JP2009004165A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of improving output performance of a fuel cell directly after startup. <P>SOLUTION: A control device 7, when an operation start of the fuel cell system 1 is commanded, gets access to a measurement impedance memory 70, and reads out a measured impedance stored at the previous system stoppage. Then, the control device 7 compares the measured impedance read out and a reference impedance stored in a reference impedance memory 51. If the measured impedance exceeds the reference impedance, the control device 7 judges that a drying process is already done at the system stoppage, and puts the system Ready On after executing humidification treatment. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system capable of performing a drying process of a fuel cell.

  If the external temperature is low, the water generated inside the fuel cell system will freeze after the fuel cell system is stopped, and the piping and valves may be damaged. When starting up, there is a problem that the supply of gas is hindered and the electrochemical reaction does not proceed sufficiently.

  In view of these problems, when there is a request to stop the system in an environment where the outside air temperature is low, a technique for preventing freezing of piping, valves, etc. by executing a drying process (scavenging process, etc.) of the fuel cell Has been proposed (see, for example, Patent Document 1 below).

JP 2005-108832 A

  However, when the system is stopped for a short time (such as when taking a break while driving on a highway), the drying process is performed in the same manner, and then the next start is performed without performing any process. Has become too dry (so-called dry-up occurs), causing problems such as a decrease in the output of the fuel cell.

  The present invention has been made in view of the circumstances described above, and an object thereof is to provide a fuel cell system capable of improving the output performance of a fuel cell immediately after starting.

  In order to achieve the above object, a fuel cell system according to the present invention is a fuel cell system that performs a drying process of a fuel cell at a predetermined timing, and determines whether or not the drying process was performed when the system was stopped last time. A determining unit; and a control unit configured to execute a wetting process when the system is started this time when the determining unit determines that the drying process is being performed when the system is stopped last time. .

  According to such a configuration, it is determined whether or not the drying process has been executed when the previous system was stopped, and when it is determined that the drying process was executed when the previous system was stopped, the wetting process is executed at the current start-up. As a result, power generation can be started with the moisture content in the fuel cell kept appropriate, and the output performance of the fuel cell immediately after startup can be improved.

  Here, in the above configuration, the determination unit includes a measurement unit that measures the impedance of the fuel cell when the system is stopped, and a storage unit that stores the measured impedance, and is stored in the previous storage unit. It is preferable to determine whether or not the drying process has been executed based on the impedance of the fuel cell measured when the system is stopped.

  Further, in the above configuration, the apparatus further includes a time measuring unit that measures an elapsed time from the previous system stop to the current system start, and the control unit is configured to perform the drying process when the previous system is stopped by the determination unit. It is further preferable that the wetting process is performed when the system is started this time, when it is determined that the elapsed time measured by the timing unit is less than the reference time.

  Further, the above configuration further includes temperature measuring means for measuring the temperature related to the fuel cell at the time of the current system startup, and the control means executes the drying process when the system is stopped last time by the judging means. And when the related temperature of the fuel cell measured by the temperature measuring unit is determined to be equal to or higher than the standard temperature, the wet process may be executed when the system is started this time. .

  Further, the fuel cell system according to the present invention is a fuel cell system that performs a drying process of the fuel cell at a predetermined timing, measuring means for measuring the impedance of the fuel cell and the related temperature of the fuel cell before stopping the system, And determining means for determining whether or not to execute the drying process when the system is stopped based on the measurement result.

  As described above, according to the fuel cell system of the present invention, it is possible to improve the output performance of the fuel cell immediately after starting.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

A. FIG. 1 is a configuration diagram of a fuel cell system 1.
The fuel cell system 1 can be mounted on a vehicle 100 such as a fuel cell vehicle (FCHV), an electric vehicle, or a hybrid vehicle. However, the fuel cell system 1 can also be applied to various mobile bodies (for example, ships, airplanes, robots, etc.) other than the vehicle 100, stationary power sources, and portable fuel cell systems.

  The fuel cell system 1 includes a fuel cell 2, an oxidizing gas piping system 3 that supplies air as an oxidizing gas to the fuel cell 2, a fuel gas piping system 4 that supplies hydrogen gas as a fuel gas to the fuel cell 2, A refrigerant piping system 5 that supplies refrigerant to the fuel cell 2, a power system 6 that charges and discharges the power of the system 1, and a control device 7 that performs overall control of the operation of the system 1 are provided. In addition, oxidizing gas and fuel gas can be named generically reaction gas.

