Toyota Jidosha Kabushiki Kaisha

Denso Corporation

Masahiro Shige

Kota Manabe

Shigetaka Hamada

Nobuyuki Orihashi

Shigeto Kajiwara

Tadaichi Matsumoto

Mikio Kizaki

Hideki Kashiwagi

A fuel cell system capable of measuring AC impedance comprises: power generation stabilizing means for stabilizing power generation in a fuel cell, and impedance measuring means for measuring the AC impedance after power generation in the fuel cell has been stabilized. Since the AC impedance in a low frequency range is measured after power generation in the fuel cell is stabilized, no external disturbance occurs during measurement, and the AC impedance can be measured with a high degree of precision. Thus, a fuel cell system and a measuring method with which AC impedance can be measured with a high degree of precision can be provided.

Fuel cell system and AC impedance measurement method

A fuel cell system according to the present invention is characterized by comprising a measurement unit which measures an impedance of a fuel cell in a predetermined frequency region, and a regulation unit which regulates an amount of a gas to be supplied to the fuel cell based on a measured value of the impedance in the predetermined frequency region. According to such a constitution, the impedance of the fuel cell in the predetermined frequency region (e.g., a low frequency region) is measured, and the amount of the gas (e.g., an amount of an oxidizing gas) to be supplied to the fuel cell is regulated based on this measured value of the impedance. Here, since the impedance of the fuel cell in the predetermined frequency region largely differs with a fuel supply state (see FIG.), the amount of the gas to be supplied to the fuel cell can be regulated based on the measured value of the impedance to realize a highly efficient and stable operation.

Fuel cell system which measures impedance

There is disclosed a fuel cell system in which a poisoned electrode catalyst can be recovered while meeting a demand for an output power. When a controller detects that an electrode catalyst is poisoned, the controller derives a target operation point adequate for recovering a function of the poisoned electrode catalyst to realize shift of an operation point so that the output power is kept constant. Specifically, a fuel cell voltage is controlled using a DC/DC converter, and an amount of an oxidizing gas to be fed from an oxidizing gas supply source is adjusted, thereby controlling a fuel cell current.

Fuel cell system

There is provided a fuel cell system in which a constantly accurate impedance measurement is made possible regardless of a response characteristic of the voltage converting device. A superimposed signal analysis section analyzes an impedance measuring signal after passing through a DC/DC converter to thereby notify a superimposed signal amplitude control section of an analysis result. A superimposed signal amplitude control section controls an amplitude value of the impedance measuring signal generated by a superimposed signal generating section based on the result notified from the superimposed signal analysis section.

Fuel cell system having a control unit for measuring impedance

Fuel cell system with constantly accurate impedance measurement

A fuel cell system according to the present invention is characterized by comprising a fuel cell, measurement means for measuring impedances of the fuel cell in two kinds or more of frequency regions, and first judgment means for judging two or more parameters concerned with an internal state of the fuel cell based on measurement results of the impedances in the respective frequency regions. According to such a constitution, the impedances in the two or more types of frequency regions (a high frequency region, a low frequency region and the like) are measured to judge two or more parameters such as a wet state of an electrolytic film of the fuel cell and a supply state of a fuel gas, which are concerned with the internal state of the fuel cell based on this measurement result. Since such judgment is performed, as compared with the conventional technology, the internal state of the fuel cell can accurately be grasped, and highly efficient and highly robust control of the fuel cell system can be performed.

Control apparatus of an electric vehicle controls a power supply system of the electric vehicle equipped with a first direct current power supply apparatus for supplying direct current power to a traction inverter, and a second direct current power supply apparatus connected in parallel with the first direct current power supply apparatus via a DC/DC converter. This control apparatus is also provided with a relay for cutting off supply of power from the first direct current power supply apparatus to the traction inverter in synchronization with the operation of the self-protection circuit in the event that the self-protection circuit of the traction inverter operates as a result of overcurrents supplied by the first direct current power supply apparatus.

Electric vehicle control apparatus

A DC/DC converter includes a reactor, IGBT devices, a dead time generation unit, and a DC-CPU. The dead time generation unit operates in response to a reference signal for a duty ratio, to output first and second activation signals provided with an inactive period corresponding to a dead time preventing both of the IGBT devices from conducting. The DC-CPU corrects a tentative duty ratio calculated as based on a voltage control value, in accordance with a value of a current flowing through the reactor, to output the reference signal. Preferably the DC-CPU associates the value of the current of the reactor with three states and when the value approaches a value at which a state transitions to a different state, the DC-CPU gradually switches a correction value.

Voltage conversion device and vehicle

The measurement precision of a current detector of the fuel cell in a fuel cell system is improved. Where the fuel cell systemhas not started operation, the vehicleis operating under regenerative operation, the fuel cellis operating under intermittent operation, or operation of the fuel cell systemhas ended, the output terminal voltage of the fuel cellis set to the OCV value of 400V via the DC/DC converterAs a result, even where the status of the fuel cellchanges from operating to stopped, the value of the current flowing over the power supply linescan be immediately and reliably set to 0 A. The control unitthen obtains the current value Ad from the fuel cell current sensor(step S), and determines the offset correction value Ac needed in order to cancel the drift amount (i.e., in order to perform zero-point correction).

Growing community of inventors

Kaizuka, Japan

Masahiro Shige