JP2013191438A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of suppressing fluctuation range of power storage amount in a power storage device, while suppressing fluctuation of generation power and melting of a metal catalyst caused thereby as well.SOLUTION: Disclosed is a fuel cell system that calculates a generation power command value SFP by performing an equalization processing that eliminates components of a frequency higher than a cutoff frequency, and thus controls its generation power so as to follow the generation power command value SFP in response to a measured amount of required power RP. The system performs a power storage amount adjustment control that suppresses fluctuation range of an SOC by varying the cutoff frequency on the basis of the SOC of a battery.

Description

  The present invention relates to a fuel cell system that supplies power generated by a fuel cell to a load.

  A fuel cell constituting a fuel cell system directly converts energy released in an oxidation reaction into electric energy by oxidizing fuel by an electrochemical process. This fuel cell has a membrane-electrode assembly in which both side surfaces of a polymer electrolyte membrane for selectively transporting hydrogen ions are sandwiched between a pair of electrodes made of a porous material. Each of the pair of electrodes is mainly composed of a carbon powder carrying a platinum-based metal catalyst, and is formed on the surface of the catalyst layer in contact with the polymer electrolyte membrane and a gas having both air permeability and electronic conductivity. And a diffusion layer.

  In such a fuel cell system, so-called “load following operation” is performed for the purpose of improving the operation efficiency. This is an operation method in which the output power (power supplied to the load) of the fuel cell system is changed so as to follow the required power from the load. For example, when the required power from the load is small, the generated power is reduced by reducing the amount of fuel supplied to the fuel cell. On the other hand, when the required power from the load is large, the generated power is increased by increasing the amount of fuel or the like supplied to the fuel cell.

  By the way, it is known that when the generated power is changed as described above, the platinum-based metal catalyst is dissolved and deposited due to the change in the generated voltage of the fuel cell, and the power generation performance of the fuel cell is deteriorated. It has been. As a countermeasure, a power storage device such as a battery capable of storing a part of the generated power is provided, and both the power generated by the fuel cell and the power discharged by the power storage device can be supplied to the load. It is generally done.

  In the fuel cell system having such a configuration, the power required from the load is leveled by a filter process to obtain a leveled required power with less fluctuation, and control is performed so that the generated power of the fuel cell follows the leveled required power. It can be carried out. In such control, the generated power and the required power may not match, but such mismatch is compensated by charging and discharging of the power storage device.

  That is, when the generated power (leveling required power) is smaller than the required power, the insufficient power is compensated by the discharge of the power storage device. When the generated power (leveling required power) is larger than the required power, surplus power is stored in the power storage device. As a result, the output power of the fuel cell system can be matched with the required power from the load while the generated power of the fuel cell is leveled to prevent the metal catalyst from being dissolved and deposited.

  As an example of such a fuel cell system, Patent Document 1 below calculates an average value of required power in a predetermined period and sets a command value of generated power based on the average value, thereby leveling the generated power. A fuel cell system is described.

  Further, in the fuel cell system, when the power storage amount of the power storage device is large, the command value of the generated power is corrected and set to be smaller than the required power. When the amount of stored electricity is small, the command value of the generated power is corrected and set larger than the required power. In this manner, the stored power amount is converged to the target stored power amount by correcting the command value of the generated power based on the stored power amount. This is because the amount of power that can be stored in the power storage device is considered to be finite, and the amount of stored power reaches 0% or 100%, so that it is impossible to level the generated power as described above. This is to prevent the situation from occurring.

JP 2004-7777 A

  In the fuel cell system described in Patent Document 1, the correction value based on the amount of power stored in the power storage device is directly added to or subtracted from the command value of the generated power. For this reason, if the amount of stored electricity fluctuates in a wide range, the command value of the generated power is greatly fluctuated by being directly affected by it, and the generated voltage fluctuates accordingly. As a result, the platinum-based metal catalyst sometimes dissolved and precipitated.

  In addition, the amount of power storage is measured or estimated by a voltage sensor or the like installed in the power storage device, but noise may occur in an input signal from the voltage sensor or the like. When such noise occurs, the noise directly adds to the command value of the generated power, so that the command value of the generated power fluctuates greatly. As a result, the generated voltage also fluctuated greatly, and the platinum-based metal catalyst sometimes dissolved and precipitated even during short-term operation.

  The present invention has been made in view of such problems, and its purpose is to suppress fluctuations in the amount of electricity stored in a power storage device, and also suppress fluctuations in generated power and dissolution of a metal catalyst resulting therefrom. It is an object of the present invention to provide a fuel cell system that can be used.

  In order to solve the above problems, a fuel cell system according to the present invention provides a required power for measuring the required power in a fuel cell system that outputs generated power from a fuel cell to the load based on required power from a load. Measuring means, control means for controlling the generated power, a power storage device connected in parallel to the fuel cell with respect to the load, for storing and discharging, and a storage amount measuring means for measuring a storage amount of the power storage device The control device calculates a leveling request power by performing a leveling process for removing a component having a frequency higher than a cut-off frequency for the measurement value of the required power, and the leveling request power The amount of electricity stored is controlled so as to suppress the fluctuation range of the amount of electricity stored by changing the cutoff frequency based on the amount of electricity stored. It is characterized by performing the control.

  In the present invention, the control device calculates the leveling request power by performing the leveling process on the measurement value of the required power, and controls the generated power so as to follow the leveling request power. The leveling process is a process for removing a component having a frequency higher than the cutoff frequency from the measured value of the required power, and is a so-called low-pass filter.

  By performing such leveling processing, even if the required power includes steep fluctuation components, such fluctuation components are removed. Since the control device controls the generated power so as to follow the leveling required power after leveling in this way, dissolution of the metal catalyst caused by fluctuations in the generated voltage is suppressed.

  Here, if the cutoff frequency of the leveling process changes, the change rate of the generated power changes, and the amount of electricity stored in the power storage device and the change rate thereof also change. This is utilized in the present invention, and the control means changes the cutoff frequency so as to suppress the fluctuation range of the charged amount. That is, based on the amount of electricity stored measured by the amount of electricity storage means, control is performed to change the cutoff frequency of the leveling process (power amount adjustment control) so that the fluctuation range of the amount of electricity stored is suppressed.

  By such power storage amount adjustment control, the fluctuation range of the power storage amount of the power storage device can be suppressed. The storage amount adjustment control corrects the command value of the generated power based on the stored power amount, but the correction is a direct operation that adds or subtracts the correction value from the command value of the generated power. It is not a thing but an indirect thing of changing the cut-off frequency of leveling processing.

  For this reason, even if the amount of stored electricity fluctuates or noise occurs in the measured value of the stored amount of electricity, the command value of the generated power does not fluctuate greatly due to the influence of such fluctuation factors. . For this reason, the fluctuation | variation of the electric power generation voltage of a fuel cell is suppressed, and melt | dissolution etc. of a metal catalyst are further suppressed.

