WO2010090091A1 - Fuel cell system - Google Patents

Fuel cell system Download PDF

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Publication number
WO2010090091A1
WO2010090091A1 PCT/JP2010/050908 JP2010050908W WO2010090091A1 WO 2010090091 A1 WO2010090091 A1 WO 2010090091A1 JP 2010050908 W JP2010050908 W JP 2010050908W WO 2010090091 A1 WO2010090091 A1 WO 2010090091A1
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WO
WIPO (PCT)
Prior art keywords
fuel cell
temperature
pump
cell system
gas
Prior art date
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PCT/JP2010/050908
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French (fr)
Japanese (ja)
Inventor
浩己 田中
良明 長沼
修 弓田
卓睦 手塚
伸和 水野
公志 藤
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トヨタ自動車株式会社
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Publication of WO2010090091A1 publication Critical patent/WO2010090091A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H01M8/04029—Heat exchange using liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
    • H01M8/04225—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells during start-up
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0432—Temperature; Ambient temperature
    • H01M8/04358—Temperature; Ambient temperature of the coolant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04768—Pressure; Flow of the coolant
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a fuel cell system including a fuel cell.
  • the fuel cell system that uses a fuel cell that generates power by an electrochemical reaction of reaction gases (fuel gas and oxidant gas) as an energy source has attracted attention.
  • the fuel cell system supplies high-pressure fuel gas from the fuel tank to the anode of the fuel cell, and also supplies air as the oxidizing gas to the cathode, and generates an electromotive force by electrochemically reacting these fuel gas and oxidizing gas. It is something to be made.
  • This type of fuel cell system has a cooling system that circulates cooling water into the stack constituting the fuel cell and cools it.
  • the temperature detection values are read from the temperature sensors provided at the inlet and the outlet of the cooling pipe, and the torque value and the rotation speed are read from the cooling liquid pump to enter the operating state of the cooling liquid pump. Based on this, there is one that estimates the temperature of the fuel cell stack (see, for example, Patent Document 1). Also, there is a temperature sensor that measures the internal temperature of the fuel cell, and controls the driving of the cooling water pump according to the internal temperature of the fuel cell (see, for example, Patent Document 2).
  • the fuel cell has a structure in which a plurality of cells are stacked and end plates are fastened from both sides of the cells to form a stack, it is difficult to provide a temperature sensor inside as in Patent Document 2. .
  • the temperature inside the fuel cell is estimated based on the temperature of the inlet and outlet of the coolant and the operating state of the coolant pump, but the coolant before the start is flowing.
  • the internal temperature and the coolant inlet / outlet temperature differed, making it difficult to accurately grasp the internal temperature.
  • the temperature of the fuel cell is further lowered by the cooling water circulating inside the fuel cell, and the startability may be lowered.
  • the present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell system capable of appropriately operating according to the temperature of the fuel cell.
  • a fuel cell system of the present invention is a fuel cell system that supplies a fuel gas and an oxidizing gas to the fuel cell, and generates electricity by causing an electrochemical reaction between the fuel gas and the oxidizing gas.
  • a cooling system that circulates a cooling medium in the fuel cell by a pump, and a cooling medium pumped from the fuel cell by driving the pump of the cooling system in a state in which power generation by the fuel cell is prohibited at a low temperature start.
  • a controller that estimates the internal temperature of the fuel cell from the temperature.
  • the temperature of the fuel cell and the cooling medium remaining in the fuel cell are the same, so the pump of the cooling system is driven in a state where power generation by the fuel cell is prohibited, and the fuel cell is sent out from the fuel cell.
  • the temperature of the cooling medium is measured, the internal temperature of the fuel cell can be estimated with high accuracy even at a low temperature start (for example, at a start below freezing point).
  • the power generation in the fuel cell can be appropriately controlled based on the internal temperature of the fuel cell estimated with high accuracy.
  • the control unit determines the peak value of the temperature of the coolant on the outlet side of the fuel cell or the temperature of the coolant on the outlet side of the fuel cell after a predetermined time has elapsed from the start of driving the pump as the internal temperature of the fuel cell It may be estimated.
  • the temperature of the cooling medium at the outlet side of the fuel cell is increased by the relatively high temperature cooling water sent from the fuel cell at the start of driving of the pump, and then gradually averages as the cooling medium circulates in the cooling system. Will be converted. Therefore, the peak value of the temperature of the cooling medium at the outlet side of the fuel cell or the temperature of the cooling medium after a predetermined time has elapsed from the start of pump driving can be estimated as the internal temperature of the fuel cell.
  • the predetermined time may be set before or after the time until the peak value is reached.
  • the control unit may stop the pump and start power generation by the fuel cell when the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature.
  • the controller may start power generation by the fuel cell by reversing the pump when the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature.
  • the reverse rotation of the pump is performed for a predetermined time, and this predetermined time is a time until the coolant sent from the fuel cell returns to the fuel cell due to the forward rotation of the pump. be able to.
  • the cooling medium is circulated, the fuel cell is further cooled and the fuel cell is not started properly (for example, freezing in the fuel cell, condensation of the oxidizing off-gas discharged from the fuel cell, etc.). It may be the resulting temperature.
  • an appropriate start-up operation can be performed according to the temperature of the fuel cell.
  • FIG. 1 is a system configuration diagram schematically showing a fuel cell system according to an embodiment of the present invention. It is a flowchart which shows control of the fuel cell by a control part. It is a figure which shows the method of prediction of the internal temperature of a fuel cell by the detection result of a temperature sensor. It is a flowchart which shows the control in the low temperature start mode by a control part. It is a graph which shows the method of measuring the internal temperature of a fuel cell. It is a graph which shows the method of measuring the internal temperature of a fuel cell. It is a graph explaining the control of the pump in the low temperature start mode. It is a graph explaining other control of the pump in the low temperature start mode.
  • the fuel cell system 1 is an in-vehicle power generation system for a fuel cell vehicle.
  • a fuel cell system for any moving body such as a ship, an aircraft, a train, and a walking robot, for example, a fuel cell
  • stationary fuel cell systems used as power generation equipment for buildings (housing, buildings, etc.).
  • air as an oxidizing gas is supplied to an air supply port of the fuel cell 20 via an air supply path 71.
  • the air supply path 71 is provided with an air filter A1 that removes particulates from the air, a compressor A3 that pressurizes the air, a pressure sensor P4 that detects the supply air pressure, and a humidifier A21 that adds required moisture to the air.
  • the compressor A3 is driven by the motor M.
  • the motor M is driven and controlled by the control unit 50.
  • the air off gas discharged from the fuel cell 20 is discharged to the outside through the exhaust path 72.
  • the exhaust path 72 is provided with a pressure sensor P1 for detecting the exhaust pressure and a pressure adjusting valve A4.
  • the pressure sensor P ⁇ b> 1 is provided in the vicinity of the air exhaust port of the fuel cell 20.
  • the pressure adjustment valve A4 functions as a pressure regulator that sets the supply air pressure to the fuel cell 20.
  • the detection signals of the pressure sensors P4 and P1 are sent to the control unit 50.
  • the control unit 50 sets the supply air pressure and the supply air flow rate to the fuel cell 20 by adjusting the motor rotation speed of the compressor A3 and the opening area of the pressure adjustment valve A4.
  • Hydrogen gas as fuel gas is supplied from the hydrogen supply source 30 to the hydrogen supply port of the fuel cell 20 through the fuel supply path 74.
  • the fuel supply path 74 includes a shutoff valve H100 that supplies or stops supplying hydrogen from the hydrogen supply source 30, a pressure sensor P6 that detects the supply pressure of hydrogen gas from the hydrogen supply source 30, and hydrogen gas to the fuel cell 20.
