JP2006216255A - Fuel cell system and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a heat value of the fuel cell by exactly increasing an evaporation amount of condensed water. <P>SOLUTION: The fuel cell system has a heat value estimation part 31 estimating a heat value of the fuel cell 3, a gas water content estimating part 32 estimating a water content in gas supplied to the fuel cell, a generated water amount estimation part 33 estimating an amount of water generated by chemical reaction, an evaporation amount estimation part 34 estimating an evaporation amount of internal moisture existing inside the fuel cell, and an evaporation amount control part 35 controlling the evaporation amount of the internal moisture. When the heat value is increased, whether condensed water is generated in the fuel cell 3 or not is judged depending on the water content, the amount of generated water, and the amount of evaporation, and the evaporation amount control part 35 controls the evaporation amount of the internal moisture. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system and a control method thereof, and more particularly, to a fuel cell system that cools heat generated by a fuel cell by means other than a radiator and a control method thereof.

  The fuel cell system is a power generation system that generates power by a chemical reaction between a fuel gas and an oxidant gas supplied to the fuel cell. In the fuel cell system, heat is generated by this chemical reaction. Conventionally, techniques for cooling the heat by means other than a radiator have been actively performed (for example, see Patent Document 1).

The fuel cell system disclosed in Patent Document 1 includes a calorific value detection unit that detects the calorific value of the fuel cell, and an evaporation amount control unit that controls the evaporation amount of internal moisture present in the fuel cell. Based on the heat generation amount of the fuel cell detected by the heat generation amount detection means, the evaporation amount of the internal moisture is controlled by the evaporation amount control means. The amount of heat generated by the fuel cell is detected based on the power output by the fuel cell, the current output by the fuel cell, or the temperature of the fuel cell. Internal moisture evaporation control is performed by adjusting the humidification amount of hydrogen and oxygen supplied to the fuel cell, or adjusting the flow rate of hydrogen and oxygen supplied to the fuel cell, and adjusting the pressure of hydrogen and oxygen supplied to the fuel cell. .
Japanese Unexamined Patent Publication No. 2002-373692 (for example, FIG. 1 and summary)

  In Patent Document 1, by adjusting the evaporation amount of internal moisture present in the fuel cell, the heat generation amount of the fuel cell is suppressed by utilizing the latent heat of evaporation of internal moisture. Further, the amount of evaporation of internal moisture is controlled by increasing the flow rates of fuel gas (hydrogen) and oxidant gas (oxygen) supplied to the fuel cell, or reducing the pressure of hydrogen and oxygen supplied to the fuel cell.

  Therefore, the amount of evaporation of internal moisture is limited by the total moisture content of the water content contained in the fuel gas or oxidant gas supplied to the fuel cell and the amount of water generated by the chemical reaction in the fuel cell. There is a limit value for the flow rate increase allowance or pressure decrease allowance that can use latent heat of vaporization. Therefore, depending on the operating point of the gas flow rate and gas pressure of the fuel cell system, there is a problem in that it may not be possible to suppress the heat generation amount using the latent heat of vaporization of internal moisture.

  In order to solve the above problems, the present invention provides a fuel cell system that generates power by a chemical reaction between a fuel gas and an oxidant gas supplied to the fuel cell, and a control method thereof. The fuel cell system is a fuel cell. A calorific value estimating means for estimating the calorific value of the gas, a gas water content estimating means for estimating the water content contained in the fuel gas or oxidant gas supplied to the fuel cell, and a generation for estimating the amount of water produced by the chemical reaction It has water amount estimation means, evaporation amount estimation means for estimating the evaporation amount of internal moisture present inside the fuel cell, and evaporation amount control means for controlling the evaporation amount of internal moisture. Evaporation amount control based on the water content estimated by the gas water content estimation means, the generated water amount estimated by the generated water amount estimation means, and the evaporation amount estimated by the evaporation amount estimation means when the calorific value increases hand It is summarized in that to control the amount of evaporation of the internal water.

  According to the fuel cell system and the control method for the fuel cell system according to the present invention, when the calorific value of the fuel cell increases, the condensed water is generated in the fuel cell based on the water content, the generated water amount, and the evaporation amount. The amount of heat generated by the fuel cell can be reduced by using the latent heat of vaporization of the condensed water, and the amount of heat generated by the fuel cell can be reduced by accurately increasing the amount of evaporation of the condensed water. it can.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(First embodiment)
[Overall configuration of fuel cell system]
As shown in FIG. 1, the fuel cell system according to the first embodiment of the present invention has, as its entire structure, a reaction gas composed of a fuel gas and an oxidant gas is supplied and a chemical reaction of the reaction gas is performed. A fuel cell 3 that generates power, a compressor 1 that supplies hydrogen gas as an example of fuel gas to the fuel cell 3, a compressor 1 that supplies air (air) as an example of oxidant gas to the fuel cell 3, and hydrogen Hydrogen tank 20 for storing gas, pressure sensors 11 and 15 for detecting the pressure of hydrogen gas and air, temperature sensors 12 and 16 for detecting the temperature of hydrogen gas and air, and the humidity of hydrogen gas and air are detected. Humidity sensors 13 and 17, flow meters 14 and 18 that detect the flow rates of hydrogen gas and air, pressure adjustment valves 6 and 7 that adjust the pressure of hydrogen gas and air, and the aforementioned fuel cell 3. A radiator 9 and a pump 8 as an example of a radiator that releases heat generated by a chemical reaction to the outside of the apparatus, a temperature sensor 19 that detects the temperature of cooling water circulating through the radiator 9 and the pump 8, and each sensor and flow rate A system controller 10 that receives sensor signals from the meters (11 to 19) and transmits control signals to the compressors 1 and 2 and the pressure regulating valves 6 and 7;

  “Fuel cell” is not only a fuel cell (unit cell) in which an anode 4 supplied with hydrogen gas and a cathode 5 supplied with air sandwich an electrolyte membrane, but also a plurality of unit cells electrically connected in series. The fuel cell stack including the concept. Hereinafter, description will be continued by taking a fuel cell stack as an example of the fuel cell.

  Fuel gas (here, hydrogen gas) is supplied to the anode 4, oxidant gas (here, air) is supplied to the cathode 5, and hydrogen gas and air chemically react within the fuel cell stack 3 to generate electric power. To do. At that time, a part of oxygen in the air is consumed from the cathode 5 and cathode off gas containing moisture generated by power generation is discharged. On the other hand, the anode off gas containing the hydrogen gas remaining without being consumed is discharged from the anode 4. The flow of hydrogen gas and air described above is realized by an anode system channel and a cathode system channel, respectively. Further, the coolant flow is realized by a coolant channel. Hereinafter, these flow paths will be described in detail.

