When a voltage measurement value of a first voltage sensor that measures voltage at a direct current end of an inverter exceeds an overvoltage threshold value, and a battery is non-chargeable, a controller of a fuel cell electric vehicle is configured to drive an electric power consumption device until the voltage measurement value falls below the overvoltage threshold value. When the voltage measurement value exceeds the overvoltage threshold value and the battery can be charged, the controller is configured to cause the fuel cell electric vehicle to continue traveling, while estimating the voltage at the direct current end using a second voltage sensor that measures output voltage of a fuel cell stack or a third voltage sensor that measures output voltage of the battery.

When a voltage measurement value of a first voltage sensor that measures voltage at a direct current end of an inverter exceeds an overvoltage threshold value, and a battery is non-chargeable, a controller of a fuel cell electric vehicle is configured to drive an electric power consumption device until the voltage measurement value falls below the overvoltage threshold value. When the voltage measurement value exceeds the overvoltage threshold value and the battery can be charged, the controller is configured to cause the fuel cell electric vehicle to continue traveling, while estimating the voltage at the direct current end using a second voltage sensor that measures output voltage of a fuel cell stack or a third voltage sensor that measures output voltage of the battery.

A method for discharging a vehicle high-voltage electrical system, which is galvanically isolated from a ground potential, in the presence of a residual current makes provision for the following step: determining whether a residual current flows between a first HV potential of the vehicle high-voltage electrical system and the ground potential or a residual current flows between a second HV potential of the vehicle high-voltage electrical system and the ground potential. The method furthermore makes provision to discharge only that Cy capacitance which exists between the ground potential and that HV potential from which or to which the residual current flows. The discharging is triggered by determining the existence of a residual current. Furthermore, an on-board vehicle electrical system and an insulation monitoring device which are designed for performing the method are described. In addition, a corresponding charging-station high-voltage electrical system is described.

A method for discharging a vehicle high-voltage electrical system, which is galvanically isolated from a ground potential, in the presence of a residual current makes provision for the following step: determining whether a residual current flows between a first HV potential of the vehicle high-voltage electrical system and the ground potential or a residual current flows between a second HV potential of the vehicle high-voltage electrical system and the ground potential. The method furthermore makes provision to discharge only that Cy capacitance which exists between the ground potential and that HV potential from which or to which the residual current flows. The discharging is triggered by determining the existence of a residual current. Furthermore, an on-board vehicle electrical system and an insulation monitoring device which are designed for performing the method are described. In addition, a corresponding charging-station high-voltage electrical system is described.

An apparatus for splitting the power of fuel cell systems in a vehicle comprises: a first fuel cell system and at least one further fuel cell system, which are configured to convert hydrogen and oxygen into water in order to generate electrical energy therefrom, and a controller unit, which is configured to actuate the first fuel cell system and the further fuel cell system with an electrical signal. The apparatus is configured to actuate the first fuel cell system and the further fuel cell system with the electrical signal in time offset fashion.

An apparatus for splitting the power of fuel cell systems in a vehicle comprises: a first fuel cell system and at least one further fuel cell system, which are configured to convert hydrogen and oxygen into water in order to generate electrical energy therefrom, and a controller unit, which is configured to actuate the first fuel cell system and the further fuel cell system with an electrical signal. The apparatus is configured to actuate the first fuel cell system and the further fuel cell system with the electrical signal in time offset fashion.

A method of controlling an air compressor motor for a fuel cell vehicle is provide. The method includes calculating a counter electromotive force constant of the air compressor motor based on a voltage and a current of the air compressor motor for the fuel cell vehicle supplying air to a fuel cell stack and a rotation speed of the air compressor motor. The method additionally includes determining whether a permanent magnet of the air compressor motor is demagnetized based on a result of comparison between the calculated counter electromotive force constant value and a pre-set counter electromotive force constant design value.

A method of controlling an air compressor motor for a fuel cell vehicle is provide. The method includes calculating a counter electromotive force constant of the air compressor motor based on a voltage and a current of the air compressor motor for the fuel cell vehicle supplying air to a fuel cell stack and a rotation speed of the air compressor motor. The method additionally includes determining whether a permanent magnet of the air compressor motor is demagnetized based on a result of comparison between the calculated counter electromotive force constant value and a pre-set counter electromotive force constant design value.

A method and system of controlling hydrogen purge are provided. The method includes estimating an air supply rate supplied to a fuel cell stack and then executing hydrogen purge based on the estimated air supply rate.

A method and system of controlling hydrogen purge are provided. The method includes estimating an air supply rate supplied to a fuel cell stack and then executing hydrogen purge based on the estimated air supply rate.