JP2024073255A - Fuel Cell Systems - Google Patents

Abstract

[Problem] To estimate the pressure acting on the anode side or the cathode side with good accuracy without using a dedicated pressure gauge. [Solution] A fuel cell system includes a flow rate detection unit that detects the flow rate of at least one of the raw fuel gas, reforming water, and oxidant gas, and obtains the driving state of the pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side based on the obtained driving state of the pump and the flow rate detected by the flow rate detection unit, using the relationship between the driving state of the pump, the flow rate, and the pressure acting on the anode side or the cathode side. [Selected Figure] Figure 2

Description

This specification discloses a fuel cell system.

A conventional fuel cell system of this type includes a fuel cell stack, a hydrogen gas supply pipe for supplying hydrogen gas to the anode of the fuel cell stack, a hydrogen gas pressure regulating valve provided in the hydrogen gas supply pipe, an anode pressure gauge provided on the anode inlet side of the hydrogen gas supply pipe, an air supply pipe for supplying air gas to the cathode of the fuel cell stack by a compressor, an air gas pressure regulating valve provided in the air supply pipe, a cathode pressure gauge provided on the cathode inlet side of the air supply pipe, and a control device for controlling the hydrogen gas pressure regulating valve and the air gas pressure regulating valve so that the pressure difference between the hydrogen gas pressure and the air gas pressure is kept within a predetermined pressure difference range according to the required output (see, for example, Patent Document 1). In this system, the opening of the hydrogen gas pressure regulating valve is controlled by the anode pressure measured by the anode pressure gauge, and the hydrogen gas supplied through the hydrogen gas supply pipe is adjusted to a predetermined pressure determined within the range in which the fuel cell system can operate, and supplied to the anode of the fuel cell stack. In addition, by controlling the opening of the air gas pressure regulating valve and the compressor speed based on the cathode pressure measured by the cathode pressure gauge, the air supplied through the air supply pipe is adjusted to a specified pressure within the range in which the fuel cell system can operate, and then supplied to the cathode of the fuel cell stack.

JP 2006-278046 A

In the above-mentioned fuel cell system, a dedicated pressure gauge is required for each of the anode inlet side of the hydrogen gas supply pipe and the cathode inlet side of the air supply pipe, which increases the size of the system and leads to increased costs.

The primary objective of the fuel cell system disclosed herein is to estimate the pressure acting on the anode or cathode side with high accuracy without using a dedicated pressure gauge.

The fuel cell system disclosed herein employs the following measures to achieve the above-mentioned primary objective:

A first fuel cell system of the present disclosure includes:
a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a flow rate detection unit that detects a flow rate of at least one of the raw fuel gas, the reforming water, and the oxidizing gas;
a control unit that acquires a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump and the flow rate detected by the flow rate detection unit, using a relationship between a value based on the driving state of the pump, a value based on the flow rate, and a value of pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
The gist of the invention is to provide the following:

The first fuel cell system disclosed herein includes a flow rate detector that detects the flow rate of at least one of the raw fuel gas, reforming water, and oxidant gas, acquires the driving state of the pump in the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side using the relationship between the driving state of the pump, the flow rate, and the pressure based on the acquired driving state of the pump and the flow rate detected by the flow rate detector. This makes it possible to estimate the pressure acting on the anode side or the cathode side with good accuracy without using a dedicated pressure gauge. Note that "relationship" includes a regression relationship (the same applies below).

In the first fuel cell system of the present disclosure, a temperature detection unit is provided that detects the temperature of at least one of the fuel cell, the reforming unit, the evaporation unit, the combustion unit, the combustion exhaust gas discharged from the combustion unit, and the oxidant gas supplied from the oxidant gas supply unit, and the control unit may estimate the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump, the flow rate detected by the flow rate detection unit, and the temperature detected by the temperature detection unit, using the relationship between a value based on the driving state of the pump, a value based on the flow rate, a value based on the temperature, and the value of the pressure acting on the anode side or the cathode side of the fuel cell. In this way, the accuracy of the pressure estimation can be further improved.

A second fuel cell system of the present disclosure includes:
a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a temperature detection unit that detects a temperature of at least one of the fuel cell, the reforming unit, the evaporating unit, the combustion unit, the combustion exhaust gas discharged from the combustion unit, and the oxidizing gas supplied from the oxidizing gas supply unit; and
a control unit that acquires a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump and the temperature detected by the temperature detection unit, using a relationship between a value based on the driving state of the pump, a value based on the temperature, and a value of the pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
The gist of the invention is to provide the following:

The second fuel cell system disclosed herein includes a temperature detection unit that detects the temperature of at least one of the fuel cell, the reforming unit, the evaporation unit, the combustion unit, the combustion exhaust gas discharged from the combustion unit, and the oxidant gas supplied from the oxidant gas supply unit, and obtains the operating state of the pump in the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side using the relationship between the operating state of the pump, temperature, and pressure based on the obtained operating state of the pump and the temperature detected by the temperature detection unit. This makes it possible to estimate the pressure acting on the anode side or the cathode side with good accuracy without using a dedicated pressure gauge.

A third fuel cell system of the present disclosure comprises:
a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a control unit that acquires a duty and a rotation speed as a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates a pressure acting on the anode side or the cathode side of the fuel cell based on the acquired duty and rotation speed of the pump using a relationship between a value based on the pump duty, a value based on the pump rotation speed, and a value of a pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
The gist of the invention is to provide the following:

In the third fuel cell system disclosed herein, the duty and rotation speed are acquired as the driving state of the pump of the raw fuel gas supply unit or the oxidant gas supply unit, and the pressure acting on the anode side or cathode side of the fuel cell is estimated based on the acquired pump duty and rotation speed, using the relationship between the pump duty, rotation speed, and pressure. This makes it possible to estimate the pressure acting on the anode side or cathode side with good accuracy without using a dedicated pressure gauge.