  The anode system flow path will be described. The compressor 1 is provided on the upstream side of the anode 4 in the anode system flow path, and the compressor 1 can pressurize the hydrogen gas from the hydrogen tank 20 and supply the hydrogen gas in a higher pressure state to the anode 4. A pressure regulating valve 6 is provided on the downstream side of the anode 4, and the pressure regulating valve 6 regulates the supply hydrogen pressure (anode operating pressure) required according to the power generation amount (output power) of the fuel cell stack 3. A pressure sensor 11, a temperature sensor 12, a humidity sensor 13, and a flow meter 14 are provided on the downstream side of the compressor 1, and can measure the anode operating pressure, the anode inlet temperature, the anode inlet humidity, and the anode gas flow rate, respectively. Here, the case where the pressure sensor 11, the temperature sensor 12, the humidity sensor 13, and the flow meter 14 are arranged downstream of the compressor 1 and upstream of the anode 4 will be described.

  The cathode system flow path will be described. A compressor 2 is provided on the upstream side of the cathode 5 in the cathode channel, and the compressor 2 can pressurize air from the atmosphere and supply air in a higher pressure state to the cathode 5. A pressure adjustment valve 7 is provided on the downstream side of the cathode 5, and the pressure adjustment valve 7 adjusts the supply air pressure (cathode operating pressure) required according to the output power of the fuel cell stack 3. A pressure sensor 15, a temperature sensor 16, a humidity sensor 17, and a flow meter 18 are provided on the downstream side of the compressor 2, and can measure the cathode operating pressure, the cathode inlet temperature, the cathode inlet humidity, and the cathode gas flow rate, respectively. Here, a case where the pressure sensor 15, the temperature sensor 16, the humidity sensor 17, and the flow meter 18 are arranged on the downstream side of the compressor 2 and on the upstream side of the cathode 5 will be described.

  The cooling water system flow path will be described. The cooling water system flow path constitutes one circulation flow path that connects the fuel cell stack 3, the radiator 9, and the pump 8. The pump 8 supplies cooling water to the fuel cell stack 3 so that the cooling water absorbs heat from the fuel cell stack 3. A radiator 9 is provided on the downstream side of the fuel cell stack 3, and the cooling water radiates heat from the radiator 9 to the outside of the fuel cell system. A temperature sensor 19 is provided on the downstream side of the fuel cell stack 3, and the temperature sensor 19 measures the temperature of the cooling water.

[System controller configuration and operation]
Next, the system control apparatus 10 will be described. The system control device 10 is electrically connected to the fuel cell stack 3, and acquires the current value and voltage value of each fuel cell constituting the fuel cell stack 3, and the current value and voltage value of the entire fuel cell stack 3. . Although not shown, the system controller 10 is electrically connected to the compressors 1 and 2, the pressure regulating valves 6 and 7, the sensors and the flow meters (11 to 19). Sensor values and flow values are acquired from the flow meters (11 to 19), and the compressors 1 and 2 and the pressure regulating valves 6 and 7 are controlled by the control signals described above.

  A specific configuration of the system control apparatus 10 will be described. As shown in FIG. 1, the system control device 10 includes a calorific value estimation means 31 (a calorific value estimation unit) that estimates a calorific value due to a chemical reaction in the fuel cell stack 3, and hydrogen supplied to the fuel cell stack 3. Gas water content estimation means 32 (gas water content estimation unit) for estimating the water content contained in gas or air, and generated water amount estimation means 33 (product water content) for estimating the amount of water produced by a chemical reaction in the fuel cell stack 3 An estimation unit), an evaporation amount estimation unit 34 (evaporation amount estimation unit) for estimating the evaporation amount of internal moisture present in the fuel cell stack 3, and an evaporation amount control unit 35 (evaporation) for controlling the evaporation amount of the internal moisture. Amount control unit), power control means 36 (power control unit) for controlling the output power of the fuel cell stack 3, and heat generation of the fuel cell system after the evaporation amount control unit 35 increases the evaporation amount of the internal moisture. Having a calorific value predicting means 37 for predicting (calorific value prediction unit), the efficiency prediction unit 38 for predicting the efficiency of the fuel cell system and a (efficiency prediction unit) a.

  When the calorific value estimated by the calorific value estimation unit 34 exceeds the predetermined calorific value, the water content estimated by the gas water content estimation unit 32, the generated water amount estimated by the generated water amount estimation unit 33, and evaporation Based on the evaporation amount estimated by the amount estimation unit 34, the evaporation amount control unit 35 controls the evaporation amount of the internal moisture. Here, the “predetermined calorific value” is selected to be lower than the required calorific value that does not degrade the performance of the fuel cell system components.

  When the sum of the water content estimated by the gas water content estimation unit 32 and the generated water amount estimated by the generated water amount estimation unit 33 is larger than the evaporation amount estimated by the evaporation amount estimation unit 34, the evaporation amount control unit 35 Increase evaporation of internal moisture.

  On the other hand, when the sum of the water content estimated by the gas water content estimation unit 32 and the generated water amount estimated by the generated water amount estimation unit 33 is equal to or less than the evaporation amount estimated by the evaporation amount estimation unit 34, the power control unit 36 limits the output power.

  When the predicted heat generation amount predicted by the heat generation amount prediction unit 37 is larger than the heat generation amount estimated by the heat generation amount estimation unit 31, the power control unit 36 limits the output power. That is, even when the sum of the water content and the amount of generated water is larger than the evaporation amount, if the predicted heat generation amount is larger than the heat generation amount, the evaporation amount control unit 35 does not increase the evaporation amount of the internal moisture, The control unit 36 limits the output power.

  The evaporation amount control unit 35 preferably includes at least one of a hydrogen gas flow rate adjustment unit that adjusts the flow rate of hydrogen gas or an air flow rate adjustment unit that adjusts the flow rate of air. In this case, the evaporation amount control unit 35 performs at least one of the increase of the hydrogen gas flow rate by the hydrogen gas flow rate adjustment unit or the increase of the air flow rate by the air flow rate adjustment unit so that the efficiency of the fuel cell system is maximized. This increases the amount of evaporation of internal moisture. In the first embodiment, a case where the gas flow rate is adjusted by the compressors 1 and 2 will be described as an example of the hydrogen gas flow rate adjustment unit and the air flow rate adjustment unit.

  The evaporation amount control unit 35 preferably includes at least one of a hydrogen gas pressure adjusting unit that adjusts the pressure of hydrogen gas and an air pressure adjusting unit that adjusts the pressure of air. In this case, the evaporation amount control unit 35 performs at least one of the reduction of the hydrogen gas pressure by the hydrogen gas pressure adjustment unit or the reduction of the air pressure by the air pressure adjustment unit so that the efficiency of the fuel cell system is maximized. This increases the amount of evaporation of internal moisture. In the second embodiment to be described later, a case where the gas pressure is adjusted by the pressure adjusting valves 6 and 7 will be described as an example of the hydrogen gas pressure adjusting unit and the air pressure adjusting unit.

  Next, the operation of the system control apparatus 10 will be described.

(1) First, the system control device 10 receives the outside air temperature signal and the vehicle speed signal from the outside air temperature sensor and the vehicle speed sensor (not shown). Then, the heat release amount θ _rad of the cooling water is calculated based on the acquired outside air temperature and vehicle speed.

