JP2008226595A - Fuel cell system and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell in which power generation amount can be decreased rapidly at a rapid load decreasing time when an output demand for the fuel cell is decreased rapidly, and which has a comparatively compact constitution. <P>SOLUTION: The fuel cell system 1 is equipped with a fuel cell 2 in which a reaction gas is supplied and power generation is carried out and the power resulting from the power generation is supplied to a prescribed load M3, an oxidizing gas supply device (air compressor 31 and motor M1) in which the oxidizing gas among the reaction gas is compressed and supplied to the fuel cell 2, and a control means 6 in which a control command is given to the oxidizing gas supply device to control its operation. The control means 6 gives the control command to the oxidizing gas supply device at the rapid load decreasing time when the decreasing rate of the output demand to the fuel cell 2 exceeds a prescribed threshold value to realize a regenerative operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell that generates power upon receiving a reaction gas, and a control method thereof.

  Currently, as a fuel cell mounted on a fuel cell vehicle or the like, a solid polymer electrolyte membrane made of a solid polymer ion exchange membrane or the like is sandwiched from both sides by an anode electrode and a cathode electrode made of a catalyst layer and the like, and the outside is paired with a pair of separators. A stack-like structure in which a plurality of unit cells sandwiched between each other is stacked is proposed. In a vehicle fuel cell system in which such a fuel cell is mounted on a vehicle such as an automobile, power generation is usually performed by supplying a fuel gas and an oxidizing gas to the anode electrode and the cathode electrode, respectively.

By the way, during the operation of the above-described vehicle fuel cell system, there is a case in which the output demand for the fuel cell rapidly decreases (for example, when the depression by the accelerator pedal is released). In recent years, a technique has been applied in which the amount of reaction gas supplied to the fuel cell is temporarily reduced when the load is suddenly reduced, thereby reducing the amount of power generation in the fuel cell system. For example, in a fuel cell system that supplies compressed air to a fuel cell, when the vehicle is suddenly decelerated, compressed air compressed by the compressor is discharged to the outside to prevent excess compressed air from being supplied to the fuel cell. The technique to do is proposed (refer patent document 1).
JP 2002-141088 A

  When the technique described in Patent Document 1 is adopted, compressed air compressed by the compressor is discharged to the outside when the vehicle is suddenly decelerated (when the load is suddenly reduced), and surplus compressed air is supplied to the fuel cell. This can be prevented and the amount of power generated by the fuel cell can be suppressed. However, there is a problem that a mechanism for discharging the compressed air compressed by the compressor to the outside is required, and the configuration becomes complicated.

  The present invention has been made in view of such circumstances, and can reduce the power generation amount of the fuel cell rapidly when the load suddenly decreases when the output demand for the fuel cell rapidly decreases, and has a relatively simple configuration. An object of the present invention is to provide a fuel cell system.

  In order to achieve the above object, a fuel cell system according to the present invention includes a fuel cell that receives a reaction gas to generate power and supplies electric power associated with the power generation to a predetermined load, and compresses an oxidizing gas in the reaction gas. In the fuel cell system comprising: an oxidizing gas supply device that supplies the fuel cell; and a control unit that provides a control command to the oxidizing gas supply device to control its operation. A control command is given to the oxidant gas supply device at the time of sudden decrease of the load exceeding a predetermined threshold value to realize the regenerative operation.

  Further, the control method of the fuel cell system according to the present invention includes a fuel cell that receives the supply of the reaction gas to generate power and supplies the electric power accompanying the power generation to a predetermined load, and compresses the oxidizing gas of the reaction gas to generate fuel. A method for controlling a fuel cell system, comprising: an oxidizing gas supply device that supplies a battery, and realizing a regenerative operation of the oxidizing gas supply device when the rate of decrease in output demand for the fuel cell exceeds a predetermined threshold Is included.

  According to such a configuration and method, when the load reduction rate of the output demand for the fuel cell exceeds a predetermined threshold, the regeneration operation of the oxidizing gas supply device can be realized and the driving of the oxidizing gas supply device can be suppressed. . Therefore, it is possible to rapidly reduce the power generation amount of the fuel cell by rapidly suppressing the supply of the oxidizing gas to the fuel cell without providing a mechanism for discharging the oxidizing gas to the outside when the load is suddenly reduced.