In the first, second or third fuel cell system of the present disclosure, the control unit may control the raw fuel gas supply unit, the reforming water supply unit and the oxidant gas supply unit so that the pressure acting on the anode side or the cathode side exceeds a predetermined pressure, thereby suppressing failure of the fuel cell (e.g., deformation of the separator, etc.).

In addition, in the first, second or third fuel cell system of the present disclosure, the control unit may estimate a pressure difference between the pressure acting on the anode side and the pressure acting on the cathode side based on the pressure acting on the anode side or the cathode side, and when the estimated pressure difference exceeds a predetermined pressure difference, control the raw fuel gas supply unit, the reforming water supply unit and the oxidant gas supply unit so that the pressure difference is reduced. In this way, failure of the fuel cell (e.g., deformation of the separator, etc.) can be suppressed.

FIG. 1 is a schematic diagram of a fuel cell system. 10 is a flowchart showing an example of a target flow rate correction process routine. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the vaporizer temperature T1, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the stack temperature T4, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the combustion section temperature T7, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the combustion exhaust gas temperature T8, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the intake air temperature T9, and the fuel side pressure Pg. 4 is a graph showing the relationship between pump duty, flow rate, and pressure. 11 is a graph comparing an estimated value and an actual value of a fuel side pressure Pg estimated using a correlation equation of a fuel pump duty Dg, a fuel flow rate Qg, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation between a fuel pump duty Dg, a reforming water flow rate Qw, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value of a fuel side pressure Pg estimated using a correlation equation of a fuel pump duty Dg, an air flow rate Qa, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation among a fuel pump duty Dg, a reforming water flow rate Qw, an air flow rate Qa, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the air pump rotation speed Na, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation among the fuel pump duty Dg, the reforming water flow rate Qw, the air pump rotation speed ^Na2 , and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation among a fuel pump duty Dg, a reforming water flow rate Qw, an air pump duty Da, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation of a fuel pump duty Dg, a vaporizer temperature T1, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value of the fuel side pressure Pg when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the reforming section temperature T2, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the stack temperature T4, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the combustion section temperature T7, and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when the fuel side pressure Pg is estimated using a correlation equation of the fuel pump duty Dg, the combustion exhaust gas temperature T8, and the fuel side pressure Pg. 10 is a flowchart showing a target flow rate correction process routine according to another embodiment. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation between a fuel pump duty Dg, an air pump rotation speed Na, and a fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value of the fuel side pressure Pg when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the air pump rotation speed ^Na2 , and the fuel side pressure Pg. 11 is a graph comparing an estimated value and an actual value when a fuel side pressure Pg is estimated using a correlation equation between a fuel pump duty Dg, an air pump duty Da, and a fuel side pressure Pg.

The embodiment for implementing this disclosure will be described with reference to the drawings.

Figure 1 is a schematic diagram of a fuel cell system 10 of this embodiment. As shown in the figure, the fuel cell system 10 of this embodiment includes a power generation module 20 including a fuel cell stack 21 that generates power by an electrochemical reaction between hydrogen in the anode gas and oxygen in the cathode gas, a raw fuel gas supply device 30 that supplies raw fuel gas (e.g., natural gas or LP gas) that is the raw material for the anode gas to the power generation module 20 via a raw fuel gas supply pipe 31, a reforming water supply device 40 that supplies reforming water required for reforming (steam reforming) the raw fuel gas to the power generation module 20, an air supply device 50 that supplies air as a cathode gas to the power generation module 20 (fuel cell stack 21), an exhaust heat recovery device 60 that recovers exhaust heat generated in the power generation module 20, and a control device 100 that controls the entire system.

The power generation module 20 includes a fuel cell stack 21, a vaporizer 22, a reformer 23, a combustor 24, and a heat exchanger 26, all of which are housed in a thermally insulating module case 29.

The fuel cell stack 21 is configured as a flat-plate type solid oxide fuel cell stack in which flat-plate-shaped single cells S and separators are alternately stacked in the plate thickness direction. Each single cell S has an electrolyte such as zirconium oxide, and an anode electrode and a cathode electrode that sandwich the electrolyte. An anode gas passage through which an anode gas flows is formed in the anode electrode of each single cell S. A cathode gas passage through which a cathode gas flows is formed in the cathode electrode of each single cell S. The separator is, for example, a stainless steel plate that is press-formed, and separates adjacent single cells S in the plate thickness direction, and blocks the anode gas flowing through the anode electrode side of one single cell S and the cathode gas flowing through the cathode electrode side of the other single cell S between the adjacent single cells S. In addition, a temperature sensor 114 is installed near the fuel cell stack 21. The temperature sensor 114 detects a temperature (stack temperature T4) that correlates with the temperature of the fuel cell stack 21.

The vaporizer 22 and reformer 23 of the power generation module 20 are disposed above the fuel cell stack 21 inside the module case 29. In addition, a combustor 24 is disposed between the fuel cell stack 21 and the vaporizer 22 and reformer 23 to generate heat required for the operation of the fuel cell stack 21 and the reactions in the vaporizer 22 and reformer 23.