  Further, in the fuel cell system according to the present invention, the control device uses, as the cutoff frequency, a first cutoff frequency that is used when the required power is increased, and a second cutoff frequency that is used when the required power is reduced, The first cut-off frequency is decreased when the charged amount is larger than a predetermined target charged amount, and the second cut-off frequency is set when the charged amount is smaller than the target charged amount. It is also preferable to reduce it.

  In this preferred embodiment, there are two frequencies (first cutoff frequency and second cutoff frequency) as cutoff frequencies used in the leveling process. The first cut-off frequency is a cut-off frequency used for leveling processing when the required power increases. The second cutoff frequency is a cutoff frequency used for the leveling process when the required power is reduced.

  When the charged amount measured by the charged amount measuring means is larger than the predetermined target charged amount, the first cutoff frequency is decreased. By reducing the first cut-off frequency, the leveling required power when the required power increases has only a small frequency component. As a result, the generated power that follows the leveling required power increases more slowly than the required power, so that the power shortage with respect to the required power is compensated by the discharge of the power storage device, and the power storage amount of the power storage device becomes the target power storage amount. It will approach.

  On the other hand, when the amount of electricity measured by the amount of electricity storage means is smaller than a predetermined target amount of electricity stored, the second cutoff frequency is decreased. By reducing the second cut-off frequency, the leveling required power when the required power is reduced has only a small frequency component. As a result, the generated power that follows the leveling required power decreases more slowly than the required power, so surplus power with respect to the required power is stored in the power storage device, and the power storage amount of the power storage device approaches the target power storage amount. It will be.

  Thus, since the amount of stored electricity changes so as to converge to the target amount of stored electricity by changing the first frequency and the second frequency, the fluctuation range of the stored amount of electricity can be further suppressed.

  Further, in the fuel cell system according to the present invention, the control device decreases the first cutoff frequency as the storage amount is larger than the target storage amount, and decreases as the storage amount is smaller than the target storage amount. It is also preferable to greatly reduce the second cutoff frequency.

  In this preferred embodiment, the control device greatly decreases the first cutoff frequency as the charged amount is larger than the target charged amount. For this reason, the electric power discharged from the power storage device is increased in order to compensate for the shortage with respect to the required power. As a result, the amount of decrease in the amount of power storage increases, and the amount of power storage can be made closer to the target power storage amount.

  Further, the second cutoff frequency is greatly reduced as the charged amount is smaller than the target charged amount. For this reason, there is a surplus with respect to the required power, and the power stored in the power storage device increases. As a result, the amount of increase in the amount of power storage increases, and the amount of power storage can be made closer to the target power storage amount.

  That is, according to this preferable aspect, more appropriate storage amount adjustment control can be performed according to the storage amount of the power storage device, and the fluctuation range of the storage amount can be further suppressed.

  Further, in the fuel cell system according to the present invention, the control device calculates the leveled demand power by multiplying a difference between the demand power and the generated power by a filter gain and then performing an integration process. It is also preferable to reduce the first cutoff frequency or the second cutoff frequency by reducing the filter gain based on the charged amount.

  In this preferred embodiment, the control device calculates the leveled demand power by multiplying the difference between the demand power and the generated power by a filter gain and then performing an integration process. When performing the storage amount adjustment control, the control device decreases the first cutoff frequency or the second cutoff frequency by decreasing the value of the filter gain based on the storage amount.

  According to this preferable aspect, the leveling process can be performed by a simple aspect of changing the value of the filter gain without performing complicated frequency calculation and control such as FFT.

  In the fuel cell system according to the present invention, the control means controls the generated power while feeding back a deviation of the charged amount with respect to the target charged amount so that the charged amount converges to the target charged amount. Is also preferable.

  According to the power storage amount adjustment control described above, control is performed so that the power storage amount of the power storage device approaches the target power storage amount only when the required power from the load fluctuates. Therefore, in a situation where there is little fluctuation in the required power from the load, there may be a certain deviation between the charged amount and the target charged amount.

  In this preferable aspect, the control means controls the generated power while feeding back the deviation of the charged amount with respect to the target charged amount so that the charged amount converges to the target charged amount. As a result, even in a situation where there is little fluctuation in the required power from the load, it is possible to control the power storage amount of the power storage device to converge to the target power storage amount, and to further suppress the fluctuation range of the power storage amount.

  In the fuel cell system according to the present invention, it is also preferable that the control device does not perform the power storage amount adjustment control when it is determined that the power storage performance of the power storage device has deteriorated.

  In a situation where the power storage performance of the power storage device is degraded, the mismatch between the generated power and the required power cannot be compensated for by charging or discharging the power storage device. For this reason, there is a possibility that the storage amount adjustment control is not properly performed and the dissolution and precipitation of the metal catalyst are accelerated instead.

  In this preferable aspect, the control device does not perform the power storage amount adjustment control when it is determined that the power storage performance of the power storage device has decreased. Thereby, in the situation where the power storage performance of the power storage device is degraded, it is possible to prevent the power storage amount adjustment control from being appropriately performed.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can also suppress the fluctuation | variation of generated electric power, the melt | dissolution of the metal catalyst resulting from this, etc. can be provided, suppressing the fluctuation range of the electrical storage amount of an electrical storage apparatus.

It is the figure which showed the system configuration | structure of the fuel cell vehicle carrying the fuel cell system which is one Embodiment of this invention. 2 is a graph showing a change with time of power generated by the fuel cell in the fuel cell system shown in FIG. 1. 2 is a graph showing a change with time of power generated by the fuel cell in the fuel cell system shown in FIG. 1. It is a control block diagram which shows the control performed in the fuel cell system shown in FIG. It is a control block diagram which shows the control performed in the fuel cell system shown in FIG. It is a figure showing the gain map in the control block diagram shown in FIG. It is a figure for demonstrating the control when the electrical storage performance of an electrical storage apparatus falls. It is a figure for demonstrating the content of the leveling process performed in another embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  FIG. 1 is a diagram showing a system configuration of a fuel cell vehicle equipped with a fuel cell system 10 according to an embodiment of the present invention. The fuel cell system 10 functions as an in-vehicle power supply system mounted on a fuel cell vehicle. The fuel cell stack 20 generates electric power by receiving supply of reaction gas (fuel gas, oxidant gas), and oxidant gas. An oxidant gas supply system 30 (oxidant gas supply means) for supplying the air to the fuel cell stack 20 and a fuel gas supply system 40 (fuel for supplying hydrogen gas as fuel gas to the fuel cell stack 20) Gas supply means), a power system 50 for controlling charge / discharge of power, and a controller 60 (control means) for overall control of the entire system.