  The fuel cell 2 is formed of, for example, a solid polymer electrolyte type and includes a stack structure in which a large number of single cells are stacked. The single cell has an air electrode (cathode) on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode (anode) on the other surface, and a pair of the air electrode and the fuel electrode sandwiched from both sides. Of separators. An oxidizing gas is supplied to the oxidizing gas channel 2a of one separator, and a fuel gas is supplied to the fuel gas channel 2b of the other separator. The fuel cell 2 generates electric power by the electrochemical reaction of the supplied fuel gas and oxidizing gas. The electrochemical reaction in the fuel cell 2 is an exothermic reaction, and the temperature of the solid polymer electrolyte fuel cell 2 is approximately 60 to 80 ° C.

  The oxidizing gas piping system 3 includes a supply path 11 through which the oxidizing gas supplied to the fuel cell 2 flows, a discharge path 12 through which the oxidizing off gas discharged from the fuel cell 2 flows, and the oxidizing gas flows bypassing the fuel cell 2. And a bypass path 17. The supply path 11 communicates with the discharge path 12 via the oxidizing gas flow path 2a. The oxidizing off gas is in a highly moist state because it contains moisture generated by the cell reaction of the fuel cell 2.

  The supply path 11 is provided with a compressor 14 that takes in outside air via an air cleaner 13, and a humidifier 15 that humidifies the oxidizing gas pumped to the fuel cell 2 by the compressor 14. The humidifier 15 exchanges moisture between the low-humidity oxidizing gas flowing in the supply passage 11 and the high-humidity oxidizing off-gas flowing in the discharge passage 12, and appropriately supplies the oxidizing gas supplied to the fuel cell 2. Humidify.

  The back pressure on the air electrode side of the fuel cell 2 is adjusted by a back pressure adjusting valve 16 disposed in the discharge path 12 near the cathode outlet. In the vicinity of the back pressure adjustment valve 16, a pressure sensor P1 for detecting the pressure in the discharge passage 12 is provided. The oxidizing off gas passes through the back pressure regulating valve 16 and the humidifier 15 and is finally exhausted into the atmosphere outside the system as exhaust gas.

  The bypass path 17 connects the supply path 11 and the discharge path 12. A supply side connection B between the bypass path 17 and the supply path 11 is located between the compressor 14 and the humidifier 15. Further, the discharge side connection portion C between the bypass path 17 and the discharge path 12 is located on the downstream side of the humidifier 15. The bypass passage 17 is provided with a bypass valve 18 which is an on-off valve (shut valve) driven by a motor or a solenoid. The bypass valve 18 is connected to the control device 7 and opens and closes the bypass path 17. In the following description, the oxidizing gas that is bypassed downstream of the bypass passage 17 through the bypass valve 18 by opening the bypass valve 18 is referred to as “bypass air”.

  The fuel gas piping system 4 includes a hydrogen supply source 21, a supply path 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 2 flows, and a supply path for supplying hydrogen offgas (fuel offgas) discharged from the fuel cell 2. 22, a circulation path 23 for returning to the junction point A of 22, a pump 24 that pumps the hydrogen off-gas in the circulation path 23 to the supply path 22, and a purge path 25 that is branched and connected to the circulation path 23. The hydrogen gas flowing out from the hydrogen supply source 21 to the supply path 22 by opening the main valve 26 is supplied to the fuel cell 2 through the pressure regulating valve 27 and other pressure reducing valves and the shutoff valve 28. The purge passage 25 is provided with a purge valve 33 for discharging the hydrogen off gas to a hydrogen diluter (not shown).

  The circulation path 23 is provided with a circulation system anode pressure sensor (detection means) P2. The circulation system anode pressure sensor P <b> 2 detects the pressure of hydrogen gas at a low temperature start (described later) under the control of the control device 7. The control device 7 detects a change in the pressure loss (hereinafter referred to as anode system pressure loss) of the fuel gas piping system 4 based on the sensor value from the circulation system anode pressure sensor P2 (details will be described later).

  The refrigerant piping system 5 includes a refrigerant channel 41 communicating with the cooling channel 2 c in the fuel cell 2, a cooling pump 42 provided in the refrigerant channel 41, and a radiator 43 that cools the refrigerant discharged from the fuel cell 2. And a bypass passage 44 that bypasses the radiator 43, and a switching valve 45 that sets the flow of cooling water to the radiator 43 and the bypass passage 44. The refrigerant flow path 41 has a temperature sensor 46 provided in the vicinity of the refrigerant inlet of the fuel cell 2 and a temperature sensor 47 provided in the vicinity of the refrigerant outlet of the fuel cell 2. The refrigerant temperature detected by the temperature sensor 47 reflects the internal temperature of the fuel cell 2 (hereinafter referred to as the temperature of the fuel cell 2). The cooling pump 42 circulates and supplies the refrigerant in the refrigerant channel 41 to the fuel cell 2 by driving the motor.

