JP4064213B2 - Method and apparatus for discharging fuel cell stack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for discharging a voltage remaining in a fuel cell stack when power generation of the fuel cell stack in which a plurality of cells are connected in series is stopped.
[0002]
[Prior art]
For example, in a polymer electrolyte fuel cell, an electrolyte membrane (electrolyte) / electrode structure in which a cathode electrode and a cathode electrode are arranged on both sides of an electrolyte membrane made of a polymer ion exchange membrane (cation exchange membrane) is separated by a separator. It is comprised by pinching and hold | maintaining. This type of fuel cell is normally used as a fuel cell stack by laminating a predetermined number of cells comprising an electrolyte membrane / electrode structure and a separator.
[0003]
In a fuel cell, a fuel gas supplied to the cathode electrode, for example, a hydrogen-containing gas, is hydrogen-ionized on the electrode catalyst and moves to the cathode electrode side through an appropriately humidified electrolyte membrane. The generated electrons are taken out to an external circuit and used as DC electric energy. Since the cathode electrode is supplied with an oxidant gas, for example, an oxygen-containing gas such as air, the hydrogen ions, the electrons and oxygen react with each other to produce water.
[0004]
In the fuel cell described above, a fuel gas channel (reactive gas channel) for flowing fuel gas facing the cathode electrode and an oxidant for flowing oxidant gas facing the cathode electrode in the plane of the separator. An agent gas channel (reactive gas channel) is provided. Further, between the separators, a cooling medium flow path for flowing a cooling medium as necessary is provided along the surface of the separator to form a fuel cell device.
[0005]
In such a fuel cell device, it is said that it is necessary to periodically stop the operation and check in order to maintain a stable power generation operation over a long period of time (see Patent Document 1).
[0006]
In the “fuel cell power generator” of Patent Document 1, the fuel gas is replaced with an inert gas at the time of inspection, the voltage remaining in the fuel cell stack is short-circuited by a short-circuit switch, and further grounded by a ground switch after the short-circuit. It is disclosed that it can be discharged and inspected safely.
[0007]
[Patent Document 1]
JP-A-9-139221 (paragraph [0018], FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in the technique according to Patent Document 1, protection of the inspector at the time of inspection is taken into consideration, but nothing is taken into consideration from the viewpoint of protecting the fuel cell stack and the cells.
[0009]
In addition, since the short-circuit switch and the ground switch are manually turned on, it is pointed out that the work efficiency is poor.
[0010]
In addition, in vehicles equipped with fuel cell stacks, so-called fuel cell vehicles, power generation of the fuel cell stack may be stopped for a long time even during normal parking for inspection purposes. It has not been.
[0011]
The present invention has been made in view of such various problems, and provides a method and apparatus for discharging a fuel cell stack that also considers protection of the fuel cell stack when power generation of the fuel cell stack is stopped. For the purpose.
[0012]
Another object of the present invention is to provide a method and apparatus for discharging a fuel cell stack that can improve the work efficiency of the discharge when power generation of the fuel cell stack is stopped.
[0013]
[Means for Solving the Problems]
In this section, for ease of understanding, reference numerals in the attached drawings are used for explanation. Therefore, the contents described in this section should not be construed as being limited to those having the reference numerals.
[0014]
In the discharge method of the fuel cell stack according to the present invention, a plurality of cells (12) are connected in series. In Connected And connected to the load and the power storage device (36) through the main contactor (32). When power generation of the fuel cell stack (14) is stopped, an inert gas (N ₂ ) And discharging the voltage remaining in the fuel cell stack has the following characteristics.