  In the fuel cell system, an oxidant gas supply device having an air compressor and a motor for driving the air compressor is employed, and control means for realizing a regenerative operation by giving a control command to the motor when the load suddenly decreases is employed. be able to.

  The fuel cell system further includes an oxidation offgas passage for circulating the oxidation offgas discharged from the fuel cell, and a back pressure valve provided in the oxidation offgas passage, and provides a control command to the back pressure valve when the load is suddenly reduced. It is possible to employ a control means for giving and reducing the opening of the back pressure valve.

  When such a configuration is adopted, the pressure loss of the oxidant off-gas flow path can be increased by reducing the degree of opening of the back pressure valve when the rate of decrease in the output demand for the fuel cell exceeds a predetermined threshold. Therefore, the amount of oxidizing gas introduced into the fuel cell can be rapidly reduced, and the power generation amount of the fuel cell can be further rapidly reduced.

  In the fuel cell system, a power storage device that stores the power generated in the fuel cell and / or the power generated by the regenerative operation of the oxidizing gas supply device, and excess power that cannot be stored in the power storage device when the load suddenly decreases is absorbed and absorbed. Power absorbing means.

  When such a configuration is adopted, when the load reduction rate of the output demand for the fuel cell exceeds a predetermined threshold, surplus power storage device cannot accumulate in the power generated in the fuel cell or the power generated by the regenerative operation of the oxidizing gas supply device Electric power can be absorbed by the power absorbing means. Therefore, the power storage device can be protected from overcharging.

  According to the present invention, it is possible to provide a fuel cell system that can rapidly reduce the amount of power generated by the fuel cell at the time of a sudden decrease in load when the output demand for the fuel cell decreases rapidly, and that has a relatively simple configuration. It becomes possible.

  Hereinafter, a fuel cell system according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an on-vehicle power generation system of a fuel cell vehicle will be described.

  First, the configuration of the fuel cell system 1 according to the embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the fuel cell system 1 according to the present embodiment receives a supply of reaction gas (oxidizing gas and fuel gas) to generate power and generate electric power associated with power generation. An oxidant gas piping system 3 for supplying air to the fuel cell 2, a fuel gas piping system 4 for supplying hydrogen gas as fuel gas to the fuel cell 2, a power system 5 for charging / discharging the power of the system, and overall control of the entire system. A control device 6 and the like are provided.

  The fuel cell 2 is formed of, for example, a solid polymer electrolyte type and has a stack structure in which a large number of single cells are stacked. The unit cell of the fuel cell 2 has a cathode electrode (air electrode) on one surface of an electrolyte made of an ion exchange membrane, an anode electrode (fuel electrode) on the other surface, and further has a cathode electrode and an anode electrode. A pair of separators are provided so as to be sandwiched from both sides. The fuel gas is supplied to the fuel gas flow path of one separator and the oxidizing gas is supplied to the oxidizing gas flow path of the other separator, and the fuel cell 2 generates electric power by this gas supply. The fuel cell 2 is provided with a current sensor 2a for detecting a current (output current) during power generation and a voltage sensor 2b for detecting a voltage (output voltage). In addition to the solid molecular electrolyte type, various types such as a phosphoric acid type and a molten carbonate type can be adopted as the fuel cell 2.

  The oxidizing gas piping system 3 includes an air compressor 31, an oxidizing gas supply path 32, a humidification module 33, an oxidizing off gas path 34, a diluter 35, a motor M <b> 1 that drives the air compressor 31, and the like. The air compressor 31 and the motor M1 constitute one embodiment of the oxidizing gas supply device in the present invention.

  The air compressor 31 is driven by the driving force of the motor M <b> 1 that operates according to the control command of the control device 6, and oxygen (oxidizing gas) taken from outside air through an air filter (not shown) is supplied to the cathode electrode of the fuel cell 2. Supply. A rotation speed detection sensor 3a for detecting the rotation speed of the motor M1 is attached to the motor M1. The oxidizing gas supply path 32 is a gas flow path for guiding oxygen supplied from the air compressor 31 to the cathode electrode of the fuel cell 2. Oxidized off gas is discharged from the cathode electrode of the fuel cell 2.