  • the pressure regulating valve H9 for reducing and adjusting the supply pressure of the fuel
  • the pressure sensor P9 for detecting the hydrogen gas pressure downstream of the hydrogen pressure regulating valve H9
  • the shutoff valve H21 for opening and closing between the hydrogen supply port of the fuel cell 20 and the fuel supply path 74.
  • a pressure sensor P5 for detecting the inlet pressure of the hydrogen gas fuel cell 20 is provided. Detection signals from the pressure sensors P5, P6, and P9 are also supplied to the control unit 50.
  • the hydrogen gas that has not been consumed in the fuel cell 20 is discharged as a hydrogen off-gas to the hydrogen circulation path 75 and returned to the downstream side of the hydrogen pressure regulating valve H9 in the fuel supply path 74.
  • the hydrogen circulation path 75 includes a temperature sensor T31 that detects the temperature of the hydrogen off-gas, a shutoff valve H22 that communicates / blocks the fuel cell 20 and the hydrogen circulation path 75, a gas-liquid separator H42 that collects moisture from the hydrogen off-gas, and a hydrogen A drain valve H41 that collects the produced water in a tank (not shown) outside the hydrogen circulation path 75 and a hydrogen pump H50 that pressurizes the hydrogen off-gas are provided.
  • the shutoff valves H21 and H22 close the anode side of the fuel cell 20.
  • a detection signal (not shown) of the temperature sensor T31 is supplied to the control unit 50.
  • the operation of the hydrogen pump H50 is controlled by the control unit 50.
  • the hydrogen off gas merges with the hydrogen gas in the fuel supply path 74 and is supplied to the fuel cell 20 for reuse.
  • the shutoff valves H100, H21, and H22 are driven by a signal from the control unit 50.
  • the hydrogen circulation path 75 is connected to the exhaust path 72 by the purge flow path 76 via the discharge control valve H51.
  • the discharge control valve H51 is an electromagnetic shut-off valve, and discharges (purges) hydrogen off-gas to the outside by operating according to a command from the control unit 50. By performing this purge operation intermittently, it is possible to prevent the cell voltage from decreasing due to repeated hydrogen off-gas circulation and increasing the impurity concentration of the hydrogen gas on the fuel electrode side.
  • a cooling path 73 for circulating the cooling water is provided at the cooling water inlet / outlet of the fuel cell 20.
  • a temperature sensor T1 for detecting the temperature of the cooling water drained from the fuel cell 20
  • a radiator (heat exchanger) C2 for radiating the heat of the cooling water to the outside
  • a pump for pressurizing and circulating the cooling water C1 and a temperature sensor T2 for detecting the temperature of the cooling water supplied to the fuel cell 20 are provided.
  • the radiator C2 is provided with a cooling fan C13 that is rotationally driven by a motor.
  • the cooling system of the present embodiment includes the cooling path 73, temperature sensors T1 and T2, a radiator (heat exchanger) C2, a pump C1, and a cooling fan C13.
  • the fuel cell 20 is configured as a fuel cell stack in which a required number of single cells that generate power upon receiving supply of fuel gas and oxidizing gas are stacked.
  • the electric power generated by the fuel cell 20 is supplied to a power control unit (not shown).
  • the power control unit includes an inverter that drives a drive motor of a vehicle, an inverter that drives various auxiliary devices such as a compressor motor and a motor for a hydrogen pump, and charging to and from a power storage means such as a secondary battery.
  • DC-DC converters for supplying power to the motors are provided.
  • the control unit 50 receives control information from a requested load such as an accelerator signal of a vehicle (not shown) and sensors (pressure sensor, temperature sensor, flow rate sensor, output ammeter, output voltmeter, etc.) of each part of the fuel cell system 1, Control the operation of valves and motors in each part.
  • a requested load such as an accelerator signal of a vehicle (not shown) and sensors (pressure sensor, temperature sensor, flow rate sensor, output ammeter, output voltmeter, etc.) of each part of the fuel cell system 1, Control the operation of valves and motors in each part.
  • FIG. 2 is a flowchart showing control of the fuel cell by the control unit 50.
  • the controller 50 obtains the cooling water outlet temperature t1 and the inlet temperature t2 in the fuel cell 20 using the temperature sensors T1 and T2 provided at the cooling water inlet / outlet of the fuel cell 20 (step S01).
  • the internal temperature ranges t1a and t2a of the fuel cell 20 tentatively predicted from the outlet temperature t1 and the inlet temperature t2 are obtained based on experimental results and simulation results, and as shown in FIG.
  • a range where the ranges t1a and t2a overlap is defined as a provisional predicted internal temperature te of the fuel cell 20 (hereinafter referred to as “provisional predicted internal temperature te”) (step S02).
  • the start mode determination temperature th is a temperature at which the fuel cell 20 may be further cooled to below freezing when the pump C1 is driven and cooling water is supplied to the fuel cell 20.
  • Step S05 when it is determined that the provisional predicted internal temperature te is equal to or lower than the start mode determination temperature th (“YES” in step S03), the control unit 50 starts the fuel cell system 1 in the low temperature start mode. (Step S04). On the other hand, when it is determined that the provisional predicted internal temperature te is higher than the start mode determination temperature th (“NO” in step S03), the control unit 50 starts the fuel cell system 1 in the normal start mode ( Step S05).
  • the pump C1 is driven to circulate cooling water to the fuel cell 20, and in this state, the fuel gas supplied to the fuel cell 20 and the oxidizing gas are electrochemically reacted to generate power. .
  • FIG. 4 is a flowchart specifically showing the control contents in the low temperature start mode by the control unit 50.
  • the pump C1 is driven to start circulation of the cooling water (step S11). At this time, the supply of the fuel gas and the oxidizing gas to the fuel cell 20 is not started. Next, the outlet temperature t1 of the cooling water by the temperature sensor T1 is monitored, and the internal temperature tn of the fuel cell 20 is estimated from the outlet temperature t1 (step S12).
  • the fuel cell 20 since the fuel cell 20 has a large heat capacity and is covered with a stack case or the like, it tends to be less likely to be cooled than a pipe connected to the fuel cell 20, for example, a pipe defining the cooling path 73. Therefore, as shown in FIG. 5, the outlet temperature t ⁇ b> 1 rises due to the relatively high-temperature cooling water sent from the fuel cell 20, and then the cooling water channel and the cooling path 73 in the fuel cell 20 are cooled with the cooling water. Will be gradually averaged by circulating.
  • the peak value (maximum value) of the outlet temperature t1 at this time is estimated as the internal temperature tn of the fuel cell 20.
  • the cooling water sent out from the fuel cell 20 may be at a lower temperature than the cooling water in the cooling path 73, and in such a case, the cooling water sent out from the fuel cell 20 has a relatively low temperature.
  • the outlet temperature t1 is lowered, and then the cooling water circulates through the cooling water passage and the cooling passage 73 in the fuel cell 20, whereby the outlet temperature t1 is gradually averaged. Therefore, in this case, the bottom value (minimum value) of the outlet temperature t1 is estimated as the internal temperature tn of the fuel cell 20.
  • the cooling water remaining on the cooling water outlet side reaches the installation location of the temperature sensor T1 (time A in FIG. 6)
  • the cooling water remaining on the cooling water inlet side in the fuel cell 20 The outlet temperature t1 when the temperature sensor T is reached (time B in FIG. 6) is averaged, or the outlet temperature t1 at a specific moment between time A and time B is the internal temperature of the fuel cell 20. It may be tn.
  • control unit 50 compares the internal temperature tn with a preset circulation determination temperature tj (step S13).