(2) The current value and voltage value of the entire fuel cell stack 3 are acquired, and based on the current value and voltage value, the higher heating value θ _hh and the amount of reaction product water (generated by the chemical reaction between hydrogen gas and air) Calculate the amount of water. Here, the “higher heating value θ _hh ” indicates the heating value when all of the generated water generated by the chemical reaction is condensed.

(3) The hydrogen gas supplied to the anode 4 and the cathode 5, the amount of water contained in the air (water content) and the amount of water discharged (evaporation amount Q out — _{H 2 O} ) are calculated. Here, the water content is calculated from the flow rate, pressure, temperature, and humidity of the hydrogen gas and air by the gas water content estimation unit 32. The evaporation amount _{Qout_H2O is} also calculated by the evaporation amount estimation unit 34 from the respective flow rates, pressures, temperatures, and humidity of hydrogen gas and air. The flow rates of hydrogen gas and air are detected by flow meters 14 and 18. The pressure (inlet pressure) at the gas supply port of the fuel cell stack 3 is detected by the pressure sensors 11 and 15. The pressure (outlet pressure) at the gas discharge port of the fuel cell stack 3 can be easily predicted by subtracting the pressure loss in the anode system channel and the cathode system channel from the inlet pressure. The temperature (inlet temperature) at the gas supply port of the fuel cell stack 3 is detected by the temperature sensors 12 and 16. The temperature (outlet temperature) at the gas discharge port of the fuel cell stack 3 is detected from the temperature sensor 19 on the assumption that the temperature is the same as the temperature of the cooling water. Humidity (inlet humidity) at the gas supply port of the fuel cell stack 3 is detected by humidity sensors 13 and 17. The humidity (exit humidity) at the gas outlet of the fuel cell stack 3 is calculated using the saturated vapor pressure corresponding to the outlet temperature, assuming that the water vapor pressure is saturated. However, since the amount of water that can be evaporated is limited by the total amount of the water content and the generated water amount, the outlet humidity is calculated based on the water content and the generated water amount when the water vapor pressure cannot be saturated.

(4) By the evaporation amount Q _{Out_H2O} by calculating the evaporation heat theta _eva water subtracting the evaporation heat theta _eva from gross calorific theta _hh, it calculates the calorific value theta _h of the fuel cell stack 3.

(5) Next, the evaporation amount _{Qout_H2O} is subtracted from the sum _{Qin_H2O of the} water content and the generated water amount to calculate the surplus condensed water amount in the fuel cell stack 3.

(6) heating value theta _h it is determined whether the above heat dissipation theta _rad, calorific theta _h determines the calorific value theta _h from the heat radiation amount theta _eva when determining that higher heat radiation theta _eva request Control to reduce the amount of heat generated. Here, if there is condensed water in the fuel cell stack 3 performs a reduction in heating value theta _h by increasing the evaporation heat theta _eva due to increased water evaporation. If the condensed water does not exist, performs a reduction of the calorific value theta _h by output restriction of the fuel cell stack 3.

  In order to increase the amount of evaporation of internal moisture, it is necessary to increase at least one of the flow rate of hydrogen gas and air or reduce the pressure.

  However, let us consider a case in which the net power is managed constant, with the power output from the fuel cell stack 3 as gross power, and the power obtained by subtracting the power consumed by the auxiliary device driving the fuel cell stack 3 from the gross power as net output. When the flow rate of hydrogen gas and air supplied to the fuel cell stack 3 is increased, the heat of evaporation increases, while the power consumption of the compressors 1 and 2 that are examples of auxiliary machines that drive the fuel cell stack 3 also increases. It is necessary to increase the output power of the fuel cell stack 3. As a result, the gross power increases and the amount of heat generation increases, so there is a problem that the amount of heat generation of the fuel cell stack 3 may increase depending on the increase in gas flow rate.

Further, when the pressure of hydrogen gas and air supplied to the fuel cell stack 3 is reduced, the heat of vaporization increases, while the efficiency of the fuel cell stack 3, that is, the current-voltage characteristics decrease. The power needs to be increased. As a result, increase and current gross power - because calorific theta _h by a decrease in voltage characteristic is increased, there is a problem that is by a reduction margin of pressure which may calorific theta _h increases.

Therefore, in the embodiment of the present invention, first, it is determined whether or not excess condensed water exists in the fuel cell stack 3. If the surplus condensed water is determined not to exist, because the reduction of the calorific value theta _h using latent heat of vaporization of the internal water is difficult, performs output restriction of the fuel cell stack 3. On the other hand, if it is determined that the surplus condensed water is present, if is predicted that can reduce the amount of heat generated theta _h by increasing the amount of evaporation of internal moisture, hydrogen gas, air flow rate increases or hydrogen gas, the air At least one of pressure reduction is performed. If predicted can not be reduced calorific theta _h increased the amount of evaporation of internal moisture, perform output restriction of the fuel cell stack 3.

For example, as shown in FIG. 2, the system control apparatus 10 includes an information storage unit that stores information on the cooling performance of the radiator 9, that is, information on the amount of heat released per unit time of the radiator 9 (map A). In FIG. 2, the heat radiation amount per unit time increases as the outside air temperature decreases and the vehicle speed increases. This is the result when the inlet temperature of the radiator 9 of the cooling water, that is, the temperature detected by the temperature sensor 19 is constant. Therefore, the system control apparatus 10 can predict the heat release amount θ _rad if the map A in FIG. 2 is provided for the cooling water temperature.

The information storage unit in the system controller 10 further includes information on the higher heating value per unit time generated by a chemical reaction between hydrogen gas and oxygen (air) in the fuel cell stack 3, for example, as shown in FIG. (Map B) is stored. In FIG. 3, the higher heating value increases as the load (output power) of the fuel cell stack 3 increases. Moreover, since the efficiency of the fuel cell stack 3 increases as the operating pressure increases, the higher heating value decreases. Therefore, the system control apparatus 10 can predict the higher heating value θ _hh of the fuel cell stack 3 if the map B of FIG. 3 is provided.

  The information storage unit in the system controller 10 further includes, for example, as shown in FIG. 4, the amount of water produced per unit time generated by the chemical reaction between hydrogen gas and air in the fuel cell stack 3 and the load on the fuel cell stack 3. Information (table A) is stored. In FIG. 4, the amount of generated water increases as the load increases, because more hydrogen gas and air necessary for the reaction are required. Therefore, the system control apparatus 10 can predict the amount of water produced by the fuel cell stack 3 if the table A shown in FIG. 4 is provided.

  The information storage unit in the system control device 10 further stores information (table B) indicating the relationship of the target operating pressure with respect to the load of the fuel cell stack 3, as shown in FIG. In FIG. 5, the target operating pressure increases as the load (output power) required for the fuel cell stack 3 increases. Note that Table B in FIG. 5 is selected as a pressure that maximizes the efficiency of the fuel cell system during normal power generation. The target inlet pressure of the anode 4 and the target inlet pressure of the cathode 5 are selected to be the same.