  The humidification module 33 exchanges moisture between the low wet state oxidizing gas flowing through the oxidizing gas supply path 32 and the high wet state oxidizing off gas flowing through the oxidizing off gas flow path 34 and is supplied to the fuel cell 2. Appropriately humidify the oxidizing gas. The oxidation off gas channel 34 is a gas channel for exhausting the oxidation off gas to the outside of the system, and a back pressure valve A1 is disposed in the vicinity of the cathode electrode outlet of the gas channel. The back pressure of the oxidizing gas supplied to the fuel cell 2 is regulated by the back pressure valve A1. The diluter 35 dilutes the hydrogen gas discharge concentration so that it falls within a preset concentration range (such as a range determined based on environmental standards). The diluter 35 communicates with the downstream of the oxidation offgas channel 34 and the downstream of the fuel offgas channel 44 described later. The hydrogen offgas and the oxygen offgas are mixed and diluted by the diluter 35 and exhausted outside the system.

  The fuel gas piping system 4 drives a fuel gas supply source 41, a fuel gas supply path 42, a fuel gas circulation path 43, a fuel off-gas flow path 44, a hydrogen circulation pump 45, a check valve 46, and a hydrogen circulation pump 45. It has a motor M2 and the like.

  The fuel gas supply source 41 supplies a fuel gas such as hydrogen gas to the fuel cell 2 and includes, for example, a high-pressure hydrogen tank or a hydrogen storage tank. The fuel gas supply path 42 is a gas flow path for guiding the fuel gas discharged from the fuel gas supply source 41 to the anode electrode of the fuel cell 2, and the gas flow path includes a tank valve H1, hydrogen gas from upstream to downstream. Valves such as a supply valve H2 and an FC inlet valve H3 are provided. The tank valve H1, the hydrogen supply valve H2, and the FC inlet valve H3 are shut valves for supplying (or shutting off) the fuel gas to the fuel cell 2, and are constituted by, for example, electromagnetic valves.

  The fuel gas circulation path 43 is a return gas flow path for recirculating unreacted fuel gas to the fuel cell 2, and the gas flow path includes an FC outlet valve H4, a hydrogen circulation pump 45, and a check valve from upstream to downstream. 46 are arranged in this order. The low-pressure unreacted fuel gas discharged from the fuel cell 2 is moderately pressurized by the hydrogen circulation pump 45 driven by the driving force of the motor M <b> 2 that operates according to the control command of the control device 6, and is supplied to the fuel gas supply path 42. Led. The backflow of the fuel gas from the fuel gas supply path 42 to the fuel gas circulation path 43 is suppressed by the check valve 46. The fuel off gas passage 44 is a gas passage for exhausting the hydrogen off gas discharged from the fuel cell 2 to the outside of the system, and a purge valve H5 is disposed in the gas passage.

  The power system 5 includes a high-voltage DC / DC converter 51, a battery 52, a traction inverter 53, an auxiliary inverter 54, a chopper circuit 55, an absorber 56, a traction motor M3, an auxiliary motor M4, and the like. The traction motor M3 and the auxiliary motor M4 correspond to an embodiment of the load in the present invention.

  The high-voltage DC / DC converter 51 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 52 and outputs it to the traction inverter 53 side, and the direct-current input from the fuel cell 2 or the traction motor M3. And a function of adjusting the voltage and outputting it to the battery 52. The charge / discharge of the battery 52 is realized by these functions of the high-voltage DC / DC converter 51. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 51.

  The battery 52 is a chargeable / dischargeable secondary battery, and is composed of various types of secondary batteries, such as nickel metal hydride batteries. The battery 52 can be charged with surplus power or supplementarily supplied with power by control of a battery computer (not shown). Part of the direct-current power generated by the fuel cell 2 is stepped up and down by the high-voltage DC / DC converter 51 and charged in the battery 52. An SOC sensor 5 a that detects a state of charge (SOC) of the battery 52 is attached to the battery 52. The battery 52 corresponds to an embodiment of the power storage device in the present invention. Instead of the battery 52, a chargeable / dischargeable capacitor other than the secondary battery, for example, a capacitor, may be employed as the power storage device.