  The fuel cell stack 20 is a solid polymer electrolyte cell stack formed by stacking a large number of cells in series. In the fuel cell stack 20, the oxidation reaction of the formula (1) occurs at the anode electrode, and the reduction reaction of the equation (2) occurs at the cathode electrode. In the fuel cell stack 20 as a whole, the electromotive reaction of the formula (3) occurs.

H2 → 2H ++ 2e- (1)
(1/2) O2 + 2H ++ 2e-> H2O (2)
H2 + (1/2) O2 → H2O (3)

  A voltage sensor 71 for detecting the output terminal voltage (stack voltage Vc) of the fuel cell stack 20 and a current sensor 72 for detecting the output current (stack current) are attached to the fuel cell stack 20.

  The oxidant gas supply system 30 has an oxidant gas passage 33 through which the oxidant gas supplied to the cathode electrode of the fuel cell stack 20 flows and an oxidant off gas passage 34 through which the oxidant off-gas discharged from the fuel cell stack 20 flows. doing. The oxidant gas passage 33 has an air compressor 32 that takes in the oxidant gas from the atmosphere via the filter 31, a humidifier 35 for humidifying the oxidant gas pressurized by the air compressor 32, and a fuel cell stack. A shutoff valve A1 for shutting off the oxidant gas supply to 20 is provided. In the oxidizing off gas passage 34, a shutoff valve A2 for shutting off the oxidizing off gas discharge from the fuel cell stack 20, a back pressure adjusting valve A3 for adjusting the oxidizing gas supply pressure, and an oxidizing gas (dry gas). And a humidifier 35 for exchanging moisture between the gas and the oxidizing off gas (wet gas).

  The fuel gas supply system 40 includes a fuel gas supply source 41, a fuel gas passage 43 through which fuel gas supplied from the fuel gas supply source 41 to the anode electrode of the fuel cell stack 20 flows, and fuel discharged from the fuel cell stack 20. A circulation passage 44 for returning off-gas to the fuel gas passage 43, a circulation pump 45 for pressure-feeding the fuel off-gas in the circulation passage 44 to the fuel gas passage 43, and an exhaust / drain passage 46 branched and connected to the circulation passage 44 Have.

  The fuel gas supply source 41 is composed of, for example, a high-pressure hydrogen tank or a hydrogen storage alloy, and stores high-pressure (for example, 35 MPa to 70 MPa) hydrogen gas. When the shut-off valve H1 is opened, the fuel gas flows out from the fuel gas supply source 41 into the fuel gas passage 43. The fuel gas is decompressed to about 200 kPa, for example, by the regulator H2 and the injector 42, and supplied to the fuel cell stack 20.

  The fuel gas supply source 41 includes a reformer that generates a hydrogen-rich reformed gas from a hydrocarbon-based fuel, and a high-pressure gas tank that stores the reformed gas generated by the reformer in a high-pressure state. It may be configured.

  In the fuel gas passage 43, a shutoff valve H1 for shutting off or allowing the supply of the fuel gas from the fuel gas supply source 41, a regulator H2 for adjusting the pressure of the fuel gas, and a fuel gas supply to the fuel cell stack 20 An injector 42 for controlling the amount, a shutoff valve H3 for shutting off the supply of fuel gas to the fuel cell stack 20, and a pressure sensor 74 are provided.

  The regulator H2 is a device that regulates the upstream side pressure (primary pressure) to a preset secondary pressure, and includes, for example, a mechanical pressure reducing valve that reduces the primary pressure. The mechanical pressure reducing valve has a housing in which a back pressure chamber and a pressure adjusting chamber are formed with a diaphragm therebetween, and the primary pressure is reduced to a predetermined pressure in the pressure adjusting chamber by the back pressure in the back pressure chamber. It has a configuration for the next pressure. By arranging the regulator H2 upstream of the injector 42, the upstream pressure of the injector 42 can be effectively reduced. For this reason, the design freedom of the mechanical structure (a valve body, a housing, a flow path, a drive device, etc.) of the injector 42 can be increased. Further, since the upstream pressure of the injector 42 can be reduced, it is possible to prevent the valve body of the injector 42 from becoming difficult to move due to an increase in the differential pressure between the upstream pressure and the downstream pressure of the injector 42. be able to. Therefore, it is possible to widen the adjustable pressure width of the downstream pressure of the injector 42 and to suppress a decrease in responsiveness of the injector 42.

  The injector 42 is an electromagnetically driven on-off valve capable of adjusting the gas flow rate and gas pressure by driving the valve body directly at a predetermined driving cycle with an electromagnetic driving force and separating it from the valve seat. The injector 42 includes a valve seat having an injection hole for injecting gaseous fuel such as fuel gas, a nozzle body for supplying and guiding the gaseous fuel to the injection hole, and an axial direction (gas flow direction) with respect to the nozzle body. And a valve body that is slidably accommodated and opens and closes the injection hole.

  In the present embodiment, the valve element of the injector 42 is driven by a solenoid that is an electromagnetic drive device, and the opening area of the injection hole can be switched in two stages by turning on and off the pulsed excitation current supplied to the solenoid. it can. By controlling the gas injection time and gas injection timing of the injector 42 by the control signal output from the controller 60, the flow rate and pressure of the fuel gas are controlled with high accuracy. The injector 42 directly opens and closes the valve (valve body and valve seat) with an electromagnetic driving force, and has a high responsiveness because its driving cycle can be controlled to a highly responsive region. The injector 42 changes its downstream area by changing at least one of the opening area (opening) and the opening time of the valve provided in the gas flow path of the injector 42 in order to supply the required gas flow rate downstream. The gas flow rate (or hydrogen molar concentration) supplied to the side is adjusted.

  The circulation passage 44 is connected to a shutoff valve H4 for shutting off the fuel off-gas discharge from the fuel cell stack 20 and an exhaust drainage passage 46 branched from the circulation passage 44. An exhaust / drain valve H5 is disposed in the exhaust / drain passage 46. The exhaust / drain valve H <b> 5 is operated according to a command from the controller 60, thereby discharging the fuel off-gas containing impurities in the circulation passage 44 and moisture to the outside. By opening the exhaust / drain valve H5, the concentration of impurities in the fuel off-gas in the circulation passage 44 decreases, and the hydrogen concentration in the fuel off-gas circulating in the circulation system can be increased.

  The fuel off-gas discharged through the exhaust / drain valve H5 is mixed with the oxidizing off-gas flowing through the oxidizing off-gas passage 34 and diluted by a diluter (not shown). The circulation pump 45 circulates and supplies the fuel off gas in the circulation system to the fuel cell stack 20 by driving the motor.