  The information storage unit in the system control device 10 further stores information (table C) indicating the relationship of the anode gas flow rate (hydrogen gas flow rate) to the load of the fuel cell stack 3, for example, as shown in FIG. ing. In FIG. 6, the flow rate of hydrogen gas increases as the load (output power) required for the fuel cell stack 3 increases. The table C in FIG. 6 is selected based on the minimum flow rate of hydrogen gas necessary for power generation of the fuel cell stack 3.

[Control method of fuel cell system]
Next, a method for controlling the fuel cell system of FIG. 1 will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 7 shows a method of reducing the heat generation amount by increasing the evaporation amount of internal moisture by controlling the flow rates of hydrogen gas and air.

(A) First, in step S10, the system control device 10 detects the outside air temperature and the vehicle speed using the outside air temperature sensor and the vehicle speed sensor. Proceeding to step S20, the heat release amount θ _rad per unit time of the radiator 9 is calculated from the outside air temperature and the vehicle speed with reference to the map A in FIG.

  (B) Proceeding to step S30, the output electric energy of the fuel cell stack 3 is detected, and the pressure sensor 11 detects the inlet pressure of the hydrogen gas fuel cell stack 3. The inlet pressure of the fuel cell stack 3 is adjusted by the pressure adjusting valves 6 and 7 so that both the anode 4 and the cathode 5 are the same. Therefore, the air inlet pressure may be detected from the pressure sensor 15.

(C) Proceeding to step S40, the heat generation amount estimation unit 31 calculates the higher heat generation amount θ _hh per unit time of the fuel cell stack 3 with reference to the map B of FIG. 3 from the output power amount and the inlet pressure. Proceeding to step S50, the hydrogen gas flow rate, the air flow rate, the hydrogen gas inlet pressure, the air inlet pressure from the pressure sensors 11, 15, temperature sensors 12, 16, humidity sensors 13, 17, and flow meters 14, 18 respectively. , The hydrogen gas inlet temperature, the air inlet temperature, the hydrogen gas inlet humidity, and the air inlet humidity are detected, and based on the detected values of these gas state quantities, the gas water content estimation unit 32 determines whether the anode 4 and the cathode 5 Calculate the water content per unit time. Next, the generated water amount estimation unit 33 calculates the generated water amount per unit time with reference to the table A of FIG. 4 from the output power. Further, a sum Q _{in_H2O of the} water content and the generated water amount is calculated.

(D) Proceeding to step S60, the evaporation amount estimation unit 34 determines the unit of the anode 4 and the cathode 5 per unit time based on the cooling water temperature, the gas state amount obtained in step S50, and the sum Q _{in_H2O of the} water content and the generated water amount. The evaporation amount _{Qout_H2O} is calculated. _Proceeding to step S70, the heat of evaporation θ _eva per unit time is calculated based on the evaporation amount Q out — _{H 2 O.}

(E) Proceeding to step S80, the heat release amount θ _rad is compared with the heat generation amount θ _h in the fuel cell stack 3 (heat amount obtained by subtracting the evaporation heat θ _eva from the higher heat generation amount θ _hh ). When the heat release amount θ _rad is lower than the heat generation amount θ _h (YES in step S80), it is determined that the heat generation amount estimated by the heat generation amount estimation unit 34 is greater than the predetermined heat generation amount, and the process proceeds to step S90. On the other hand, if the heat release amount θ _rad is greater than or equal to the heat generation amount θ _h (NO in step S80), it is determined that the heat generation amount has not increased beyond the predetermined heat generation amount, and the process returns to step S10.

(F) In step S90, the sum Q _{in_H2O of the} water content and the amount of produced water is compared with the evaporation amount Q _{out_H2O} . When the sum Q _{in_H2O of the} water content and the generated water amount is _larger than the drainage amount Q _{out_H2O} (YES in step S90), it is determined that excess condensed water exists in the fuel cell stack 3, and the process proceeds to step S110. Whether the calorific value can be reduced by using the latent heat of vaporization of the condensed water after step S110, in other words, whether the calorific value can be reduced by increasing the evaporation amount of internal moisture. Judgment is made. When the sum Q _{in_H2O of the} water content and the amount of produced water is less than or equal to the amount of drainage Q _{out_H2O} (NO in step S90), there is no excess condensed water in the fuel cell stack 3, so the latent heat of vaporization of the condensed water is used. Therefore, it is determined that it is difficult to reduce the heat generation amount, and the process proceeds to step S100. In step S100, it performs the reduction of the heating value theta _h by output restriction of the fuel cell stack 3.

  (G) In step S110, a temporary value of the target gas flow rate (here, air flow rate) is set. The provisional value is set as a value slightly increased to the provisional value (flow rate Q ′ = Q ′ + ΔQ (Q ′: provisional value, ΔQ: slight increase amount)). The initial value of the provisional value is set as the target gas flow rate in the operating state of the current fuel cell system. Proceeding to step S120, the required output power amount P 'corresponding to the provisional value of the target gas flow rate is calculated.

(H) Proceeding to step S130, the target inlet pressure of the fuel cell stack 3 is calculated from the required output power amount P ′ with reference to the table B of FIG. Required power amount P 'from a target inlet pressure by referring to the map B of FIG. 3, higher heating value θ per unit of the fuel cell stack 3 times' calculates the _hh. Proceeding to step S140, the flow rate of hydrogen gas (anode gas flow rate) is calculated from the required output power amount P ′ with reference to the table C of FIG. The temperature sensors 12 and 16 and the humidity sensors 13 and 17 detect the hydrogen gas inlet temperature, the air inlet temperature, the hydrogen gas inlet humidity, and the air inlet humidity, respectively. Based on the target value of the gas state quantity and these detected values, the water content per unit time of the anode 4 and the cathode 5 is calculated. Next, the amount of generated water per unit time is calculated from the required output power amount P ′ with reference to the table A of FIG. Furthermore, the sum Q ′ in — _{H 2 O} of the water content and the amount of reaction product water is calculated.

(I) Proceeding to step S150, the temperature sensor 19 detects the temperature of the cooling water. Next, the evaporation amount Q ′ out — _{H 2 O} per unit time of the anode 4 and the cathode 5 is calculated based on the cooling water temperature, the target value and detection value of the gas state quantity, and the sum Q ′ in — _{H 2 O} of the water content and the generated water quantity. Proceeds to step S160, 'based on _{Out_H2O,} evaporation heat θ per unit time' evaporation amount Q to calculate the _eva.

(Nu) _Proceeding to step S170, the total _{Q'in_H2O of the} water content and the amount of reaction product water is _compared with the evaporation amount _{Q'out_H2O} . When the sum Q ′ in — _{H 2 O of the} water content and the generated water amount is _larger than the evaporation amount Q ′ _{out_H 2 O} (YES in step S170), it is determined that condensed water exists, and the process proceeds to step S180. On the other hand, when the sum Q ′ _{in_H 2 O of the} water content and the amount of generated water is _{equal to} or less than the evaporation amount Q ′ _{out_H 2 O} (NO in step S170), since the condensed water does not exist, the heat generation amount can be reduced using latent heat of evaporation. it is determined that it is difficult, the flow proceeds to step S200, similarly to step S100, performs the reduction of the heating value theta _h by output restriction of the fuel cell system.