The vaporizer 22 heats the raw fuel gas from the raw fuel gas supply device 30 and the reforming water from the reforming water supply device 40 with heat from the combustor 24, preheats the raw fuel gas, and evaporates the reforming water to generate steam. The raw fuel gas preheated by the vaporizer 22 is mixed with steam, and the mixed gas flows from the vaporizer 22 into the reformer 23. A temperature sensor 111 is installed near the outlet of the vaporizer 22. The temperature sensor 111 is used to detect the temperature of the vaporizer 22 (vaporization section temperature T1) and to estimate the temperature of the reformer 23 immediately after (reforming section temperature T2). The temperature sensor 111 may be installed in the reformer 23 (for example, near the outlet side of the reforming catalyst), or may be installed in both the vaporizer 22 and the reformer 23.

The reformer 23 has a Ru-based or Ni-based reforming catalyst filled therein, and generates hydrogen gas and carbon monoxide by a reaction (steam reforming reaction) of the mixed gas from the vaporizer 22 with the reforming catalyst in the presence of heat from the combustor 24. Furthermore, the reformer 23 generates hydrogen gas and carbon dioxide by a reaction (carbon monoxide shift reaction) between the carbon monoxide generated in the steam reforming reaction and steam. As a result, the reformer 23 generates anode gas containing hydrogen, carbon monoxide, carbon dioxide, steam, unreformed raw fuel gas, etc. The anode gas generated by the reformer 23 flows into the anode gas passage of each single cell S through the anode gas piping 71 and is supplied to the anode electrode.

Air serving as a cathode gas flows into the cathode gas passage of each unit cell S via a cathode gas pipe 72 and is supplied to the cathode electrode. Oxide ions (O ²⁻ ) are generated in the cathode electrode of each unit cell S, and the oxide ions pass through the electrolyte and react with hydrogen and carbon monoxide at the anode electrode to obtain electric energy.

The anode gas (hereinafter referred to as "anode off-gas") that was not used in the electrochemical reaction (power generation) in each unit cell S is supplied to the combustor 24 through the anode off-gas piping 73, and the cathode gas (hereinafter referred to as "cathode off-gas") that was not used in the electrochemical reaction (power generation) in each unit cell S is supplied to the combustor 24 through the cathode off-gas piping 74. The anode off-gas is a combustible gas containing fuel components such as hydrogen and carbon monoxide, and is mixed with the cathode off-gas containing oxygen in the combustor 24 and combusted. The combustor 24 is provided with an ignition device 25 for igniting the mixed gas of the anode off-gas and the cathode off-gas introduced into the combustor 24. The combustor 24 is also provided with a temperature sensor 117 for detecting the temperature of the combustor 24 (combustion section temperature T7).

The combustion exhaust gas generated by the combustion of the mixed gas in the combustor 24 is supplied to the condenser 62 through the combustion exhaust gas pipe 75. The combustion exhaust gas pipe 75 is formed to pass through the reformer 23, the vaporizer 22, and the heat exchanger 26 in order, and after supplying the heat required for steam reforming, the heat required for generating steam, and the heat required for raising the temperature of the cathode gas (air), it is supplied to the condenser 62. A combustion catalyst 28 (oxidation catalyst) for burning unburned fuel contained in the combustion exhaust gas is provided near the outlet of the combustion exhaust gas pipe 75. In addition, a temperature sensor 118 for detecting the temperature of the combustion exhaust gas (combustion exhaust gas temperature T8) flowing through the combustion exhaust gas pipe 75 is provided between the vaporizer 22 and the heat exchanger 26 in the combustion exhaust gas pipe 75.

The raw fuel gas supply device 30 has a raw fuel gas supply pipe 31 that connects a raw fuel supply source 1 that supplies raw fuel gas to a vaporizer 22, and on-off valves (two valves) 32, 33, a fuel pump 36, and a desulfurizer 38 installed in the raw fuel gas supply pipe 31. By operating the fuel pump 36, the raw fuel gas is pumped (supplied) from the raw fuel supply source 1 to the vaporizer 22 via the desulfurizer 38. In addition, a flow sensor 39 is installed in the raw fuel gas supply pipe 31 to detect the flow rate per unit time of the raw fuel gas flowing through the raw fuel gas supply pipe 31 (fuel flow rate Qg).

The reforming water supply device 40 has a reforming water tank 42 that stores reforming water, a reforming water supply pipe 41 that connects the reforming water tank 42 and the vaporizer 22, and a reforming water pump 43 installed in the reforming water supply pipe 41. By operating the reforming water pump 43, the reforming water in the reforming water tank 42 is pumped (supplied) by the reforming water pump 43 to the vaporizer 22. In this embodiment, the reforming water pump 43 is configured as a fixed volume pump (e.g., a plunger pump) and has a constant discharge volume per unit stroke.

The air supply device 50 has an air supply pipe 51 connected to a cathode gas pipe 72 installed in the module case 29, an air filter 52 provided at the inlet of the air supply pipe 51, and an air pump 53 installed in the air supply pipe 51. By operating the air pump 53, air as a cathode gas is sucked into the air supply pipe 51 through the air filter 52, and is pressure-fed (supplied) through the cathode gas pipe 72 to the fuel cell stack 21 (cathode electrode). The air flowing through the cathode gas pipe 72 is heated by heat exchange with the high-temperature combustion exhaust gas flowing through the combustion exhaust gas pipe 75 in the heat exchanger 26. In addition, a flow rate sensor 54 is installed in the air supply pipe 51 to detect the flow rate (air flow rate Qa) of the air flowing through the air supply pipe 51 per unit time. In addition, a temperature sensor may be installed to detect the temperature of the air (suction air temperature T9) sucked into the air supply pipe 51 as the air pump 53 is driven.