  The power system 50 includes a DC / DC converter 51, a battery 52, a traction inverter 53, a traction motor 54, and auxiliary machinery 55. The fuel cell system 10 is configured as a parallel hybrid system in which a DC / DC converter 51 and a traction inverter 53 are connected to the fuel cell stack 20 in parallel. The DC / DC converter 51 boosts the DC voltage supplied from the battery 52 and outputs it to the traction inverter 53, and the DC power generated by the fuel cell stack 20, or the regenerative power collected by the traction motor 54 by regenerative braking. And a function of charging the battery 52 by stepping down the voltage. The charge / discharge of the battery 52 is controlled by these functions of the DC / DC converter 51. Further, the operation point (output voltage, output current) of the fuel cell stack 20 is controlled by voltage conversion control by the DC / DC converter 51.

  The battery 52 functions as a surplus power storage source, a regenerative energy storage source during regenerative braking, and an energy buffer during load fluctuations associated with acceleration or deceleration of the fuel cell vehicle. As the battery 52, for example, a secondary battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium secondary battery is suitable. An SOC sensor 73 for detecting SOC (State of charge) is attached to the battery 52.

  The traction inverter 53 is, for example, a PWM inverter driven by a pulse width modulation method, and converts a DC voltage output from the fuel cell stack 20 or the battery 52 into a three-phase AC voltage in accordance with a control command from the controller 60. The rotational torque of the traction motor 54 is controlled. The traction motor 54 is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.

  Auxiliary machines 55 are motors (for example, power sources such as pumps) arranged in each part in the fuel cell system 10, inverters for driving these motors, and various on-vehicle auxiliary machines. (For example, an air compressor, an injector, a cooling water circulation pump, a radiator, etc.) is a general term.

  The controller 60 is a computer system including a CPU, a ROM, a RAM, and an input / output interface, and controls each part of the fuel cell system 10. For example, when the controller 60 detects that the state of the ignition switch IG is ON, the controller 60 starts the operation of the fuel cell system 10 and is output from the accelerator opening signal ACC output from the accelerator sensor or the vehicle speed sensor. The required power from the load is obtained based on the vehicle speed signal VV and the like. That is, the controller 60 has a function as required power detection means for detecting required power. The required power from the load is the total value of the vehicle running power and the auxiliary machine power.

  Here, the auxiliary power is the power consumed by auxiliary equipment such as a humidifier, an air compressor, a hydrogen pump, and a cooling water circulation pump. That is, in the fuel cell system 10 of the present embodiment, the traction motor 54 and the auxiliary machine, which are power sources of the fuel cell vehicle, correspond to a load that receives power supply from the fuel cell system 10.

  Then, the controller 60 determines the distribution of the output power of each of the fuel cell stack 20 and the battery 52, and the oxidant gas supply system 30 and the fuel so that the generated power FP of the fuel cell stack 20 matches the target power. The operating point (output voltage, output current) of the fuel cell stack 20 is controlled by controlling the gas supply system 40 and the DC / DC converter 51 to adjust the output voltage of the fuel cell stack 20. Further, the controller 60 outputs, for example, each of the U-phase, V-phase, and W-phase AC voltage command values to the traction inverter 53 as a switching command so as to obtain a target torque corresponding to the accelerator opening, The output torque of the motor 54 and the rotation speed are controlled.

  In the fuel cell system 10 of the present embodiment, as described above, the control by the controller 60 is performed so that the power supplied (output) from the fuel cell system 10 to the load changes according to the change in the required power RP from the load. Is done. The time change of the required power RP, the generated power FP of the fuel cell stack 20, and the system power SP actually supplied from the fuel cell system 10 to the load will be described with reference to FIGS.

  FIG. 2 shows the state of the generated power FP and the system power SP when the required power RP from the load changes in a situation where the SOC of the battery 52 is less than 50% which is the target storage amount TSOC as the target value. It is a graph which shows a time change. FIG. 2 shows a time change when the required power RP decreases from W0 to W1 at time t1, and then the required power RP decreases from W1 to W0 at time t2.

  When the required power RP increases from W0 to W1 at time t1, the controller 60 immediately increases the generated power FP of the fuel cell stack 20 to W1. That is, the power output of the fuel cell system 10 is controlled so that the required power RP is entirely covered by the generated power FP. For this reason, the generated power FP and the system power SP are equal from the time t1 to the time t2.

  Subsequently, when the required power RP decreases from W1 to W0 at time t2, the controller 60 decreases the generated power FP of the fuel cell stack 20 to W0. At this time, the control is performed so as not to immediately decrease to W0 but to suppress the decrease in the generated power FP and to reduce the decrease rate. At this time, a surplus is generated in the generated power FP, but the surplus is stored in the battery 52. As a result, the system power SP supplied from the fuel cell system 10 to the load immediately decreases to W0.

  At time t2, since the generated power FP of the fuel cell stack 20 so far was large, the proton conductivity of the polymer electrolyte membrane has been improved, and the fuel cell stack 20 is generating power with high power generation efficiency. It has become. It is known that the proton conductivity of the polymer electrolyte membrane does not decrease immediately even if the generated power FP of the fuel cell stack 20 is decreased thereafter, but decreases with a certain delay. That is, the power generation efficiency is high when the generated power FP of the fuel cell stack 20 is reduced.

  Therefore, in the present embodiment, as described above, even after time t2 when the system power SP decreases, the generated power FP in the fuel cell stack 20 is not immediately decreased, so that the power generation is performed with high power generation efficiency. We are using. Since the surplus of the generated power FP at this time is stored in the battery 52, the SOC of the battery 52 can be brought close to the target storage amount TSOC of 50%. Note that the target power storage amount TSOC is not limited to 50%, and is appropriately set according to the type and configuration of the battery 52. Generally, it is set in the range of 40% to 80%.

  On the other hand, at time t1, the generated electric power FP of the fuel cell stack 20 so far has been small, so the proton conductivity of the polymer electrolyte membrane is reduced, and the fuel cell stack 20 is generating power with low power generation efficiency. It is in a state. It is known that the proton conductivity of the polymer electrolyte membrane does not increase immediately even if the generated power FP of the fuel cell stack 20 is increased thereafter, but increases with a certain delay. That is, when the generated power FP of the fuel cell stack 20 is increased, the power generation efficiency is low.

  For this reason, it is desirable from the viewpoint of power generation efficiency of the fuel cell stack 20 that the generated power FP of the fuel cell stack 20 is not immediately increased after time t1 and the shortage is compensated by discharge from the battery 52. However, in that case, the SOC of the battery 52 is further reduced. If the SOC further decreases from a state where the SOC is less than the target power storage amount TSOC of 50%, the burden on the battery 52 increases and the battery 52 deteriorates in a short period of time. Therefore, in the present embodiment, as shown in FIG. 2, in a situation where the SOC of the battery 52 is less than 50%, which is the target charged amount TSOC, the generated power FP is immediately increased at time t1. That is, the generated power FP of the fuel cell stack 20 is controlled while taking into consideration both the SOC variation of the battery 52 and the power generation efficiency of the fuel cell stack 20.

