Fuel cell system and control method for fuel cell system

Patent metadata

Field	Value
Publication number	US-10020523-B2
Application number	US-201515561179-A
Country	US
Kind code	B2
Filing date	Mar 27, 2015
Priority date	Mar 27, 2015
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

A fuel cell system includes a fuel supply unit that supplies a fuel to electrolyte membrane of fuel cell, an oxidant supply unit that supplies an oxidant to the electrolyte membrane, and an electricity generation control unit that controls electricity generation by the fuel cell by controlling supply of the oxidant by the oxidant supply unit and supply of the fuel by the fuel supply unit. the fuel cell system includes a wet/dry state detection unit configured to detect a wet/dry state of the electrolyte membrane, a flow rate adjustment unit configured to adjust a flow rate of the fuel supplied to the fuel cell by the fuel supply unit; and a temperature adjustment unit configured to adjust a temperature of the oxidant supplied to the fuel cell by the oxidant supply unit. when reducing an amount of water in the electrolyte membrane in accordance with a signal output from the wet/dry state detection unit, the electricity generation control unit is configured to reduce the flow rate of the fuel, and increase the temperature of the oxidant in accordance with the signal from the wet/dry state detection unit, compared with when increasing the amount of water in the electrolyte membrane.

First claim

The invention claimed is:

1. A fuel cell system including a fuel supply unit that supplies a fuel to an electrolyte membrane of a fuel cell, an oxidant supply unit that supplies an oxidant to the electrolyte membrane, and an electricity generation control unit that controls electricity generation by the fuel cell by controlling supply of the oxidant by the oxidant supply unit and supply of the fuel by the fuel supply unit, the fuel cell system comprising:
a wet/dry state detection unit configured to detect a wet/dry state of the electrolyte membrane;
a flow rate adjustment unit configured to adjust a flow rate of the fuel supplied by the fuel supply unit to the fuel cell; and
a temperature adjustment unit configured to adjust temperature of the oxidant supplied by the oxidant supply unit to the fuel cell, wherein
when reducing an amount of water in the electrolyte membrane in accordance with a signal output from the wet/dry state detection unit, the electricity generation control unit is configured to reduce the flow rate of the fuel, and increases the temperature of the oxidant in accordance with the signal from the wet/dry state detection unit, compared with when increasing the amount of water in the electrolyte membrane.

2. A fuel cell system including a fuel supply unit that supplies a fuel to an electrolyte membrane of a fuel cell, an oxidant supply unit that supplies an oxidant to the electrolyte membrane, and an electricity generation control unit that controls electricity generation by the fuel cell by controlling supply of the oxidant by the oxidant supply unit and supply of the fuel by the fuel supply unit, the fuel cell system comprising:
a wet/dry state detection unit configured to detect a wet/dry state of the electrolyte membrane;
a flow rate adjustment unit configured to adjust a flow rate of the fuel supplied by the fuel supply unit to the fuel cell; and
a temperature adjustment unit configured to adjust temperature of the oxidant supplied by the oxidant supply unit to the fuel cell, wherein
the fuel cell includes
a refrigerant flow passage configured to allow a refrigerant for cooling the fuel cell to flow therethrough,
an oxidant flow passage configured to allow the oxidant to flow therethrough while facing one surface of a corresponding one of the electrolyte membrane, and
a fuel flow passage configured to allow the fuel to flow therethrough, in a direction opposite to a direction of the oxidant flowing through the oxidant flow passage, while facing the other surface of the corresponding one of the electrolyte membrane,

the temperature adjustment unit is configured to supply the refrigerant to the refrigerant flow passage,
the fuel supply unit is configured to circulate the fuel discharged from one end of the fuel flow passage to the other end of the fuel flow passage, and
when reducing an amount of water in the electrolyte membrane in accordance with a signal output from the wet/dry state detection unit, the electricity generation control unit is configured to reduce the flow rate of a fuel circulated to the fuel flow passages, and increase the temperature of the oxidant in accordance with the signal from the wet/dry state detection unit, compared with when increasing the amount of water in the electrolyte membrane.

