Toyota Jidosha Kabushiki Kaisha

Chiaki Mizutani

Shigeki Hasegawa

Kazuo Yamamoto

Yuji Ishikawa

Ikuyasu Kato

Miho Hatazaki

Provided is a fuel cell system including: a fuel cell; a reactant gas supply section; a converter; an alternating-current superimposing unit; a phase difference deriving unit configured to derive a phase difference that is a phase lag of an alternating-current voltage relative to an alternating current in an alternating-current component output from the fuel cell; and a first inference unit. The first inference unit infers that the fuel cell is in an inappropriate wet state, when the absolute value of an amount of change in the phase difference has become equal to or larger than a predetermined criterion value immediately after the magnitude of a change in the value of at least one of parameters that are a flow rate of a reactant gas, a stoichiometric ratio, and an output current has exceeded a predetermined criterion.

Fuel cell system and method for inferring wet state of fuel cell

A fuel cell monitoring device includes: an impedance measuring part measuring an impedance at each fuel cell and an impedance at a fuel cell stack as a whole; a water content estimating part calculating a water content estimated value at each fuel cell using a gas diffusion resistance obtained from a measurement result about the impedance at each fuel cell, and calculating a water content reference estimated value indicating a water content in each fuel cell using a gas diffusion resistance obtained from a measurement result about the impedance at the fuel cell stack as a whole; and a determining part detecting at least either the occurrence of deterioration of catalyst in the fuel cell or the occurrence of a distribution failure of reactive gas at the fuel cell by determining based on the magnitude of the water content estimated value relative to the water content reference estimated value.

Fuel cell monitoring device and method of determining state of fuel cell

A fuel cell system includes: a fuel cell; a voltage detector; a current detector; an alternating current signal supply unit; a phase difference calculation unit configured to calculate, based on detected alternating voltage and detected alternating current, a phase difference between the detected alternating current and the detected alternating voltage; and an estimation unit configured to estimate, in accordance with the phase difference, an electric power generation distribution feature amount representing an electric power generation distribution in a cell surface of the fuel cell, with use of a predetermined relationship between the electric power generation distribution feature amount and the phase difference. The electric power generation distribution feature amount includes a value indicating a difference between a maximum value and a minimum value of local current density in the cell surface.

Fuel cell system

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.

Growing community of inventors

Nisshin, Japan

Chiaki Mizutani