  The traction inverter 53 and the auxiliary inverter 54 are pulse width modulation type PWM inverters, and convert DC power output from the fuel cell 2 or the battery 52 into three-phase AC power in accordance with a given control command, thereby obtaining a traction motor. Supplied to M3 and auxiliary motor 4. The traction motor M3 is a motor for driving the wheels 7L and 7R. The traction motor M3 is provided with a rotation speed detection sensor 5b for detecting the rotation speed. The auxiliary motor M4 is a motor for driving various auxiliary machines, and is a generic term for M1 that drives the air compressor 31, a motor M2 that drives the hydrogen circulation pump 45, and the like.

  The chopper circuit 55 takes in the output power of the fuel cell 2 and absorbs it in the absorber 56 while chopping the output of the fuel cell 2 in accordance with the duty ratio set by the control device 6. An embodiment of power absorbing means for absorbing output power (surplus power) of the fuel cell 2 is configured. As the absorber 56, for example, a resistor, an electric double layer capacitor, or the like can be employed. The absorber 56 is attached with a measuring instrument 5c that measures the power absorbed by the absorber 56 (consumed power).

  The control device 6 is constituted by a CPU, a ROM, a RAM, and the like, and integrally controls each part of the system based on each sensor signal input. Specifically, the control device 6 determines the fuel based on the sensor signals sent from the accelerator pedal sensor 6a, the SOC sensor 5a, the rotation speed detection sensor 5b, and the like that detect the operation amount (accelerator opening) of the accelerator pedal. The required output power for the battery 2 is calculated. At this time, the control device 6 uses a shift lever or the like for selecting an operation mode (P: parking mode, R: reverse mode, N: neutral mode, D: drive mode, B: regenerative brake mode) of the traction motor M3. On the basis of a signal sent from the operation unit 8, whether or not there is an output request from the traction motor M <b> 3 is determined.

  Then, the control device 6 controls the output voltage and output current of the fuel cell 2 so as to generate output power corresponding to the output required power. Further, the control device 6 controls output pulses and the like of the traction inverter 53 and the auxiliary machine inverter 54 to control the traction motor M3 and the auxiliary machine motor M4.

  Further, the control device 6 determines whether or not the output request to the fuel cell 2 has suddenly decreased based on the sensor signal of the accelerator pedal sensor 6a and the output request to the fuel cell 2 has rapidly decreased (whether the output request reduction rate has exceeded a predetermined threshold). Or not). The threshold value (threshold value of the output request reduction rate) employed when performing such a sudden load decrease determination can be appropriately set according to the specification, scale, etc. of the fuel cell system 1. When the control device 6 determines that the reduction rate of the output request for the fuel cell 2 exceeds a predetermined threshold (when the load suddenly decreases), the control device 6 immediately suppresses power generation by the fuel cell 2. Control is performed to reduce the supply amount of air (oxidizing gas) among the reaction gases. That is, the control device 6 functions as an embodiment of the control means in the present invention.

  Specifically, the control device 6 performs control for reducing the supply of air (oxidizing gas) supplied to the fuel cell 2 by suppressing the driving of the air compressor 31 when the load suddenly decreases. At this time, the control device 6 causes the motor M1 that drives the air compressor 31 to perform a regenerative operation (regenerative braking operation) in order to immediately suppress the supply of air from the air compressor 31 to the fuel cell 2. The control command is given to suppress the driving of the air compressor 31, and the electric power generated by the regenerative operation of the motor M1 is supplied from the motor M1 to the battery 52.

  Furthermore, the control device 6 gives a valve closing command to the back pressure valve A1 when the load is suddenly reduced, and performs control to reduce the opening of the back pressure valve A1, and gives a control command to the chopper circuit 55, Control is performed to cause the absorber 56 to absorb surplus power generated from the fuel cell 2 via the chopper circuit 55.

  Next, the motor regeneration control function of the control device 6 will be described using the functional block diagram of FIG. 2 and the time chart of FIG.

