JP2008140618A - Fuel cell system - Google Patents

Abstract

Even if a power generation command value fluctuates greatly, gas supply is controlled with high responsiveness to the power generation command without increasing the drive frequency of an injector.
A fuel cell system includes a fuel cell stack that generates power upon receiving a supply of a reaction gas, an injector that controls the supply of the reaction gas to the fuel cell stack, and a secondary pressure of the injector that is allowable with reference to a target pressure. A controller for controlling the opening and closing of the injector so as to converge within the range of the upper limit value and the allowable error lower limit value. When the amount of change per unit time in the power generation command value to the fuel cell stack exceeds a predetermined threshold, the controller controls the opening / closing of the injector using the allowable error upper limit value as a new target pressure.
[Selection] Figure 3

Description

  The present invention relates to a fuel cell system having an on-off valve that controls supply of a reaction gas to a fuel cell stack.

  In recent years, low-pollution vehicles have been developed as part of efforts to deal with environmental problems, and one of them is a fuel cell vehicle using a fuel cell system as an on-vehicle power source. A fuel cell system causes an electrochemical reaction by supplying a reaction gas to a membrane-electrode assembly in which an anode electrode is disposed on one surface of an electrolyte membrane and a cathode electrode is disposed on the other surface, and chemical energy is generated. Is an energy conversion system that converts electricity into electrical energy. In particular, a solid polymer electrolyte fuel cell system using a solid polymer membrane as an electrolyte is easy to downsize at low cost and has a high output density, so that it is expected to be used as an in-vehicle power source. Yes.

  As a means for controlling the flow rate and pressure of the fuel gas supplied to the fuel cell stack with high accuracy, for example, a configuration using an injector having excellent responsiveness as disclosed in JP-A-2005-302563 is known. Yes.

In the conventional fuel cell system, as shown in FIG. 5, the target pressure of the fuel gas supplied to the fuel cell stack is calculated based on the power generation command value, and the secondary pressure of the injector is set to the upper limit of the allowable error based on the target pressure. The gas injection time and injection timing of the injector are controlled so as to converge between the value and the allowable error lower limit value. The target pressure is the power generation indication value output from the accelerator pedal, taking into account the power generation characteristics of the fuel cell stack (such as the relationship between the fuel gas pressure and the power generation efficiency, and the relationship between the fuel gas pressure and the cross leak amount). Based on the calculation, the fuel gas consumption and the pressure increase in the fuel cell stack are taken into consideration.
JP 2005-302563 A

  However, conventionally, since control is performed so that the gas injection of the injector is restricted when the secondary pressure of the injector reaches the target pressure, when the amount of change per unit time of the power generation instruction value increases (for example, FIG. 5). During the time t0 to t1), the gas supply from the ejector cannot catch up with the target pressure. Then, since the average value of the secondary pressure (actual pressure) of the injector becomes lower than the target pressure, in order to make the secondary pressure of the injector follow the target pressure with good response, the injector's It is necessary to increase the driving frequency.

  However, when the drive frequency of the injector is increased, there is a problem that the mechanical durability of the injector is lowered and mechanical noise is increased.

  Accordingly, the present invention solves such a problem and proposes a fuel cell system capable of controlling the gas supply with high responsiveness to the power generation command without increasing the drive frequency of the on-off valve even when the power generation command value fluctuates greatly. This is the issue.

  In order to solve the above-described problems, a fuel cell system according to the present invention includes a fuel cell stack that generates power upon receiving a supply of a reaction gas, an on-off valve that controls the supply of the reaction gas to the fuel cell stack, and an on-off valve. Control means for controlling opening / closing of the on-off valve so that the next pressure converges within a range between an allowable error upper limit value and an allowable error lower limit value with reference to the target pressure. When the change amount per unit time of the power generation command value to the fuel cell stack exceeds a predetermined threshold, the control means controls the opening / closing valve with the allowable error upper limit value as a new target pressure.

  With this configuration, it is possible to follow the gas supply with high responsiveness to the power generation command value without increasing the drive frequency of the on-off valve.