The exhaust heat recovery device 60 has a hot water storage tank 61 that stores hot water, a condenser 62 that exchanges heat between the hot water and the combustion exhaust gas supplied from the combustion exhaust gas piping 75 to condense the water vapor contained in the combustion exhaust gas, a circulation pipe 63 connected to the hot water storage tank 61 and the condenser 62, and a circulation pump 64 incorporated in the circulation pipe 63. The hot water stored in the hot water storage tank 61 is introduced into the condenser 62 by operating the circulation pump 64, and is heated by heat exchange with the combustion exhaust gas in the condenser 62, and then returned to the hot water storage tank 61.

The condensed water obtained by condensing the water vapor in the combustion exhaust gas through heat exchange with the hot water from the hot water storage tank 61 is introduced into the reforming water tank 42 through the condensed water pipe 44. The reforming water tank 42 is equipped with a water purifier (not shown) that purifies the condensed water that has passed through the condensed water pipe 44. The combustion exhaust gas from which the water vapor has been removed in the condenser 62 is discharged into the atmosphere through the combustion exhaust gas exhaust pipe 76.

An input terminal of a power conditioner 80 is connected to the output terminal of the fuel cell stack 21, and the output terminal of the power conditioner 80 is connected to a power line 3 from the power system 2 to a load 4 via a relay. The power conditioner 80 has a DC/DC converter that converts the DC power output from the fuel cell stack 21 into DC power of a predetermined voltage (e.g., DC 250V to 300V), and an inverter that converts the converted DC power into AC power of a voltage (e.g., AC 200V) that can be connected to the power system. This makes it possible to convert the DC power from the fuel cell stack 21 into AC power and supply it to a load 4 such as a home appliance. A power supply board 81 is connected to the power conditioner 80. The power supply board 81 converts the DC power from the fuel cell stack 21 and the AC power from the power system 2 into low-voltage DC power, and supplies it to the fuel pump 36, the reforming water pump 43, the air pump 53, the circulation pump 64, and other auxiliary devices, the flow rate sensors 39, 54, the temperature sensors 111, 114, 117, 118, the current sensor 121 that detects the current (output current I) output from the fuel cell stack 21, the voltage sensor 122 that detects the voltage (output voltage V) output from the fuel cell stack 21, and the control device 100. In addition, a cooling fan and a ventilation fan (not shown) for cooling the power conditioner 80 and the power supply board 81 are arranged in the auxiliary device room where the power conditioner 80 and the power supply board 81 are arranged. The cooling fan sends air to the heat generating parts of the power conditioner 80 and the power supply board 81. The air that has cooled the heat generating parts and has been heated is discharged into the atmosphere by the ventilation fan.

The control device 100 is configured as a microprocessor centered on the CPU 101, and includes, in addition to the CPU 101, a ROM 102 for storing processing programs, a RAM 103 for temporarily storing data, and an input/output port (not shown). Various detection signals from the flow rate sensors 39, 54, temperature sensors 111, 114, 117, 118, current sensor 121, voltage sensor 122, etc. are input to the control device 100 via the input port. In addition, the control device 100 outputs various control signals to the solenoids of the on-off valves 32, 33, the pump motor of the fuel pump 36, the pump motor of the reformed water pump 43, the pump motor of the air pump 53, the pump motor of the circulation pump 64, the ignition device 25, the solenoid of the solenoid valve 82, etc. via the output port. In addition, a remote control (not shown) is connected to the control device 100 via a wireless or wired communication line. The control device 100 executes various controls based on signals from the remote control operated by the user of the fuel cell system 10.

Here, in the fuel cell system 10 of this embodiment, the fuel cell stack 21 is a stack of flat plate type single cells, which has the advantage of a higher output density per unit area compared to cylindrical cells. On the other hand, flat plate type cells tend to be at a disadvantage in terms of mechanical strength compared to cylindrical cells, and if the pressure on the anode side, the pressure on the cathode side, or the pressure difference between the anode side pressure and the cathode side pressure in the fuel cell stack 21 becomes too large, there is a risk of damaging the cells (electrolyte). Therefore, in the fuel cell system 10 of this embodiment, the system is operated and controlled so that the pressure on the anode side, the pressure on the cathode side, and the pressure difference between these do not exceed their respective allowable ranges, thereby preventing damage to the cells. The operation of the fuel cell system 10 during power generation is described below.

During power generation, the CPU 101 of the control device 100 controls the supply amount of raw fuel gas, reforming water, and air so that a current (current command Ireq) corresponding to the required output required for the system is output from the fuel cell stack 21. The supply amount of raw fuel gas is controlled by setting the fuel flow rate corresponding to the current command Ireq to the target fuel flow rate Fgtag so that the fuel utilization rate Uf matches the target utilization rate Uftag, and setting the duty (fuel pump duty Dg) of the pump motor of the fuel pump 34 by feedback control so that the fuel flow rate Fg detected by the flow sensor 39 matches the set target fuel flow rate Fgtag, and driving and controlling the pump motor. The fuel utilization rate Uf is the ratio of the amount of anode gas used for power generation to the amount of anode gas supplied to the anode. The amount of the reforming water supplied is controlled by setting a target reforming water flow rate Fwtag based on the target fuel flow rate Fgtag so that the steam carbon ratio SC in the reformer 23 coincides with the target ratio SCtag, setting the duty (reforming water pump duty Dw) of the pump motor of the reforming water pump 43 so that reforming water of the set target reforming water flow rate Fwtag is supplied, and driving and controlling the pump motor. The steam carbon ratio SC is the molar ratio of carbon contained in the hydrocarbons in the raw fuel gas to the steam added for steam reforming. The amount of air supplied is controlled by setting a target air flow rate Ftag by feedback control so that the temperature (stack temperature) T4 detected by the temperature sensor 114 coincides with the target temperature T4tag, and setting the duty (air pump duty Da) of the pump motor of the air pump 53 by feedback control so that the air flow rate Fa detected by the flow rate sensor 54 coincides with the set target air flow rate Ftag, and driving and controlling the pump motor.