[0015]
(1) During the discharge process (FIG. 2), the process of measuring the voltage (Vc) of each cell (S8), and among the measured voltages of each cell, the lowest cell voltage (Vmin) is a predetermined value (V1) or more. When Close the main contactor (S11) and discharge, By the stack voltage (Vh) which is the voltage across the fuel cell stack Said Store in power storage device (36) Stacked ( S8 “No”), when the lowest cell voltage is not more than a predetermined value, Open the main contactor And not discharging (S8 “Yes”). Since the discharge is continued only when the voltage is equal to or higher than a predetermined minimum cell voltage (V1), the voltage of a specific cell is lowered and the cell is protected without being damaged. Further, since the discharge process is automatically performed, the work efficiency is high. Furthermore, the electricity to be discharged is stored in the power storage device. product Therefore, the electricity of the fuel cell stack can be used effectively. For example, it can be used as a power source for downverters and various pumps.
[0016]
(2) In the feature (1), the minimum cell voltage is Said A process of measuring a duration (T) that is less than or equal to a predetermined value (S12), and when the measured duration reaches a predetermined time (S12 “Yes”), Said A process for determining that the discharge process has been completed, so that the discharge process can be automatically completed. By maintaining the duration for which the minimum cell voltage is equal to or less than the predetermined value for a predetermined time, the fuel gas is surely replaced with the inert gas, and the voltage remaining in the cell can be discharged more reliably.
[0017]
(3) In the above feature (1) or (2), the fuel cell stack stack The process of measuring the voltage (Vh) (S7) and the measurement The stack When the voltage becomes equal to or lower than the predetermined value (V2), there is a step (S19) for determining that the discharge process is completed, so that the discharge process can be automatically completed as a fuel cell stack.
[0019]
In the discharge device for a fuel cell stack according to the present invention, a plurality of cells (12) are connected in series. In Connected, Connected to the load and the power storage device (36) through the main contactor (32). When power generation of the fuel cell stack (14) is stopped, an inert gas (N ₂ ) And a means for measuring the voltage (Vc) of each cell during the discharge process in the apparatus for discharging the voltage remaining in the fuel cell stack, and the measured voltage of each cell When the minimum cell voltage (Vmin) is equal to or higher than a predetermined value (V1), Close the main contactor (S11) and discharge, By the stack voltage (Vh) which is the voltage across the fuel cell stack Said Store in power storage device (36) Loading When the minimum cell voltage is a predetermined value or less, Open the main contactor Discharge control means (16) for controlling so as not to discharge. Also in this case, the voltage of a specific cell is lowered, and this cell is protected without being damaged. Further, since the discharge process is automatically performed, the work efficiency is high.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
FIG. 1 shows a configuration of a fuel cell system 10 to which an embodiment of the present invention is applied.
[0022]
The fuel cell system 10 basically controls a fuel cell stack 14 in which a plurality of cells 12 are electrically connected in series, and the overall operation of the fuel cell system 10 including the fuel cell stack 14. And a control unit 16.
[0023]
As is well known, each cell 12 has a structure in which a fuel cell composed of an anode electrode, an electrolyte membrane (in this embodiment, a solid polymer membrane) and a cathode electrode is sandwiched and held by a separator. The generated voltage (cell voltage) Vc of each cell 12 is detected by the control unit 16.
[0024]
In the fuel cell stack 14, the cells 12 configured as described above are stacked, terminal plates 18 and 20 as voltage extraction plates are attached to both ends, and both sides of the terminal plates 18 and 20 are held and fixed by end plates 22. The structure is made.
[0025]
Then, the voltage across the fuel cell stack 14 generated in the terminal plates 18 and 20 (usually a stack voltage that is a high voltage) Vh is detected by the control unit 16, and the stack voltage Vh is detected as a contactor (main contactor). 32 is applied to a high-voltage load, for example, a motor for propelling the vehicle, and is connected to one input side (also a DC output side) of a capacitor 36 which is a power storage device that stores electricity through a contactor (capacitor contactor) 34. Applied.
[0026]
The capacitor 36 supplies the stored electricity to a high voltage load as needed and also supplies it to the downverter 86. The downverter 86 supplies the stack voltage Vh to the low voltage battery 88 as a low voltage. The output voltage of the low-voltage battery 88 is applied to auxiliary devices that operate at a low voltage, such as the control unit 16.