  When the amount of change per unit time of the power generation command value to the fuel cell stack exceeds a predetermined threshold, the control means opens and closes until the secondary pressure of the on-off valve reaches the allowable error upper limit by one gas injection. Control to keep the valve open.

  For example, an injector is suitable as the on-off valve. Since the injector is excellent in responsiveness, highly accurate reaction gas supply control to the fuel cell stack can be realized.

  According to the present invention, the gas supply can be made to follow the power generation command value with high responsiveness without increasing the drive frequency of the on-off valve.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a system configuration of a fuel cell system 10 that functions as an in-vehicle power supply system for a fuel cell vehicle.

  The fuel cell system 10 includes a fuel cell stack 20 that generates power upon receiving supply of reaction gases (oxidation gas and fuel gas), a fuel gas piping system 30 that supplies hydrogen gas as fuel gas to the fuel cell stack 20, an oxidation An oxidizing gas piping system 40 that supplies air as gas to the fuel cell stack 20, a power system 60 that controls charging / discharging of power, and a controller 70 that controls the entire system are provided.

  The fuel cell stack 20 is, for example, a solid polymer electrolyte cell stack formed by stacking a large number of cells in series. The cell has a cathode electrode on one surface of an electrolyte membrane made of an ion exchange membrane, an anode electrode on the other surface, and a pair of separators so as to sandwich the cathode electrode and the anode electrode from both sides. Yes. 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 stack 20 generates power by this gas supply.

  The fuel gas piping system 30 includes a fuel gas supply source 31, a fuel gas supply passage 35 through which fuel gas (hydrogen gas) supplied from the fuel gas supply source 31 to the anode electrode of the fuel cell stack 20 flows, and a fuel cell stack. A circulation passage 36 for recirculating the fuel off-gas (hydrogen off-gas) discharged from the fuel gas supply passage 35 to the fuel gas supply passage 35, and a circulation pump 37 for pressure-feeding the fuel off-gas in the circulation passage 36 to the fuel gas supply passage 35. And an exhaust passage 39 branched and connected to the circulation passage 36.

  The fuel gas supply source 31 is composed of, for example, a high-pressure hydrogen tank or a hydrogen storage alloy, and stores, for example, 35 MPa or 70 MPa of hydrogen gas. When the shut-off valve 32 is opened, hydrogen gas flows out from the fuel gas supply source 31 into the fuel gas supply channel 35. The hydrogen gas is decompressed to, for example, about 200 kPa by the regulator 33 and the injector 34 and supplied to the fuel cell stack 20.

  The fuel gas supply source 31 includes a reformer that generates hydrogen-rich reformed gas from hydrocarbon fuel, a high-pressure gas tank that stores the reformed gas generated by the reformer in a high-pressure state, and You may comprise.

  The regulator 33 is a device that regulates the upstream pressure (primary pressure) to a preset secondary pressure. In the present embodiment, a mechanical pressure reducing valve that reduces the primary pressure is employed as the regulator 33. The mechanical pressure reducing valve has a structure 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. Thus, a publicly known configuration for the secondary pressure can be employed.

  By arranging the regulator 33 on the upstream side of the injector 34, the upstream pressure of the injector 33 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 34 can be raised. In addition, since the upstream pressure of the injector 34 can be reduced, the valve body of the injector 34 is less likely to move due to an increase in the differential pressure between the upstream pressure and the downstream pressure of the injector 34. be able to. Therefore, the adjustable pressure width of the downstream pressure of the injector 34 can be widened, and a decrease in responsiveness of the injector 34 can be suppressed.

  The injector 34 is an electromagnetically driven on-off valve capable of adjusting the gas flow rate and gas pressure by driving the valve body directly with a predetermined driving cycle with an electromagnetic driving force and separating it from the valve seat. The injector 34 has a valve body for opening or closing the fuel gas supply passage 35, a solenoid coil for driving the valve body, an armature integrated with the valve body, and a stator for housing the solenoid coil. Then, by energizing the solenoid coil, the armature is attracted to the stator and the valve element is moved to a predetermined valve opening position or valve closing position.