Next, we will explain the process of correcting the target fuel flow rate Fgtag, the target reforming water flow rate Fwtag, and the target air flow rate Fatag so that the anode pressure, the cathode pressure, and the differential pressure between them do not exceed their respective allowable ranges. Figure 2 is a flowchart showing an example of a target flow rate correction process routine. This routine is executed repeatedly at predetermined time intervals (e.g., every few msec or every tens of msec) during power generation.

When the target flow rate correction processing routine is executed, the CPU 101 of the control device 100 first inputs data necessary for processing, such as the fuel pump duty Dg, the air pump duty Da, the flow rate data Q detected by the flow rate sensors 39, 54, etc., and the temperature data T detected by the temperature sensors 111, 114, 117, 118, etc. (step S100). In this embodiment, the flow rate data Q includes one or more of the fuel flow rate Qg, the air flow rate Qa, and the reforming water flow rate Qw. The reforming water flow rate Qw can be obtained from the driving state (discharge count) of the reforming water pump 43, since the reforming water pump 43 is configured as a fixed-volume pump. Of course, a flow rate sensor may be provided in the reforming water supply pipe 41, and the reforming water flow rate Qw may be obtained by the flow rate sensor. The temperature data T includes one or more of the vaporizer temperature T1, the reforming section temperature T2, the stack temperature T4, the combustion section temperature T7, the combustion exhaust gas temperature T8, and the intake air temperature T9.

Then, the CPU 101 estimates the fuel side pressure Pg, which is the pressure near the anode side inlet of the fuel cell stack 21, using the regression equation of the following equation (1) based on the fuel pump duty Dg, flow rate data Q, and temperature data T input in step S100 (step S110). The coefficients a, b, c and constant d in equation (1) are obtained by multiple regression analysis using the fuel pump duty Dg, flow rate data Q, and temperature data T as explanatory variables and the fuel side pressure Pg as the objective variable. This makes it possible to accurately estimate the fuel side pressure Pg from the detection data of the sensor equipped in the fuel cell system 10, without using a dedicated pressure sensor.

Pg=a・Dg+b・Q+c・T+d … (1)

Next, the CPU 101 estimates the air side pressure Pa, which is the pressure near the inlet on the cathode side of the fuel cell stack 21, using the regression equation of the following equation (2) based on the air pump duty Da, flow rate data Q, and temperature data T input in step S100 (step S120). The coefficients e, f, g and constant h in equation (2) are obtained by multiple regression analysis using the air pump duty Da, flow rate data Q, and temperature data T as explanatory variables and the air side pressure Pa as the objective variable. This makes it possible to accurately estimate the air side pressure Pa from the detection data of the sensor equipped in the fuel cell system 10, without using a dedicated pressure sensor.

Pa = e Da + f Q + g T + h … (2)

After estimating the fuel side pressure Pg and the air side pressure Pa, the CPU 101 subtracts the air side pressure Pa from the fuel side pressure Pg to calculate the differential pressure Pd (=Pg-Pa) between the two (step S130). The CPU 101 then determines whether the fuel side pressure Pg is equal to or greater than a positive threshold value α, and whether the differential pressure Pd is equal to or greater than a positive threshold value γ (step S140). Here, the threshold values α and γ are set to positive values near the upper limits of the allowable ranges of the fuel side pressure Pg and the differential pressure Pd to prevent the fuel cell stack 21 from failing. If the CPU 101 determines that the fuel side pressure Pg is less than the threshold value α and the differential pressure Pd is less than the threshold value γ, the process proceeds to step S160. On the other hand, when the CPU 101 determines that the fuel side pressure Pg is equal to or greater than the threshold value α, or that the differential pressure Pd is equal to or greater than the threshold value γ, it performs a downward correction on the target fuel flow rate Qgtag and the target reforming water flow rate Qwtag (step S150) and proceeds to step S160. Note that the downward correction may be performed on either the target fuel flow rate Qgtag or the target reforming water flow rate Qwtag. Also, when the differential pressure Pd is equal to or greater than the threshold value γ, instead of or in addition to the downward correction on the target fuel flow rate Qgtag and the target reforming water flow rate Qwtag, an upward correction on the target air flow rate Qtag may be performed.

Next, the CPU 101 determines whether the air side pressure Pa is equal to or greater than a positive threshold value β, and whether the differential pressure Pd is less than a negative threshold value -γ (step S140). Here, the threshold value β is set to a positive value near the upper limit of the allowable range of the air side pressure Pa, and the threshold value -γ is set to a negative value near the lower limit of the allowable range of the differential pressure Pd. If the CPU 101 determines that the air side pressure Pa is less than the threshold value β and the differential pressure Pd is equal to or greater than the threshold value -γ, it ends this routine. On the other hand, if the CPU 101 determines that the air side pressure Pa is equal to or greater than the threshold value β or that the differential pressure Pd is less than the threshold value -γ, it corrects the target air flow rate Qtag by decreasing it (step S170) and ends this routine. In addition, when the differential pressure Pd is less than the threshold value -γ, instead of or in addition to the decreasing correction of the target air flow rate Qtag, an increasing correction of the target fuel flow rate Qgtag or the target reforming water flow rate Qwtag may be performed.

