Apparatus for measuring an impedance of fuel cell and method of measuring an impedance of fuel cell

Patent metadata

Field	Value
Publication number	US-10290885-B2
Application number	US-201415324842-A
Country	US
Kind code	B2
Filing date	Jul 11, 2014
Priority date	Jul 11, 2014
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

An apparatus for measuring an impedance of a fuel cell is configured to: output an AC current to a fuel cell; and adjust an impedance so that an impedance between the fuel cell and a load device becomes higher than an impedance between a secondary battery and the load device at a frequency of the AC current output to the fuel cell. The apparatus is also configured to: adjust the AC current so that a positive-electrode side AC potential difference matches a negative-electrode side AC potential difference; and calculate an impedance of the fuel cell on the basis of the adjusted AC current and at least one AC potential difference of the positive-electrode side AC potential difference and the negative-electrode side AC potential difference.

First claim

The invention claimed is:

1. An apparatus for measuring an impedance of a fuel cell, the apparatus being used for a system that includes a fuel cell, a secondary battery, and a load device connected to the fuel cell and the secondary battery, the apparatus comprising:
an AC power supply unit configured to output an AC current to the fuel cell;
an AC adjusting unit configured to adjust the AC current so that a positive-electrode side AC potential difference matches a negative-electrode side AC potential difference, the positive-electrode side AC potential difference being a difference between an electric potential of the fuel cell on a positive electrode side and a middle electric potential, the negative-electrode side AC potential difference being a difference between an electric potential of the fuel cell on a negative electrode side and the middle electric potential, the middle electric potential being an electric potential at a midpoint between a positive electrode and a negative electrode of the fuel cell;
an impedance calculating unit configured to calculate an impedance of the fuel cell on a basis of the adjusted AC current and at least one AC potential difference of the positive-electrode side AC potential difference and the negative-electrode side AC potential difference; and
an impedance adjusting unit configured to adjust the impedance of the fuel cell so that an impedance obtained by synthesizing an impedance of a route between the fuel cell and the load device and the impedance of the fuel cell becomes higher than an impedance obtained by synthesizing an impedance of a route between the secondary battery and the load device and the impedance of the fuel cell at a frequency of the AC current output from the AC power supply unit.

2. The apparatus for measuring an impedance of a fuel cell according to claim 1 ,
wherein the impedance adjusting unit is constituted from a reactance component arranged between the fuel cell and the load device.

3. The apparatus for measuring an impedance of a fuel cell according to claim 1 ,
wherein the impedance adjusting unit is constituted from a reactor disposed inside a power converter, the power converter being configured to convert an electric power from the fuel cell into a second electric power.

4. The apparatus for measuring an impedance of a fuel cell according to claim 3 ,
wherein a voltage of the power converter on a load device side is higher than a voltage of the power converter on a fuel cell side, and
wherein a semiconductor switch in the power converter is arranged on the load device side with respect to the reactor and is not arranged on the fuel cell side.

5. A method of measuring an impedance of a fuel cell, the method being used for a system that includes a fuel cell, a secondary battery, and a load device connected to the fuel cell and the secondary battery, the method comprising:
outputting an AC current to the fuel cell;
adjusting an impedance of the fuel cell so that an impedance obtained by synthesizing an impedance of a route between the fuel cell and the load device and the impedance of the fuel cell becomes higher than an impedance obtained by synthesizing an impedance of a route between the secondary battery and the load device and the impedance of the fuel cell at a frequency of the AC current output to the fuel cell;
adjusting the AC current so that a positive-electrode side AC potential difference matches a negative-electrode side AC potential difference, the positive-electrode side AC potential difference being a difference between an electric potential of the fuel cell on a positive electrode side and a middle electric potential, the negative-electrode side AC potential difference being a difference between an electric potential of the fuel cell on a negative electrode side and the middle electric potential, the middle electric potential being an electric potential at a midpoint between a positive electrode and a negative electrode of the fuel cell; and
calculating an impedance of the fuel cell on a basis of the adjusted AC current and at least one AC potential difference of the positive-electrode side AC potential difference and the negative-electrode side AC potential difference.

Assignees

• Nissan Motor

Inventors

• Matsumoto Michihiko
• Akashi Kotaro
• Kaneko Yohei
• Sato Masashi

Classifications

• H01M8/04

  Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids · CPC title

• G01R31/40

  Testing power supplies (testing photovoltaic devices H02S50/10) · CPC title

• H01M8/04544 Primary

  Voltage · CPC title

• H01M8/04656

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

• H01M8/04574

  Current · CPC title