  In the present embodiment, the opening area of the injection hole of the injector 34 can be switched in two stages by turning on / off the pulse excitation current supplied to the solenoid coil. By controlling the gas injection time and gas injection timing of the injector 34 according to the injection command output from the controller 70, the flow rate and pressure of the fuel gas are controlled with high accuracy. The injector 34 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 34 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 34 in order to supply the required gas flow rate downstream. The gas flow rate (or hydrogen molar concentration) supplied to the side (fuel cell stack 20 side) is adjusted.

  In addition, since the gas flow rate is adjusted by opening and closing the valve body of the injector 34 and the gas pressure supplied downstream of the injector 34 is reduced from the gas pressure upstream of the injector 34, the injector 34 is controlled by a pressure regulating valve (pressure reducing valve or regulator). Can also be interpreted. Further, in this embodiment, a variable pressure control valve capable of changing the pressure adjustment amount (pressure reduction amount) of the upstream gas pressure of the injector 34 so as to match the required pressure within a predetermined pressure range in accordance with the gas demand. Can also be interpreted. The injector 34 functions as a variable gas supply device that adjusts the gas state (gas flow rate, hydrogen molar concentration, gas pressure) on the upstream side of the fuel gas supply flow path 35 and supplies it to the downstream side.

  The fuel gas supply channel 35 includes a primary pressure sensor 81 for detecting the upstream pressure (primary pressure) of the injector 34, a primary temperature sensor 83 for detecting the upstream temperature of the injector 34, and the injector 34. Secondary pressure sensors 82 for detecting the downstream pressure (secondary pressure) are respectively attached.

  An exhaust passage 39 is connected to the circulation passage 36 via an exhaust valve 38. The exhaust valve 38 is operated according to a command from the controller 70, and thereby discharges the fuel off-gas and impurities including impurities in the circulation flow path 36 to the outside. By opening the exhaust valve 38, the concentration of impurities in the fuel off-gas in the circulation passage 36 decreases, and the concentration of hydrogen in the fuel off-gas that is circulated increases.

  The diluter 50 is supplied with the fuel off-gas discharged through the exhaust valve 38 and the exhaust passage 39 and the oxidizing off-gas flowing through the discharge passage 45 to dilute the fuel off-gas. The diluted exhaust gas of the fuel off-gas is silenced by a muffler (silencer) 51, flows through the tail pipe 52, and is exhausted outside the vehicle.

  The oxidizing gas piping system 40 includes an oxidizing gas supply passage 44 through which oxidizing gas supplied to the cathode electrode of the fuel cell stack 20 flows, and a discharge passage 45 through which oxidizing off gas discharged from the fuel cell stack 20 flows. ing.

  The oxidizing gas supply flow path 44 is provided with an air compressor 42 that takes in the oxidizing gas via the filter 41 and a humidifier 43 for humidifying the oxidizing gas that is pumped by the air compressor 42. The discharge passage 45 is provided with a back pressure adjustment valve 46 for adjusting the oxidizing gas supply pressure and a humidifier 43.

  The humidifier 43 accommodates a water vapor permeable membrane bundle (hollow fiber membrane bundle) composed of a large number of water vapor permeable membranes (hollow fiber membranes). A highly humid oxidizing off gas (wet gas) containing a large amount of water generated by the battery reaction flows inside the water vapor permeable membrane, while a low wet oxidizing gas taken from the atmosphere is outside the water permeable membrane. (Dry gas) flows. Oxidizing gas can be humidified by performing water exchange between the oxidizing gas and the oxidizing off gas across the water vapor permeable membrane.

  The power system 60 includes a DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, and a current sensor 84.

  The DC / DC converter 61 is a DC voltage converter, which boosts the DC voltage from the battery 62 and outputs it to the traction inverter 63, and steps down the DC voltage from the fuel cell stack 20 or the traction motor 64. And a function of charging the battery 62. The charge / discharge of the battery 62 is controlled by these functions of the DC / DC converter 61. Further, the operation point (output voltage, output current) of the fuel cell stack 20 is controlled by the voltage conversion control by the DC / DC converter 61.