(L) In step S180, the heat release amount θ ′ _rad is compared with the heat generation amount θ ′ _h (a value obtained by subtracting the evaporation heat θ ′ _eva from the higher heat generation amount θ ′ _hh ). If heat dissipation theta _'rad calorific value theta' or less _h (NO in step S180), the process returns to step S110, again at step S110 and later, 'calorific value by increasing the _eva theta' evaporation theta internal moisture _Judge whether _h can be reduced. If the heat release amount θ ′ _rad is higher than the heat generation amount θ ′ _h (YES in step S180), the heat generation amount of the fuel cell stack 3 can be reduced using the latent heat of vaporization of the condensed water, and the process proceeds to step S190.

  (W) In step S190, the target cathode gas (air) flow rate is changed, and the compressor 2 is controlled to achieve the target cathode gas flow rate. Thus, the evaporation amount control unit 35 can increase the evaporation amount of the condensed water and reduce the heat generation amount of the fuel cell stack 3.

[Effects of First Embodiment]
As described above, according to the first embodiment, the following effects are produced.

Condensed water is generated in the fuel cell stack 3 based on the water content estimated by the gas water content estimation unit 32, the generated water amount estimated by the generated water amount estimation unit 33, and the evaporation amount estimated by the evaporation amount estimation unit 34. Therefore, when it is determined that condensed water is generated when the calorific value θ ′ _h of the fuel cell stack is larger than the predetermined calorific value, the latent heat of vaporization of the condensed water is determined. Since the amount of heat generated by the fuel cell stack can be reduced by using the above, the amount of heat generated by the fuel cell stack 3 can be reduced by increasing the amount of condensed water evaporated by the evaporation amount control unit 35. 1 effect>.

When the sum Q ′ in — _{H 2 O of the} water content estimated by the gas water content estimation unit 32 and the generated water amount estimated by the generated water amount estimation unit 33 is _larger than the evaporation amount Q ′ _{out_H 2 O} estimated by the evaporation amount estimation unit 34, that is, fuel When surplus condensed water exists in the battery stack 3, the amount of generated heat can be reduced by using the latent heat of evaporation of the condensed water. Therefore, by increasing the evaporation amount of the condensed water in the fuel cell stack 3 by the evaporation amount control unit 35, the power control unit 36 can reduce the heat generation amount without limiting the output power of the fuel cell stack 3. <Effects of claim 2>

The sum Q ′ in — _{H 2 O} of the water content estimated by the gas water content estimation unit 32 and the water content estimated by the generated water amount estimation unit 33 is equal to or less than the evaporation amount Q ′ _{out_H 2 O} estimated by the evaporation amount estimation unit 34. In this case, that is, when there is no excessive condensed water in the fuel cell stack 3, it is difficult to reduce the heat generation amount by using the latent heat of vaporization of the condensed water. The amount of heat generation can be reduced by limiting the above <Effect of Claim 3>.

When the sum Q ′ in — _{H 2 O of the} water content estimated by the gas water content estimation unit 32 and the generated water amount estimated by the generated water amount estimation unit 33 is larger than the evaporation amount Q ′ _{out_H 2 O} estimated by the evaporation amount estimation unit 34, that is, In the case where excess condensed water exists in the fuel cell stack 3,
While there is a possibility that the amount of heat generated can be reduced by using the latent heat of vaporization of the condensed water in the fuel cell stack 3, the load (output power) of the fuel cell stack 3 increases or the efficiency of the fuel cell stack 3 decreases. When there is a possibility that the heat generation amount of the fuel cell stack 3 is increased, the heat generation amount predicted by the heat generation amount prediction unit 37 and the heat generation amount estimated by the heat generation amount estimation unit 31 are compared.

  Accordingly, when the predicted heat generation amount is equal to or less than the heat generation amount, the evaporation amount control unit 35 increases the evaporation amount of the condensed water in the fuel cell stack 3 and the power control unit 36 performs output restriction. The calorific value can be reduced without any problem. On the other hand, when the predicted heat generation amount is larger than the heat generation amount, the power control unit 36 can limit the output power to reduce the heat generation amount.

  In addition, according to the first embodiment, the following effects occur.

  When the heat generation amount of the fuel cell stack 3 is greater than the required heat generation amount determined from the heat dissipation amount of the radiator 9, the evaporation amount control unit 35 performs control to reduce the heat generation amount.

  However, if there is surplus condensed water determined by subtracting the amount of drainage (evaporation) from the sum of the amount of water entering the fuel cell stack 3 (water content) and the amount of produced water, the gas flow rate of the fuel cell stack 3 In this case, the amount of heat generated by the fuel cell stack 3 can be reduced by utilizing the latent heat of vaporization of the internal moisture. On the other hand, the amount of heat generated by the fuel cell stack 3 may increase due to an increase in the load (output power amount) of the fuel cell stack 3 or a decrease in power generation efficiency of the fuel cell stack 3. Therefore, when it is predicted that the amount of heat generated can be reduced by evaporating the internal moisture, the amount of heat generated can be reduced without limiting the output by performing control to increase the gas flow rate of the fuel cell stack 3. On the other hand, if it is predicted that the amount of generated heat cannot be reduced by increasing the gas flow rate, the amount of generated heat can be reduced by limiting the output of the fuel cell stack 3.

  In addition, when there is no excessive condensed water, it is difficult to reduce the heat generation amount using the latent heat of evaporation of the internal moisture, and thus the heat generation amount can be reduced by limiting the output of the fuel cell stack 3. .

(Second Embodiment)
In the second embodiment, instead of changing the target cathode gas (air) flow rate in the first embodiment, the target inlet pressure of the fuel cell stack 3 is changed to thereby evaporate condensed water. Will be described in which the amount of heat generated by the fuel cell stack 3 is reduced.

  The overall configuration of the fuel cell system according to the second embodiment is the same as that shown in FIG. 1, and illustration and description thereof are omitted. Similarly, the configuration of the system control apparatus 10 is the same as that in FIG.

  The information storage unit in the system control device 10 further stores information (table D) indicating the relationship of the cathode gas flow rate (air flow rate) to the load of the fuel cell stack 3, for example, as shown in FIG. Yes. In FIG. 8, the air flow rate increases as the load (output power) required for the fuel cell stack 3 increases. Note that the table D in FIG. 8 is selected based on the minimum flow rate of air necessary for power generation of the fuel cell stack 3.

  Next, a control method of the fuel cell system according to the second embodiment will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 9 shows a method of reducing the heat generation amount by increasing the evaporation amount of internal moisture by controlling the pressures of hydrogen gas and air. Further, the flowchart of FIG. 9 is obtained by changing a part of the flowchart of FIG. S310 to S400 in FIG. 9 are the same as S10 to S100 in FIG.

(A) In step S410, a temporary value of the target inlet pressure of the fuel cell stack 3 is set. The provisional value is set as a value slightly reduced to the provisional value (pressure P _r ′ = P _r ′ + ΔP _r (P _r ′: provisional value, ΔP _r : slight reduction)). The initial value of the provisional value is set as the target inlet pressure in the operating state of the current fuel cell system.

