An insulation fault response method for a fuel cell vehicle, comprising: when a vehicle starts, detecting whether a fuel cell is in a startup state or not; when the fuel cell is not in the startup state, reading a first insulation resistance detected by a fuel cell control unit and a second insulation resistance detected by a cell management system; when the first insulation resistance indicates that the vehicle is in an insulation fault, executing a first control policy; and when the second insulation resistance indicates that the vehicle in an insulation fault, executing a second control policy, wherein the first control policy is different from the second control policy, and wherein when the first insulation resistance is less than a first threshold and/or the second insulation resistance is less than a second threshold, the vehicle is in an insulation fault.

A control method and system of a fuel cell electric vehicle stack. The control method comprises obtaining insulation resistance of the stack, comprising at least two sub-stacks connected in parallel; and disconnecting a sub-stack with insulation failure from a DC bus and then causing the stack to enter a failure mode when it is determined that the insulation resistance of the stack is smaller than a first preset threshold. The stack is determined to have an insulation failure when it is determined that the insulation resistance of the stack is smaller than the first preset threshold. The sub-stack with the insulation failure is located and disconnected the sub-stack with insulation failure from a DC bus, and the stack is then caused to run in a failure mode to perform failure protection, avoid deterioration of the insulation failure and burnout of the stack and improve the safety performance of the stack.

A supply device for supplying electricity to at least one consumer includes: a primary power supply in which there is a first fuel cell device having a first performance; a voltage transformer which connects the primary power supply to a secondary power supply having a battery; and a measuring device for detecting an insulation resistance of the primary power supply and/or of the secondary power supply. A second fuel cell device having a second performance is connected in series with the first fuel cell device in the primary power supply, wherein a bridge circuit comprising a switch is connected in parallel with each of the fuel cell devices and wherein the switches of the bridge circuits can be switched in accordance with the detected insulation resistance. A fuel cell vehicle and a method for limiting voltage in a supply device are also provided.

A method for determining membrane humidification by determining the membrane protonic resistance of a fuel cell stack at humidified conditions, and normalizing the base resistance of the fuel cell stack against the base resistance of a reference fuel cell stack.

Described are systems and methods for directly monitoring the conductivity of the coolant used to regulate the temperature of a fuel cell. The system includes a coolant loop that acts as a conduit for the coolant, an ion exchanger configured to deionize the coolant, and a conductivity sensor configured to output an electrical signal indicating a conductivity of the coolant. The system also includes a processor in communication with the conductivity sensor and a memory having instructions that, when executed by the processor, cause the processor to determine the conductivity of the coolant based on the electrical signal from the conductivity sensor and determine when the ion exchanger requires servicing based on the conductivity of the coolant.

A system for measuring the insulation resistance of a fuel cell vehicle is provided. The system includes a fuel cell that supplies power, a rechargeable high-voltage battery, and a bidirectional converter, disposed between an output terminal of the fuel cell and the high-voltage battery, to adjust a voltage at the output terminal of the fuel cell. A fast measurement unit measures the insulation resistance of the fuel cell vehicle by being connected to the output terminal of the fuel cell and a second measurement unit measures the insulation resistance of the fuel cell vehicle by being connected to the output terminal of the high-voltage battery. A controller operates the bidirectional converter based on the state of the fuel cell vehicle and measure the insulation resistance of the fuel cell vehicle using the first measurement unit or the second measurement unit

A cooling circuit for a fuel cell includes at least one channel, a mechanical support, a first sensor, and a second sensor. Each channel is formed in a bipolar plate of the fuel cell, and is adapted to permit a cooling fluid to flow. The first sensor senses a flow rate of the cooling fluid. The second sensor senses an electrical conductivity of the cooling fluid. Both the first sensor and the second sensor are installed on the mechanical support.

A direct isopropanol fuel cell adapted for use in ambient conditions and utilizing as fuel isopropanol and water preferably with isopropanol at relatively high concentrations representing 30% to 90% isopropanol.

A method for controlling a fuel cell system including a fuel cell, includes measuring an impedance of the fuel cell that includes a solid polymer electrolyte membrane to generate electric power via an electrochemical reaction between a fuel gas and an oxidant gas. An output electric current output from the fuel cell is increased to a threshold electric current value when the impedance is equal to or higher than a threshold impedance value and a target electric current value is larger than the threshold electric current value. The output electric current is maintained at the threshold electric current value. The output electric current is increased from the threshold electric current value to the target electric current value.

A state determination device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising: an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; and an anode reaction resistance estimation/calculation unit configured to calculate an estimation value of a reaction resistance of an anode electrode of the fuel cell on the basis of a measurement value of the internal impedance, wherein: the predetermined frequency is selected such that a difference between the estimation value of the reaction resistance of the anode electrode during hydrogen starvation and the estimation value of the reaction resistance of the anode electrode during oxygen starvation is not smaller than a predetermined value.