  The battery 62 is a power storage device capable of storing and discharging electric power, and functions as a regenerative energy storage source at the time of brake regeneration and an energy buffer at the time of load fluctuation accompanying acceleration or deceleration of the fuel cell vehicle. As the battery 62, for example, a secondary battery such as a nickel / cadmium storage battery, a nickel / hydrogen storage battery, or a lithium secondary battery is suitable.

  The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 is a three-phase AC motor, for example, and constitutes a power source of the fuel cell vehicle.

  The current sensor 84 detects the output current (sweep current) of the fuel cell stack 20.

  The controller 70 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 70 receives an activation signal output from an ignition switch (not shown), the controller 70 starts operation of the fuel cell system 10 and an accelerator opening signal output from an accelerator sensor (not shown), Based on a vehicle speed signal output from a vehicle speed sensor (not shown), the required power of the entire system is obtained. The required power of the entire system is the total value of the vehicle running power and the auxiliary machine power.

  Auxiliary power includes, for example, power consumed by in-vehicle auxiliary equipment (humidifiers, air compressors, hydrogen pumps, cooling water circulation pumps, etc.), and devices required for vehicle travel (transmissions, wheel control devices, steering devices) , And suspension devices), and power consumed by devices (such as air conditioners, lighting fixtures, and audio devices) disposed in the passenger space.

  Then, the controller 70 determines the distribution of the output power of the fuel cell stack 20 and the battery 62, and the rotational speed of the air compressor 42 and the valve opening of the injector 34 so that the power generation amount of the fuel cell stack 20 matches the target power. And adjusting the output voltage of the fuel cell stack 20 by controlling the DC / DC converter 61 and adjusting the output voltage of the fuel cell stack 20. Voltage and output current). Further, the controller 70 outputs, for example, each U-phase, V-phase, and W-phase AC voltage command value to the traction inverter 63 as a switching command so that the target vehicle speed according to the accelerator opening is obtained, and the traction motor 64 output torque and rotation speed are controlled.

FIG. 2 shows functional blocks related to injector control.
Based on the operating state of the fuel cell stack 20 (the output current of the fuel cell stack 20 detected by the current sensor 84), the controller 70 determines the amount of fuel gas consumed by the fuel cell stack 20 (hereinafter referred to as “fuel consumption”). (Fuel consumption calculation function: B1). In the present embodiment, the fuel consumption is calculated and updated every calculation cycle of the controller 70 using a specific calculation expression representing the relationship between the output current value of the fuel cell stack 20 and the fuel consumption. .

  Based on the operating state of the fuel cell stack 20 (current value during power generation of the fuel cell stack 20 detected by the current sensor 84), the controller 70 sets the target pressure value of the fuel gas at the downstream position of the injector 34 (to the fuel cell stack 20). Target gas supply pressure) (target pressure value calculation function: B2). In the present embodiment, the map data representing the relationship between the current value of the fuel cell stack 20 and the target pressure value is used for each calculation cycle of the controller 70 at the position (pressure adjustment). Is calculated and updated at a target pressure value at a pressure adjustment position).

  The controller 70 calculates the feedback correction flow rate based on the deviation between the calculated target pressure value and the pressure value (detected pressure value) at the downstream position (pressure adjustment position) of the injector 34 detected by the secondary pressure sensor 82 ( Feedback correction flow rate calculation function: B3). The feedback correction flow rate is a fuel gas flow rate (pressure difference reduction correction flow rate) that is added to the fuel consumption in order to reduce the deviation between the target pressure value and the detected pressure value. In the present embodiment, the feedback correction flow rate is calculated and updated every calculation cycle of the controller 70 using the PI type feedback control law.

Specifically, the controller 70 multiplies the deviation (e) between the target pressure value and the detected pressure value by a proportional gain (K _P ) to generate a proportional feedback correction flow rate (proportional term: P = K _P × e). In addition to calculating the integral feedback correction flow rate (integral term: I = K _I × ∫ (e) dt) by multiplying the time integral value of deviation (∫ (e) dt) by the integral gain (K _I ). The feedback correction flow rate including a value obtained by adding these is calculated.

