Fuel cell system and method for controlling the fuel cell system

Patent metadata

Field	Value
Publication number	US-2019273437-A1
Application number	US-201916284062-A
Country	US
Kind code	A1
Filing date	Feb 25, 2019
Priority date	Mar 5, 2018
Publication date	Sep 5, 2019
Grant date	—

Abstract

The present disclosure is made in order to reduce inaccuracy of current sensors. A fuel cell system 100 comprises a converter 150 configured to convert output voltage of the fuel cell 1, and a current sensor CS 1 including a preliminarily magnetized magnetic core MC 1 and configured to measure current flowing in the converter 150 from the fuel cell 1. A controller 160 comprises, as driving modes of the fuel cell system 100, a first driving mode DM 1 in which a maximum current value IL1max in a target circuit of current measurement by the current sensor CS 1 is lower than a current value for preliminary magnetization of the magnetic core and a second driving mode DM 2 in which the maximum current value IL2max in the target circuit is higher than the maximum current value IL1max in the target circuit in the first driving mode DM 1. When an accumulated temperature value IT of the current sensor CS 1 in the first driving mode DM 1 has exceeded a threshold ITth, the second driving mode DM 2 is executed and subsequently the first driving mode DM 1 is executed.

First claim

What is claimed is:

1 . A fuel cell system comprising:
a fuel cell; a converter configured to convert output voltage of the fuel cell; a current sensor comprising a preliminarily magnetized magnetic core and configured to measure current flowing in the converter from the fuel cell; a temperature sensor configured to measure temperature of the current sensor; and a controller configured to control the fuel cell system, wherein the controller comprises: as driving modes of the fuel cell system, a first driving mode in which a maximum current value in a target circuit of current measurement by the current sensor is lower than a current value for preliminary magnetization of the magnetic core; and a second driving mode in which a maximum current value in the target circuit is higher than the maximum current value in the target circuit in the first driving mode, and wherein when an accumulated temperature value of the current sensor in the first driving mode has exceeded a threshold, the controller executes the second driving mode on a predetermined condition and subsequently the first driving mode.

2 . The fuel cell system according to claim 1 , wherein
the converter comprises a plurality of circuits connected in parallel to each other to form multiple phases, wherein the target circuit connects one of the plurality of circuits forming the multiple phases and the fuel cell, and wherein when compared on a condition that electric power required from the fuel cell is equal, the controller uses one or more circuits from among the plurality of circuits forming the multiple phases to drive the converter in the second driving mode, wherein number of the one or more circuits to be used in the second driving mode is smaller than number of circuits used in the first driving mode and the one or more circuits to be used comprises at least one of the plurality of circuits in which the accumulated temperature value of the current sensor has exceeded the threshold.

3 . The fuel cell system according to claim 2 , wherein
a rest of the plurality of circuits forming the multiple phases except for the circuit connected to the fuel cell via the target circuit also comprise current sensors comprising preliminarily magnetized magnetic cores and configured to measure the current flowing in the circuits from the fuel cell, and wherein the controller is configured to choose at least one of the plurality of circuits that is unfixed as the one or more circuits to be used in the second driving mode when the number of the one or more circuits to be used is smaller than a maximum number of the plurality of circuits forming the multiple phases, and when the accumulated temperature values of two or more of the current sensors have exceeded the threshold and the number of the one or more circuits to be used is smaller than a maximum number, the controller uses the one or more circuits including at least one circuit preferentially chosen from among circuits equipped with the two or more of the current sensors in order of the accumulated temperature value from highest to lowest and uses the at least one of the plurality of circuits in the second driving mode.

4 . The fuel cell system according to claim 1 , wherein
the controller sets output voltage of the converter in the second driving mode higher than output voltage in the first driving mode so as to raise the maximum current value in the target circuit higher than the maximum current value in the target circuit in the first driving mode when compared on a condition that electric power required from the fuel cell is equal.

5 . A method for controlling a fuel cell system,
the fuel cell system comprising: a fuel cell; a converter configured to convert output voltage of the fuel cell; a current sensor comprising a preliminarily magnetized magnetic core and configured to measure current flowing in the converter from the fuel cell; and a temperature sensor configured to measure temperature of the current sensor, the method for controlling the fuel cell system comprising:
(a) executing a first driving mode in which a maximum current value in a target circuit of current measurement by the current sensor is lower than a current value for preliminary magnetization of the magnetic core;
(b) executing a second driving mode in which a maximum current value in the target circuit is higher than the maximum current value in the target circuit in the first driving mode, wherein
when an accumulated temperature value of the current sensor has exceeded a threshold in a step (a), a process of the method is switched to the step (b) on a predetermined condition, and subsequently the process is switched to the step (a).

6 . The method for controlling the fuel cell system according to claim 5 , wherein
the converter comprises a plurality of circuits connected in parallel to each other to form multiple phases, wherein the target circuit connects one of the plurality of circuits forming the multiple phases and the fuel cell, and wherein in the step (b), when compared on a condition that electric power required from the fuel cell is equal, one or more circuits from among the plurality of circuits forming the multiple phases are used to drive the converter, wherein number of the one or more circuits to be used in the step (b) is smaller than number of circuits used in the step (a) and the one or more circuits to be used comprises at least one of the plurality of circuits in which the accumulated temperature value of the current sensor has exceeded the threshold.

7 . The method for controlling the fuel cell system according to claim 6 , wherein
a rest of the plurality of circuits forming the multiple phases except for the circuit connected to the fuel cell via the target circuit also comprise current sensors comprising preliminarily magnetized magnetic cores and configured to measure the current flowing in the circuits from the fuel cell, and wherein in the step (b), at least one of the plurality of circuits that is unfixed is chosen as the one or more circuits to be used when the number of the one or more circuits to be used is smaller than a maximum number of the plurality of circuits forming the multiple phases, and when the accumulated temperature values of two or more of the current sensors have exceeded the threshold and the number of the one or more circuits to be used is smaller than a maximum number in the step (b), the one or more circuits including at least one circuit preferentially chosen from among circuits equipped with the two or more of the current sensors in order of the accumulated temperature value from highest to lowest are used and the at least one of the plurality of circuits is used.

8 . The method for controlling the fuel cell system according to claim 5 , wherein
in the step (b), output voltage of the converter is set higher than output voltage in the first driving mode so as to raise the maximum current value in the target circuit higher than the maximum current value in the target circuit in the step (a) when compared on a condition that electric power required from the fuel cell is equal.

Assignees

• Toyota Motor Co Ltd

Inventors

• Tano Yutaka
• Umehara Takahiro

Classifications

• H01M8/04373

  of auxiliary devices, e.g. reformers, compressors, burners · CPC title

• H01M8/04992

  characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence · CPC title

• H01M2250/20

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

• H01M8/04895

  Current · CPC title

• H01M8/04597

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