  • the temperature range in which the internal temperature tn of the fuel cell 20 is equal to or less than the circulation determination temperature tj is that when the cooling water is circulated and the fuel cell 20 is cooled, the fuel cell 20 becomes too low in temperature, causing a problem in smooth start-up.
  • Non-circulation zone temperature that is, since the cooling water contains a freezing point depressant such as glycerin and may be 0 ° C. or lower, when the low-temperature cooling water is supplied to the fuel cell 20, the inside of the fuel cell 20 is frozen or exhausted. A malfunction may occur in the smooth start-up of the fuel cell 20 due to condensation of water in the passage 72 or the like.
  • the temperature range in which the internal temperature tn of the fuel cell 20 is higher than the circulation determination temperature tj is that the fuel cell 20 does not become too low temperature even when the cooling water is circulated, The circulation zone temperature that can be started.
  • step S15 fuel gas and oxidizing gas are supplied to the fuel cell 20 to start power generation.
  • the fuel cell 20 is cooled with the fuel gas and oxidation while continuing the operation of the pump C1 to cool the fuel cell 20. Gas is supplied to start power generation (step S15).
  • the temperature of the cooling water sent out from the fuel cell 20 is driven by driving the pump C1 in a state where power generation by the fuel cell 20 is prohibited at a low temperature start. From this, the internal temperature tn of the fuel cell 20 is estimated. Therefore, the internal temperature tn in the fuel cell 20 can be estimated with high accuracy at the start, and the power generation control of the fuel cell 20 can be appropriately performed.
  • the peak value of the temperature of the cooling water sent out from the fuel cell 20 or the temperature of the cooling water after a predetermined time has elapsed from the start of driving of the pump C1 is estimated as the internal temperature tn of the fuel cell 20, so even if the temperature is low Even during startup, the internal temperature tn of the fuel cell 20 can be estimated with extremely high accuracy.
  • the pump C1 When the internal temperature tn of the fuel cell 20 is grasped and the internal temperature tn is equal to or lower than the circulation region temperature tj, the pump C1 is stopped and power generation by the fuel cell 20 is started. Further cooling of the fuel cell 20 due to the circulation can be suppressed. As a result, the temperature of the fuel cell 20 can be rapidly increased, and startability at low temperatures such as below freezing can be improved.
  • the pump C1 when the internal temperature tn of the fuel cell 20 is grasped and the internal temperature tn is equal to or lower than the circulation region temperature tj, the pump C1 is stopped to further cool the fuel cell 20.
  • the internal temperature tn when the internal temperature tn of the fuel cell 20 is grasped, the internal temperature tn is equal to or lower than the circulation region temperature tj.
  • the pump C1 may be reversely rotated for the period of normal rotation.
  • the relatively high temperature cooling water sent from the fuel cell 20 to the cooling path 73 is once returned to the fuel cell 20.
  • the cooling of the fuel cell 20 caused by circulating the cooling water at a low temperature can be further effectively suppressed, and the temperature of the fuel cell 20 can be increased rapidly. Startability at low temperatures can be improved.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
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Abstract

Disclosed is a fuel cell system (1) whereby a fuel gas and an oxidation gas are supplied to a fuel cell (20) and the fuel gas and the oxidation gas are made to undergo an electrochemical reaction to generate electricity. The system has a structure whereby cooling water is circulated within the fuel cell (20) by means of a pump (C1), and is equipped with a control unit (50) which, at the time of low-temperature starting, drives the pump (C1) while the fuel cell (20) is not permitted to generate electricity, and which measures the internal temperature of the fuel cell (20) based on the temperature of the cooling water that is discharged from the fuel cell (20).

Description

燃料電池システムFuel cell system
　本発明は、燃料電池を備えた燃料電池システムに関する。 The present invention relates to a fuel cell system including a fuel cell.
　近年、反応ガス（燃料ガス及び酸化ガス）の電気化学反応によって発電する燃料電池をエネルギ源とする燃料電池システムが注目されている。燃料電池システムは、燃料電池のアノードに燃料タンクから高圧の燃料ガスを供給するとともに、カソードに酸化ガスとしての空気を供給し、これら燃料ガスと酸化ガスとを電気化学反応させ、起電力を発生させるものである。 Recently, a fuel cell system that uses a fuel cell that generates power by an electrochemical reaction of reaction gases (fuel gas and oxidant gas) as an energy source has attracted attention. The fuel cell system supplies high-pressure fuel gas from the fuel tank to the anode of the fuel cell, and also supplies air as the oxidizing gas to the cathode, and generates an electromotive force by electrochemically reacting these fuel gas and oxidizing gas. It is something to be made.
　この種の燃料電池システムには、燃料電池を構成するスタック内へ冷却水を循環させて冷却する冷却系を有している。
　このような冷却系を備えた燃料電池システムにおいて、冷却配管の入口及び出口に設けた温度センサから温度検出値を読み込むと共に、冷却液ポンプからトルク値及び回転速度を読み込み冷却液ポンプの運転状態に基づいて、燃料電池スタックの温度推定を行うものがある（例えば、特許文献１参照）。
　また、燃料電池の内部温度を測定する温度センサを設け、燃料電池の内部温度によって冷却水ポンプの駆動を制御するものがある（例えば、特許文献２参照）。 This type of fuel cell system has a cooling system that circulates cooling water into the stack constituting the fuel cell and cools it.
In the fuel cell system having such a cooling system, the temperature detection values are read from the temperature sensors provided at the inlet and the outlet of the cooling pipe, and the torque value and the rotation speed are read from the cooling liquid pump to enter the operating state of the cooling liquid pump. Based on this, there is one that estimates the temperature of the fuel cell stack (see, for example, Patent Document 1).
Also, there is a temperature sensor that measures the internal temperature of the fuel cell, and controls the driving of the cooling water pump according to the internal temperature of the fuel cell (see, for example, Patent Document 2).
特開２００４－２３４９０６号公報JP 2004-234906 A 特開２００３－３６８７４号公報JP 2003-36874 A
　ところで、燃料電池は、複数のセルを積層させ、これらセルの両側からエンドプレートを締め付けてスタックとした構造であるので、特許文献２のように、内部に温度センサを設けることは困難であった。このため、特許文献１のように、冷却液の入口及び出口の温度と冷却液ポンプの運転状態に基づいて、燃料電池内の温度を推定しているが、始動前などの冷却液が流れていない運転停止時では、内部の温度と冷却液の入口及び出口の温度とが食い違い、内部の温度を正確に把握することが困難であった。そして、低温始動時においては、燃料電池内部に循環する冷却水によって燃料電池の温度をさらに低下させてしまい、始動性を低下させることがあった。 By the way, since the fuel cell has a structure in which a plurality of cells are stacked and end plates are fastened from both sides of the cells to form a stack, it is difficult to provide a temperature sensor inside as in Patent Document 2. . For this reason, as in Patent Document 1, the temperature inside the fuel cell is estimated based on the temperature of the inlet and outlet of the coolant and the operating state of the coolant pump, but the coolant before the start is flowing. When there was no shutdown, the internal temperature and the coolant inlet / outlet temperature differed, making it difficult to accurately grasp the internal temperature. At the time of cold start, the temperature of the fuel cell is further lowered by the cooling water circulating inside the fuel cell, and the startability may be lowered.
　本発明は、上記事情に鑑みてなされたもので、燃料電池の温度に応じて適切に運転を行うことが可能な燃料電池システムを提供することを目的としている。 The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel cell system capable of appropriately operating according to the temperature of the fuel cell.