  The power system 6 includes a high-voltage DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, and various auxiliary inverters 65, 66, and 67. The high-voltage DC / DC converter 61 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 62 and outputs it to the traction inverter 63 side, and the direct-current input from the fuel cell 2 or the traction motor 64. And a function of adjusting the voltage and outputting it to the battery 62. The charge / discharge of the battery 62 is realized by these functions of the high-voltage DC / DC converter 61. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 61.

  The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 (power generation device) is, for example, a three-phase AC motor. The traction motor 64 constitutes, for example, a main power source of the vehicle 100 on which the fuel cell system 1 is mounted, and is connected to the wheels 101L and 101R of the vehicle 100. The auxiliary machine inverters 65, 66, and 67 control the driving of the motors of the compressor 14, the pump 24, and the cooling pump 42, respectively.

  The control device 7 is configured as a microcomputer having a CPU, ROM, and RAM therein. The CPU executes a desired calculation according to the control program, and performs various processes and controls such as control of normal operation and control of low efficiency operation described later. The ROM stores control programs and control data processed by the CPU. The RAM is mainly used as various work areas for control processing.

  The control device 7 includes various pressure sensors (P 1, P 2) and temperature sensors (46, 47), an outside air temperature sensor 51 that detects the outside air temperature in the environment where the fuel cell system 1 is placed, and the accelerator opening of the vehicle 100. Detection signals from various sensors such as an accelerator opening sensor are detected, and a control signal is output to each component (compressor 14, back pressure adjusting valve 16, bypass valve 18, etc.).

  Further, the control device 7 performs a drying process when a predetermined condition is satisfied when the fuel cell system 1 is stopped (including the end). In the embodiment described below, a scavenging process for scavenging the inside of the fuel cell 2 will be described as an example of the drying process.

  Furthermore, when the fuel cell system 1 is started, the control device (determination unit, control unit) 7 determines whether or not the drying process was executed when the system was stopped last time. The wetting process is executed.

  Here, whether or not the drying process was executed when the system was stopped last time is determined based on the impedance of the fuel cell 2 measured when the system was stopped last time. More specifically, first, the control device (measuring means) 7 measures the impedance of the fuel cell 2 every time the system is stopped. When measuring the impedance of the fuel cell 2, the control device 7 predetermines the voltage (FC voltage) of the fuel cell 2 detected by the voltage sensor 72 and the current (FC current) of the fuel cell 2 detected by the current sensor 73. Are sampled at a sampling rate and subjected to Fourier transform processing (FFT operation processing or DFT operation processing). Then, the control device 7 measures (derived) the impedance of the fuel cell 2 by, for example, dividing the FC voltage signal after the Fourier transform process by the FC current signal after the Fourier transform process.

  The control device 7 stores the impedance (measurement impedance) of the fuel cell 2 measured in this way in the measurement impedance memory (storage means) 70 and stops the system. Thereafter, when a system start command is input, for example, by turning on an ignition switch, the control device 7 reads out the measurement impedance at the previous system stop stored in the measurement impedance memory 70 and stores it in the reference impedance memory 51. The reference impedance being read out is read and both impedances are compared.

  Here, the reference impedance is a reference value for determining whether or not the drying process has been performed when the system is stopped, and is obtained in advance by an experiment or the like. Note that the measured impedance when the drying process is performed by an experiment or the like may be mapped and stored in the reference impedance memory 51 as a reference impedance. If the control device 7 determines that the drying process was executed when the system was stopped last time as a result of comparing both impedances, the control apparatus 7 performs the wet process. As described above, when the drying process is performed when the system is stopped last time, the power generation can be started with the moisture content in the fuel cell 2 properly maintained by executing the wetting process at the start. Hereinafter, control when the fuel cell system 1 is stopped and started will be described.

<Processing flow at the end of operation>
FIG. 2 is a flowchart showing a processing flow when the fuel cell system 1 is stopped.
When the operation stop of the fuel cell system 1 is instructed by the ignition switch OFF operation or the like by the driver of the vehicle 100, the control device 7 uses the temperature sensors 46, 47, etc. (FC temperature) is measured (Step S10 → Step S20). In this embodiment, the FC temperature is measured. May be used.