  The controller 70 calculates a feedforward corrected flow rate corresponding to the deviation between the previously calculated target pressure value and the currently calculated target pressure value (feedforward corrected flow rate calculation function: B4). The feedforward correction flow rate is a change in the fuel gas flow rate due to the change in the target pressure value (correction flow corresponding to the pressure difference). In the present embodiment, the feedforward correction flow rate is calculated and updated every calculation cycle of the controller 70 using a specific calculation formula representing the relationship between the deviation of the target pressure value and the feedforward correction flow rate.

  Based on the gas state upstream of the injector 34 (the pressure of the fuel gas detected by the primary side pressure sensor 81 and the temperature of the fuel gas detected by the primary side temperature sensor 83), the controller 70 detects the static gas upstream of the injector 34. The static flow rate is calculated (static flow rate calculation function: B5). In the present embodiment, the static flow rate is calculated and updated every calculation cycle of the controller 70 using a specific calculation formula representing the relationship between the pressure and temperature of the fuel gas upstream of the injector 34 and the static flow rate. To do.

  The controller 70 calculates the invalid injection time of the injector 34 based on the upstream gas state (fuel gas pressure and temperature) of the injector 34 and the applied voltage (invalid injection time calculation function: B6). Here, the invalid injection time means the time required from when the injector 34 receives a control signal from the controller 70 until the actual injection is started. In the present embodiment, the invalid injection time is calculated for each calculation cycle of the controller 70 using map data representing the relationship between the pressure and temperature of the fuel gas upstream of the injector 34, the applied voltage, and the invalid injection time. We are going to update.

  The controller 70 calculates the injection flow rate of the injector 34 by adding the fuel consumption amount, the feedback correction flow rate, and the feedforward correction flow rate (injection flow rate calculation function: B7). Then, the controller 70 calculates the basic injection time of the injector 34 by multiplying the value obtained by dividing the injection flow rate of the injector 34 by the static flow rate by the drive period of the injector 34, and also calculates the basic injection time and the invalid injection time. Are added to calculate the total injection time of the injector 34 (total injection time calculation function: B8). Here, the drive cycle means a stepped (on / off) waveform cycle representing the opening / closing state of the injection hole of the injector 34. In the present embodiment, the controller 70 sets the drive cycle to a constant value.

  The controller 70 controls the gas injection time and the gas injection timing of the injector 34 by outputting an injection command for realizing the total injection time of the injector 34 calculated through the above procedure to the fuel cell. The flow rate and pressure of the fuel gas supplied to the stack 20 are adjusted.

Next, a method for setting the target pressure of the injector 34 will be described with reference to FIG.
During normal operation, the controller 70 controls the injector 34 to open and close so that the secondary pressure of the injector 34 converges within the range of the allowable error upper limit value and the allowable error lower limit value with reference to the target pressure.

  When the change amount per unit time of the power generation instruction value to the fuel cell stack 20 exceeds a predetermined threshold (period t0 to t1), the controller 70 sets the allowable error upper limit value as a new target pressure. . Thus, by setting the allowable error upper limit value as a new target pressure, the injector 34 continues to supply gas by one gas injection until the secondary pressure reaches the allowable error upper limit value. The gas supply can sufficiently follow the power generation command value without increasing the power.

  However, if the allowable error upper limit value is close to the upper limit of the mechanical strength of the injector 34, setting the allowable error upper limit value as a new target pressure may damage the injector 34. It is preferable to set the target pressure during normal operation as a control target without setting a new target pressure.

  It should be noted that the period during which the allowable error upper limit is operated as the new target pressure is such a short time that the vehicle is accelerated rapidly, so that the cross leak of the fuel cell stack 20 caused by setting the target pressure higher is , Hardly a problem. In addition, because of the power generation characteristics of the fuel cell stack 20, the power generation efficiency is increased at an operation point where the gas supply pressure is high. Therefore, temporarily operating with the allowable error upper limit as a new target pressure is also from the viewpoint of energy efficiency. It can be said that there is no problem.

  Due to the power generation characteristics of the fuel cell stack 20, there are operating points where the generated power is sensitive to fluctuations in the gas supply pressure and operating points where the generated power is less affected by fluctuations in the gas supply pressure. . For the former, the pressure adjustment range (difference between the allowable error upper limit value and the allowable error lower limit value) can be set narrow, and for the latter, the pressure adjustment range can be set wide.