3 to 7 are graphs comparing the estimated and actual values of the fuel-side pressure Pg estimated using a correlation equation between the fuel pump duty Dg, flow data Q (reforming water flow rate Qw), temperature data T (evaporator temperature T1, stack temperature T4, combustion section temperature T7, combustion exhaust gas temperature T8, intake air temperature T9), and the fuel-side pressure Pg. Note that each figure also shows the estimated value when the fuel-side pressure Pg is estimated based only on the fuel pump duty Dg. When the reforming water flow rate Qw and the vaporizer temperature T1 are added as explanatory variables, the coefficient of determination ^R2 is 0.887 (see FIG. 3), when the reforming water flow rate Qw and the stack temperature T4 are added as explanatory variables, the coefficient of determination ^R2 is 0.915 (see FIG. 4), when the reforming water flow rate Qw and the combustion section temperature T7 are added as explanatory variables, the coefficient of determination ^R2 is 0.879 (see FIG. 5), when the reforming water flow rate Qw and the combustion exhaust gas temperature T8 are added as explanatory variables, the coefficient of determination ^R2 is 0.906 (see FIG. 6), and when the reforming water flow rate Qw and the intake air temperature T9 are added as explanatory variables, the coefficient of determination ^R2 is 0.868 (see FIG. 7). In either case, it was confirmed that the estimated value estimated using the regression equation including the flow rate data Q and the temperature data T as explanatory variables was in good agreement with the actual value. Here, the reason why the flow rate data Q (reforming water flow rate Qw) has a correlation with the pressure (fuel side pressure Pg) is that a predetermined relationship shown in Fig. 8 has been confirmed by experiment between the pump duty, flow rate, and pressure under constant temperature conditions (25°C) and constant atmospheric pressure conditions (101.3 kPa). Also, the reason why the temperature data T has a correlation with the pressure (fuel side pressure Pg) is that as the temperature inside the power generation module 20 increases, the generation of steam is promoted in the vaporizer 22, for example, and the like, which is believed to result in an increase in pressure due to volume expansion.

In the fuel cell system 10 of the present embodiment described above, the fuel pump duty Dg, flow data Q, and temperature data T of the fuel pump 34 are used as explanatory variables, and the fuel side pressure Pg is used as a response variable to estimate the fuel side pressure Pg based on the fuel pump duty Dg, flow data Q, and temperature data T using a regression equation (regression relationship) obtained by multiple regression analysis with the fuel pump duty Da, flow data Q, and temperature data T of the air pump 53 as explanatory variables, and the air side pressure Pa as a response variable to estimate the air side pressure Pa based on the air pump duty Da, flow data Q, and temperature data T using a regression equation (regression relationship) obtained by multiple regression analysis with the air pump duty Da, flow data Q, and temperature data T of the air pump 53 as explanatory variables, and the air side pressure Pa as a response variable. In this way, by estimating the pressure using a regression relationship in which the flow data Q and temperature data T are added as explanatory variables to the driving state of the pump, the pressure acting on the anode side or cathode side can be estimated with good accuracy without using a dedicated pressure gauge.

In the above embodiment, the regression equation for estimating the fuel side pressure Pg includes both the flow rate data Q and the temperature data T as explanatory variables, but it may also include only one of the flow rate data Q and the temperature data T, although the accuracy of the estimation will be slightly reduced. Similarly, the regression equation for estimating the air side pressure Pa includes both the flow rate data Q and the temperature data T as variables, but it may also include only one of the flow rate data Q and the temperature data T, although the accuracy of the estimation will be slightly reduced.

9 to 11 are graphs comparing the estimated value and the actual value when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the flow rate data Q (fuel flow rate Qg, reforming water flow rate Qw, air flow rate Qa), and the fuel side pressure Pg. In addition, each figure also shows the estimated value when the fuel side pressure Pg is estimated based only on the fuel pump duty Dg. When the fuel flow rate Qg is added as an explanatory variable, the coefficient of determination R ² is 0.712 (see FIG. 9). When the reforming water flow rate Qw is added as an explanatory variable, the coefficient of determination R ² is 0.867 (see FIG. 10). When the air flow rate Qa is added as an explanatory variable, the coefficient of determination R ² is 0.465 (see FIG. 11). In either case, it was confirmed that the estimated value estimated using the regression equation to which the flow rate data Q is added as an explanatory variable is in good agreement with the actual value.

FIG. 12 is a graph comparing the estimated value and the actual value when the fuel side pressure Pg is estimated using a correlation equation between the fuel pump duty Dg, the reforming water flow rate Qw, the air flow rate Qa, and the fuel side pressure Pg. In addition, each figure also shows the estimated value when the fuel side pressure Pg is estimated based only on the fuel pump duty Dg. When the reforming water flow rate Qw and the air flow rate Qa are added as explanatory variables, the coefficient of determination ^R2 is 0.885 (see FIG. 12). It was confirmed that the estimated value estimated using the regression equation adding the reforming water flow rate Qw and the air flow rate Qa as explanatory variables is in good agreement with the actual value. FIGS. 13, 14, and 15 are graphs comparing the estimated value and the actual value when the fuel side pressure Pg is estimated using a correlation equation adding the air pump rotation speed Na, the air pump rotation speed ^Na2 , and the air pump duty Da as explanatory variables instead of the air flow rate Qa. When the reforming water flow rate Qw and the air pump rotation speed Na are added as explanatory variables, the coefficient of determination ^R2 is 0.930 (see FIG. 13), when the reforming water flow rate Qw and the air pump rotation speed ^Na2 are added as explanatory variables, the coefficient of determination ^R2 is 0.945 (see FIG. 14), and when the reforming water flow rate Qw and the air pump duty Da are added as explanatory variables, the coefficient of determination ^R2 is 0.937 (see FIG. 15). In all cases, it was confirmed that the estimated values estimated using the regression equation were in good agreement with the actual values.