  The control device 7 compares the measured FC temperature with a reference temperature set in a memory (not shown) or the like (step S30). When the measured FC temperature is equal to or higher than the reference temperature, the control device 7 proceeds to step S50 without performing the scavenging process. On the other hand, if the measured FC temperature is lower than the reference temperature, the control device 7 performs a scavenging process to prepare for the next low temperature start (step S40), and then proceeds to step S50.

  Here, the scavenging process means scavenging the inside of the fuel cell 2 by discharging the moisture in the fuel cell 2 to the outside at the end of the operation of the fuel cell system 2, and the scavenging process of the cathode system (oxidizing gas piping system 3). In the scavenging process, the oxidizing gas is supplied to the oxidizing gas channel 2a by the compressor 14 in a state where the supply of hydrogen gas to the fuel cell 2 is stopped, and generated water remaining in the oxidizing gas channel 2a by the supplied oxidizing gas is included. This is done by discharging moisture to the discharge path 12. In addition to (or instead of) this, scavenging processing of the anode system (fuel gas piping system 4) is also performed, but since it can be explained in the same manner, the explanation is omitted here.

  In step S50, the control device 7 measures the impedance of the fuel cell 2 as described above. And the control apparatus 7 stops the said system, after storing the measurement impedance obtained by the impedance measurement in the measurement impedance memory 70 (step S60).

<Processing flow at start-up>
FIG. 3 is a flowchart showing a processing flow at the start of the fuel cell system 1.
As shown in FIG. 3, when the start of operation of the fuel cell system 1 is instructed, for example, by an ON operation of an ignition switch by the driver of the vehicle 100 (step S <b> 100), the control device 7 accesses the measurement impedance memory 70. Then, the measured impedance stored when the system was stopped last time is read (step S200). Then, the control device 7 reads the read measurement impedance and the reference impedance stored in the reference impedance memory 51, and compares both impedances (step S300). As described above, the reference impedance is a reference value for determining whether or not the drying process has been performed when the system is stopped, and is obtained in advance through experiments or the like.

  Since the control device 7 determines that the drying process is not performed when the system is stopped because the measured impedance is equal to or lower than the reference impedance (step S400; NO), the process proceeds to step S600 without performing the wetting process. On the other hand, since the control device 7 determines that the drying process is performed when the system is stopped because the measured impedance exceeds the reference impedance (step S400; YES), the controller 7 performs the wet process (step S500), and then performs the step. Proceed to S600.

  Here, the wetting process can be performed by various methods, and typical processes include (1) performing warm-up operation and (2) increasing the back pressure on the air electrode side. Each will be described below.

(1) Warm-up operation Warm-up operation refers to an operation in which the fuel cell 2 can be heated in a short time compared to the normal operation by causing the fuel cell 2 to self-heat, and reacts compared to the normal operation. This includes low-efficiency operation that increases gas loss due to shortage of gas. In the present embodiment, such a low-efficiency operation, that is, a low-efficiency operation that decreases the power generation efficiency of the fuel cell 2 and increases the heat generation amount is performed as the wet treatment.

  FIG. 4 is a diagram showing the relationship between the output current (hereinafter referred to as “FC current”) of the fuel cell 2 and the output voltage (hereinafter referred to as “FC voltage”). FIG. 4 shows a case where the fuel cell system 1 performs a normal operation by a solid line, and a case where a low efficiency operation is performed by a dotted line.

  When the fuel cell system 1 is normally operated, the fuel cell 2 is operated in a state where the air stoichiometric ratio is set to 1.0 or more (theoretical value) so that high power generation efficiency can be obtained while suppressing power loss (see FIG. (See solid line part 4). Here, the air stoichiometric ratio means an oxygen surplus ratio, and indicates how much oxygen is supplied to oxygen necessary for reacting with hydrogen without excess or deficiency.

  On the other hand, when the fuel cell 2 is warmed up, the fuel cell 2 is set with the air stoichiometric ratio set to less than 1.0 (theoretical value) in order to increase the power loss and raise the temperature of the fuel cell 2. (See the dotted line portion in FIG. 4). When the air stoichiometric ratio is set to be low and the low efficiency operation is performed, the power loss (that is, the heat loss) is positively increased in the energy that can be extracted by the reaction between hydrogen and oxygen. Thus, since the air stoichiometric ratio is set lower in the low-efficiency operation than in the normal operation, the amount of water taken away by air is reduced, and the wetness is higher than in the normal operation.