  FIG. 3 is a graph showing temporal changes in the generated power FP and the system power SP when the required power RP from the load changes in a situation where the SOC of the battery 52 is greater than 50%, which is the target storage amount TSOC. is there. FIG. 3 shows a time change when the required power RP decreases from W1 to W0 at time t4 after the required power RP increases from W0 to W1 at time t3.

  Unlike the case of FIG. 2, when the required power RP increases from W0 to W1 at time t3, the controller 60 does not immediately increase the generated power FP of the fuel cell stack 20 to W1, but suppresses the increase in the generated power FP, Control the increase rate to be gradual. At this time, the generated power FP alone is less than the required power RP, but the shortage is compensated by the discharge from the battery 52. As a result, the system power SP supplied from the fuel cell system 10 to the load immediately increases to W1.

  At time t3, since the generated power FP of the fuel cell stack 20 until then was small, the proton conductivity of the polymer electrolyte membrane was lowered, and the fuel cell stack 20 was generating power with low power generation efficiency. It has become. It is known that the proton conductivity of the polymer electrolyte membrane does not increase immediately even if the generated power FP of the fuel cell stack 20 is increased thereafter, but increases with a certain delay. That is, when the generated power FP of the fuel cell stack 20 is increased, the power generation efficiency is low.

  Therefore, in the present embodiment, as described above, even after the time t3 when the system power SP increases, the power generation FP in the fuel cell stack 20 is not immediately increased, thereby suppressing power generation in a state where the power generation efficiency is low. Yes. Since the shortage of the generated power FP at this time is compensated by the discharge of the battery 52, the SOC of the battery 52 is reduced, and the SOC can be brought close to 50% that is the target charged amount TSOC.

  On the other hand, when the required power RP decreases from W1 to W0 at time t4, the controller 60 immediately decreases the generated power FP of the fuel cell stack 20 to W0. That is, the power output of the fuel cell system 10 is controlled so that the surplus of the generated power FP does not occur.

  At time t4, since the generated power FP of the fuel cell stack 20 so far was large, the proton conductivity of the polymer electrolyte membrane has been improved, and the fuel cell stack 20 is generating power with high power generation efficiency. It has become. It is known that the proton conductivity of the polymer electrolyte membrane does not decrease immediately even if the generated power FP of the fuel cell stack 20 is decreased thereafter, but decreases with a certain delay. That is, the power generation efficiency is high when the generated power FP of the fuel cell stack 20 is reduced.

  Therefore, it is desirable from the viewpoint of power generation efficiency of the fuel cell stack 20 that the generated power FP of the fuel cell stack 20 is not immediately decreased after time t4 and the surplus is stored in the battery 52. However, in that case, the SOC of the battery 52 further increases. If the SOC further increases from the situation where the SOC is greater than the target power storage amount TSOC of 50%, the burden on the battery 52 increases and the battery 52 deteriorates in a short period of time. Therefore, in the present embodiment, as shown in FIG. 3, in a situation where the SOC of the battery 52 is larger than the target charged amount TSOC of 50%, the generated power FP is immediately reduced at time t4. That is, the generated power FP of the fuel cell stack 20 is controlled while taking into consideration both the SOC variation of the battery 52 and the power generation efficiency of the fuel cell stack 20.

  As described above, in the fuel cell system 10 according to the present embodiment, when the required power RP from the load increases, the increase in the generated power FP from the fuel cell stack 20 is suppressed, while the decrease in the required power RP. In some cases, a decrease in the generated power FP from the fuel cell stack 20 is suppressed. Thereby, the operation efficiency of the fuel cell system 10 is improved. On the other hand, in the fuel cell system 10 according to the present embodiment, the suppression of the increase in the generated power FP when the required power RP from the load increases and the suppression of the decrease in the generated power FP when the required power RP decreases are always performed. This is not based on the SOC of the battery 52. In order to control the SOC of the battery 52 so as to approach 50%, which is the target storage amount TSOC, with the change in the generated power FP, the above control constitutes a storage amount adjustment control that suppresses the fluctuation range of the SOC.

  In this embodiment, the fluctuation range of the SOC is suppressed by the power storage amount adjustment control, so that the burden on the battery 52 is reduced and the deterioration of the battery 52 is suppressed. Further, by suppressing the fluctuation range of the SOC, there is an advantage that the capacity of the battery 52 can be reduced and the battery 52 can be reduced in size.

  Furthermore, the SOC of the battery 52 is suppressed from reaching 0% or 100% by the power storage amount adjustment control. For this reason, the control which suppresses the increase of the above-mentioned generated electric power FP and the control which suppresses the reduction | decrease in the generated electric power FP are always executable.

  Next, the specific contents of the power storage amount adjustment control described above will be described in more detail with reference to FIGS. 4, 5, and 6. FIG. 4 is a control block diagram showing the contents performed by the controller 60, and shows processing for controlling the generated power FP based on the required power RP and the SOC.

  As shown in FIG. 4, the controller 60 generates a generated power command value SFP, which is a control command value of the generated power FP, based on the required power RP, the SOC of the battery 52, and the target charged amount TSOC that is the target value of SOC. decide. The controller 60 controls the flow rate of the fuel gas and the DC / DC converter 51 so that the generated power FP matches the generated power command value SFP.

  In FIG. 4, the control block CT1 receives an input of the SOC and the required power RP (or the corrected required power RP0 based on the input), and determines how to change the generated power FP based on the input. The generated power command value SFP is output. The generated power command value SFP output from the control block CT1 is finally controlled so as to coincide with the input required power RP (or corrected required power RP0). Specific processing of the control block CT1 will be described later.

  For the SOC of the battery 52, the target charged amount TSOC is set as the target value. The controller 60 calculates the deviation between the SOC and the target charged amount TSOC (reference numeral SM2) and inputs it to the PID control block P1. The PID control block P1 is a control block that calculates an addition amount necessary for the required power RP with a normal PID in order to set the deviation to zero.

  Here, the required power RP may be directly input to the control block CT1. That is, the PID control block P1 may be omitted and the addition indicated by the symbol SM1 in FIG. 4 may not be performed. Even in this aspect, it is possible to suppress the fluctuation range of the SOC, and it is included in the embodiment of the present invention.

  However, in the present embodiment, as shown in FIG. 4, the required power RP is not directly input to the control block CT1, but the corrected required power RP0 obtained by adding the addition calculated by the PID control block P1 is controlled. Input to block CT1.

