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US 2018/0294494 A1Published application
Fuel cell system
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsChiaki Mizutani, Yuji Ishikawa, Shigeki Hasegawa
Life of this patent
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Abstract
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.
Claims12
A fuel cell system comprising:
- a fuel cell stack configured to include a plurality of cells and to output direct output current;
- a signal superimposing unit configured to superimpose on the output current an alternating current signal whose current value is controlled, the alternating current signal including alternating current components at a first frequency and a second frequency higher than the first frequency;
- a voltage measurement unit configured to measure a voltage value of the output current to which the alternating current signal has been applied;
- a phase difference acquisition unit configured to acquire a phase difference between a phase of the first frequency of the current value in the alternating current signal and a phase of the first frequency of the voltage value measured by the voltage measurement unit;
- a calculation unit configured to calculate an amount of water in at least one of the plurality of cells by using the alternating current signal;
- and
- a use determination unit configured to
- determine not to use a calculation result obtained by the calculation unit when at least a condition of an absolute value of the phase difference being larger than a first absolute value and a condition of the absolute value of the phase difference being smaller than a fourth absolute value is satisfied, and
- determine to use the calculation result obtained by the calculation unit when the absolute value of the phase difference is within a range between a second absolute value smaller than the first absolute value and a third absolute value larger than the fourth absolute value.
6 more elements
A fuel cell system comprising:
- a fuel cell stack configured to include a plurality of cells and to output direct output current;
- a signal superimposing unit configured to superimpose on the output current an alternating current signal whose voltage value is controlled, the alternating current signal including alternating current components at a first frequency and a second frequency higher than the first frequency;
- a current measurement unit configured to measure a current value of the output current to which the alternating current signal has been applied;
- a phase difference acquisition unit configured to acquire a phase difference between a phase of the first frequency of a voltage value in the alternating current signal and a phase of the first frequency of the current value measured by the current measurement unit;
- a calculation unit configured to calculate an amount of water in at least one of the plurality of cells by using the alternating current signal;
- and
- a use determination unit configured to
- determine not to use a calculation result obtained by the calculation unit when at least a condition of an absolute value of the phase difference being larger than a first absolute value and a condition of the absolute value of the phase difference being smaller than a fourth absolute value is satisfied, and
- determine to use the calculation result obtained by the calculation unit when the absolute value of the phase difference is within a range between a second absolute value smaller than the first absolute value and a third absolute value larger than the fourth absolute value.
6 more elements
Dependencies are inferred from the claim text.