(2) Back pressure increase on the air electrode side The back pressure on the air electrode side can be adjusted by the back pressure adjusting valve 16. In the present embodiment, as the wetting process, the opening of the back pressure adjustment valve 16 is reduced so that the back pressure on the air electrode side of the fuel cell 2 is higher than that during normal operation. As a result, a differential pressure is generated between the inlet pressure and the outlet pressure on the air electrode side of the fuel cell 2, and the residual water in the fuel cell 2 is difficult to move to the outlet side where the pressure is high. Becomes higher. The back pressure on the air electrode side may be increased intermittently. In that case, the opening degree increase and the opening degree reduction of the back pressure adjustment valve 16 may be repeated.

  Here, each of the wet processes (1) and (2) may be executed alone or in combination with each other. When combined, the processing may be performed in parallel or sequentially. For example, (1) after performing the warm-up operation, (2) increasing the back pressure on the air electrode side may be executed as necessary.

  When the control device 7 proceeds to step S500, the control device 7 performs “Ready On” by notifying the driver that the normal operation is possible. Specifically, the driver is notified that normal operation is possible by lighting a text message of “Ready On” on an indicator or the like or sounding a sound effect. When executing “Ready On”, the control device 7 ends the above-described processing.

  As described above, according to the present embodiment, whether or not the drying process was executed when the system was stopped last time is determined based on the impedance of the fuel cell measured when the system was stopped last time. If it is determined that the drying process was performed when the system was stopped last time, the power generation can be started with the moisture amount in the fuel cell kept appropriate by performing the wetting process at the start. The output performance of the fuel cell can be improved.

B. Modification <Modification 1>
In the present embodiment described above, when the drying process was executed when the system was stopped last time, the wetting process was always executed at the start, but further conditions may be added. FIG. 5 is a flowchart showing a processing flow at the start of the fuel cell system 1 according to Modification 1. Note that steps corresponding to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  When the control device 7 determines that the drying process was performed when the system was stopped last time, the elapsed time from the previous system stop time to the current system start time is derived using a timer (timer) built in the control device 7. (Step S410). The control device 7 compares the derived elapsed time with a reference time set in a memory (not shown), and if the elapsed time is equal to or longer than the set reference time (step S411; NO), the previous run From this time, it is determined that a sufficient time has elapsed from the current travel to the current travel, and the process proceeds to step S600 without performing the wetting process. On the other hand, when the measured elapsed time is less than the set reference time (step S411; YES), the control device (control device) 7 does not have enough time from the previous travel to the current travel ( For example, it is determined that the vehicle is traveling on a highway or the like, and the process proceeds to step S500 to perform a wet process. Note that the subsequent operation can be described in the same manner as in the present embodiment, and thus the description thereof is omitted.

<Modification 2>
In the first modification described above, the elapsed time from the previous system stop to the current start is exemplified as a further condition, but a different condition may be added instead (or in addition).
FIG. 6 is a flowchart showing a processing flow at the start of the fuel cell system 1 according to Modification 2. Note that steps corresponding to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  When determining that the drying process was performed when the system was stopped last time, the control device 7 measures the FC temperature using the temperature sensors (temperature measuring means) 46 and 47 (step S420). In Modification 2, the FC temperature is measured, but the temperature of the peripheral components of the fuel cell 2 and the outside air temperature (related temperature of the fuel cell) may be measured and used. The control device 7 compares the measured FC temperature with a standard operating temperature set in a memory (not shown), and when the measured FC temperature is lower than the set standard temperature (step S421; NO), It is determined that there is no risk of dry-up, and the process proceeds to step S600 without performing the wetting process. On the other hand, if the measured FC temperature is equal to or higher than the set standard temperature (step S421; YES), the control device (control means) 7 determines that there is a risk of dry-up, and proceeds to step S500 to wet. Process. Note that the subsequent operation can be described in the same manner as in the present embodiment, and thus the description thereof is omitted.

