A fuel cell system FCS includes a fuel cell 10, a high voltage circuit 21 for driving an electromotor 42, and a relay 41 for electrically connecting or blocking the fuel cell 10 to or from the high voltage circuit 21. A control unit 50 obtains insulation decrease information in accordance with a request for starting the fuel cell, and performs, when a specified insulation decrease occurred region is not a fuel cell region SE1 including the fuel cell and the cooling circuit, conductivity reduction process on cooling liquid using a conductivity reduction unit 113 before having a relay 41 connect, and has the relay 41 connect after completing the conductivity reduction process.

A fuel cell assembly according to an exemplary aspect of the present disclosure includes, among other things, a first fuel cell stack in series with a variable resistor and a second fuel cell stack in parallel with the first fuel cell stack and in series with a contactor. A resistance level of the variable resistor is adjusted in response to deactivating the contactor. A method of regulating a fuel cell assembly is also disclosed.

The disclosure relates to an isolation and voltage regulation circuit for an electrochemical power source, the circuit comprising: an input terminal (202) for coupling to the power source and receiving an input voltage (Vin) from the power source; an output terminal (204) for coupling to a load; a diode circuit (206) connected between the input terminal and the output terminal; a diode controller (208) configured to control electrical conduction through the diode circuit between the input terminal and the output terminal, the diode controller having a first controller input (210) coupled to the output terminal and a second controller input (212); and a reference controller (220) configured to set a voltage at the second controller input (212) in accordance with a comparison between the input voltage (Vin) and a reference voltage (Vref).

A plurality of high voltage unit controllers each includes: a monitoring unit that monitors the hard shutdown signal sent through the dedicated wire lines; and a shutdown unit that, based on a monitoring result of the monitoring unit, stops operation of the high voltage unit that is under control of this high voltage unit controller, and further stops at least part of control functions of this high voltage unit controller.

A fuel cell system of the present disclosure performs a first and a second catalyst activation process, and the first catalyst activation process is performed where a flow rate of the air supplied to the fuel cell by the air compressor is reduced to be less than that before the refresh control is performed while keeping an amount of a current drawn from the fuel cell by the fuel cell converter at the same value as that before the refresh control is performed, and the second catalyst activation process is performed where the value of the current drawn from the fuel cell by the fuel cell converter is increased to be greater than that before the refresh control is performed while keeping the flow rate of the air supplied to the fuel cell by the air compressor at the same value as that before the refresh control is performed.

A fuel cell system and a method of controlling the system are provided. The fuel cell system includes: a fuel cell having a plurality of cells to generate power through a reaction between hydrogen supplied to an anode space and oxygen supplied to a cathode space; a power storage device to be charged with power generated by the fuel cell or discharged to supply power; and a controller. The controller recirculates hydrogen, diffused from the anode space to the cathode space, into the anode space by supplying power charged in the power storage device to the fuel cell when the power generation of the fuel cell is stopped. The controller is configured to control whether to supply the power to the fuel cell based on a pressure measured in the anode space and voltages of the cells that constitute the fuel cell.

The present disclosure provides a fuel cell system comprising a hot box, an air tube, an electrical heater and a thermal sensor. The hot box may comprise a fuel cell stack having a plurality of fuel cell units joined together. Each fuel cell unit of the fuel cell stack unit has an anode, a cathode and an electrolyte sandwiched between the anode and cathode. An air tube having an upper end and lower end is configured to receive ambient air at a second inlet. The electrical heater is integrated within the air tube and configured to heat the fuel cell stack by introducing hot air at a cathode side of a plurality of fuel cell units. Further, the fuel system is configured to operate in different modes comprising a startup mode, a normal mode, a dump load mode and hot standby mode with the use of the integrated electrical heater.

A fuel cell including at least one sealing gasket (10), said sealing gasket (10) comprising a main body (12) and a heater member (14) having a heater element (16) and a power supply portion (18), the heater element (16) being embedded in the main body (12) and the power supply portion (18) being accessible from outside the main body (12).

A fuel cell assembly according to an exemplary aspect of the present disclosure includes, among other things, a first fuel cell stack in series with a variable resistor and a second fuel cell stack in parallel with the first fuel cell stack and in series with a contactor. A resistance level of the variable resistor is adjusted in response to deactivating the contactor.

Disclosed is a method for controlling a pressure regulating valve (6) for regulating the internal pressure (P.sub.int) of a fluid circuit (3) in an electrochemical device (2), said fluid circuit (3) being fed by a compressor (4) drawing air at an external pressure (P.sub.ext) and compressing same at the internal pressure (P.sub.int) according to a compression ratio (A); said method comprises a step of measuring the external pressure (P.sub.ext), determining an internal pressure set point (P.sub.int*) on the basis of the external pressure (P.sub.ext) measured and the compression range (B), so as to promote overall efficiency (R1) of the electrochemical device (2) and the compressor (4) according to the internal pressure (P.sub.int) and the compression ratio (A), and a step of controlling the pressure regulating valve (6) so as to reach the internal pressure set point (P.sub.int*).