  First, the control device 6 determines that the operation mode of the traction motor M3 is in the drive mode (D range operation) and that the time of sudden load reduction has arrived based on the sensor signal from the accelerator pedal sensor 6a. As shown in FIG. 2, the target value Air-ref of the amount of air discharged from the air compressor 31 is set (gas target value setting function: B1). Then, the control device 6 calculates the actual air discharge amount accompanying the driving of the air compressor 31 from the rotation speed of the motor M1 (sensor signal of the rotation speed detection sensor 3a), and this calculated value is a measured value (current value). As air-mes, a deviation ΔAir1 between the target value Air-ref and the measured value Air-mes is calculated (gas deviation calculating function: B2).

  Next, the control device 6 determines whether or not the calculated deviation ΔAir1 is smaller than a predetermined threshold value ΔAir-lim (gas deviation determination function: B3). This threshold value ΔAir-lim is a value determined by the characteristics of the air compressor 31 and the motor M1, and is set corresponding to a value at which the motor M1 is inertial or decelerated in terms of performance. Subsequently, when the deviation ΔAir1 is smaller than the threshold value ΔAir-lim, the control device 6 determines that a regenerative operation is required and sets a deviation (second deviation) ΔAir2 between the target value Air-ref and the threshold value ΔAir-lim. Calculate (second deviation calculation function: B4), and calculate a deviation (third deviation) ΔAir3 between the calculated second deviation ΔAir2 and the measured value Air-mes (third deviation calculation function: B5). Then, the control device 6 adopts the calculated third deviation ΔAir3 as a command value for causing the motor M1 to perform a regenerative operation (regenerative brake operation), and executes PI control on the motor M1 (regenerative control function: B6). Thereafter, the processing in this routine is terminated.

  When the rotational speed of the air compressor 31 is lowered according to the target value of the time history as shown in FIG. 3A, the motor M1 is simply decelerated according to the threshold value ΔAir-lim, as shown in FIG. As in the time history A, the motor M1 does not stop immediately. On the other hand, in the present embodiment, a deviation (third) between the deviation (second deviation) ΔAir2 obtained from the target value Air-ref and the threshold value ΔAir-lim and the measured value Air-mes that is the current value. Deviation) ΔAir3 is set as a command value, and PI control for setting the command value to a target value Air-ref (for example, zero) is executed. When the motor M1 performs a regenerative operation according to this PI control, the rotational speed of the motor M1 can be rapidly reduced as shown in the time history B shown in FIG. Further, since the supply amount of air (oxidizing gas) to the fuel cell 2 rapidly decreases as the rotational speed of the motor M1 rapidly decreases, the power generation of the fuel cell 2 as shown in FIG. The amount can be drastically reduced, and the amount of power generation corresponding to the shaded area can be reduced as compared with the case where the motor M1 is decelerated by inertia without causing the motor M1 to perform a regenerative operation. Further, while the regenerative operation of the motor M1 is being performed, the electric power accompanying the regenerative operation of the motor M1 is supplied to the battery 52, so that the battery 52 can be charged with this electric power.

  Next, the back pressure valve control function of the control device 6 will be described using the functional block diagram of FIG.

  First, the control device 6 determines that the operation mode of the traction motor M3 is in the drive mode (D range operation) and that the time of sudden load reduction has arrived based on the sensor signal from the accelerator pedal sensor 6a. As shown in FIG. 4, the required output power (target power value) Preq is set from the accelerator opening (required power setting function: B11). Then, the control device 6 calculates the actual output power from the sensor signals of the current sensor 2a and the voltage sensor 2b, sets this calculated value as the measured value (current value) Pmes, and the deviation ΔP1 between the target value Preq and the measured value Pmes. Is calculated (power deviation calculation function: B12).