[0027]
On the other hand, a fuel gas supply port 24 and an air supply port 26 are provided on one end side of the end plate 22 constituting the fuel cell stack 14, and a discharge port 28 for fuel gas and water, etc. is provided on the other end side. Air and water discharge ports 30 are provided.
[0028]
The fuel gas supply port 24 actually has hydrogen (H) as a fuel gas from the fuel gas cylinder 50 through an on-off valve (fuel valve) 52 and a pressure control valve 54 when the fuel cell stack 14 generates power. ₂ ) Is supplied, but when it is determined that power generation of the fuel cell stack 14 is stopped and a certain condition is satisfied, it is chemically stable from the replacement gas cylinder 56 via the on-off valve (replacement gas valve) 58. Nitrogen (N ₂ ) Is supplied through the pressure control valve 54. The replacement gas valve 58 is closed when the fuel gas is supplied, and the fuel valve 52 is closed when the replacement gas is supplied. As the inert gas, a rare gas such as He, Ne, or Ar can be used in addition to nitrogen.
[0029]
Compressed air is supplied to the air supply port 26 through the compressor 60 from a communication port to the outside air that is the atmosphere. The pressure of the compressed air is detected by the pressure sensor 62, and the opening degree of the pressure control valve 54 for the fuel gas (hydrogen) and the replacement gas (nitrogen) is adjusted according to the detected pressure of the pressure sensor 62.
[0030]
Further, an on-off valve (hydrogen purge valve) 70 is provided between the fuel gas discharge port 28 and the exhaust system. Further, an open / close valve (circulation valve) 71 and a circulation pump 72 are connected between the fuel gas discharge port 28 and the supply port 24. These on-off valves 70 and 71 can be replaced with three-way valves.
[0031]
When the circulation valve 71 is closed and the hydrogen purge valve 70 is opened, the exhaust port 28 and the exhaust system are communicated, and water and hydrogen are supplied from the exhaust port 28 to the exhaust system and discharged. When the purge valve 70 is closed and the circulation valve 71 is opened and the supply port 24 is in communication with the discharge port 28 through the circulation pump 72, hydrogen from the discharge port 28 is returned to the supply port 24 by the circulation pump 72. Hydrogen is effectively used.
[0032]
The air and water discharge port 30 communicates with the outside air via a discharge pressure valve 73 that is a pressure control valve.
[0033]
A charging voltage is supplied to the other input side of the capacitor 36 from a commercial AC power source (not shown) via a plug, a charger 82 and a contactor (charger contactor) 84 to charge the capacitor 36. As described above, the battery 88 is connected via the downverter 86 to the DC output side of the capacitor 36 (also on the DC input side from the fuel cell stack 14 or the regenerative DC input side from the high voltage load). .
[0034]
The control unit 16 includes a CPU (Central Processing Unit) 90, a memory 92 such as a ROM (Read Only Memory) / RAM (Random Access Memory), a counter / timer (referred to as a timer) 94, which is a counting / timer, and an A / D. It is composed of a control board on which an interface (I / F) 96 such as a converter, D / A converter, and driver is mounted.
[0035]
The control unit 16 (the CPU 90) executes a program stored in the memory 92 in response to various inputs (input from the input device 98 or detection input such as the cell voltage Vc and the stack voltage Vh). The overall fuel cell system 10 is controlled. For example, when the fuel cell system 10 is mounted on a vehicle, the control unit 16 configures the input device 98 such as an ignition switch position, a transmission position, a parking brake, an accelerator pedal, an air conditioner switch, and the like. Depending on the state, cell voltage Vc, and stack voltage Vh, opening / closing control of the contactors 32, 34, 84, adjustment of the exhaust pressure of the exhaust pressure valve 73, opening / closing of the on / off valves 52, 58, 70, 71, pump 72 and compressor 60 And the capacitor 36 and the downverter 86 are controlled. As described above, an input device 98 such as a keyboard can be connected to the control unit 16 through the interface 96.