(B) Proceeding to step S420, the required output power amount P ′ corresponding to the temporary value of the target inlet pressure of the fuel cell stack 3 is calculated. Proceeds to step S430, 'with reference to the map B of FIG. 3 and a target inlet pressure, higher heating value θ per unit of the fuel cell stack 3 times' required power P is calculated _hh.

(C) In step S440, the flow rate of the hydrogen gas is calculated from the required output power amount P ′ with reference to the table C in FIG. Next, the flow rate of air is calculated from the required output power amount P ′ with reference to the table D of FIG. The temperature sensors 12 and 16 and the humidity sensors 13 and 17 detect the hydrogen gas inlet temperature, the air inlet temperature, the hydrogen gas inlet humidity, and the air inlet humidity, respectively. Based on the target value of the gas state quantity and these detected values, the water content per unit time of the anode 4 and the cathode 5 is calculated. Next, the amount of generated water per unit time is calculated from the required output power amount P ′ with reference to the table A of FIG. Furthermore, the sum Q ′ in — _{H 2 O} of the water content and the amount of reaction product water is calculated.

(D) Proceeding to step S450, the temperature of the cooling water is detected from the temperature sensor 19. Next, the evaporation amount Q ′ out — _{H 2 O} per unit time of the anode 4 and the cathode 5 is calculated based on the cooling water temperature, the target value and detection value of the gas state amount, and the sum Q ′ in — _{H 2 O} of the water content and the generated water amount. Proceeds to S460 step, 'based on _{Out_H2O,} evaporation heat θ per unit time' evaporation amount Q to calculate the _eva.

(E) Proceeding to step S470, the sum Q ′ in — _{H 2 O of the} water content and the amount of reaction product water is _compared with the evaporation amount Q ′ _{out_H 2 O.} When the sum Q ′ in — _{H 2 O of the} water content and the generated water amount is _larger than the evaporation amount Q ′ _{out_H 2 O} (YES in step S470), it is determined that condensed water exists, and the process proceeds to step _S480 . On the other hand, when the sum Q ′ _{in_H 2 O of the} water content and the generated water amount is _{equal to} or less than the evaporation amount Q ′ _{out_H 2 O} (NO in step S470), since the condensed water does not exist, the heat generation amount can be reduced by using latent heat of evaporation. it is determined that it is difficult, the flow proceeds to step S500, similarly to step S400, performs the reduction of the heating value theta _h by output restriction of the fuel cell system.

(F) In step S480, the heat release amount θ ′ _rad is compared with the heat generation amount θ ′ _h (a value obtained by subtracting the evaporation heat θ ′ _eva from the higher heat generation amount θ ′ _hh ). If heat dissipation theta _'rad calorific value theta' or less _h (NO in S480 step), the process returns to step S410, again at step S410 and later, 'calorific value by increasing the _eva theta' evaporation theta internal moisture _Judge whether _h can be reduced. If the heat release amount θ ′ _rad is higher than the heat generation amount θ ′ _h (YES in step S480), the heat generation amount of the fuel cell stack 3 can be reduced using the latent heat of vaporization of the condensed water, and the process proceeds to step S490.

  (G) In step S490, the target inlet pressure of the fuel cell stack 3 is changed, and the pressure regulating valves 6 and 7 are controlled so as to be the target inlet pressure. Thus, the evaporation amount control unit 35 can increase the evaporation amount of the condensed water and reduce the heat generation amount of the fuel cell stack 3.

  As described above, according to the second embodiment, the following effects are produced.

  When the heat generation amount of the fuel cell stack 3 is greater than the required heat generation amount determined from the heat dissipation amount of the radiator 9, the evaporation amount control unit 35 performs control to reduce the heat generation amount.

  However, if there is surplus condensed water determined by subtracting the amount of drainage (evaporation) from the sum of the amount of water entering the fuel cell stack 3 (water content) and the amount of produced water, the gas flow rate of the fuel cell stack 3 In this case, the amount of heat generated by the fuel cell stack 3 can be reduced by utilizing the latent heat of vaporization of the internal moisture. On the other hand, the amount of heat generated by the fuel cell stack 3 may increase due to an increase in the load (output power amount) of the fuel cell stack 3 or a decrease in power generation efficiency of the fuel cell stack 3. Therefore, when it is predicted that the amount of heat generated can be reduced by evaporating the internal moisture, the amount of heat generated can be reduced without performing output restriction by performing control to reduce the gas pressure of the fuel cell stack 3. On the other hand, when it is predicted that the heat generation amount cannot be reduced even if the gas pressure is reduced, the heat generation amount can be reduced by limiting the output of the fuel cell stack 3.

  In addition, when there is no excessive condensed water, it is difficult to reduce the heat generation amount using the latent heat of evaporation of the internal moisture, and thus the heat generation amount can be reduced by limiting the output of the fuel cell stack 3. .

(Third embodiment)
In the third embodiment, by changing the target cathode gas (air) flow rate in the first embodiment and changing the target inlet pressure of the fuel cell stack 3 in the second embodiment. A case where the amount of heat generated by the fuel cell stack 3 is reduced by increasing the evaporation amount of the condensed water will be described.

  The overall configuration of the fuel cell system according to the third embodiment is the same as that shown in FIG. 1, and illustration and description thereof are omitted. Similarly, the configuration of the system control apparatus 10 is the same as that in FIG.

  The information storage unit in the system control apparatus 10 further stores information (map C) indicating the efficiency of the fuel cell stack with respect to the gas pressure and the gas flow rate, for example, as shown in FIG. Note that a map C in FIG. 10 is a system efficiency map when the load of the fuel cell stack 3 is constant.

  Next, a control method of the fuel cell system according to the third embodiment will be described with reference to the flowchart of FIG. In addition, the flowchart of FIG. 11 shows the method of controlling the pressure of hydrogen gas and air. Further, the flowchart of FIG. 11 is obtained by changing a part of the flowchart of FIG. Since S10 to S100 in FIG. 7 are the same, illustration and description are omitted, and description will be made from S600.

  (A) In step S600, a flag is set to zero as data necessary for determining whether or not the calorific value can be reduced by increasing the evaporation amount of internal moisture. Proceeding to step S610, a temporary value of the target gas flow rate (here, air flow rate) is set. The provisional value is set as a value slightly increased to the provisional value (flow rate Q ′ = Q ′ + ΔQ (Q: provisional value, ΔQ: slight increase amount)). The initial value of the provisional value is set as the target gas flow rate in the operating state of the current fuel cell system.

  (B) In step S611, the provisional value of the target gas flow rate is compared with the predetermined gas flow rate. If the provisional value is smaller than the predetermined gas flow rate (YES in step S611), the process proceeds to step S612. If the provisional value is greater than or equal to the predetermined gas flow rate (NO in step S611), the process proceeds to step S605. The “predetermined gas flow rate” is selected as the maximum gas flow rate that can be discharged by the gas supply device.