16 to 20 are graphs comparing the estimated and actual values of the fuel side pressure Pg estimated using a correlation equation between the fuel pump duty Dg, temperature data T (evaporator temperature T1, reformer temperature T2, stack temperature T4, combustor temperature T7, and exhaust gas temperature T8), and the fuel side pressure Pg. Each figure also shows the estimated value of the fuel side pressure Pg estimated based only on the fuel pump duty Dg. When the vaporizer temperature T1 was added as an explanatory variable, the coefficient of determination ^R2 was 0.836 (see FIG. 16), when the reformer temperature T2 was added as an explanatory variable, the coefficient of determination ^R2 was 0.826 (see FIG. 17), when the stack temperature T4 was added as an explanatory variable, the coefficient of determination ^R2 was 0.829 (see FIG. 18), when the combustor temperature T7 was added as an explanatory variable, the coefficient of determination ^R2 was 0.827 (see FIG. 19), and when the combustion exhaust gas temperature T8 was added as an explanatory variable, the coefficient of determination ^R2 was 0.890 (see FIG. 20). In all cases, it was confirmed that the estimated values estimated using the regression equation were in good agreement with the actual values.

In the above-described embodiments, the fuel side pressure Pg (estimated value) estimated using a regression equation combining various data such as the fuel pump duty Dg with flow rate data Q and temperature data T as explanatory variables was compared with the actual value. Considering these comparison results and the fact that the anode side and cathode side of the fuel cell system 10 are connected via the anode off-gas piping 73, the combustor 24, and the cathode off-gas piping 74, it is considered that the fuel side pressure Pg estimated using a regression equation of other combinations of flow rate data Q and temperature data T as explanatory variables (for example, a regression equation using the fuel pump duty Dg, fuel flow rate Qg, and vaporizer temperature T1 as explanatory variables and the fuel side pressure Pg as the objective variable, or a regression equation using the fuel pump duty Dg, air flow rate Qa, and stack temperature T4 as explanatory variables and the fuel side pressure Pg as the objective variable) also matches well with the actual value. Similarly, the air side pressure Pa, which is estimated using a regression equation that combines the air pump duty Da with various data such as flow rate data Q and temperature data T as explanatory variables, is also thought to be in good agreement with the actual value.

In the above embodiment, the fuel side pressure Pg is estimated using a regression equation in which the fuel pump duty Dg is added with the flow rate data Q and the temperature data T as explanatory variables, and the air side pressure Pa is estimated using a regression equation in which the air pump duty Dg is added with the flow rate data Q and the temperature data T as explanatory variables. However, the fuel side pressure Pg may be estimated using a regression equation in which the fuel pump duty Dg is added with the rotation speed of the fuel pump 34 (fuel pump rotation speed Ng) or the rotation speed of the air pump 53 (air pump rotation speed Na), or the air side pressure Pa may be estimated using a regression equation in which the air pump duty Da is added with the fuel pump rotation speed Ng or the air pump rotation speed Na. A target flow rate correction processing routine according to another embodiment is shown in FIG. 21. Note that the same step numbers are used for the steps of the target flow rate correction processing routine in FIG. 21 that are the same as those in the routine in FIG. 2, and their descriptions will be omitted to avoid duplication.

21, the CPU 101 inputs data necessary for processing, such as the fuel pump duty Dg, the air pump duty Da, the fuel pump rotation speed Ng, and the air pump rotation speed Na (step S100B). Next, the CPU 101 estimates the fuel side pressure Pg based on the fuel pump duty Dg and the fuel pump rotation speed Ng using the regression equation of the following equation (3) (step S110B). The coefficients a', b' and constant c' in equation (3) are obtained by multiple regression analysis using the fuel pump duty Dg and the air pump rotation speed Na as explanatory variables and the fuel side pressure Pg as the objective variable. This makes it possible to accurately estimate the fuel side pressure Pg from the detection data of the sensor provided in the fuel cell system 10 without using a dedicated pressure sensor. Note that the air pump duty Da may be used as the explanatory variable instead of the air pump rotation speed a.

Pg=a'・Dg+b'・Ng+c' …(3)

Next, the CPU 101 estimates the air side pressure Pa based on the air pump duty Da and the air pump rotation speed Na using the regression equation of the following equation (4) (step S120B), and executes the processing of steps S130 to S170. The coefficients e', f' and constant g' in equation (4) are obtained by multiple regression analysis using the air pump duty Da and the fuel pump rotation speed Ng as explanatory variables and the air side pressure Pa as the objective variable. This makes it possible to accurately estimate the air side pressure Pa from the detection data of the sensor equipped in the fuel cell system 10, without using a dedicated pressure sensor. Note that the fuel pump duty Dg may be used as the explanatory variable instead of the fuel pump rotation speed Ng.

Pa = e' Da + f' Na + g' ... (4)

22, 23, and 24 are graphs comparing the estimated value and the actual value when estimating the fuel side pressure Pg using a correlation equation in which the air pump rotation speed Na, the air pump rotation speed ^Na2 , and the air pump duty Da are added to the fuel pump duty Dg, respectively. When the air pump rotation speed Na is added as an explanatory variable, the coefficient of determination ^R2 is 0.770 (see FIG. 22). When the air pump rotation speed ^Na2 is added as an explanatory variable, the coefficient of determination ^R2 is 0.831 (see FIG. 23). When the air pump duty Da is added as an explanatory variable, the coefficient of determination ^R2 is 0.777 (see FIG. 24). In all cases, it was confirmed that the estimated value estimated using the regression equation was in good agreement with the actual value.