  For example, when the SOC is lower than the target power storage amount TSOC, the PID control block P1 calculates an addition (increase) to the required power RP necessary to make up for this shortage, and the controller 60 performs the addition. Minutes are added to the required power RP (symbol SM1). The required power RP increases correspondingly to become the corrected required power RP0, and the corrected required power RP0 is input to the control block CT1.

  As a result, the generated power command value SFP that is controlled to coincide with the correction required power RP0 also increases, and thus the generated power FP increases. The increased generated power FP compensates for the shortage of SOC, and the SOC approaches the target power storage amount TSOC. In addition, since the internal process of the PID control block P1 includes an integral term, a steady deviation between the SOC and the target charged amount TSOC is suppressed.

  That is, the controller 60 controls the generated power FP while feeding back the deviation between the SOC and the target charged amount TSOC so that the SOC converges to the target charged amount TSOC. Thus, the SOC of the battery 52 is controlled so as to converge to the target charged amount TSOC even in a situation where the required power RP from the load is small, and the fluctuation range of the SOC is further suppressed.

  The deviation between the SOC and the target charged amount TSOC is added to the generated power command value SFP output from the control block CT1, and the generated power FP may be controlled to match the new generated power command value after the addition. Conceivable. However, in that case, the deviation between the SOC and the target charged amount TSOC is suppressed, but if noise occurs in the input signal from the SOC sensor 73, the generated power FP may fluctuate greatly due to the influence of the noise. There is sex. As will be described in detail later, in the present embodiment, the generated power FP is added to the input side (required power RP) instead of the output side, so that the generated power FP can be detected by noise or measurement of the SOC sensor 73. It is prevented from being directly affected by value fluctuations.

  Next, specific processing of the control block CT1 will be described with reference to FIG. FIG. 5 is a control block diagram showing the contents performed by the controller 60, and shows the specific processing performed inside the control block CT1 shown in FIG. As described above, the control block CT1 receives the SOC and the required power RP (or the corrected required power RP0 based on the input), determines how to change the generated power FP, It is a control block which outputs generated electric power command value SFP.

  The basic process in the control block CT1 is to calculate a deviation between the input correction request power RP0 and the current generated power command value SFP (reference numeral SM3), and multiply this by a gain (gain PG or gain MG). An integration process is performed (symbol ITG), and a generated power command value SFP to be output is calculated. However, by providing the saturators PST and MST, different gains (gain PG and gain MG, respectively) are applied when the deviation between the correction required power RP0 and the generated power command value SFP is positive and negative. Is characteristic.

  The saturator PST is a control block that allows a signal to pass only when the deviation is positive, that is, when the correction required power RP0 is larger than the generated power command value SFP, and otherwise outputs 0. The saturator MST is a control block that passes a signal only when the deviation is negative, that is, when the correction required power RP0 is smaller than the generated power command value SFP, and outputs 0 at other times. Therefore, when the correction required power RP0 is larger than the generated power command value SFP, the gain PG is multiplied by the deviation between the two, and when the correction required power RP0 is smaller than the generated power command value SFP, the deviation between the two is obtained. Is multiplied by a gain MG.

  Here, the gain PG and the gain MG are not fixed values, and the values are changed by the SOC of the battery 52. Specifically, the value is determined with reference to the gain map shown in FIG.

  FIG. 6 is a diagram illustrating a gain map PGM that defines the relationship between the SOC and the gain PG, and a gain map MGM that defines the relationship between the SOC and the gain MG. As shown in FIG. 6, the gain map PGM has a constant value G0 when the SOC is 50% or less, which is the target charged amount TSOC. On the other hand, when the SOC exceeds 50%, which is the target power storage amount TSOC, the value is set to gradually decrease as the SOC increases.

  On the other hand, the gain map MGM has a constant value G0 when the SOC is 50% or more, which is the target storage amount TSOC. On the other hand, when the SOC falls below 50%, which is the target power storage amount TSOC, the value is set to gradually decrease as the SOC decreases.

  In the fuel cell system 10 according to the present embodiment, as a result of the gain map PGM and the gain map MGM being set as described above in the controller 60, the power storage amount adjustment control already described is performed, and the change in the required power RP The corresponding change in the generated power FP is as shown in FIGS.

  That is, when the required power RP increases, the deviation between the corrected required power RP0 and the generated power command value SFP becomes positive. At this time, the gain PG multiplied by the deviation becomes a high value (G0) when the SOC is smaller than the target charged amount TSOC, so the generated power command value SFP immediately increases. As a result, the generated power FP immediately increases (from time t1 to time t2 in FIG. 2).

  On the other hand, when the SOC is larger than the target charged amount TSOC, the value of the gain PG decreases as the SOC increases. Therefore, the increase in the generated power command value SFP is suppressed. As a result, the increase in the generated power FP is suppressed, and the increasing speed of the generated power FP becomes slow (from time t3 to time t4 in FIG. 3).

  Further, when the required power RP decreases, the deviation between the corrected required power RP0 and the generated power command value SFP becomes negative. At this time, the gain MG multiplied by the deviation becomes a high value (G0) when the SOC is larger than the target charged amount TSOC, so the generated power command value SFP is immediately reduced. As a result, the generated power FP decreases immediately (after time t4 in FIG. 3). On the other hand, when the SOC is smaller than the target charged amount TSOC, the value of the gain MG decreases as the SOC decreases. Therefore, the decrease in the generated power command value SFP is suppressed. As a result, the decrease in the generated power FP is suppressed, and the decrease rate of the generated power FP becomes slow (after time t2 in FIG. 2).

  Thus, in the present embodiment, by having the gain maps PGM and MGM set so that the gain changes according to the SOC, the storage amount adjustment control as shown in FIGS. 2 and 3 is realized. Yes.

  According to the gain map PGM, the greater the difference between the SOC of the battery 52 and the target charged amount TSOC (the greater the SOC), the greater the amount of suppression of the increase in the generated power FP when the required power RP increases. In order to control, the electric power discharged from the battery 52 is increased in order to compensate for the shortage with respect to the required power RP. For this reason, the amount of decrease in the SOC increases, and the SOC can be brought closer to the target charged amount TSOC.

  Further, according to the gain map MGM, the greater the difference between the target charged amount TSOC and the SOC of the battery 52 (the smaller the SOC), the greater the amount of suppression of the decrease in the generated power FP when the required power RP decreases. Thus, the surplus power stored in the battery 52 is increased. For this reason, the increase amount of SOC becomes large, and it is possible to bring the SOC closer to the target power storage amount TSOC.

  Here, after the control block CT1 that performs the control as described above removes a component having a frequency higher than a predetermined cutoff frequency from the input required power RP (or the corrected required power RP0 based thereon). It can be said that it is a kind of leveling device that outputs the generated power command value SFP. That is, the generated power command value SFP corresponds to the leveling request power in the present invention. Setting the gain PG and the gain MG by the gain map PGM and the gain map MGM corresponds to setting the cutoff frequency (first cutoff frequency and second cutoff frequency, respectively) of the leveling device.

