Working Principle and Development Trend
of Fuel Cell Electric Vehicles
I. Introduction to hydrogen fuel cell vehicles
FCEV uses electricity to power the motor. Compared with other electric vehicles, FCEV uses hydrogen fuel cells to generate electricity instead of drawing electricity only from batteries. During the vehicle design process, vehicle manufacturers define the power of the vehicle by the size of the motor, which receives power from appropriately sized fuel cells and battery packs. Although automakers can design a FCEV with plug-in functionality to charge the battery, most FCEVs today use batteries to recover braking energy, provide additional power during short acceleration events, and smooth the power provided by the fuel cell by selecting idle or shutting down the fuel cell during low power demand. FCEV uses pure hydrogen stored in the vehicle's fuel tank as fuel. Similar to traditional internal combustion engines, they can be refueled in less than 4 minutes and have a range of more than 500km. FCEV does not produce harmful tailpipe emissions, only water vapor and hot air. Figure 1 shows the main components of a hydrogen fuel cell electric vehicle.
(1) Auxiliary battery: In electric vehicles, the low-voltage auxiliary battery provides power to start the vehicle before the drive battery is engaged; it also provides power for vehicle accessories.
(2) Battery pack: This high-voltage battery stores energy generated by regenerative braking and provides supplemental power to the electric drive motor.
(3) Direct current/direct current (DC/DC) converter: This device converts the high-voltage DC power from the power battery pack into the low-voltage DC power required to operate vehicle accessories and charge auxiliary batteries.
(4) Electric drive motor: This motor uses the power from the fuel cell and the power battery pack to drive the wheels. Some vehicles use an integrated motor-generator that performs both drive and regeneration functions.
(5) Fuel cell stack: A component that uses hydrogen and oxygen to generate electricity.
(6) Fuel filler: A nozzle on the fuel dispenser connects to a receptacle on the vehicle through the filler port to refuel the vehicle.
(7) Fuel tank (hydrogen): Hydrogen is stored on board the vehicle.
(8) FCEV power electronics controller: This device manages the power delivered by the fuel cell and power battery, controlling the speed of the drive motor and the torque it produces.
(9) Thermal management system (cooling): This system maintains the proper operating temperature range for the fuel cell, motor, power electronics, and other components.
(10) Transmission: The transmission transfers the mechanical power of the electric drive motor to the wheels.