(C) In step S612, a temporary value of the target inlet pressure of the fuel cell stack 3 is set. The provisional value is set as a value slightly reduced to the provisional value (pressure P _r ′ = P _r ′ + ΔP _r (P _r : provisional value, ΔP _r : slight reduction amount)). The initial value of the provisional value is set as the target inlet pressure in the operating state of the current fuel cell system.

  (D) Proceeding to step S613, the provisional value of the target gas pressure is compared with the predetermined gas pressure. When the provisional value is larger than the predetermined gas pressure (YES in step S613), the process proceeds to step S620. If the provisional value is equal to or lower than the predetermined gas pressure (NO in step S613), the process returns to step S610.

(E) Proceeding to step S620, the required output power amount P ′ corresponding to the temporary value of the target inlet pressure of the fuel cell stack 3 is calculated. Proceeds to step S630, 'with reference to the map B of FIG. 3 and a target inlet pressure, higher heating value θ per unit time fuel cell stack 3' required power P is calculated _hh.

(F) Proceeding to S640, the hydrogen gas flow rate is calculated from the required output power amount P ′ with reference to the table C of FIG. The temperature sensors 12 and 16 and the humidity sensors 13 and 17 detect the hydrogen gas inlet temperature, the air inlet temperature, the hydrogen gas inlet humidity, and the air inlet humidity, respectively. Based on the target value of the gas state quantity and these detected values, the water content per unit time of the anode 4 and the cathode 5 is calculated. Next, the amount of generated water per unit time is calculated from the output power with reference to the table A in FIG. Further, the sum Q ′ in — _{H 2 O} of the water content and the generated water amount is calculated.

(G) Proceeding to step S650, the temperature sensor 19 detects the temperature of the cooling water. Next, the evaporation amount Q ′ out — _{H 2 O} per unit time of the anode 4 and the cathode 5 is calculated based on the cooling water temperature, the target value and detection value of the gas state amount, and the sum Q ′ in — _{H 2 O} of the water content and the generated water amount. Proceeds to S660 step, 'based on _{Out_H2O,} evaporation heat θ per unit time' evaporation amount Q to calculate the _eva.

(H) Proceeding to step S670, the sum Q ′ in — _{H 2 O of the} water content and the amount of generated water is _compared with the evaporation amount Q ′ _{out_H 2 O.} When the sum Q ′ in — _{H 2 O of the} water content and the generated water amount is _larger than the evaporation amount Q ′ _{out_H 2 O} (YES in step S670), it is determined that excess condensed water exists in the fuel cell stack 3, and the process proceeds to step S680. When the sum Q ′ _{in_H 2 O of the} water content and the generated water amount is _{equal to} or less than the evaporation amount Q ′ _{out_H 2 O} (NO in step S670), it is difficult to reduce the heat generation amount using latent heat of evaporation because the condensed water does not exist. It is determined that there is, and the process returns to step S610.

(I) In step S680, the heat release amount θ ′ _rad is compared with the heat generation amount θ ′ _h (a value obtained by subtracting the evaporation heat θ ′ _eva from the higher heat generation amount θ ′ _hh ). When the heat release amount θ ′ _rad is equal to or less than the heat release amount θ ′ _h (NO in step S680), the process returns to step S612. When the heat release amount θ ′ _rad is higher than the heat generation amount θ ′ _h (YES in step S680), the process proceeds to step S710.

  (J) In step S710, the efficiency β of the fuel cell stack 3 is calculated from the target air flow rate and the target inlet pressure with reference to the map C shown in FIG. When the gas pressure is increased, the power generation efficiency of the fuel cell stack 3 is increased. However, the power consumption of the auxiliary machine is increased, so that the system efficiency is lowered, and when the gas flow rate is increased, the power consumption of the auxiliary machine is increased. Therefore, the calculation is based on the fact that the system efficiency decreases.

(K) Proceeding to step S720, the efficiency β calculated in step S710 is compared with the efficiency β ₀ . Next, the combination of the target gas flow rate with the higher efficiency and the target inlet pressure is maintained. The initial value of efficiency β ₀ is selected as 0. Further, after the comparison between the efficiency β and the efficiency β ₀ is completed, a value with higher efficiency is set as the initial value β ₀ .

  (M) Proceeding to step S730, the flag is set to 1 as data indicating that it is determined that the amount of heat generation can be reduced by increasing the evaporation amount of internal moisture. Thereafter, the process returns to step S610.

(N) On the other hand, if NO in step S611, if the flag is 1 in step S605, the process proceeds to step S690. If the flag is not 1, the process proceeds to S700 steps performed to reduce the heating value theta _h by output restriction of the fuel cell system. In step S690, the target gas flow rate and the target inlet pressure are changed to the values held in step S720, and the compressors 1 and 2 and the pressure regulating valves 6 and 7 are controlled so as to be the target gas flow rate and the target inlet pressure.

  As described above, according to the third embodiment, the following effects are produced.

  When the evaporation amount control unit 35 increases the evaporation amount of excess moisture (internal moisture) in the fuel cell stack 3 without reducing the output by the power control unit 36, By selecting the operating point of the gas flow rate at which the efficiency β becomes higher, it is possible to suppress a reduction in fuel consumption <the effect of claim 5>.

When the evaporation amount control unit 35 increases the evaporation amount of excess moisture (internal moisture) in the fuel cell stack 3 without reducing the output by the power control unit 36, Since the operating point of the gas flow rate or the gas pressure with higher efficiency can be selected, it is possible to suppress a reduction in fuel consumption <the effect of claim 6>.
(Other embodiments)
As described above, the present invention has been described according to the first to third embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the entire configuration of the fuel cell system shown in FIG. 1 may include a humidifier that humidifies at least one of hydrogen gas or air supplied to the fuel cell stack 3. That is, the evaporation amount control unit 35 may include humidification amount adjusting means for adjusting the humidification amount of at least one of hydrogen gas or air. In this case, the amount of heat generated by the humidifier can be reduced from that during normal operation, thereby increasing the amount of evaporation of internal moisture and reducing the amount of heat generation. For this reason, in changing the operating point of the gas flow rate or gas pressure of the fuel cell stack 3, the allowance for increasing the gas flow rate or reducing the gas pressure can be reduced. Therefore, since the operating point of the gas flow rate or gas pressure at which the efficiency β of the fuel cell system becomes higher can be selected, it is possible to suppress a decrease in fuel consumption.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

  The present invention can be used in a control device and a control method for improving the cooling capacity of a fuel cell stack by means other than a radiator.

1 is a block diagram showing an overall configuration of a fuel cell system according to a first embodiment of the present invention. It is an example of the graph which shows the heat dissipation per unit time of a radiator. It is an example of the graph which shows the high calorific value per unit time which arises by the chemical reaction of hydrogen gas and air in a fuel cell stack. It is an example of the graph which shows the amount of produced water per unit time which arises by the chemical reaction of hydrogen gas and air in a fuel cell stack. It is a graph which shows an example of the relationship of the target operating pressure with respect to the load of a fuel cell stack. It is a graph which shows an example of the relationship of the anode gas flow volume (fuel gas flow volume) with respect to the load of a fuel cell stack. It is a flowchart which shows an example of the procedure of the method of controlling the fuel cell system of FIG. It is a graph which shows an example of the relationship of the cathode gas flow rate (air flow rate) with respect to the load of a fuel cell stack. It is a flowchart which shows the procedure of the control method of the fuel cell system concerning 2nd Embodiment. It is a graph which shows an example of the efficiency of a fuel cell stack with respect to gas pressure and gas flow rate. It is a flowchart which shows the procedure of the control method of the fuel cell system concerning 3rd Embodiment.