[0036]
The fuel cell system 10 according to this embodiment is basically configured as described above. Next, an operation during power generation and a discharge processing operation when power generation is stopped will be described.
[0037]
First, an operation during power generation for driving a high-voltage load such as a motor or an air conditioner will be briefly described.
[0038]
At this time, the replacement gas valve 58 is closed, the fuel valve 52 is opened, hydrogen can be supplied from the fuel gas cylinder 50 to the fuel cell stack 14, and the air exhaust pressure valve 73 is opened to a predetermined opening. Thus, the amount of air supplied from the compressor 60 to the air supply port 26 is adjusted. The pressure of this air amount is detected by the pressure sensor 62, and the opening of the pressure control valve 54 is adjusted to the opening corresponding to the detected pressure, whereby a predetermined amount of hydrogen is supplied to the fuel supply port 24. .
[0039]
Further, normally, the circulation valve 71 is opened, and the discharge port 28 and the supply port 24 are communicated with each other via the circulation pump 72. During this time, when the hydrogen purge valve 70 is opened intermittently, the discharge port 28 and the exhaust port 28 are exhausted. Communication with the system.
[0040]
In this manner, hydrogen, which is a fuel gas, is supplied to the anode electrode of each cell 12 through the supply port 24, while air is supplied to the cathode electrode of each cell 12 through the supply port 26, thereby As a result, an electrochemical reaction occurs, and a high voltage (stack voltage, which is a voltage across both ends) Vh, which is a series voltage of the cell voltage Vc of each cell 12, is generated between the terminal plates 18 and 20.
[0041]
This stack voltage Vh is supplied to the high voltage load through the main contactor 32. When the high-voltage load is a vehicle motor, generally, the stack voltage Vh from the fuel cell stack 14 is supplied to the high-voltage load during idling or at a constant speed, and the capacitor contactor 34 is also closed during acceleration. Electricity is supplied to the high voltage load. On the other hand, at the time of deceleration, electricity is regenerated from the motor functioning as a generator to the capacitor 36, and electricity is accumulated in the capacitor 36. The above description is the operation during power generation.
[0042]
Next, the discharge process by the control unit 16 of the fuel cell stack 14 when power generation is stopped will be described based on the control flowchart of FIG.
[0043]
In step S1, it is first determined whether or not there is a request for a discharge process. If there is a request, the process proceeds to step S2. Here, the discharge request is a condition stored in the memory 92 in advance when the inspector inputs a request command from the input device 98 when the fuel cell system 10 needs to be inspected (referred to as the former condition). Occurs when the latter condition is satisfied. For example, in the case of a vehicle, when the condition stored in advance in the memory 92 is satisfied, the input of the charger 82 is further input when the transmission (not shown) is in the parking position and the parking brake is applied. A state in which an AC voltage is supplied to the side (a state in which the plug of the charger 82 is connected to an external AC power source) or the like.
[0044]
In this embodiment, the control operation when the latter condition is satisfied and the discharge control is automatically performed will be described.
[0045]
In this case, in step S2, whether or not the discharge process is completed is determined by whether or not the discharge completion flag Fd is set (Fd = 1).
[0046]
If the discharge process has not been started or has not been completed, the discharge completion flag Fd is cleared, and the process proceeds to step S3.
[0047]
In step S3, a preparation process for starting and continuing the discharge process is performed. That is, in order to discharge the fuel cell stack 14, the fuel valve 52 is closed, the replacement gas valve 58 is opened, the main contactor 32, the capacitor contactor 34, and the charger contactor 84 are turned on, and the downverter 86 is turned on. The device 82 is turned on, the circulation valve 71 is opened, and the circulation pump 72 is driven.