  Next, the control device 6 determines whether or not the calculated deviation ΔP1 is smaller than a predetermined threshold ΔPlim (power deviation determination function: B13). This threshold value ΔPlim is a value corresponding to the amount of power decrease determined by the suppression capability of the air compressor 31, and is set corresponding to a value at which the motor M1 is inertial or decelerated in terms of performance. Subsequently, when the deviation ΔP1 is smaller than the threshold value ΔPlim, the control device 6 calculates a deviation (second deviation) ΔP2 between the target value Preq and the threshold value ΔPlim, assuming that a regenerative operation is necessary (second deviation). Calculation function: B14), a deviation (third deviation) ΔP3 between the calculated second deviation ΔP2 and the measured value Pmes is calculated (third deviation calculation function: B15). Then, the control device 6 adopts the calculated third deviation ΔP3 as a command value for causing the motor M1 to perform a regenerative operation (regenerative brake operation), and executes PI control on the motor M1 (regenerative control function: B16). .

  Subsequently, the control device 6 employs the calculated third deviation ΔP3 as an opening command value for controlling the opening of the back pressure valve A1, and suppresses the pressure in the oxidant off-gas flow path 34 within an allowable range. Thus, control is performed to reduce the opening of the back pressure valve A1 while performing upper and lower limit processing (back pressure valve opening reducing function: B17). Thereafter, the processing in this routine is terminated. In this way, when the load is suddenly reduced, the regenerative operation of the motor M1 is performed and the opening of the back pressure valve A1 is reduced, so that the pressure loss of the oxidant off-gas flow path 34 increases, and the amount of air introduced into the fuel cell 2 Can be drastically reduced, and the power generation amount of the fuel cell 2 can be further rapidly reduced.

  Next, the power absorption control function of the control device 6 will be described using the functional block diagram of FIG.

  The functions of B21 to B25 in this control are the functions of B11 to B15 shown in FIG. 4 (required power setting function B11, power deviation calculation function B12, power deviation determination function B13, second deviation calculation function B14, third Since it is substantially the same as the deviation calculation function B15), the description thereof is omitted. After calculating the third deviation ΔP3 by the third deviation calculating function B25, the control device 6 searches the duty map of the built-in memory and calculates the first duty ratio Dr1 corresponding to the third deviation ΔP3 (first Duty ratio setting function: B26).

  On the other hand, the control device 6 calculates the power (previous value) Pabs-req calculated in the previous routine and absorbed by the absorber 56, and the power actually absorbed by the absorber 56 (by measurement of the measuring device 5c). The obtained measurement value) Pabs-mes and the deviation ΔPabs are calculated (absorption power deviation calculation function: B27), and PI control is executed using the deviation ΔPabs as a command value to calculate the second duty ratio Dr2 (first 2 duty ratio setting function: B28). Thereafter, the controller 6 adds the first duty ratio Dr1 and the second duty ratio Dr2 to calculate the third duty ratio Dr3 (third duty calculation function: B29), and calculates the calculated third duty ratio Dr3. Is controlled as a command value for the chopper circuit 55, and the control for the chopper circuit 55 is started.

  That is, when the deviation ΔPabs calculated by the absorbed power deviation function B27 is not zero, the absorption value is insufficient by the deviation ΔPabs. Therefore, the second duty ratio Dr2 and the duty map corresponding to this shortage Is added to the first duty ratio Dr1 to obtain a third duty ratio Dr3, and the amount of power to be taken into the chopper circuit 55 from the fuel cell 2 is set in accordance with the third duty ratio Dr3 and taken into the chopper circuit 55. The process for absorbing the received power by the absorber 56 is executed, and the process in this routine is terminated.

  In the fuel cell system 1 according to the embodiment described above, the regenerative operation of the motor M1 that drives the air compressor 31 is realized when the rate of decrease in the output request for the fuel cell 2 exceeds a predetermined threshold, and the air is regenerated. The drive of the compressor 31 can be suppressed. Therefore, it is possible to rapidly reduce the power generation amount of the fuel cell 2 by rapidly suppressing the supply of the oxidizing gas to the fuel cell 2 without providing a mechanism for discharging the oxidizing gas to the outside when the load is suddenly reduced. Become.

  In the fuel cell system 1 according to the embodiment described above, the pressure loss of the oxidant off-gas channel 34 can be increased by reducing the opening of the back pressure valve A1 when the load is suddenly reduced. Therefore, the amount of oxidizing gas introduced into the fuel cell 2 can be rapidly reduced, and the power generation amount of the fuel cell 2 can be further rapidly reduced.