<Modification 3>
In the above-described embodiment, whether or not the drying process is performed when the FC system is stopped is determined based on the FC temperature, but may be determined based on the FC temperature and the measured impedance. FIG. 7 is a flowchart showing a processing flow when the fuel cell system 1 according to Modification 3 is stopped. Note that steps corresponding to those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  When the operation stop of the fuel cell system 1 is instructed by the ignition switch OFF operation or the like by the driver of the vehicle 100, the control device (measurement means) 7 uses the temperature sensors (measurement means) 46, 47 and the like. While measuring FC temperature, the measurement impedance of the fuel cell 2 is calculated | required (step S10-> step S20 '). Since the method for deriving the measurement impedance has been described in the present embodiment, a description thereof will be omitted. Further, instead of measuring the FC temperature, the temperature of the peripheral parts of the fuel cell 2 or the outside air temperature (related temperature of the fuel cell) may be measured and used. Then, the control device (determination unit) 7 refers to the dry-up function to determine the risk of dry-up of the electrolyte membrane (step S30 '). FIG. 8 is a diagram illustrating a dry-up function, where the vertical axis indicates the measured impedance and the horizontal axis indicates the FC temperature.

  A region A in FIG. 8 indicates a region where there is a risk of dry-up of the electrolyte membrane (dry-up risk region), and is obtained in advance by an experiment or the like. This dry-up function is set in a memory (not shown) of the control device 7 at the time of manufacture and shipment. Of course, the value and area A indicated in the dry-up function can be set and changed as appropriate.

  When the control device 7 determines that there is a risk of dry-up because the measured FC temperature and the derived measured impedance exist in the region A of FIG. 8 (step S30 ′; YES), the scavenging process and the fuel cell 2 The process proceeds to step S60 without performing impedance measurement. On the other hand, the controller 7 determines that there is no danger of dry-up because the measured FC temperature and the derived measured impedance are out of the area A in FIG. 8 (step S30 ′; NO). Proceed to step S40 for processing. Since subsequent operations can be described in the same manner as in the present embodiment, description thereof is omitted.

  As described above, according to the third modification, the FC temperature and the measured impedance of the fuel cell 2 are detected when the system is stopped, and the risk of dry-up of the electrolyte membrane is determined based on the detection result. Here, when there is no risk of dry-up, drying processing such as scavenging is performed when the system is stopped, while when there is a risk of dry-up, drying processing such as scavenging is not performed when the system is stopped. For this reason, even if the system is started and stopped repeatedly in a short time, it is possible to suppress the problem that the electrolyte membrane is dried up.

It is a block diagram of the fuel cell system which concerns on this embodiment. It is a flowchart which shows the processing flow at the time of a system stop. It is a flowchart which shows the processing flow at the time of system starting. It is a graph which shows the relationship between FC electric current and FC voltage. 10 is a flowchart showing a processing flow at the time of system startup according to Modification 1; 10 is a flowchart showing a processing flow at the time of system startup according to Modification 2. 10 is a flowchart showing a processing flow when the system is stopped according to Modification 3. It is the figure which illustrated the dry up function.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 7 ... Control apparatus, 46, 47 ... Temperature sensor, 51 ... Reference impedance memory, 70 ... Measurement impedance memory, 72 ... -Voltage sensor, 73 ... current sensor.

Claims (5)

A fuel cell system for drying a fuel cell at a predetermined timing,
A judging means for judging whether or not the drying process was executed at the time of the previous system stop;
The fuel cell system further comprising: a control unit that executes a wetting process when the system is started this time when the determining unit determines that the drying process is being performed when the system is stopped last time. The determination means includes
Measuring means for measuring the impedance of the fuel cell when the system is stopped;
Storage means for storing the measured impedance,
2. The fuel cell system according to claim 1, wherein it is determined whether or not the drying process has been executed based on the impedance of the fuel cell measured at the time of the previous system stop stored in the storage unit. It further includes a time measuring means for measuring the elapsed time from the previous system stop to the current system start,
The control means, when it is determined by the determination means that the drying process is being performed at the time of the previous system stop, and when it is determined that the elapsed time measured by the time measurement means is less than a reference time, The fuel cell system according to claim 1 or 2, wherein the wet processing is executed at the time of starting the system this time. It further comprises temperature measuring means for measuring the relevant temperature of the fuel cell at the time of system startup,
The control means determines that the drying process is being executed by the determination means when the system was stopped last time, and the related temperature of the fuel cell measured by the temperature measurement means is determined to be equal to or higher than a standard temperature. 3. The fuel cell system according to claim 1, wherein the wetting process is executed when the system is started this time. A fuel cell system for drying a fuel cell at a predetermined timing,
Measuring means for measuring the impedance of the fuel cell before the system is shut down and the associated temperature of the fuel cell;
A fuel cell system comprising: a determination unit that determines whether to perform the drying process when the system is stopped based on the measurement result.

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