[0048]
Next, in step S4, the compressor 60 is driven by setting the rotational speed of the compressor 60 to a predetermined rotational speed for discharging.
[0049]
In steps S5 and S6, the opening of the exhaust pressure valve 73 is set to a predetermined opening, and the hydrogen purge valve 70 is opened for a predetermined time. Steps S5 and S6 may be performed before or after or simultaneously.
[0050]
The supply of the fuel gas hydrogen, which is the reaction gas, to the fuel cell stack 14 is stopped by the processes in steps S3 to S6. Nitrogen, which is a replacement gas led from the replacement gas cylinder 56 via the replacement gas valve 58, has a predetermined opening based on the opening pressure of the exhaust pressure valve 73 and the detected pressure of air by the pressure sensor 62 according to the rotation speed of the compressor 60. Then, it is introduced into the supply port 24 through the pressure control valve 54 opened at, and supplied to the fuel cell stack 14. In this case, since the circulation valve 71 is opened, nitrogen is positively returned from the discharge port 28 to the supply port 24 via the circulation pump 72, and the nitrogen gas can be effectively utilized.
[0051]
As a result, the inside of each cell 12 is replaced with nitrogen gas, while the voltage remaining in each cell 12 is mainly the main contactor 32 since the main contactor 32 and the capacitor contactor 34 are turned on. Is consumed by an equivalent resistance composed of the resistance (floating resistance) of the line from the secondary side to the capacitor 36 and the input impedance of the capacitor 36, and is gradually discharged (discharged). However, at the time of this discharge, in particular, since the stack voltage Vh is high at the initial stage, most of the electricity is stored in the capacitor 36, and the electricity can be used effectively. The electricity stored in the capacitor 36 can be used, for example, as a power source for the downverter 86 or a power source for the pump 72 during discharge.
[0052]
Next, in step S7, the stack voltage Vh, which is the voltage between the terminal plates 18 and 20, is measured, and it is determined whether or not the measured stack voltage Vh is lower than a predetermined voltage V2.
[0053]
Since the stack voltage Vh is a high voltage at the beginning of the discharge process, this determination is not established. Therefore, in step S8, the voltage value of the cell voltage Vc of each cell 12 is measured and confirmed, and the lowest (lowest) cell voltage value of the measured cell voltage Vc is selected. It is determined whether or not the lowest cell voltage Vmin is lower than a predetermined voltage V1.
[0054]
Also in this case, since the cell voltage Vc is high at the beginning of discharge, this determination is not satisfied. Next, in step S9, the set time (minimum time) of the timer 94 for defining the duration of time below the minimum cell voltage Vmin. The duration (T) during which the cell voltage Vmin is equal to or less than a predetermined value) is set to a predetermined time Ts. Note that the duration of the minimum cell voltage Vmin being equal to or less than the predetermined value V1 is defined in order to avoid damage to the corresponding cell 12 and to complete the discharge more reliably as the duration elapses. .
[0055]
During the process of step S9, since the discharge process is not completed, the discharge completion flag Fd is cleared (F ← 0) in step S10. At this time, if it has already been cleared, the cleared state is maintained.
[0056]
In step S11, the main contactor 32 is also turned on. At this time as well, the ON state is continued if it is already in the ON state.
[0057]
The above-described steps S1 “Yes”, S2 “No”, S3-S6, S7 “No”, and S8 “No” -S11 are repeated to discharge the voltage remaining in the fuel cell stack 14. The
[0058]
When the determination in step S8 is established during the discharge, that is, when the lowest cell voltage Vmin becomes lower than the predetermined voltage V1, the set time T of the timer 94 is zero (T = T = step S12). It is determined whether it is 0).
[0059]
If the set time T is not zero in step S12, the set time T of the timer 94 is subtracted by 1 (T ← T-1) in step S13. At this time as well, in step S14, the discharge is regarded as incomplete, and the discharge completion flag Fd is cleared in step S14.