3. The fuel cell system according to claim 1 , wherein
when reducing the amount of water in the electrolyte membrane, the electricity generation control unit is configured to perform control for reducing the flow rate of the fuel using the flow rate adjustment unit in priority to control for increasing the temperature of the oxidant using the temperature adjustment unit.

4. The fuel cell system according to claim 1 , wherein
when reducing the amount of water in the electrolyte membrane, the electricity generation control unit is configured to reduce the flow rate of the fuel, and also increases the temperature of the oxidant in accordance with the signal from the wet/dry state detection unit so as to reduce a difference between a wetness degree of the electrolyte membrane and a target value thereof.

5. The fuel cell system according to claim 4 , wherein
the temperature adjustment unit includes a cooling device configured to supply a refrigerant to the fuel cell,
the electricity generation control unit includes
a priority control unit configured to set an order of control over operation of the temperature adjustment unit and operation of the flow rate adjustment unit,
a flow rate computation unit configured to reduce the flow rate of the fuel supplied to the fuel cell on the basis of temperature of the fuel cell and the wetness degree of the electrolyte membrane, and
a temperature computation unit configured to control the temperature of the fuel cell on the basis of the flow rate of the fuel and the wetness degree of the electrolyte membrane, and

when a dry operation for reducing the amount of water in the electrolyte membrane is executed, the priority control unit sets a temperature at the time of a wet operation as the temperature of the fuel cell in the flow rate computation unit, the temperature at the time of the wet operation being lower than the temperature of the fuel cell.

6. The fuel cell system according to claim 5 , wherein
a lower limit of a range where the cooling device is able to adjust the temperature of the fuel cell is set as the temperature at the time of the wet operation.

7. The fuel cell system according to claim 6 , wherein
when the dry operation is executed, the flow rate computation unit makes a reduction speed high compared with when the temperature of the fuel cell is used in place of the temperature at the time of the wet operation, the reduction speed being a speed of reduction in the flow rate of the fuel supplied to the fuel cell, and
the temperature computation unit reduces the temperature of the fuel cell as the flow rate of the fuel supplied to the fuel cell decreases, and increases the temperature of the fuel cell as the wetness degree of the electrolyte membrane increases.

8. The fuel cell system according to claim 1 , wherein
the fuel supply unit includes
a circulation passage configured to circulate a fuel discharged from the fuel cell back to the fuel cell, and
a circulation pump provided in the circulation passage so as to adjust a circulation flow rate of a fuel circulated to the fuel cell, and

when reducing the amount of water in the electrolyte membrane, the electricity generation control unit is configured to reduce an amount of water contained in the fuel circulated to the fuel cell via the circulation passage by reducing the circulation flow rate of the fuel.

9. The fuel cell system according to claim 1 , wherein
the fuel cell includes
a refrigerant flow passage configured to allow a refrigerant for cooling the fuel cell to flow therethrough,
an oxidant flow passage configured to allow the oxidant to flow therethrough while facing one surface of a corresponding one of the electrolyte membrane, and
a fuel flow passage configured to allow a fuel to flow therethrough, in a direction opposite to a direction of the oxidant flowing through the oxidant flow passage, while facing the other surface of the corresponding one of the electrolyte membrane,

the temperature adjustment unit is configured to supply the refrigerant to the refrigerant flow passage, and
the fuel supply unit is configured to circulate a fuel discharged from one end of the fuel flow passage to the other end of the fuel flow passage.

10. The fuel cell system according to claim 1 , wherein
the wet/dry state detection unit is configured to detect an impedance of the fuel cell and outputs the impedance as a signal related to the wetn

Assignees

• Nissan Motor

Inventors

• Ikeda Nobuhisa
• Aoki Tetsuya

Classifications

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04708

  of fuel cell reactants · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M8/04858

  Electric variables · CPC title

• H01M8/04604

  Power, energy, capacity or load · CPC title