Explanation of symbols

1, 2 ... Compressor 3 ... Fuel cell stack (fuel cell)
DESCRIPTION OF SYMBOLS 4 ... Anode 5 ... Cathode 6, 7 ... Pressure regulating valve 8 ... Pump 9 ... Radiator 10 ... System control device 11, 15 ... Pressure sensor 12, 16, 19 ... Temperature sensor 13, 17 ... Humidity sensor 14, 18 ... Flow meter 20 ... Hydrogen tank 31 ... Heat generation amount estimation unit (heat generation amount estimation means)
32 ... Gas water content estimation part (gas water content estimation means)
33 ... Generated water amount estimation unit (generated water amount estimation means)
34: Evaporation amount estimation unit (evaporation amount estimation means)
35: Evaporation amount control unit (evaporation amount control means)
36 ... Power control unit (power control means)
37 ... Heat generation amount prediction unit (heat generation amount prediction means)
38 ... Efficiency prediction means θeva ... Heat release amount θeva ... Evaporation heat θhh ... Higher heat release amount θh ... Heat release amount θrad ... Heat release amount

Claims (14)

In a fuel cell system that generates power by a chemical reaction between a fuel gas and an oxidant gas supplied to the fuel cell,
A calorific value estimating means for estimating the calorific value of the fuel cell;
Gas water content estimation means for estimating the water content contained in the fuel gas or oxidant gas supplied to the fuel cell;
A generated water amount estimating means for estimating a generated water amount generated by the chemical reaction;
An evaporation amount estimating means for estimating an evaporation amount of internal moisture existing inside the fuel cell;
Evaporation amount control means for controlling the evaporation amount of the internal moisture,
When the heat generation amount estimated by the heat generation amount estimation means increases, the water content estimated by the gas water content estimation means, the generated water amount estimated by the generated water amount estimation means, and the evaporation amount estimation means The fuel cell system, wherein the evaporation amount control means controls the evaporation amount of the internal moisture based on the estimated evaporation amount.   When the sum of the water content estimated by the gas water content estimation unit and the generated water amount estimated by the generated water amount estimation unit is larger than the evaporation amount estimated by the evaporation amount estimation unit, the evaporation amount control unit The fuel cell system according to claim 1, wherein the evaporation amount of the internal moisture is increased. Power control means for controlling the output power of the fuel cell;
When the sum of the water content estimated by the gas water content estimation unit and the generated water amount estimated by the generated water amount estimation unit is equal to or less than the evaporation amount estimated by the evaporation amount estimation unit, the power control unit The fuel cell system according to claim 2, wherein the output power is limited. Power control means for controlling the output power of the fuel cell;
A calorific value predicting means for predicting a calorific value of the fuel cell system after the evaporation amount control means increases the evaporation amount of the internal moisture;
4. The power control unit limits the output power when the predicted heat generation amount predicted by the heat generation amount prediction unit is larger than the heat generation amount estimated by the heat generation amount estimation unit. The fuel cell system described. An efficiency predicting means for predicting the efficiency of the fuel cell system;
The evaporation amount control means includes at least one of a fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas or an oxidant gas flow rate adjusting means for adjusting the flow rate of the oxidant gas,
The evaporation amount control means increases the flow rate of the fuel gas by the fuel gas flow rate adjustment means or sets the flow rate of the oxidant gas by the oxidant gas flow rate adjustment means so that the efficiency of the fuel cell system is maximized. 5. The fuel cell system according to claim 1, wherein the amount of evaporation of the internal moisture is increased by performing at least one of the increases. An efficiency predicting means for predicting the efficiency of the fuel cell system;
The evaporation amount control means includes at least one of a fuel gas pressure adjusting means for adjusting the pressure of the fuel gas or an oxidant gas pressure adjusting means for adjusting the pressure of the oxidant gas,
The evaporation amount control means reduces the pressure of the fuel gas by the fuel gas pressure adjusting means or reduces the pressure of the oxidant gas by the oxidant gas pressure adjusting means so that the efficiency of the fuel cell system is maximized. 6. The fuel cell system according to claim 1, wherein the amount of evaporation of the internal moisture is increased by performing at least one of the reductions. The evaporation amount control means includes a humidification amount adjusting means for adjusting a humidification amount of at least one of the fuel gas or the oxidant gas,
5. The evaporation amount control unit according to claim 1, wherein the humidification amount adjustment unit increases the evaporation amount of the internal moisture by decreasing the humidification amount from that during normal operation. 6. Fuel cell system. In a control method of a fuel cell system for generating power by a chemical reaction between a fuel gas and an oxidant gas supplied to the fuel cell,
Estimating the amount of heat generated by the fuel cell;
Estimating the water content contained in the fuel gas or oxidant gas supplied to the fuel cell;
Estimating the amount of water produced by the chemical reaction;
Estimating the amount of evaporation of internal moisture present inside the fuel cell;
And a step of controlling the evaporation amount of the internal moisture based on the water content, the generated water amount, and the evaporation amount when the calorific value increases.   The step of controlling the evaporation amount of the internal moisture is a step of increasing the evaporation amount of the internal moisture when the sum of the water content and the generated water amount is larger than the evaporation amount. The fuel cell system control method described.   When the sum of the water content and the generated water amount is equal to or less than the evaporation amount, the step of limiting the output power of the fuel cell is performed instead of the step of controlling the evaporation amount of the internal moisture. Item 10. A fuel cell system control method according to Item 9. Predicting the amount of heat generated by the fuel cell system after increasing the amount of evaporation of the internal moisture;
The method of controlling a fuel cell system according to claim 9 or 10, further comprising: limiting output power of the fuel cell when the predicted heat generation amount is larger than the estimated heat generation amount.   The step of controlling the evaporation amount of the internal moisture is performed by increasing at least one of the flow rate of the fuel gas or the flow rate of the oxidant gas so that the efficiency of the fuel cell system is maximized. 9. The method of controlling a fuel cell system according to claim 8, wherein the method is a step of increasing the evaporation amount of moisture.   The step of controlling the evaporation amount of the internal moisture is performed by reducing at least one of the pressure of the fuel gas or the pressure of the oxidant gas so that the efficiency of the fuel cell system is maximized. 9. The method of controlling a fuel cell system according to claim 8, wherein the method is a step of increasing the evaporation amount of moisture.   The step of controlling the evaporation amount of the internal moisture is a step of increasing the evaporation amount of the internal moisture by decreasing the humidification amount of at least one of the fuel gas or the oxidant gas from that during normal operation. A control method for a fuel cell system according to claim 8.

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