Fuel cell system and method of identifying power leakage area

Patent metadata

Field	Value
Publication number	US-10873098-B2
Application number	US-201816111545-A
Country	US
Kind code	B2
Filing date	Aug 24, 2018
Priority date	Aug 29, 2017
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

When reduction of insulation resistance is detected, an FC positive side relay is opened, and a switching element is turned OFF. When the insulation resistance has returned to a normal value as a result of the relay opening and the switching element turning OFF, it is identified that the power leakage is occurring in the area between the positive side relay and the diode.

First claim

What is claimed is:

1. A fuel cell system comprising:
a fuel cell stack;
a diode that prevents backflow of current to a positive electrode of the fuel cell stack;
a relay circuit including:
a negative side relay corresponding to a negative electrode of the fuel cell stack; and
a positive side relay arranged between the positive electrode of the fuel cell stack and the diode;

a power leakage detector configured to output a power leakage detection signal to be input to the fuel cell stack via the negative side relay, and detect reduction of insulation resistance; and
a controller programmed to control opening/closing of the positive side relay, control opening/closing of the negative side relay, and acquire a detection result from the power leakage detector,
wherein the controller is further programmed to execute isolation processing by opening the positive side relay when the reduction of the insulation resistance is detected in a state where the positive side relay and the negative side relay are closed, and to identify that power leakage is occurring in an area between the positive side relay and the diode when the insulation resistance has returned to a normal value as a result of the isolation processing.

2. The fuel cell system in accordance with claim 1 , wherein
the controller is further programmed to open the negative side relay when the insulation resistance is still reduced after the isolation processing, and to identify that the power leakage is occurring in an area of the fuel cell stack when the insulation resistance has returned to the normal value as a result of opening the negative side relay.

3. The fuel cell system in accordance with claim 1 , wherein
the controller is further programmed to open the negative side relay when the insulation resistance is still reduced after the isolation processing, and to identify that the power leakage is occurring in an area other than the area between the positive side relay and the diode or an area other than an area of the fuel cell stack when the insulation resistance is still reduced after the negative side relay has been opened.

4. A fuel cell system comprising:
a fuel cell stack;
a diode that prevents backflow of current to a positive electrode of the fuel cell stack;
a switching element disposed between the fuel cell stack and the diode and having a function of switching a conductive state between wiring connected to a negative electrode of the fuel cell stack and wiring connected to the positive electrode of the fuel cell stack;
a relay circuit disposed between the fuel cell stack and the switching element, the relay circuit including a positive side relay corresponding to the positive electrode of the fuel cell stack, and a negative side relay corresponding to the negative electrode of the fuel cell stack;
a power leakage detector configured to output a power leakage detection signal to be input to the fuel cell stack via the negative side relay, and detect reduction of insulation resistance; and
a controller programmed to control opening/closing of the positive side relay, control opening/closing of the negative side relay, control the switching element, and acquire a detection result from the power leakage detector,
wherein the controller is further programmed to execute isolation processing by opening the positive side relay, opening the negative side relay, and by putting the switching element in an isolated state when the reduction of the insulation resistance is detected in a state where the positive side relay and the negative side relay are closed, to execute conduction control by putting the switching element in a conductive state while maintaining a state where the positive side relay and the negative side relay are open when the insulation resistance has returned to a normal value as a result of the isolation processing, and to identify that power leakage is occurring in an area between the positive side relay and the diode when the reduction of the insulation resistance occurs as a result of the conduction control by putting the switching element in the conductive state.

5. The fuel cell system in accordance with claim 4 ,
wherein the controller is further programmed to identify the power leakage is occurring in an area of the fuel cell stack when the insulation resistance is at a normal value after the conduction control.

6. The fuel cell system in accordance with claim 4 ,
wherein the controller is further programmed to identify the power leakage is occurring in an area other than the area between the positive side relay and the diode or an area other than an area of the fuel cell stack when the insulation resistance is still reduced after the isolation processing.

7. The fuel cell system in accordance with claim 1 further comprising:
a high voltage auxiliary machine; and
a circuit capable of electrically isolating the high voltage auxiliary machine from the fuel cell stack, wherein
the controller is further programmed to control the circuit to electrically isolate the high voltage auxiliary machine from the power leakage detector, before executing the isolation processing, and to identify the power leakage is occurring in an area of the high voltage auxiliary machine when the insulation resistance has returned to the normal value as a result of isolating the high voltage auxiliary machine.

8. The fuel cell system in accordance with claim 1 ,
wherein the controller is programmed to execute the isolation processing when the fuel cell system transitions to a stopped state.

9. The fuel cell system in accordance with claim 4 further comprising:
a high voltage auxiliary machine; and
a circuit capable of electrically isolating the high voltage auxiliary machine from the fuel cell stack, wherein
the controller is further programmed to control the circuit to electrically isolate the high voltage auxiliary machine from the power leakage detector, before executing the isolation processing, and to identify the power leakage is occurring in an area of the high voltage auxiliary machine when the insulation resistance has returned to the normal value as a result of isolating the high voltage auxiliary machine.

10. The fuel cell system in accordance with claim 4 ,
wherein the controller is programmed to execute the isolation processing when the fuel cell system transitions to a stopped state.

Assignees

• Toyota Motor Co Ltd

Inventors

• Saito Hiromu
• Toriumi Keiichi

Classifications

• H01M2250/20

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

• H01M8/04619 Primary

  of fuel cell stacks · CPC title

• H01M8/04559

  of fuel cell stacks · CPC title

• H01M8/04679

  of fuel cell stacks · CPC title

• Y02E60/50

  Fuel cells · CPC title