[0060]
However, at this time, since the cell voltage Vc is a value equal to or lower than the minimum cell voltage Vmin, the main contactor 32 is turned off in step S15 so that the minimum cell voltage Vmin is not excessively decreased. When the main contactor 32 is turned off, the minimum cell voltage temporarily rises. In this way, the cell 12 is protected.
[0061]
When a set time T elapses in a series of steps S1 “Yes”, S2 “No”, S3-S6, S7 “No”, S8 “Yes”, S12 “No”, and S13-S15, the minimum cell voltage Vmin is It is determined that the predetermined duration Ts that is equal to or less than the predetermined value V1 has been reached, and the determination in step S12 is established (T = 0). At this time, the discharge completion flag Fd is set in step S16 (Fd ← 1), and it is considered that the discharge is completed. In step S17, the main contactor 32 is turned off and the discharge process is normally completed.
[0062]
Note that step S7 is provided as another example determination step in which the discharge process is normally completed. In step S7, when the stack voltage Vh of the fuel cell stack 14 becomes equal to or lower than the predetermined voltage V2, it is determined that the discharge is sufficiently completed even if the predetermined duration Ts is not reached. Also in this case, the discharge completion flag Fd is set in step S18 (Fd ← 1), and in step S19, it is considered that the main contactor 32 is turned off and the discharge process is normally completed.
[0063]
If it is determined in step S17 or step S19 that the discharge process has been completed normally, the discharge completion flag Fd is Fd = 1. For this reason, determination of step S2 in the next processing cycle is established, and the process proceeds to step S20 and subsequent steps.
[0064]
At this time, in steps S20 to S23, an organized process (end preparation process) is performed in accordance with the completion of the discharge process. That is, in step S20, the replacement gas valve 58 is closed, the capacitor contactor 34, the charger contactor 84, and the main contactor 32 are turned off, the downverter 86 and the charger 82 are turned off, the circulation valve 71 is closed, and the circulation pump 72 is turned on. A non-driving state (off state) is set.
[0065]
In step S21, the compressor 60 is further brought into a non-driven state (OFF state, that is, the rotation speed is zero). In the next step S22, the exhaust pressure valve 73 is fully opened, and the exhaust port 30 is communicated with the atmosphere. Further, in step S23, the hydrogen purge valve 70 is closed.
[0066]
In this way, the discharge process by the control unit 16 of the fuel cell stack 14 when power generation is stopped is completed.
[0067]
As described above, according to the above-described embodiment, the cell voltage Vc of each cell 12 is measured during the discharge process (FIG. 2), and the lowest cell voltage Vmin among the measured cell voltages Vc of each cell 12 is the predetermined voltage V1. Since the discharge is performed when the voltage is equal to or higher than the above and the discharge is not performed when the minimum cell voltage Vmin is equal to or lower than the predetermined voltage V1, the voltage of a specific cell is lowered, and this cell is not damaged. The cell 12 is protected, and as a result, the fuel cell stack 14 itself is protected.
[0068]
Further, the stack voltage Vh that is the voltage across the fuel cell stack 14 is measured, and when the measured stack voltage Vh becomes equal to or lower than the predetermined voltage V2, it is determined that the discharge process has been completed. As shown in FIG. 14, the discharge process can be automatically completed.
[0069]
That is, in this embodiment, since the discharge process is performed automatically instead of manually, the work efficiency is high. In particular, it is difficult to manually set the rotation speed of the compressor 60, and it is possible to prevent a flow rate higher than necessary from flowing through the fuel cell stack 14. In addition, since the opening degree of the exhaust pressure valve 73 can be automatically set to an appropriate value, damage to the fuel cell stack 14 due to excessive pressure can be prevented. In this way, in this embodiment, the work efficiency is improved and the stack is protected at the time of the discharge process when the fuel cell stack 14 stops generating power.