　上記目的を達成するために、本発明の燃料電池システムは、燃料電池に燃料ガス及び酸化ガスを供給し、これら燃料ガスと酸化ガスとを電気化学反応させて発電する燃料電池システムであって、前記燃料電池内に冷却媒体をポンプによって循環させる冷却系と、低温始動時に、前記燃料電池による発電を禁止した状態にて前記冷却系のポンプを駆動させ、前記燃料電池から送り出された冷却媒体の温度から前記燃料電池の内部温度を推定する制御部とを備えている。 In order to achieve the above object, a fuel cell system of the present invention is a fuel cell system that supplies a fuel gas and an oxidizing gas to the fuel cell, and generates electricity by causing an electrochemical reaction between the fuel gas and the oxidizing gas. A cooling system that circulates a cooling medium in the fuel cell by a pump, and a cooling medium pumped from the fuel cell by driving the pump of the cooling system in a state in which power generation by the fuel cell is prohibited at a low temperature start. And a controller that estimates the internal temperature of the fuel cell from the temperature.
　始動時においては、燃料電池と燃料電池内に残留する冷却媒体との温度は一致しているので、燃料電池による発電を禁止した状態で冷却系のポンプを駆動させ、これにより燃料電池から送り出された冷却媒体の温度を測定すれば、低温始動時（例えば、氷点下での始動時）であっても、燃料電池の内部温度を高精度に推定することができる。そして、高精度に推定した燃料電池の内部温度に基づいて、燃料電池での発電を適切に制御することができる。 At the time of start-up, the temperature of the fuel cell and the cooling medium remaining in the fuel cell are the same, so the pump of the cooling system is driven in a state where power generation by the fuel cell is prohibited, and the fuel cell is sent out from the fuel cell. If the temperature of the cooling medium is measured, the internal temperature of the fuel cell can be estimated with high accuracy even at a low temperature start (for example, at a start below freezing point). The power generation in the fuel cell can be appropriately controlled based on the internal temperature of the fuel cell estimated with high accuracy.
　前記制御部は、前記燃料電池の出口側における冷却媒体の温度のピーク値あるいは前記ポンプの駆動開始から所定時間経過後における前記燃料電池の出口側における冷却媒体の温度を前記燃料電池の内部温度と推定するものでも良い。 The control unit determines the peak value of the temperature of the coolant on the outlet side of the fuel cell or the temperature of the coolant on the outlet side of the fuel cell after a predetermined time has elapsed from the start of driving the pump as the internal temperature of the fuel cell It may be estimated.
　燃料電池の出口側における冷却媒体の温度は、ポンプの駆動開始時に燃料電池から送り出された相対的に温度の高い冷却水によって上昇し、その後、冷却系内を冷却媒体が循環することによって次第に平均化されることとなる。したがって、燃料電池の出口側における冷却媒体の温度のピーク値あるいはポンプ駆動開始から所定時間経過後における冷却媒体の温度を燃料電池の内部温度と推定することができる。なお、前記所定時間は、前記ピーク値に達するまでの時間の前後に設定されてもよい。 The temperature of the cooling medium at the outlet side of the fuel cell is increased by the relatively high temperature cooling water sent from the fuel cell at the start of driving of the pump, and then gradually averages as the cooling medium circulates in the cooling system. Will be converted. Therefore, the peak value of the temperature of the cooling medium at the outlet side of the fuel cell or the temperature of the cooling medium after a predetermined time has elapsed from the start of pump driving can be estimated as the internal temperature of the fuel cell. The predetermined time may be set before or after the time until the peak value is reached.
　前記制御部は、推定した前記燃料電池の内部温度が所定温度以下である場合に、前記ポンプを停止させて前記燃料電池による発電を開始させても良い。 The control unit may stop the pump and start power generation by the fuel cell when the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature.
　かかる構成とすることによって、冷却媒体を循環させることによる燃料電池の更なる冷却を抑制し、燃料電池の始動性を向上させることができる。 By adopting such a configuration, it is possible to suppress further cooling of the fuel cell by circulating the cooling medium, and to improve the startability of the fuel cell.
　前記制御部は、推定した前記燃料電池の内部温度が所定温度以下である場合に、前記ポンプを逆転させて前記燃料電池による発電を開始させても良い。ここで、前記ポンプの逆転は所定時間実施されるものであり、この所定時間は、前記ポンプが正回転したことにより前記燃料電池から送り出された冷却媒体が当該燃料電池に戻るまでの時間とすることができる。
また、前記所定温度は、冷却媒体を循環させると前記燃料電池が更に冷却されて当該燃料電池の始動に不具合（例えば、燃料電池内の凍結、燃料電池から排出された酸化オフガスの凝縮等）が生じる温度でもよい。 The controller may start power generation by the fuel cell by reversing the pump when the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature. Here, the reverse rotation of the pump is performed for a predetermined time, and this predetermined time is a time until the coolant sent from the fuel cell returns to the fuel cell due to the forward rotation of the pump. be able to.
In addition, when the cooling medium is circulated, the fuel cell is further cooled and the fuel cell is not started properly (for example, freezing in the fuel cell, condensation of the oxidizing off-gas discharged from the fuel cell, etc.). It may be the resulting temperature.
　かかる構成では、燃料電池から送り出された冷却媒体を再度燃料電池内へ戻すことによって燃料電池の更なる冷却を抑制することが可能となり、始動性を向上させることができる。 In such a configuration, it is possible to suppress further cooling of the fuel cell by returning the cooling medium sent out from the fuel cell back into the fuel cell, thereby improving startability.
　本発明の燃料電池システムによれば、燃料電池の温度に応じて適切な始動時運転を行うことができる。 According to the fuel cell system of the present invention, an appropriate start-up operation can be performed according to the temperature of the fuel cell.
本発明の実施形態に係る燃料電池システムを概略的に示すシステム構成図である。1 is a system configuration diagram schematically showing a fuel cell system according to an embodiment of the present invention. 制御部による燃料電池の制御を示すフローチャートである。It is a flowchart which shows control of the fuel cell by a control part. 温度センサの検出結果による燃料電池の内部温度の予測の仕方を示す図である。It is a figure which shows the method of prediction of the internal temperature of a fuel cell by the detection result of a temperature sensor. 制御部による低温時始動モードでの制御を示すフローチャートである。It is a flowchart which shows the control in the low temperature start mode by a control part. 燃料電池の内部温度の測定の仕方を示すグラフ図である。It is a graph which shows the method of measuring the internal temperature of a fuel cell. 燃料電池の内部温度の測定の仕方を示すグラフ図である。It is a graph which shows the method of measuring the internal temperature of a fuel cell. 低温時始動モードにおけるポンプの制御を説明するグラフ図である。It is a graph explaining the control of the pump in the low temperature start mode. 低温時始動モードにおけるポンプの他の制御を説明するグラフ図である。It is a graph explaining other control of the pump in the low temperature start mode.
　まず、本発明の一実施形態に係る燃料電池システム１の全体構成を説明する。この燃料電池システム１は燃料電池車両の車載発電システムであるが、車載用の燃料電池システム以外にも、船舶，航空機，電車、歩行ロボット等のあらゆる移動体用の燃料電池システムや、例えば燃料電池が建物（住宅、ビル等）用の発電設備として用いられる定置用の燃料電池システムへの適用も可能である。 First, the overall configuration of the fuel cell system 1 according to an embodiment of the present invention will be described. The fuel cell system 1 is an in-vehicle power generation system for a fuel cell vehicle. In addition to the in-vehicle fuel cell system, a fuel cell system for any moving body such as a ship, an aircraft, a train, and a walking robot, for example, a fuel cell However, it can also be applied to stationary fuel cell systems used as power generation equipment for buildings (housing, buildings, etc.).
