A method for a frost start of a fuel cell device having a fuel cell stack, in which a plurality of fuel cells electrically switched in series is pressed by a compression force of a clamping device between two end plates, comprises determining the presence of frost start conditions, reducing the compression force by means of the clamping, and operating the fuel cells in a frost start operation, in which a compression force acting on the fuel cells of the fuel cell stack and reduced as compared to that of a normal operation is maintained. A fuel cell device as well as a motor vehicle having a fuel cell device with a controller adapted to carry out such a method for a frost start of the fuel cell device are also provided.

A fuel cell system includes: a fuel cell stack; a first cooling medium circuit through which a cooling medium for cooling the fuel cell stack flows; an ion exchanger that removes ions in the cooling medium; a second cooling medium circuit in which the average ion concentration of the cooling medium is lower than that of the cooling medium in the first cooling medium circuit; a switching valve that switches between a flow state and a low flow state; a pump configured to cause the cooling medium in the second cooling medium circuit to flow into the first cooling medium circuit; and a control unit that, when a stop period of the fuel cell system is longer than a reference period, drives the pump with the switching valve switched to the flow state after the instruction to start the fuel cell system is input.

The present invention comprises a method and system for improving the energy efficiency of a vanadium flow battery, VFB. This is achieved by simultaneously reconditioning the VFB through in-situ activation of the electrodes.

A control apparatus for a vehicle plant, which is capable of reducing computational load and a storage capacity in a case where the vehicle plant is controlled using a plurality of periodic function values having a plurality of frequencies different from each other. A control apparatus for a fuel cell device includes a first ECU and a second ECU. The second ECU calculates superposition sine wave value of one of frequencies Z to nZ (Hz) based on a frequency command value by a thinning method using a data group of one set of reference sine wave values, stored in a map. The second ECU executes an AC superposition control using the superposition sine wave value, and calculates impedance of the fuel cell device during execution of the AC superposition control. The first ECU executes fuel cell (FC) humidification control process such that the impedance becomes equal to a target value.

A fuel cell system includes: a fuel cell stack; a first cooling medium circuit through which a cooling medium for cooling the fuel cell stack flows; an ion exchanger that removes ions in the cooling medium; a second cooling medium circuit in which the average ion concentration of the cooling medium is lower than that of the cooling medium in the first cooling medium circuit; a switching valve that switches between a flow state and a low flow state; a pump configured to cause the cooling medium in the second cooling medium circuit to flow into the first cooling medium circuit; and a control unit that, when a stop period of the fuel cell system is longer than a reference period, drives the pump with the switching valve switched to the flow state after the instruction to start the fuel cell system is input.

A method includes selecting a test waveform to inject to a battery from a first DC converter, determining a first resulting ripple that will be generated in response to injecting the test waveform, determining at least one offset waveform to inject to at least one second DC power source from at least one second DC converter such that one or more second ripples will be provided that will cancel the first resulting ripple if the battery is charging, injecting the test waveform to the battery, injecting the at least one offset waveform to the at least one second DC power source, determining if the first resulting ripple has been cancelled, and determining if the battery is charging or discharging based on the step of determining if the first resulting ripple has been cancelled.

A method includes selecting a test waveform to inject to a battery from a first DC converter, determining a first resulting ripple that will be generated in response to injecting the test waveform, determining at least one offset waveform to inject to at least one second DC power source from at least one second DC converter such that one or more second ripples will be provided that will cancel the first resulting ripple if the battery is charging, injecting the test waveform to the battery, injecting the at least one offset waveform to the at least one second DC power source, determining if the first resulting ripple has been cancelled, and determining if the battery is charging or discharging based on the step of determining if the first resulting ripple has been cancelled.

A control apparatus for a vehicle plant, which is capable of reducing computational load and a storage capacity in a case where the vehicle plant is controlled using a plurality of periodic function values having a plurality of frequencies different from each other. A control apparatus for a fuel cell device includes a first ECU and a second ECU. The second ECU calculates a superposition sine wave value of one of frequencies Z to nZ (Hz) based on a frequency command value by a thinning method using a data group of one set of reference sine wave values, stored in a map. The second ECU executes an AC superposition control using the superposition sine wave value, and calculates impedance of the fuel cell device during execution of the AC superposition control. The first ECU executes an FC humidification control process such that the impedance becomes equal to a target value.

A redox flow battery system includes a plurality of branch circuits electrically connecting a plurality of battery cell parts in parallel; a switching unit configured to switch conduction states of a closed loop in which the branch circuits are connected together; a circulation mechanism; a detection unit; a determination unit configured to determine whether or not a voltage difference between the open circuit voltages of the battery cell parts is more than a predetermined value; and a control unit configured to control a switching operation of the switching unit such that, when the determination unit determines the voltage difference to be more than the predetermined value, the closed loop is brought into a non-conducting state and, when the determination unit determines the voltage difference to be equal to or less than the predetermined value, the closed loop is brought into a conducting state.

A fuel cell internal state detection system includes estimation object state quantity setting unit for setting a suitable estimation object state quantity as an index of an internal state, an impedance value acquisition unit configured to obtain an impedance value of a fuel cell, an impedance usability judging unit configured to judge whether or not the obtained impedance value is usable for the calculation of the estimation object state quantity, estimation object state quantity calculation unit for calculating the estimation object state quantity set by the estimation object state quantity setting unit on the basis of the obtained impedance value when the impedance value is judged to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit, and an unusable-scene process execution unit configured to perform an unusable-scene process when the impedance value is judged not to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit.