Fuel cell system

Abstract

In a fuel cell system including a solid state polymer type fuel cell, the wet state of the electrolyte film of the fuel cell stack is judged according to the irregularities of the AC impedance of thefuel cell stack. For example, when the moisture amount of the electrolyte film is appropriate, the value of the AC impedance is almost constant and has small irregularities. Moreover, when the moisture amount of the electrolyte film is too much, the value of the AC impedance changes greatly. It should be noted that the AC impedance of the fuel cell stack is measured by analyzing the frequency of the high-frequency noise generated from the inverter arranged in the fuel cell system.

Description

technical field [0001] The present invention relates to fuel cell systems. Background technique [0002] In a solid polymer fuel cell using a solid polymer membrane as an electrolyte membrane, it is known that the wet state of the electrolyte membrane affects the output voltage of the fuel cell. In addition, there is known a technique for determining various states of a fuel cell by measuring the AC impedance of the fuel cell. For example, Japanese Patent Laid-Open No. 2003-86220 describes a technique for estimating the water state inside the fuel cell, that is, the wet state of the electrolyte membrane, by measuring the AC impedance (complex impedance) of the fuel cell. In this technique, the AC impedance is measured at a predetermined timing, and the wet state of the electrolyte membrane at the timing is estimated. [0003] However, there are still parameters that have not been paid attention to regarding the relationship between the AC impedance of the fuel cell and the...

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Problems solved by technology

[0003] However, there are still parameters that have not been paid attention to regarding the relationship between the AC impedance of the fuel cell and the wet state of the electrolyte membrane.

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