　図１に示すように、酸化ガス（反応ガス）としての空気は、空気供給路７１を介して燃料電池２０の空気供給口に供給される。空気供給路７１には、空気から微粒子を除去するエアフィルタＡ１、空気を加圧するコンプレッサＡ３、供給空気圧を検出する圧力センサＰ４、及び空気に所要の水分を加える加湿装置Ａ２１が設けられている。コンプレッサＡ３は、モータＭによって駆動される。このモータＭは、制御部５０によって駆動制御される。 As shown in FIG. 1, air as an oxidizing gas (reactive gas) is supplied to an air supply port of the fuel cell 20 via an air supply path 71. The air supply path 71 is provided with an air filter A1 that removes particulates from the air, a compressor A3 that pressurizes the air, a pressure sensor P4 that detects the supply air pressure, and a humidifier A21 that adds required moisture to the air. The compressor A3 is driven by the motor M. The motor M is driven and controlled by the control unit 50.
　燃料電池２０から排出される空気オフガスは、排気路７２を経て外部に放出される。排気路７２には、排気圧を検出する圧力センサＰ１、及び圧力調整弁Ａ４が設けられている。圧力センサＰ１は、燃料電池２０の空気排気口近傍に設けられている。圧力調整弁Ａ４は、燃料電池２０への供給空気圧を設定する調圧器として機能する。 The air off gas discharged from the fuel cell 20 is discharged to the outside through the exhaust path 72. The exhaust path 72 is provided with a pressure sensor P1 for detecting the exhaust pressure and a pressure adjusting valve A4. The pressure sensor P <b> 1 is provided in the vicinity of the air exhaust port of the fuel cell 20. The pressure adjustment valve A4 functions as a pressure regulator that sets the supply air pressure to the fuel cell 20.
　圧力センサＰ４，Ｐ１の検出信号は、制御部５０に送られる。制御部５０は、コンプレッサＡ３のモータ回転数及び圧力調整弁Ａ４の開度面積を調整することによって、燃料電池２０への供給空気圧や供給空気流量を設定する。 The detection signals of the pressure sensors P4 and P1 are sent to the control unit 50. The control unit 50 sets the supply air pressure and the supply air flow rate to the fuel cell 20 by adjusting the motor rotation speed of the compressor A3 and the opening area of the pressure adjustment valve A4.
　燃料ガス（反応ガス）としての水素ガスは、水素供給源３０から燃料供給路７４を介して燃料電池２０の水素供給口に供給される。燃料供給路７４には、水素供給源３０から水素を供給しあるいは供給を停止する遮断弁Ｈ１００、水素供給源３０からの水素ガスの供給圧力を検出する圧力センサＰ６、燃料電池２０への水素ガスの供給圧力を減圧して調整する水素調圧弁Ｈ９、水素調圧弁Ｈ９の下流の水素ガス圧力を検出する圧力センサＰ９、燃料電池２０の水素供給口と燃料供給路７４間を開閉する遮断弁Ｈ２１、及び水素ガスの燃料電池２０の入口圧力を検出する圧力センサＰ５が設けられている。圧力センサＰ５，Ｐ６，Ｐ９の検出信号も制御部５０に供給される。 Hydrogen gas as fuel gas (reaction gas) is supplied from the hydrogen supply source 30 to the hydrogen supply port of the fuel cell 20 through the fuel supply path 74. The fuel supply path 74 includes a shutoff valve H100 that supplies or stops supplying hydrogen from the hydrogen supply source 30, a pressure sensor P6 that detects the supply pressure of hydrogen gas from the hydrogen supply source 30, and hydrogen gas to the fuel cell 20. The pressure regulating valve H9 for reducing and adjusting the supply pressure of the fuel, the pressure sensor P9 for detecting the hydrogen gas pressure downstream of the hydrogen pressure regulating valve H9, and the shutoff valve H21 for opening and closing between the hydrogen supply port of the fuel cell 20 and the fuel supply path 74. , And a pressure sensor P5 for detecting the inlet pressure of the hydrogen gas fuel cell 20 is provided. Detection signals from the pressure sensors P5, P6, and P9 are also supplied to the control unit 50.
　燃料電池２０で消費されなかった水素ガスは、水素オフガスとして水素循環路７５に排出され、燃料供給路７４の水素調圧弁Ｈ９の下流側に戻される。水素循環路７５には、水素オフガスの温度を検出する温度センサＴ３１、燃料電池２０と水素循環路７５を連通／遮断する遮断弁Ｈ２２、水素オフガスから水分を回収する気液分離器Ｈ４２、回収した生成水を水素循環路７５外の図示しないタンク等に回収する排水弁Ｈ４１、及び水素オフガスを加圧する水素ポンプＨ５０が設けられている。 The hydrogen gas that has not been consumed in the fuel cell 20 is discharged as a hydrogen off-gas to the hydrogen circulation path 75 and returned to the downstream side of the hydrogen pressure regulating valve H9 in the fuel supply path 74. The hydrogen circulation path 75 includes a temperature sensor T31 that detects the temperature of the hydrogen off-gas, a shutoff valve H22 that communicates / blocks the fuel cell 20 and the hydrogen circulation path 75, a gas-liquid separator H42 that collects moisture from the hydrogen off-gas, and a hydrogen A drain valve H41 that collects the produced water in a tank (not shown) outside the hydrogen circulation path 75 and a hydrogen pump H50 that pressurizes the hydrogen off-gas are provided.
　遮断弁Ｈ２１，Ｈ２２は、燃料電池２０のアノード側を閉鎖する。温度センサＴ３１の図示しない検出信号は、制御部５０に供給される。水素ポンプＨ５０は、制御部５０によって動作が制御される。 The shutoff valves H21 and H22 close the anode side of the fuel cell 20. A detection signal (not shown) of the temperature sensor T31 is supplied to the control unit 50. The operation of the hydrogen pump H50 is controlled by the control unit 50.
　水素オフガスは、燃料供給路７４で水素ガスと合流し、燃料電池２０に供給されて再利用される。遮断弁Ｈ１００，Ｈ２１，Ｈ２２は、制御部５０からの信号で駆動される。 The hydrogen off gas merges with the hydrogen gas in the fuel supply path 74 and is supplied to the fuel cell 20 for reuse. The shutoff valves H100, H21, and H22 are driven by a signal from the control unit 50.
　水素循環路７５は、排出制御弁Ｈ５１を介して、パージ流路７６によって排気路７２に接続されている。排出制御弁Ｈ５１は、電磁式の遮断弁であり、制御部５０からの指令によって作動することにより、水素オフガスを外部に排出（パージ）する。このパージ動作を間欠的に行うことによって、水素オフガスの循環が繰り返されて燃料極側の水素ガスの不純物濃度が増すことによるセル電圧の低下を防止することができる。 The hydrogen circulation path 75 is connected to the exhaust path 72 by the purge flow path 76 via the discharge control valve H51. The discharge control valve H51 is an electromagnetic shut-off valve, and discharges (purges) hydrogen off-gas to the outside by operating according to a command from the control unit 50. By performing this purge operation intermittently, it is possible to prevent the cell voltage from decreasing due to repeated hydrogen off-gas circulation and increasing the impurity concentration of the hydrogen gas on the fuel electrode side.
