the required power of load becomes), given predetermined current Iref not yet reaches in the situation of demand current, fuel cell power supply discharges by discharging and recharging energy-storage units, carrys out makeup energy; At current value corresponding to the overall power requirement of system, diminish (, the required power of load diminishes), given predetermined current Iref is not yet reduced in the situation of demand current, and the energy more than needed that fuel cell produces can be used for charging to discharging and recharging energy-storage units, realizes energy buffer memory.
Wherein, the interchange output in the embodiment of the present invention is not limited to alternating voltage grade, is not limited to single-phase output or three-phase output; Inverter is not limited to inversion topological circuit structure and inversion control mode and output waveform thereof; Discharging and recharging energy-storage units comprises and is not limited only to lead-acid battery, lithium ion battery, Ni-MH battery, nickel-cadmium cell, super capacitor etc., in the situation that the voltage on line side in the electric power system of employing fuel cell power supply is abnormal, discharges and recharges energy-storage units and release energy as DC load energy supply; After discharging and recharging energy-storage units and boosting by bidirectional, dc power conversion cells D C/DC3 and direct current power converter unit DC/DC2, by inverter unit, be AC load energy supply again; Discharge and recharge energy-storage units is cell of fuel cell energy supply simultaneously, prepares the startup of fuel cell.After fuel cell puts into operation, discharge and recharge energy-storage units and carry out charging energy-storing.
When fuel cell is normally worked, a part of electric energy of fuel cell output is powered to AC load after by direct current power converter unit DC/DC2, inverter unit, another part electric energy powers to DC load and energy-storage module after by bidirectional, dc power conversion cells D C/DC3, the working frequency ripple wave electric current causing because of the existence of AC load for direct current power converter unit DC/DC2, by the current tracking of bidirectional, dc power conversion cells D C/DC3, control and can well suppress, make fuel cell realize constant current and control.In embodiments of the present invention, the power topological structure of each direct current power converter unit includes but not limited to isolated form, non-isolation type switch change-over structure, keeps 1.2kW constant, AC load power P with DC load power
aCby the 800W 2.4kW that uprushes, it is example, in the accompanying drawing of the embodiment of the present invention, Fig. 3 a shows the waveform of the output current of fuel cell, Fig. 3 b shows the waveform of the input current of direct current power converter unit DC/DC2, Fig. 3 c shows the waveform of the input current of bidirectional, dc power conversion cells D C/DC3, just representing to flow into, negative indication flows out, in conjunction with Fig. 3 a to Fig. 3 c, the output current of visible fuel cell has been followed the tracks of the output current settings 40-80A of fuel cell well, without low frequency and working frequency ripple wave.
The fuel cell power supply of the embodiment of the present invention is by monitoring and obtain each power output and energy storage power, and by the power sum getting, control the power stage of fuel cell, realized according to the power demand of electric supply installation and controlled fuel cell raising energy, so that fuel cell steady operation, the life-span of improving fuel cell; And, in the fuel cell power supply that the embodiment of the present invention provides, the generated energy of fuel cell is undertaken being passed to inverter after one-level conversion by direct current power converter unit DC/DC2, realize the power conversion link that reduces fuel cell output energy, improved the power conversion efficiency of alternating current-direct current output.
In addition, the fuel cell power supply that the embodiment of the present invention provides also comprises filter unit, this filter unit can be for being connected to the energy storage capacitor 5 of the input of inverter, for energy storage filtering, provide inverter can the storage of energy, in embodiments of the present invention, energy storage capacitor 5 includes but not limited to electrochemical capacitor, thin-film capacitor and super capacitor etc.
The embodiment of the present invention also provides a kind of electric power system, this electric power system comprises any fuel cell power supply that embodiment of the present invention foregoing provides, Fig. 4 is according to the schematic diagram of the electric power system of the embodiment of the present invention, as shown in Figure 4, the electric power system of this embodiment also comprises mains ac power supply 10, Active Power Factor Correction (Active Power Factor Correction, be called for short APFC) unit 11, the 3rd converter unit 12(direct current power converter unit DC/DC1) and by-pass switch 13, the second output of the fuel cell power supply that embodiment of the present invention foregoing provides is exported by the interchange of by-pass switch 13 access electric power systems, the direct current output of the first output access electric power system, the operation principle of this electric power system is:
In the normal situation of net side civil power, when Active Power Factor Correction APFC unit, direct current power converter unit DC/DC1 are DC load energy supply, for discharging and recharging energy-storage units, charge or supply charging; AC load adopts the direct energy supply of civil power by alternating current bypass switch element; Also can, by civil power by Active Power Factor Correction APFC unit, then by inverter unit, be reverse into the mode energy supply that exchanges output.In the situation that voltage on line side is abnormal, Active Power Factor Correction APFC unit and direct current power converter unit DC/DC1 are out of service, discharge and recharge energy-storage units and release energy as DC load energy supply; After discharging and recharging energy-storage units and boosting by bi-directional power conversion cells D C/DC3 and direct current power converter unit DC/DC2, by inverter unit, be AC load energy supply again; Discharge and recharge energy-storage units is cell of fuel cell energy supply simultaneously, prepares the startup of fuel cell.After fuel cell puts into operation, operation principle is identical with the principle of the fuel cell power supply that embodiment of the present invention foregoing provides, and repeats no more herein.
From above description, can find out, the present invention is supplemented or stores the output energy of fuel cell by bidirectional, dc power conversion unit, realized when bearing power generation dynamic change, avoid the generated output of fuel cell to be subject to the impact of bearing power, and then reached raising generating efficiency.
Obviously, those skilled in the art should be understood that, above-mentioned each module of the present invention or each step can realize with general calculation element, they can concentrate on single calculation element, or be distributed on the network that a plurality of calculation elements form, alternatively, they can be realized with the executable program code of calculation element, thereby, they can be stored in storage device and be carried out by calculation element, or they are made into respectively to each integrated circuit modules, or a plurality of modules in them or step are made into single integrated circuit module to be realized.Like this, the present invention is not restricted to any specific hardware and software combination.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.