  Next, the opening / closing timing of the injector 34 will be described with reference to FIG. In the figure, A shows the opening / closing timing of the injector 34 according to the conventional example, and B shows the opening / closing timing of the injector 34 according to the present embodiment.

  In the conventional example, when the change amount per unit time of the power generation command value exceeds a predetermined threshold at the time t0, the drive frequency of the injector 34 is increased to compensate for the gas supply delay with respect to the power generation command value. The gas injection was performed a plurality of times until the time t2 when the secondary pressure of the gas coincided with the target pressure.

  On the other hand, in the present embodiment, when the change amount per unit time of the power generation command value exceeds a predetermined threshold at the timing of time t0, the injector 34 continues until the time t1 when the secondary pressure reaches the allowable error upper limit value. Since the gas supply is continued by one gas injection, the gas supply can be made to quickly follow the power generation command value without increasing the drive frequency.

  In addition, when the gas injection of the injector 34 is PID-controlled, there is a possibility that the gas injection is interrupted in the middle due to the influence of the feedback control before the secondary pressure of the injector 34 reaches the allowable error upper limit value. Therefore, it is preferable to cancel the feedback control during the period in which the injector 34 is controlled with the allowable error upper limit value as the new target pressure.

  As described above, according to this embodiment, when the amount of change per unit time of the power generation instruction value exceeds a predetermined threshold, the target pressure of the secondary pressure of the injector 34 is set to the allowable error upper limit value. Therefore, it is possible to quickly follow the gas supply with respect to the power generation command value without increasing the drive frequency. Further, since it is not necessary to increase the drive frequency of the injector 34, the mechanical durability of the injector 34 is not lowered and the generation of mechanical noise can be suppressed.

  In the above-described embodiment, the usage form in which the fuel cell system 10 is used as the in-vehicle power supply system is illustrated, but the usage form of the fuel cell system 10 is not limited to this example. For example, the fuel cell system 10 may be mounted as a power source of a mobile body (robot, ship, aircraft, etc.) other than the fuel cell vehicle. Further, the fuel cell system 10 according to the present embodiment may be used as a power generation facility (stationary power generation system) such as a house or a building.

1 is a system configuration diagram of a fuel cell system according to an embodiment. It is a functional block diagram of the injector control concerning this embodiment. It is a graph which shows the time change of the target pressure of the secondary pressure of the injector concerning this embodiment. It is a timing chart which shows the opening / closing timing of an injector. It is a graph which shows the time change of the target pressure of the secondary pressure of the injector concerning a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 20 ... Fuel cell stack 30 ... Fuel gas piping system 31 ... Fuel gas supply source 32 ... Shut-off valve 33 ... Regulator 34 ... Injector 35 ... Fuel gas supply flow path 40 ... Oxidizing gas piping system 41 ... Filter 42 ... Air compressor 43 ... Humidifier 44 ... Oxidizing gas supply flow path 60 ... Power system 61 ... DC / DC converter 62 ... Battery 63 ... Traction inverter 64 ... Traction motor 70 ... Controller

Claims (3)

A fuel cell stack that generates power upon receiving the supply of a reaction gas;
An on-off valve for controlling supply of a reaction gas to the fuel cell stack;
Control means for controlling opening and closing of the on-off valve so that the secondary pressure of the on-off valve converges within a range of an allowable error upper limit value and an allowable error lower limit value with reference to a target pressure;
With
The control means controls opening and closing of the on-off valve with the allowable error upper limit value as a new target pressure when a change amount per unit time of the power generation command value to the fuel cell stack exceeds a predetermined threshold value. Fuel cell system. The fuel cell system according to claim 1,
When the amount of change per unit time in the power generation command value to the fuel cell stack exceeds a predetermined threshold, the control means causes the secondary pressure of the on-off valve to be set to the allowable error upper limit value by a single gas injection. A fuel cell system that controls to keep the on-off valve open until it reaches The fuel cell system according to claim 1 or 2, wherein
The fuel cell system, wherein the on-off valve is an injector.

Images