　燃料電池２０の冷却水出入口には、冷却水を循環させる冷却路７３が設けられている。冷却路７３には、燃料電池２０から排水される冷却水の温度を検出する温度センサＴ１、冷却水の熱を外部に放熱するラジエータ（熱交換器）Ｃ２、冷却水を加圧して循環させるポンプＣ１、及び燃料電池２０に供給される冷却水の温度を検出する温度センサＴ２が設けられている。ラジエータＣ２には、モータによって回転駆動される冷却ファンＣ１３が設けられている。
本実施形態の冷却系は、これら冷却路７３、温度センサＴ１，Ｔ２、ラジエータ（熱交換器）Ｃ２、ポンプＣ１、及び冷却ファンＣ１３を備えて構成されている。 A cooling path 73 for circulating the cooling water is provided at the cooling water inlet / outlet of the fuel cell 20. In the cooling path 73, a temperature sensor T1 for detecting the temperature of the cooling water drained from the fuel cell 20, a radiator (heat exchanger) C2 for radiating the heat of the cooling water to the outside, and a pump for pressurizing and circulating the cooling water C1 and a temperature sensor T2 for detecting the temperature of the cooling water supplied to the fuel cell 20 are provided. The radiator C2 is provided with a cooling fan C13 that is rotationally driven by a motor.
The cooling system of the present embodiment includes the cooling path 73, temperature sensors T1 and T2, a radiator (heat exchanger) C2, a pump C1, and a cooling fan C13.
　燃料電池２０は、燃料ガスと酸化ガスの供給を受けて発電する単セルを所要数積層してなる燃料電池スタックとして構成されている。燃料電池２０が発生した電力は、図示しないパワーコントロールユニットに供給される。パワーコントロールユニットは、車両の駆動モータを駆動するインバータと、コンプレッサモータや水素ポンプ用モータなどの各種の補機類を駆動するインバータと、二次電池等の蓄電手段への充電や該蓄電手段からのモータ類への電力供給を行うＤＣ－ＤＣコンバータなどが備えられている。 The fuel cell 20 is configured as a fuel cell stack in which a required number of single cells that generate power upon receiving supply of fuel gas and oxidizing gas are stacked. The electric power generated by the fuel cell 20 is supplied to a power control unit (not shown). The power control unit includes an inverter that drives a drive motor of a vehicle, an inverter that drives various auxiliary devices such as a compressor motor and a motor for a hydrogen pump, and charging to and from a power storage means such as a secondary battery. DC-DC converters for supplying power to the motors are provided.
　制御部５０は、図示しない車両のアクセル信号などの要求負荷や燃料電池システム１の各部のセンサ（圧力センサ、温度センサ、流量センサ、出力電流計、出力電圧計等）から制御情報を受け取り、システム各部の弁類やモータ類の運転を制御する。 The control unit 50 receives control information from a requested load such as an accelerator signal of a vehicle (not shown) and sensors (pressure sensor, temperature sensor, flow rate sensor, output ammeter, output voltmeter, etc.) of each part of the fuel cell system 1, Control the operation of valves and motors in each part.
　次に、制御部５０による燃料電池システムの始動時の制御を説明する。
　図２は制御部５０による燃料電池の制御を示すフローチャートである。
　制御部５０は、燃料電池２０の冷却水出入口に設けられた温度センサＴ１，Ｔ２によって燃料電池２０における冷却水の出口温度ｔ１及び入口温度ｔ２を求める（ステップＳ０１）。 Next, the control at the start of the fuel cell system by the control unit 50 will be described.
FIG. 2 is a flowchart showing control of the fuel cell by the control unit 50.
The controller 50 obtains the cooling water outlet temperature t1 and the inlet temperature t2 in the fuel cell 20 using the temperature sensors T1 and T2 provided at the cooling water inlet / outlet of the fuel cell 20 (step S01).
　これら出口温度ｔ１及び入口温度ｔ２からそれぞれ暫定的に予測される燃料電池２０の内部温度の範囲ｔ１ａ，ｔ２ａを実験結果やシミュレーション結果等に基づいて求め、図３に示すように、これら内部温度の範囲ｔ１ａ，ｔ２ａが重なる範囲を燃料電池２０の暫定的な予測内部温度ｔｅ（以下、「暫定予測内部温度ｔｅ」という。）とする（ステップＳ０２）。 The internal temperature ranges t1a and t2a of the fuel cell 20 tentatively predicted from the outlet temperature t1 and the inlet temperature t2 are obtained based on experimental results and simulation results, and as shown in FIG. A range where the ranges t1a and t2a overlap is defined as a provisional predicted internal temperature te of the fuel cell 20 (hereinafter referred to as “provisional predicted internal temperature te”) (step S02).
　次に、この暫定予測内部温度ｔｅを、予め設定した始動モード判定温度ｔｈと比較する（ステップＳ０３）。この始動モード判定温度ｔｈは、ポンプＣ１を駆動させて燃料電池２０に冷却水を供給した場合に燃料電池２０が更に冷却されて氷点下になる可能性のある温度である。 Next, the provisional predicted internal temperature te is compared with a preset start mode determination temperature th (step S03). The start mode determination temperature th is a temperature at which the fuel cell 20 may be further cooled to below freezing when the pump C1 is driven and cooling water is supplied to the fuel cell 20.
　この比較の結果、暫定予測内部温度ｔｅが始動モード判定温度ｔｈ以下であると判定（ステップＳ０３で「ＹＥＳ」）されると、制御部５０は低温時始動モードにて燃料電池システム１を始動させる（ステップＳ０４）。
これに対して、暫定予測内部温度ｔｅが始動モード判定温度ｔｈよりも高いと判定（ステップＳ０３で「ＮＯ」）されると、制御部５０は通常始動モードにて燃料電池システム１を始動させる（ステップＳ０５）。 As a result of this comparison, when it is determined that the provisional predicted internal temperature te is equal to or lower than the start mode determination temperature th (“YES” in step S03), the control unit 50 starts the fuel cell system 1 in the low temperature start mode. (Step S04).
On the other hand, when it is determined that the provisional predicted internal temperature te is higher than the start mode determination temperature th (“NO” in step S03), the control unit 50 starts the fuel cell system 1 in the normal start mode ( Step S05).
　この通常始動モードでは、ポンプＣ１が駆動されて燃料電池２０に冷却水が循環され、この状態にて、燃料電池２０に供給される燃料ガスと酸化ガスとを電気化学反応させて発電が行われる。 In this normal start mode, the pump C1 is driven to circulate cooling water to the fuel cell 20, and in this state, the fuel gas supplied to the fuel cell 20 and the oxidizing gas are electrochemically reacted to generate power. .
　次に、低温時始動モードでの燃料電池システム１の始動制御について説明する。
　図４は、制御部５０による低温時始動モードでの制御内容を具体的に示したフローチャートである。 Next, start control of the fuel cell system 1 in the low temperature start mode will be described.
FIG. 4 is a flowchart specifically showing the control contents in the low temperature start mode by the control unit 50.
　低温時始動モードにおいては、まず、ポンプＣ１が駆動され、冷却水の循環が開始される（ステップＳ１１）。この時点で燃料電池２０への燃料ガスおよび酸化ガスの供給は開始しない。
　次いで、温度センサＴ１による冷却水の出口温度ｔ１が監視され、この出口温度ｔ１から、燃料電池２０の内部温度ｔｎが推定される（ステップＳ１２）。 In the low temperature start mode, first, the pump C1 is driven to start circulation of the cooling water (step S11). At this time, the supply of the fuel gas and the oxidizing gas to the fuel cell 20 is not started.
Next, the outlet temperature t1 of the cooling water by the temperature sensor T1 is monitored, and the internal temperature tn of the fuel cell 20 is estimated from the outlet temperature t1 (step S12).
