Toyota Jidosha Kabushiki Kaisha

Nippon Soken, Inc.

Denso Corporation

Hisamitsu Pharmaceutical Company, Inc.

Yuji Ishikawa

Takashi Yamamoto

Shigeki Hasegawa

Keigo Suematsu

Takashi Yamada

Ikuyasu Kato

Seiji Tokumoto

Yuichi Sakajo

Kazuyoshi Kaminaka

Kazuya Machida

Chiaki Mizutani

Syuya Kawahara

A measurement error of a water content depends on a phase difference of a low frequency. The low frequency is a lower one of two frequencies in an alternating current signal used for calculating an impedance of a cell. The phase difference is a difference between a phase of a current value of an alternating current signal applied to a fuel cell stack and a phase of a voltage value of output current. The calculated value of the water content is not used when the phase difference of the low frequency indicates that the measurement error may largely fluctuate.

Fuel cell system

A fuel cell system includes: a low-frequency superimposition section superimposing a the low-frequency signal on a fuel cell; and an impedance computation section configured to compute low-frequency impedance of the fuel cell at a time when the low-frequency superimposition section superimposes the low-frequency signal on the fuel cell. The fuel cell system includes: a diagnosing section diagnosing a degree of dryness inside the fuel cell on the basis of low-frequency impedance; and an oxidant gas amount adjustment section configured to adjust an amount of oxidant gas in the fuel cell. The diagnosing section is configured to diagnose the degree of dryness inside the fuel cell on the basis of the low-frequency impedance when the oxidant gas amount adjustment section adjusts the amount of the oxidant gas to be equal to or smaller than a reference gas amount.

An AC component &#x394;I addition unit of a diagnostic device superimposes an alternating current on an output current of a fuel cell. A Zn calculation unit calculates a cell impedance with respect to the alternating current with regard to any of a plurality of cells. A diagnosis unit diagnoses that any cell is subjected to hydrogen deficiency when an absolute value of the cell impedance exceeds (absolute value of a reference impedance+a predetermined value &#x3b2;). It is diagnosed that any cell is subjected to oxygen deficiency when the absolute value of the cell impedance is smaller than (absolute value of the reference impedance&#x2212;a predetermined value &#x3b1;).

Diagnostic device

A current measurement device includes a measurement part that is constituted by including a resistance part having a predetermined electric resistance value and a pair of current collector parts for extracting a potential difference generated by a current that flows the resistance part; a potential difference detector that is connected to the pair of current collector parts and detects a potential difference generated in the resistance part; and a current detector that detects the current that flows through the inside of a fuel cell. The measurement part is disposed to be integrated with one separator of the pair of separators and the pair of current collectors is disposed so as to overlap with the resistance part when seen from a direction orthogonal to the stacking direction of the cells.

Current measurement device

In a fuel cell monitoring device, a gas-diffusion resistance calculation section calculates a gas-diffusion resistance Rindicating a difficulty of diffusing reaction gas to a catalyst layer in a fuel cell based on a gas reaction resistance Rcalculated by a resistance calculation section. A second diffusion resistance calculation section calculates a second diffusion resistance Rvarying depending on a dried-up in the fuel cell based on a proton transfer resistance Rcalculated by the resistance calculation section. A first diffusion resistance calculation section calculates a first diffusion resistance Rvarying depending on a flooding in the fuel cell by subtracting the second diffusion resistance Rfrom the gas-diffusion resistance R. A water content calculation section calculates a water content of the fuel cell based on the first diffusion resistance. A recovery control section adjusts the water content in the fuel cell based on the calculated water content.

Fuel cell monitoring device

To improve an output of a fuel cell and power generation efficiency by enhancing drainage of the fuel cell upon actuation below freezing temperature. In a fuel cell system that generates power by supplying fuel gas and oxidant gas, the output of the fuel cell is measured when a temperature of the fuel cell after the actuation below freezing temperature exceeds 0 degree, and if a value of the output is equal to or less than a reference output value, pressure pulsation is applied to a cathode electrode to drain water built up in the fuel cell.

Growing community of inventors

Aichi-ken, Japan

Yuji Ishikawa