  For example, when the gain PG or gain MG is a high value (G0) after time t1 in FIG. 2 or after time t4 in FIG. 3, this corresponds to the case where the cutoff frequency is set high. For this reason, the time change of the generated power command value SFP output is a time change that follows the input correction request power RP0 at high speed.

  On the other hand, when the gain PG or the gain MG is a low value after time t2 in FIG. 2 or after time t3 in FIG. 3, this corresponds to the case where the cutoff frequency is set low. As a result of removing the steep fluctuation component from the input correction request power RP0, the time change of the generated power generation command value SFP is more gradual than the time change of the input correction request power RP0. .

  As described above, in the fuel cell system 10 according to the present embodiment, the controller 60 changes the cutoff frequency of the control block CT1 so as to suppress the fluctuation range of the SOC. That is, by setting the gain PG or the gain MG based on the SOC measured by the SOC sensor 73, the cutoff frequency is changed, and control for suppressing the fluctuation range of the SOC (power storage amount adjustment control) is performed.

  In addition, although the above-described power storage amount adjustment control corrects the generated power command value SFP based on the SOC, the correction is performed directly by adding or subtracting a correction value to the generated power command value SFP. However, this is an indirect method of changing the cutoff frequency of the control block CT1.

  For this reason, even if the SOC fluctuates or noise occurs in the measured value of the SOC, the generated power command value SFP (and the generated power FP) greatly fluctuates due to the influence of such fluctuation factors. There is nothing. For this reason, fluctuations in the stack voltage Vc of the fuel cell stack 20 are suppressed, and dissolution of the metal catalyst and the like are suppressed.

  Subsequently, the control of the fuel cell system 10 performed when the storage performance of the battery 52 is reduced will be described. The storage performance of the battery 52 gradually decreases due to repeated use over a long period of time or charging and discharging. . In a state where the power storage performance is deteriorated, the amount of power that can be stored is small, so that sufficient charge / discharge that compensates for the mismatch between the generated power and the required power cannot be performed. For this reason, if it is attempted to perform the storage amount adjustment control as described above in such a state, the storage amount adjustment control may not be performed properly, and the dissolution and deposition of the metal catalyst may be accelerated instead.

  In order to prevent this, the fuel cell system 10 sets a filter gain lower limit value for the gain PG and the like. When the value of the gain PG or the like set by the gain map shown in FIG. 6 falls below the filter gain lower limit value, the filter gain lower limit value is set as the gain PG or the like.

  In addition, the controller 60 changes the filter gain lower limit value according to the storage performance of the battery 52. In a state where the power storage performance of the battery 52 is lowered, the power storage amount adjustment control is suppressed by setting the filter gain lower limit value higher. Further, the filter gain lower limit value is set to a higher value so that the storage amount adjustment control is not performed in a state where the storage performance has deteriorated.

  FIG. 7 is a diagram for explaining the control when the storage performance of the battery 52 is lowered, and shows the relationship between the storage performance of the battery 52 and the filter gain lower limit value. The “power storage performance” shown on the horizontal axis of FIG. 7 is calculated from the temperature of the battery 52, and the temperature (low temperature) when the power storage performance of the battery 52 is not deteriorated is 100%. The temperature (high temperature) when the power storage performance is significantly lowered and charging / discharging cannot be performed is set to 0%.

  The battery 52 includes a temperature sensor for measuring the temperature, and the measured value is input to the controller 60. Thereby, the controller 60 always grasps the state of the storage performance of the battery 52, and updates the filter gain lower limit value at a predetermined cycle based on the storage performance. It should be noted that the relationship between the temperature of the battery 52 and the power storage performance can be obtained in advance through experiments or the like.

  When the temperature of the battery 52 is low and the power storage performance is equal to or higher than the threshold value TH, the filter gain lower limit value is set to min0. min0 is sufficiently low, and the value such as the gain PG set by the gain map shown in FIG. 6 is set to a value that hardly falls below min0.

  When the temperature of the battery 52 rises and the power storage performance falls below the threshold value TH, the filter gain lower limit value is set to a value higher than min0 as shown in FIG. Thereafter, as the temperature of the battery 52 further increases, the lower limit value of the filter gain is set to a higher value, and finally set to min1 (in a state where the storage performance is remarkably reduced to near 0%). . In this embodiment, min1 has a value equal to G0 in FIG. That is, when the power storage performance is close to 0%, the gain PG and the gain MG are both set to be constant at G0, so that the power storage amount adjustment control is not executed. Note that min1 may be set as a value higher than G0.

  As described above, the controller 60 does not perform the storage amount adjustment control when determining that the storage performance of the battery 52 has decreased. As a result, in a situation where the power storage performance of the battery 52 is degraded, the power storage amount adjustment control is prevented from being appropriately performed.

  Subsequently, another embodiment of the present invention will be described. In the present embodiment, only the leveling process performed by the control block CT1 is different, and the rest is the same as the fuel cell system 10. Therefore, hereinafter, the control block will be referred to as a control block CT2, and only the content of the leveling process performed by the control block CT2 will be described, and the other description will be omitted.

  Similar to the control block CT1, the control block CT2 receives the SOC and the correction request power RP0, determines how to change the generated power FP based on the input, and generates the generated power command value SFP. Output. The control block CT2 is a leveling device called a so-called low-pass filter that outputs a generated power command value SFP after removing a component having a frequency higher than a predetermined cut-off frequency from the input correction request power RP0. .

  The control block CT2 has a setting table that stores the relationship between the SOC and the cutoff frequency, and the cutoff frequency is set according to the input SOC while referring to the setting table. FIG. 8 shows the contents of the setting table.

  As shown in FIG. 8, a plurality of values corresponding to the SOC are set as the cutoff frequency. In addition, a set value (first cutoff frequency) when the required power RP (and correction required power RP0) increases and a set value (second cutoff frequency) when it decreases are set.

  In a state where the SOC is appropriate (for example, a state where the SOC is 40% to 80%), the reference cutoff frequency Fc is set as the cutoff frequency regardless of whether the required power RP increases or decreases. The reference cut-off frequency Fc is a relatively high frequency, and for example, the output generated power command value SFP can follow the input correction request power RP0 at high speed, for example, after time t1 in FIG. The frequency is such that

  When the SOC is high (for example, 80% to 90%), the absolute value of the deviation (ΔSOC) between the SOC and the target power storage amount TSOC is multiplied by a predetermined proportional constant K and multiplied by 1. A value obtained by dividing the reference cutoff frequency Fc by the value (hereinafter referred to as an adjusted cutoff frequency Fc2) is set as the cutoff frequency when the required power RP increases. On the other hand, the cut-off frequency when the required power RP decreases is not changed with the reference cut-off frequency Fc.