　一般に、燃料電池２０は熱容量が大きく、また、スタックケースなどに覆われているため、燃料電池２０に接続されている配管、例えば冷却路７３を画成する配管よりも冷却され難い傾向にある。したがって、図５に示すように、出口温度ｔ１は、燃料電池２０から送り出された相対的に温度の高い冷却水によって上昇し、その後、燃料電池２０内の冷却水流路及び冷却路７３を冷却水が循環することによって次第に平均化されることとなる。 Generally, since the fuel cell 20 has a large heat capacity and is covered with a stack case or the like, it tends to be less likely to be cooled than a pipe connected to the fuel cell 20, for example, a pipe defining the cooling path 73. Therefore, as shown in FIG. 5, the outlet temperature t <b> 1 rises due to the relatively high-temperature cooling water sent from the fuel cell 20, and then the cooling water channel and the cooling path 73 in the fuel cell 20 are cooled with the cooling water. Will be gradually averaged by circulating.
このような現象から、出口温度ｔ１の上昇は、燃料電池２０内の残存冷却水によるものと推定することができる。したがって、本実施形態では、このときの出口温度ｔ１のピーク値（最大値）を燃料電池２０の内部温度ｔｎと推定する。 From such a phenomenon, it can be estimated that the increase in the outlet temperature t1 is due to the remaining cooling water in the fuel cell 20. Therefore, in this embodiment, the peak value (maximum value) of the outlet temperature t1 at this time is estimated as the internal temperature tn of the fuel cell 20.
　ただし、燃料電池２０から送り出された冷却水が、冷却路７３内の冷却水よりも低温である場合もあり、かかる場合には、燃料電池２０から送り出された相対的に温度の低い冷却水によって出口温度ｔ１が下がり、その後、燃料電池２０内の冷却水流路及び冷却路７３を冷却水が循環することにより、出口温度ｔ１が次第に平均化されることとなる。
したがって、この場合は、出口温度ｔ１のボトム値（最小値）を燃料電池２０の内部温度ｔｎと推定する。 However, the cooling water sent out from the fuel cell 20 may be at a lower temperature than the cooling water in the cooling path 73, and in such a case, the cooling water sent out from the fuel cell 20 has a relatively low temperature. The outlet temperature t1 is lowered, and then the cooling water circulates through the cooling water passage and the cooling passage 73 in the fuel cell 20, whereby the outlet temperature t1 is gradually averaged.
Therefore, in this case, the bottom value (minimum value) of the outlet temperature t1 is estimated as the internal temperature tn of the fuel cell 20.
　なお、図６に示すように、ポンプＣ１の駆動開始時点から燃料電池２０内の冷却水が温度センサＴ１の設置場所まで流れてくるまでの平均時間Ｔにおける出口温度ｔ１、すなわち、燃料電池２０内の冷却水出口側に残留していた冷却水が温度センサＴ１の設置場所に到達したとき（図６中の時点Ａ）と、燃料電池２０内の冷却水入口側に残留していた冷却水が温度センサＴの設置場所に到達したとき（図６の時点Ｂ）とを平均した時点における出口温度ｔ１、あるいは時点Ａから時点Ｂの間の特定の瞬間における出口温度ｔ１を燃料電池２０の内部温度ｔｎとしても良い。 As shown in FIG. 6, the outlet temperature t1 at the average time T from when the driving of the pump C1 starts until the cooling water in the fuel cell 20 flows to the installation location of the temperature sensor T1, that is, within the fuel cell 20 When the cooling water remaining on the cooling water outlet side reaches the installation location of the temperature sensor T1 (time A in FIG. 6), the cooling water remaining on the cooling water inlet side in the fuel cell 20 The outlet temperature t1 when the temperature sensor T is reached (time B in FIG. 6) is averaged, or the outlet temperature t1 at a specific moment between time A and time B is the internal temperature of the fuel cell 20. It may be tn.
　そして、制御部５０は、上述のごとく燃料電池２０の内部温度ｔｎを推定したら、この内部温度ｔｎを、予め設定した循環判定温度ｔｊと比較する（ステップＳ１３）。 Then, after estimating the internal temperature tn of the fuel cell 20 as described above, the control unit 50 compares the internal temperature tn with a preset circulation determination temperature tj (step S13).
　ここで、燃料電池２０の内部温度ｔｎが循環判定温度ｔｊ以下の温度領域とは、冷却水を循環させて燃料電池２０を冷却させると燃料電池２０が低温となり過ぎて円滑な始動に不具合が生じる無循環領域温度である。つまり、冷却水にはグリセリン等の氷点降下剤が含まれていて０℃以下になり得るため、低温の冷却水が燃料電池２０に供給されると、燃料電池２０の内部が凍結したり、排気路７２内で水分が凝縮する等して、燃料電池２０の円滑な始動に不具合が生じることがある。 Here, the temperature range in which the internal temperature tn of the fuel cell 20 is equal to or less than the circulation determination temperature tj is that when the cooling water is circulated and the fuel cell 20 is cooled, the fuel cell 20 becomes too low in temperature, causing a problem in smooth start-up. Non-circulation zone temperature. That is, since the cooling water contains a freezing point depressant such as glycerin and may be 0 ° C. or lower, when the low-temperature cooling water is supplied to the fuel cell 20, the inside of the fuel cell 20 is frozen or exhausted. A malfunction may occur in the smooth start-up of the fuel cell 20 due to condensation of water in the passage 72 or the like.
一方、燃料電池２０の内部温度ｔｎが循環判定温度ｔｊよりも高い温度領域とは、冷却水を循環させても燃料電池２０が低温となり過ぎることがなく、上記不具合を生じることなく燃料電池２０を始動することが可能な循環領域温度である。 On the other hand, the temperature range in which the internal temperature tn of the fuel cell 20 is higher than the circulation determination temperature tj is that the fuel cell 20 does not become too low temperature even when the cooling water is circulated, The circulation zone temperature that can be started.
　この比較の結果、図７に示すように、燃料電池２０の内部温度ｔｎを把握した時点にて、その内部温度ｔｎが循環判定温度ｔｊ以下であれば（ステップＳ１３で「ＹＥＳ」）、ポンプＣ１を停止させることにより、燃料電池２０の冷却を停止させる（ステップＳ１４）。 As a result of this comparison, as shown in FIG. 7, when the internal temperature tn of the fuel cell 20 is grasped, if the internal temperature tn is equal to or lower than the circulation determination temperature tj (“YES” in step S13), the pump C1 Is stopped to stop the cooling of the fuel cell 20 (step S14).
　そして、このようにポンプＣ１を停止させた状態にて、燃料電池２０に燃料ガス及び酸化ガスを供給して発電を開始させる（ステップＳ１５）。
　これに対して、内部温度ｔｎが循環判定温度ｔｊより高ければ（ステップＳ１３で「ＮＯ」）、ポンプＣ１の運転を継続させて燃料電池２０の冷却を行いつつ、燃料電池２０に燃料ガス及び酸化ガスを供給して発電を開始させる（ステップＳ１５）。 Then, in a state where the pump C1 is stopped in this way, fuel gas and oxidizing gas are supplied to the fuel cell 20 to start power generation (step S15).
On the other hand, if the internal temperature tn is higher than the circulation determination temperature tj (“NO” in step S13), the fuel cell 20 is cooled with the fuel gas and oxidation while continuing the operation of the pump C1 to cool the fuel cell 20. Gas is supplied to start power generation (step S15).
