A startup control method for a fuel cell is provided. The method includes calculating available power of a high-voltage battery when a startup of the fuel cell is requested. An air compressor is then driven based on a calculated magnitude of the available power of the high-voltage battery and a low-voltage battery is charged with the power of the high-voltage battery after the driving of the air compressor is completed.

A fuel cell system includes: a fuel cell; a fuel cell step-up converter having an input terminal, wherein the input terminal is connected to the fuel cell; a secondary cell; a secondary cell step-up converter having an input terminal an output terminal, wherein the input terminal is connected to the secondary cell. wherein the output terminal is connected to an output terminal of the fuel cell step-up converter; and a control device configured to control at least the fuel cell step-up converter and the secondary cell step-up converter to control the fuel cell system, wherein, the control device executes interruption control when the control device executes continuity control and an output of the fuel cell system is requested to be greater than an output of the secondary cell in the continuity control, wherein the continuity control is a control to control the secondary cell step-up converter to output an input voltage from the secondary cell without stepping up the input voltage, wherein the interruption control is a control to interrupt an electrical connection between the fuel cell system and the secondary cell.

A motor driving control method for controlling a motor speed so that a speed measured value of a motor follows a speed command value is provided. The method includes driving the motor by repeating an on section where a torque is generated in the motor and an off section where a torque is not generated in the motor at a regular period, based on the speed command value, wherein the driving includes applying a phase voltage to only one of multiple phases of the motor in the on section by a pulse width modulation scheme.

When controlling the power generation state of a fuel cell stack based on a generated current command value, a control device sets the generated current command value based on a generated power command value and a generated voltage acquired by a voltage sensor such that the following expression is satisfied, regardless of whether a bleed valve is opened or closed: generated current command value=generated power command value/generated voltage.

Disclosed are a device and a method for controlling a fuel cell system, in which during operation of the fuel cell system, the device and method determine a minimum motoring current limit value applied to a motor for driving a fuel cell vehicle by varying an output current limit threshold value of the fuel cell stack by determining an available output current of the stack and by varying an available voltage lower limit threshold value of the stack by determining an available operating voltage of the stack, thereby preventing the fuel cell vehicle from rattling due to excessive limitation of output current of the stack. They also control the pressures of an anode and a cathode of the stack by monitoring whether the performance of the stack is degraded as limitation of output current of the stack is suppressed, thereby suppressing degradation of the performance of the stack.

A fuel cell system includes a first converter to convert power, which is output from a fuel cell stack or a battery, into power in a specific level, a second converter to convert power which is input to or output from the battery, a power relay assembly to control power flow between a super capacitor and the first converter, and a controller to control outputs of the first converter and the second converter, depending on a starting state or an operating state of the fuel cell system, and to control an operation of the power relay assembly.

An alarm system for detecting a gas leakage from a vehicle is provided. The alarm system includes a control unit and one or more gas leakage sensors configured to be temporarily arranged on or at the vehicle. The control unit is arranged to obtain information indicating locations of the one or more gas leakage sensors while temporarily arranged on or at the vehicle. The control unit is also arranged to identify, upon generate a warning alert signal in the alarm system, the location of a gas leakage sensor based on the obtained information as the gas leakage sensor detects a gas leakage.

Systems and methods for monitoring the isolation resistance of one or more fuel cells are described herein. In one example, a system includes a current transformer having a hollow core. First and second portions of a load line from a fuel cell are located within the hollow core. The first portion of the load line is electrically between an anode of a fuel cell and an electrical load, while the second portion of the load line being electrically between a cathode of the fuel cell and the electrical load. The current transformer is configured to output an electrical signal proportional to a current passing through the hollow core. This electrical signal can then be used to determine the isolation resistance of the fuel cell.

A fuel cell system includes: an external load connected to a fuel cell; an electric power adjusting unit configured to adjust a generated electric power of the fuel cell in accordance with electric power consumption of the external load; a humidity control unit configured to control humidity of an electrolyte membrane in the fuel cell on the basis of the generated electric power of the fuel cell; an output voltage detecting unit configured to detect an output voltage of the fuel cell; and a cross leakage determining unit configured to cause the humidity control unit to increase the humidity of the electrolyte membrane when the fuel cell generates the electric power, the cross leakage determining unit being configured to determine whether a cross leakage amount increases or not on the basis of a change in the output voltage at that time.

A fuel cell system includes a fuel cell unit configured to generate an amount of electrical power for supply to a varying electrical load and a fuel cell controller configured to receive a first indication that the varying electrical load is at a local maximum within a predetermined period, and, in response, operate the fuel cell unit with an operational parameter having a first value such that the fuel cell unit produces a limited maximum amount of electrical power that is a predetermined percentage of a maximum rated power output of the fuel cell unit. The fuel cell controller is also configured to receive an indication that the varying electrical load has reduced, and, in response, operate the fuel cell unit with the operational parameter having a second value such that the fuel cell unit produces an amount of electrical power below the limited maximum amount of electrical power.