[0070]
Further, in a vehicle equipped with the fuel cell stack 14, the power generation of the fuel cell stack 14 may be stopped for a long time even during normal parking that is not intended for inspection. Can also be discharged, and the average use time of the fuel cell stack 14, that is, the so-called average life can be extended.
[0071]
In addition, when discharging, the main contactor 32 and the capacitor contactor 34 are turned on and electricity is stored in the capacitor 36, so that energy can be effectively used.
[0072]
Various set values such as the predetermined voltages V1 and V2 can be set to optimum values experimentally or experimentally for each fuel cell stack 14.
[0073]
Further, the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification.
[0074]
【The invention's effect】
As described above, according to the present invention, it is possible to execute the discharge process considering the protection of the fuel cell stack itself when the power generation of the fuel cell stack is stopped.
[0075]
Further, according to the present invention, since the discharge process performed when the fuel cell stack stops generating power can be automatically performed, the work efficiency of the discharge process can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a fuel cell system to which an embodiment of the present invention is applied.
FIG. 2 is a control flowchart of automatic discharge processing.
[Explanation of symbols]
10 ... Fuel cell system 12 ... Cell
14 ... Fuel cell stack 16 ... Control unit
18, 20 ... Terminal plate 22 ... End plate
24 ... Fuel gas supply port 26 ... Air supply port
28 ... Exhaust port for fuel gas and water 30 ... Exhaust port for air and water
32 ... Contactor (Main contactor)
34 ... Contactor (capacitor contactor)
36 ... Capacitor 50 ... Fuel gas cylinder
52 ... Open / close valve (fuel valve) 54 ... Pressure control valve
56 ... Replacement gas cylinder 58 ... Open / close valve (replacement gas valve)
60 ... Compressor 62 ... Pressure sensor
70 ... Open / close valve (hydrogen purge valve) 71 ... Open / close valve (circulation valve)
72 ... circulation pump 73 ... exhaust pressure valve
82 ... Charger 86 ... Downverter
88 ... Low voltage battery 90 ... CPU
92 ... Memory 94 ... Timer
96 ... Interface 98 ... Input device

Claims (4)

When a plurality of cells are connected in series and the power generation of the fuel cell stack connected to the load and the power storage device through the main contactor is stopped, an inert gas is supplied to the anode electrode and remains in the fuel cell stack In the method of discharging the voltage,
Measuring the voltage of each cell during the discharge process;
During the voltage of each cell measured, when the lowest cell voltage is equal to or greater than a predetermined value, the discharging closing the main contactor, and accumulated in the electric storage device by the stack voltage is voltage across the fuel cell stack, A method of discharging a fuel cell stack, comprising: opening the main contactor and not discharging when the minimum cell voltage is equal to or lower than a predetermined value. The method of discharging a fuel cell stack according to claim 1,
further,
Measuring the duration that the lowest cell voltage is less than or equal to the predetermined value;
And a step of determining that the discharge process has been completed when the measured duration has reached a predetermined time. The method for discharging a fuel cell stack according to claim 1 or 2,
further,
Measuring the stack voltage;
And a step of determining that the discharge process has been completed when the measured stack voltage is equal to or lower than a predetermined value. When a plurality of cells are connected in series and the power generation of the fuel cell stack connected to the load and the power storage device through the main contactor is stopped, an inert gas is supplied to the anode electrode and remains in the fuel cell stack In the device for discharging the voltage,
Means for measuring the voltage of each cell during the discharge process;
During the voltage of each cell measured, when the lowest cell voltage is equal to or greater than a predetermined value, the discharging closing the main contactor, and accumulated in the electric storage device by the stack voltage is voltage across the fuel cell stack, A discharge control device for a fuel cell stack, comprising: a discharge control means for controlling so that the main contactor is not opened and discharged when the minimum cell voltage is equal to or lower than a predetermined value.

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