　以上、説明したように、上記実施形態にかかる燃料電池システムによれば、低温始動時に、燃料電池２０による発電を禁止した状態にてポンプＣ１を駆動させ、燃料電池２０から送り出される冷却水の温度から燃料電池２０の内部温度ｔｎを推定している。したがって、始動時に燃料電池２０内の内部温度ｔｎを高精度に推定することが可能となり、燃料電池２０の発電制御を適切に行なうことができる。 As described above, according to the fuel cell system according to the above-described embodiment, the temperature of the cooling water sent out from the fuel cell 20 is driven by driving the pump C1 in a state where power generation by the fuel cell 20 is prohibited at a low temperature start. From this, the internal temperature tn of the fuel cell 20 is estimated. Therefore, the internal temperature tn in the fuel cell 20 can be estimated with high accuracy at the start, and the power generation control of the fuel cell 20 can be appropriately performed.
　また、燃料電池２０内から送り出された冷却水の温度のピーク値あるいはポンプＣ１の駆動開始から所定時間経過後における冷却水の温度を燃料電池２０の内部温度ｔｎと推定しているので、たとえ低温始動時であっても燃料電池２０の内部温度ｔｎを極めて高精度に推定することができる。 Further, the peak value of the temperature of the cooling water sent out from the fuel cell 20 or the temperature of the cooling water after a predetermined time has elapsed from the start of driving of the pump C1 is estimated as the internal temperature tn of the fuel cell 20, so even if the temperature is low Even during startup, the internal temperature tn of the fuel cell 20 can be estimated with extremely high accuracy.
　そして、燃料電池２０の内部温度ｔｎを把握した時点にて、その内部温度ｔｎが循環領域温度ｔｊ以下である場合に、ポンプＣ１を停止させて燃料電池２０による発電を開始させるので、冷却水を循環させることによる燃料電池２０の更なる冷却を抑制することができる。これにより、燃料電池２０を急速に昇温させることが可能となり、氷点下などの低温時における始動性を向上させることができる。 When the internal temperature tn of the fuel cell 20 is grasped and the internal temperature tn is equal to or lower than the circulation region temperature tj, the pump C1 is stopped and power generation by the fuel cell 20 is started. Further cooling of the fuel cell 20 due to the circulation can be suppressed. As a result, the temperature of the fuel cell 20 can be rapidly increased, and startability at low temperatures such as below freezing can be improved.
　なお、上記実施形態では、燃料電池２０の内部温度ｔｎを把握した時点にて、その内部温度ｔｎが循環領域温度ｔｊ以下であったときに、ポンプＣ１を停止させて燃料電池２０の更なる冷却を中止することで低温での始動性を高めたが、例えば図８に示すように、燃料電池２０の内部温度ｔｎを把握した時点にて、その内部温度ｔｎが循環領域温度ｔｊ以下であったときには、ポンプＣ１を正転させた時間だけ逆転させても良い。 In the above embodiment, when the internal temperature tn of the fuel cell 20 is grasped and the internal temperature tn is equal to or lower than the circulation region temperature tj, the pump C1 is stopped to further cool the fuel cell 20. However, as shown in FIG. 8, for example, when the internal temperature tn of the fuel cell 20 is grasped, the internal temperature tn is equal to or lower than the circulation region temperature tj. In some cases, the pump C1 may be reversely rotated for the period of normal rotation.
　このようにすると、燃料電池２０から冷却路７３に送り出された相対的に温度の高い冷却水が燃料電池２０に一旦戻されることとなる。これにより、低温時に冷却水を循環させることにより生じる燃料電池２０の冷却をより一層効果的に抑制し得て、燃料電池２０を急速に昇温させることが可能になるので、特に氷点下などの極低温時における始動性を向上させることができる。 In this way, the relatively high temperature cooling water sent from the fuel cell 20 to the cooling path 73 is once returned to the fuel cell 20. As a result, the cooling of the fuel cell 20 caused by circulating the cooling water at a low temperature can be further effectively suppressed, and the temperature of the fuel cell 20 can be increased rapidly. Startability at low temperatures can be improved.
　１…燃料電池システム、２０…燃料電池、５０…制御部、７３…冷却路（冷却系）、Ｃ１…ポンプ。 DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 20 ... Fuel cell, 50 ... Control part, 73 ... Cooling path (cooling system), C1 ... Pump.

Claims (7)

  1. 　燃料電池に燃料ガス及び酸化ガスを供給し、これら燃料ガスと酸化ガスとを電気化学反応させて発電する燃料電池システムであって、
    　前記燃料電池内に冷却媒体をポンプによって循環させる冷却系と、
    　低温始動時に、前記燃料電池による発電を禁止した状態にて前記冷却系のポンプを駆動させ、前記燃料電池から送り出された冷却媒体の温度から前記燃料電池の内部温度を推定する制御部とを備えている燃料電池システム。     A fuel cell system for generating power by supplying a fuel gas and an oxidizing gas to a fuel cell and electrochemically reacting the fuel gas and the oxidizing gas,
    A cooling system for circulating a cooling medium in the fuel cell by a pump;
    A controller that drives the cooling system pump in a state in which power generation by the fuel cell is prohibited at a low temperature start, and estimates the internal temperature of the fuel cell from the temperature of the cooling medium sent from the fuel cell. Fuel cell system.
  2. 　請求項１に記載の燃料電池システムであって、
    　前記制御部は、前記燃料電池の出口側における冷却媒体の温度のピーク値あるいは前記ポンプの駆動開始から所定時間経過後における前記燃料電池の出口側における冷却媒体の温度を前記燃料電池の内部温度と推定する燃料電池システム。     The fuel cell system according to claim 1,
    The control unit determines the peak value of the temperature of the coolant on the outlet side of the fuel cell or the temperature of the coolant on the outlet side of the fuel cell after a predetermined time has elapsed from the start of driving the pump as the internal temperature of the fuel cell. Fuel cell system to estimate.
  3. 　請求項２に記載の燃料電池システムであって、
    　前記所定時間は、前記ピーク値に達するまでの時間の前後に設定される燃料電池システム。     The fuel cell system according to claim 2, wherein
    The fuel cell system, wherein the predetermined time is set before and after the time until the peak value is reached.
  4. 　請求項１から請求項３のいずれかに記載の燃料電池システムであって、
    　前記制御部は、推定した前記燃料電池の内部温度が所定温度以下である場合に、前記ポンプを停止させて前記燃料電池による発電を開始させる燃料電池システム。     The fuel cell system according to any one of claims 1 to 3, wherein
    The control unit is a fuel cell system that stops the pump and starts power generation by the fuel cell when the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature.
  5. 　請求項１から請求項３のいずれかに記載の燃料電池システムであって、
    　前記制御部は、推定した前記燃料電池の内部温度が所定温度以下である場合に、前記ポンプを逆転させて前記燃料電池による発電を開始させる燃料電池システム。     The fuel cell system according to any one of claims 1 to 3, wherein
    When the estimated internal temperature of the fuel cell is equal to or lower than a predetermined temperature, the control unit reverses the pump and starts power generation by the fuel cell.
  6. 　請求項５に記載の燃料電池システムであって、
    　前記ポンプの逆転は、正回転により前記燃料電池から送り出された冷却媒体が前記燃料電池に戻るまでの所定時間実施される燃料電池システム。     The fuel cell system according to claim 5, wherein
    The reverse rotation of the pump is a fuel cell system that is performed for a predetermined time until the cooling medium sent out from the fuel cell by forward rotation returns to the fuel cell.
  7. 　請求項４から請求項６のいずれかに記載の燃料電池システムであって、
    　前記所定温度は、冷却媒体を循環させると前記燃料電池が更に冷却されて当該燃料電池の始動に不具合が生じる温度である燃料電池システム。     The fuel cell system according to any one of claims 4 to 6,
    The fuel cell system is a temperature at which the predetermined temperature is a temperature at which the fuel cell is further cooled when a cooling medium is circulated to cause a problem in starting the fuel cell.
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