  Further, in the fuel cell system 1 according to the embodiment described above, the battery 52 cannot accumulate in the electric power generated in the fuel cell 2 or the electric power generated by the regenerative operation of the motor M1 that drives the air compressor 31 when the load is suddenly reduced. Surplus power can be absorbed by the power absorption means (the chopper 55 and the absorber 56). Therefore, the battery 52 can be protected from overcharging.

  In the above embodiment, the example in which the opening degree control of the back pressure valve A1 (FIG. 4) and the power absorption control by the power absorbing means (FIG. 5) are performed separately has been shown. You can also. Further, the regeneration control of the motor M1 of the air compressor 31 (FIGS. 2, 4, and 5), the opening control of the back pressure valve A1 (FIG. 4), and the power absorption control (FIG. 5) by the power absorption means. You may carry out simultaneously.

  Moreover, in the above embodiment, although the example which mounted the fuel cell system which concerns on this invention in the fuel cell vehicle was shown, it concerns on this invention to various mobile bodies (a robot, a ship, an aircraft, etc.) other than a fuel cell vehicle. A fuel cell system can also be installed. Further, the fuel cell system according to the present invention may be applied to a stationary power generation system used as a power generation facility for a building (house, building, etc.).

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a functional block diagram for demonstrating motor regeneration control at the time of the load sudden change of the fuel cell system shown in FIG. (A) is a time chart showing the time history of the target speed of the air compressor, (B) is a time chart showing the time history of the actual speed of the air compressor, and (C) shows the time history of the output of the fuel cell. It is a time chart. FIG. 2 is a functional block diagram for explaining motor regeneration control and back pressure valve control during a sudden load change of the fuel cell system shown in FIG. 1. It is a functional block diagram for demonstrating motor regeneration control and electric power absorption control at the time of the load sudden change of the fuel cell system shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 6 ... Control apparatus (control means), 31 ... Air compressor (oxidation gas supply apparatus), 34 ... Oxidation off gas flow path, 52 ... Battery (power storage device), 55 ... Chopper circuit (Power absorption means), 56 ... absorber (power absorption means), A1 ... back pressure valve, M1 ... motor (oxidizing gas supply device), M3 ... traction motor (predetermined load).

Claims (5)

A fuel cell that receives the supply of the reactive gas to generate power and supplies the electric power accompanying the power generation to a predetermined load; an oxidizing gas supply device that compresses the oxidizing gas of the reactive gas and supplies the compressed fuel gas to the fuel cell; In a fuel cell system, comprising a control means for giving a control command to the oxidant gas supply device and controlling its operation,
The control means is configured to realize a regenerative operation by giving a control command to the oxidant gas supply device when the load suddenly decreases when the rate of decrease in output demand for the fuel cell exceeds a predetermined threshold.
Fuel cell system. The oxidizing gas supply device has an air compressor, and a motor that drives the air compressor,
The control means is for realizing a regenerative operation by giving a control command to the motor when the load is suddenly reduced.
The fuel cell system according to claim 1. An oxidation off-gas flow path for circulating the oxidation off-gas discharged from the fuel cell;
A back pressure valve provided in the oxidizing off gas flow path,
The control means gives a control command to the back pressure valve when the load is suddenly reduced to reduce the opening of the back pressure valve.
The fuel cell system according to claim 1 or 2. A power storage device that stores electric power generated in the fuel cell and / or electric power generated by a regenerative operation of the oxidizing gas supply device;
Power absorption means for taking in and absorbing surplus power that cannot be stored in the power storage device when the load suddenly decreases,
The fuel cell system according to any one of claims 1 to 3. A fuel cell that receives the supply of a reactive gas to generate power and supplies the electric power accompanying the power generation to a predetermined load; and an oxidizing gas supply device that compresses the oxidizing gas of the reactive gas and supplies the compressed fuel gas to the fuel cell. A fuel cell system control method comprising:
Including the step of realizing the regenerative operation of the oxidizing gas supply device when the load reduction rate of the output demand for the fuel cell exceeds a predetermined threshold.
Control method of fuel cell system.

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