Fuel cell system

Patent metadata

Field	Value
Publication number	US-9755253-B2
Application number	US-201314381779-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Feb 29, 2012
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A fuel cell system includes a fuel cell stack, a compressor, a cathode flow passage, a bypass flow passage branching from the cathode flow passage, thereby bypassing the stack, a bypass valve adjusting a bypass flow rate, a stack flow rate sensor detecting a flow rate to the stack, and a compressor flow rate sensor detecting a flow rate into the compressor. A flow rate for the stack depending on a state of a fuel cell and a flow rate the compressor controls depending on a requirement different from that of the stack are calculated. A control unit controls, when the flow rate required from the compressor is more than that required by the stack, the compressor based on the flow rate required from the compressor and a detected compressor flow rate, and controls the bypass valve based on the flow rate required by the stack and a detected stack flow rate.

First claim

The invention claimed is:

1. A fuel cell system, comprising:
a fuel cell stack;
a cathode compressor configured to supply a cathode gas;
a cathode flow passage connected to the fuel cell stack, for the cathode gas to flow;
a bypass flow passage branching from the cathode flow passage upstream of the fuel cell stack, thereby bypassing the fuel cell stack;
a bypass valve provided on the bypass flow passage, and configured to adjust a cathode flow rate flowing through the bypass flow passage;
a stack flow rate sensor configured to detect a cathode flow rate supplied to the fuel cell stack;
a compressor flow rate sensor configured to detect a cathode flow rate taken into the cathode compressor; and
a controller configured to:
calculate a flow rate necessary for the fuel cell stack depending on a state of a fuel cell;
calculate a flow rate which required from the cathode compressor depending on a requirement different from the requirement by the fuel cell stack; and
select a first cathode flow rate control when the flow rate required from the cathode compressor is more than the flow rate required by the fuel cell stack, the first cathode flow rate control being performed so as to control the cathode compressor based on the flow rate required from the cathode compressor and a compressor flow rate detected by the compressor flow rate sensor, and control the bypass valve based on the flow rate required by the fuel cell stack and a stack flow rate detected by the stack flow rate sensor, and
select a second cathode flow rate control when the flow rate required by the fuel cell stack is more than the flow rate required from the cathode compressor, the second cathode flow rate control being performed so as to control the cathode compressor based on the flow rate required by the fuel cell stack and the stack flow rate detected by the stack flow rate sensor.

2. The fuel cell system according to claim 1 , wherein when the flow rate required by the fuel cell stack becomes more than the flow rate required from the cathode compressor, the controller is configured to compulsorily apply valve close control to the bypass valve.

3. The fuel cell system according to claim 2 , wherein:
the controller is configured to calculate a second flow rate required from the cathode compressor based on a difference between an air flow rate required by the fuel cell stack based on the state of the fuel cell and an actual stack flow rate; and
the controller is configured to control the cathode compressor by using a larger one of the flow rate required from the cathode compressor and the second flow rate required from the cathode compressor.

4. The fuel cell system according to claim 1 , wherein:
the controller is configured to calculate a second flow rate required from the cathode compressor based on a difference between an air flow rate required by the fuel cell stack based on the state of the fuel cell and an actual stack flow rate; and
the controller is configured to control the cathode compressor by using a larger one of the flow rate required from the cathode compressor and the second flow rate required from the cathode compressor.

5. The fuel cell system according to claim 3 , wherein calculating the second flow rate required from the cathode compressor is further based on a first lower limit flow rate for the cathode compressor that is a surge avoidance flow rate and a second lower limit flow rate for the cathode compressor that is a dilution flow rate for diluting gas not consumed by the fuel cell stack.

Assignees

• Nissan Motor

Inventors

• Asai Yoshitomo
• Takeda Hiroshi

Classifications

• H01M8/0438

  Pressure; Ambient pressure; Flow · CPC title

• H01M8/04746

  Pressure; Flow · CPC title

• H01M2250/20

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

• H01M8/04111 Primary

  using a compressor turbine assembly · CPC title

• H01M8/04776

  at auxiliary devices, e.g. reformer, compressor, burner · CPC title