In the above-described embodiment and other embodiments, the CPU 101 estimates the fuel side pressure Pg and the air side pressure Pa using the respective regression equations. However, it is also possible to estimate only one of the fuel side pressure Pg and the air side pressure Pa, and detect the other pressure directly using a pressure sensor.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described. In the embodiment, the fuel cell stack 21 corresponds to the "fuel cell" of the present disclosure, the reformer 23 corresponds to the "reforming section", the vaporizer 22 corresponds to the "evaporation section", the combustor 24 corresponds to the "combustion section", the power generation module 20 corresponds to the "power generation module", the raw fuel gas supply device 30 corresponds to the "raw fuel gas supply section", the reforming water supply device 40 corresponds to the "reforming water supply section", the air supply device 50 corresponds to the "oxidizer gas supply section", the flow rate sensors 39 and 54 correspond to the "flow rate detection section", and the CPU 101 of the control device 100 that executes the target flow rate correction processing routine corresponds to the "control section". Also, the temperature sensors 111, 114, 117, and 118 correspond to the "temperature sensors".

The correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

Although the above describes the form for implementing this disclosure using embodiments, this disclosure is in no way limited to these embodiments, and it goes without saying that this disclosure can be implemented in various forms without departing from the spirit of this disclosure.

This disclosure can be used in the fuel cell system manufacturing industry, etc.

1 raw fuel supply source, 2 power system, 3 power line, 4 load, 10 fuel cell system, 20 power generation module, 21 fuel cell stack, 22 vaporizer, 23 reformer, 24 combustor, 25 ignition device, 26 heat exchanger, 28 combustion catalyst, 29 module case, 30 raw fuel gas supply device, 31 raw fuel gas supply pipe, 32, 33 on-off valve, 34 fuel pump, 35 desulfurizer, 39 flow sensor, 40 reforming water supply device, 41 reforming water supply pipe, 42 reforming water tank, 43 reforming water pump, 44 condensed water pipe, 50 air supply device, 51 air supply pipe, 52 air filter, 53 air pump, 54 flow sensor, 60 exhaust heat recovery device, 61 hot water tank, 62 condenser, 63 circulation pipe, 64 circulation pump, 71 anode gas pipe, 72 Cathode gas piping, 73 Anode off gas piping, 74 Cathode off gas piping, 75 Combustion exhaust gas piping, 80 Power conditioner, 81 Power supply board, 100 Control device, 101 CPU, 102 ROM, 103 RAM, 111, 114, 117, 118 Temperature sensor, 121 Current sensor, 122 Voltage sensor.

Claims (6)

a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a flow rate detection unit that detects a flow rate of at least one of the raw fuel gas, the reforming water, and the oxidizing gas;
a control unit that acquires a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump and the flow rate detected by the flow rate detection unit, using a relationship between a value based on the driving state of the pump, a value based on the flow rate, and a value of pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
A fuel cell system comprising: 2. The fuel cell system according to claim 1,
a temperature detection unit that detects a temperature of at least one of the fuel cell, the reforming unit, the evaporating unit, the combustion unit, the combustion exhaust gas discharged from the combustion unit, and the oxidizing gas supplied from the oxidizing gas supply unit,
the control unit estimates the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump, the flow rate detected by the flow rate detection unit, and the temperature detected by the temperature detection unit, using a relationship between a value based on the driving state of the pump, a value based on the flow rate, a value based on the temperature, and a value of the pressure acting on the anode side or the cathode side of the fuel cell.
Fuel cell system. a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a temperature detection unit that detects a temperature of at least one of the fuel cell, the reforming unit, the evaporating unit, the combustion unit, the combustion exhaust gas discharged from the combustion unit, and the oxidizing gas supplied from the oxidizing gas supply unit; and
a control unit that acquires a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates the pressure acting on the anode side or the cathode side of the fuel cell based on the acquired driving state of the pump and the temperature detected by the temperature detection unit, using a relationship between a value based on the driving state of the pump, a value based on the temperature, and a value of the pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
A fuel cell system comprising: a power generation module including: a fuel cell that generates power by a reaction between a fuel gas supplied to an anode side and an oxidant gas supplied to a cathode side; a reforming section that uses water vapor to reform a raw fuel gas into the fuel gas; an evaporation section that evaporates reforming water to generate the water vapor; and a combustion section that combusts an off-gas discharged from the fuel cell;
a reforming water supply unit that supplies the reforming water to the evaporator by driving a pump;
a raw fuel gas supply unit that supplies the raw fuel gas to the reforming unit by driving a pump;
an oxidant gas supply unit that supplies the oxidant gas to a cathode side of the fuel cell by driving a pump;
a control unit that acquires a duty and a rotation speed as a driving state of a pump of the raw fuel gas supply unit or the oxidant gas supply unit, and estimates a pressure acting on the anode side or the cathode side of the fuel cell based on the acquired duty and rotation speed of the pump using a relationship between a value based on the pump duty, a value based on the pump rotation speed, and a value of a pressure acting on the anode side or the cathode side of the fuel cell, and controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit based on the estimated pressure;
A fuel cell system comprising: 5. The fuel cell system according to claim 1,
the control unit controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit so that the pressure acting on the anode side or the cathode side exceeds a predetermined pressure, the pressure being reduced.
Fuel cell system. 5. The fuel cell system according to claim 1,
the control unit estimates a differential pressure between the pressure acting on the anode side and the pressure acting on the cathode side based on the pressure acting on the anode side or the cathode side, and when the estimated differential pressure exceeds a predetermined differential pressure, controls the raw fuel gas supply unit, the reforming water supply unit, and the oxidant gas supply unit so as to reduce the differential pressure.
Fuel cell system.

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