  The adjusted cutoff frequency Fc2 is a lower frequency than the reference cutoff frequency Fc. Therefore, when the required power RP increases, as a result of removing the steep fluctuation component from the input correction required power RP0, the temporal change in the generated power command value SFP output is the input correction required power. Compared to the time change of RP0, it becomes gradual. The generated power FP is insufficient with respect to the required power RP, and the battery 52 is prompted to discharge. As a result, the power storage balance of the battery 52 becomes negative, and the higher SOC approaches the target power storage amount TSOC.

  In a state where the SOC is further increased and becomes equal to or higher than the upper limit (for example, 90%), the cutoff frequency when the required power RP increases is set to be the adjusted cutoff frequency Fc2 as described above. Note that as ΔSOC increases, the adjusted cut-off frequency Fc2 has a lower value than the above.

  On the other hand, the cutoff frequency when the required power RP decreases is set to infinity. That is, the input correction required power RP0 is output as it is as the generated power command value SFP. That is, when the required power RP decreases, the generated power FP is quickly reduced, and as a result, the battery 52 is also discharged. For this reason, the power storage balance of the battery 52 is greatly negative, and the SOC that is equal to or higher than the upper limit immediately decreases and approaches the target power storage amount TSOC.

  In a state where the SOC is low (for example, a state of 20% to 40%), the adjusted cutoff frequency Fc2 is set as a cutoff frequency when the required power RP decreases. On the other hand, the cut-off frequency when the required power RP is increased remains the reference cut-off frequency Fc.

  The adjusted cutoff frequency Fc2 is a lower frequency than the reference cutoff frequency Fc. Therefore, when the required power RP decreases, as a result of removing the steep fluctuation component from the input correction required power RP0, the time change of the generated power command value SFP output is the input correction required power. Compared to the time change of RP0, it becomes gradual. The generated power FP becomes surplus with respect to the required power RP and is stored in the battery 52. As a result, the storage balance of the battery 52 becomes positive, and the lower SOC approaches the target storage amount TSOC.

  In a state where the SOC is further lowered and is lower than the lower limit (for example, 20%), the cutoff frequency when the required power RP decreases is set to be the adjusted cutoff frequency Fc2 as described above. Note that as ΔSOC increases, the adjusted cut-off frequency Fc2 has a lower value than the above.

  On the other hand, the cutoff frequency when the required power RP increases is set to infinity. That is, the input correction required power RP0 is output as it is as the generated power command value SFP. That is, when the required power RP increases, the generated power FP is quickly increased. As a result, excess power is also stored in the battery 52 in this case. For this reason, the power storage balance of the battery 52 becomes a large plus, and the SOC that is equal to or lower than the lower limit immediately increases and approaches the target power storage amount TSOC.

  As described above, the controller 60 changes the cutoff frequency of the control block CT2 so as to suppress the fluctuation range of the SOC. In other words, the control for suppressing the fluctuation range of the SOC (power storage amount adjustment control) is performed by setting the cutoff frequency based on the SOC measured by the SOC sensor 73 and the setting table shown in FIG.

  In the present embodiment, similar to the control performed by the control block CT1, the correction of the generated power command value SFP based on the SOC is performed by an indirect method of changing the cutoff frequency of the control block CT2. For this reason, even if the SOC fluctuates or noise occurs in the measured value of the SOC, the generated power command value SFP (and the generated power FP) greatly fluctuates due to the influence of such fluctuation factors. There is nothing. For this reason, fluctuations in the stack voltage Vc of the fuel cell stack 20 are suppressed, and dissolution of the metal catalyst and the like are suppressed.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10: Fuel cell system 20: Fuel cell stack 30: Oxidant gas supply system 31: Filter 32: Air compressor 33: Oxidant gas passage 34: Oxidation off-gas passage 35: Humidifier 40: Fuel gas supply system 41: Fuel gas supply Source 42: Injector 43: Fuel gas passage 44: Circulation passage 45: Circulation pump 46: Exhaust drain passage 50: Electric power system 51: DC / DC converter 52: Battery 53: Traction inverter 54: Traction motor 55: Auxiliary machinery 60: Controller 71: Voltage sensor 72: Current sensor 73: SOC sensor 74: Pressure sensor A2: Shut-off valve A3: Back pressure adjustment valve ACC: Accelerator opening signal VV: Vehicle speed signal FP: Generated power H1: Shut-off valve H2: Regulator H3: Shut-off valve H4: Shut-off valve H5: Exhaust drain valve IG: Igni Switch PG, MG: Gain PGM, MGM: Gain map PST, MST: Saturator RP: Required power RP0: Correction required power SP: System power SFP: Generated power command value TSOC: Target power storage amount TH: Threshold voltage Vc: Stack voltage CT1 , CT2: Control block P1: PID control block Reference cutoff frequency: Fc

Claims (6)

In the fuel cell system for outputting the generated power from the fuel cell to the load based on the required power from the load,
Required power measuring means for measuring the required power;
Control means for controlling the generated power;
A power storage device connected in parallel to the fuel cell with respect to the load for performing power storage and discharge;
A storage amount measuring means for measuring a storage amount of the power storage device;
With
The controller is
For the measured value of the required power, calculate the leveled required power by performing a leveling process that removes a frequency component higher than the cutoff frequency,
The generated power is controlled to follow the leveling required power,
A fuel cell system that performs power storage amount adjustment control that suppresses a fluctuation range of the power storage amount by changing the cutoff frequency based on the power storage amount. The control device, as the cutoff frequency,
A first cut-off frequency used when the required power increases;
A second cutoff frequency used when the required power is reduced,
If the amount of electricity stored is greater than a predetermined target amount of electricity, reduce the first cutoff frequency,
2. The fuel cell system according to claim 1, wherein the second cutoff frequency is decreased when the charged amount is smaller than the target charged amount. The controller is
The more the power storage amount is greater than the target power storage amount, the greater the first cutoff frequency,
3. The fuel cell system according to claim 2, wherein the second cutoff frequency is greatly decreased as the charged amount is smaller than the target charged amount. 4. The controller is
The leveled required power is calculated by multiplying the difference between the required power and the generated power by a filter gain and then performing an integration process,
4. The fuel cell system according to claim 3, wherein the first cutoff frequency or the second cutoff frequency is decreased by decreasing the filter gain based on the charged amount. 5.   The control means controls the generated power while feeding back a deviation of the charged amount relative to the target charged amount so that the charged amount converges to the target charged amount. Item 5. The fuel cell system according to any one of Items 4.   The fuel cell system according to any one of claims 1 to 5, wherein the control device does not perform the power storage amount adjustment control when it is determined that the power storage performance of the power storage device has deteriorated. .

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