Fuel Cell System

Patent metadata

Field	Value
Publication number	US-10654376-B2
Application number	US-201816224090-A
Country	US
Kind code	B2
Filing date	Dec 18, 2018
Priority date	Dec 26, 2017
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

A fuel cell system includes: a converter that boosts a voltage input from a fuel cell; a voltage control device that can control a voltage input from an electricity storage unit; a drive circuit that converts direct-current electricity input from the converter and the voltage control device into alternating-current electricity and outputs the converted electricity to the load; a relay that switches between a connected state in which the fuel cell and the drive circuit are connected to each other and a disconnected state in which they are disconnected from each other; and a controller that determines whether the relay is welded by different determination methods using an index current value between the relay and the fuel cell and a first index voltage value between the relay and the converter when the fuel cell system is to be stopped.

First claim

What is claimed is:

1. A fuel cell system comprising:
a fuel cell;
a converter that boosts a voltage input from the fuel cell and outputs the boosted voltage;
an electricity storage unit configured to store electricity;
a voltage control device that is connected to a line on an output side of the converter and configured to be able to control a voltage input from the electricity storage unit and supply the voltage input from the electricity storage unit to the line;
a drive circuit that is connected to the line and drives a load;
a relay that is disposed between the converter and a position at which the voltage control device is connected to the line, and switches between a connected state in which the fuel cell and the drive circuit are electrically connected to each other and a disconnected state in which the fuel cell and the drive circuit are electrically disconnected from each other;
an index current acquisition unit configured to acquire an index current value between the relay and the fuel cell;
a first index voltage acquisition unit configured to acquire a first index voltage value between the relay and the converter; and
a controller,
wherein the controller is configured to:
when the fuel cell system is to be stopped, make an initial current determination of determining whether the relay is welded, by creating a state where electricity is not supplied from the voltage control device and disconnecting the relay, and then comparing a first set value and the index current value that is acquired after transmitting a signal to the drive circuit to cause the load to discharge electricity;
when the initial current determination finds that the index current value does not exceed the first set value, determine that the relay is not welded;
when the initial current determination finds that the index current value is equal to or larger than the first set value, deem it indeterminable that the relay is not welded, and make a re-determination by creating a state where electricity is supplied from the voltage control device and connecting the relay to shift a high voltage-side voltage between the voltage control device and the drive circuit to a first state of having been boosted to a first voltage, and then disconnecting the relay while maintaining the state where electricity is supplied from the voltage control device to shift the high voltage-side voltage to a second state of having been stepped down to a second voltage lower than the first voltage, and then comparing a second set value and a first difference that is a difference between the first index voltage value in the first state and the first index voltage value in the second state; and
when the re-determination finds that the first difference is equal to or larger than the second set value, determine that the relay is welded.

2. The fuel cell system according to claim 1 , further comprising a second index voltage acquisition unit configured to acquire a second index voltage value between the fuel cell and the converter,
wherein the controller is configured to:
when the fuel cell system is to be stopped, make a comparative determination of comparing the second index voltage value and a third set value at a timing of after creating a state where electricity is not supplied from the voltage control device and disconnecting the relay and before making the initial current determination;
when the comparative determination finds that the second index voltage value is equal to or larger than the third set value, make the initial current determination;
when the comparative determination finds that the second index voltage value does not exceed the third set value, make an initial voltage determination of determining whether the relay is welded by comparing a fourth set value and a second difference that is a difference between the first index voltage values before and after electric discharge in response to the signal;
when the initial voltage determination finds that the second difference does not exceed the fourth set value, determine that the relay is not welded; and
when the initial voltage determination finds that the second difference is equal to or larger than the fourth set value, deem it indeterminable that the relay is not welded, and make the re-determination.

3. The fuel cell system according to claim 1 , further comprising a notification unit configured to give a notification that the relay is welded, wherein the controller is configured to cause the notification unit to give the notification that the relay is welded when the controller determines that the relay is welded.

Assignees

• Toyota Motor Co Ltd

Inventors

• Toriumi Keiichi

Classifications

• H01M8/04656

  of auxiliary devices, e.g. batteries, capacitors · CPC title

• B60L2240/549

  Current · CPC title

• H01M8/04597

  of auxiliary devices, e.g. batteries, capacitors · CPC title

• B60Y2400/202

  Fuel cells · CPC title

• H01H47/002

  Monitoring or fail-safe circuits · CPC title