Fuel Cell Electric Vehicles (FCEVs), sometimes referred to as hydrogen cars, represent a fascinating approach to electric mobility. Like all-electric vehicles, FCEVs harness the power of electricity to drive an electric motor. However, instead of solely relying on a battery charged from the grid, FCEVs generate their own electricity onboard through a fuel cell. This fuel cell is powered by hydrogen, setting them apart from battery electric vehicles (BEVs).
In designing these vehicles, manufacturers determine the necessary power output by selecting the size of the electric motor, which is then paired with a fuel cell and battery system of appropriate capacity. While it’s technically possible to equip an FCEV with plug-in capabilities for battery charging, the current generation of FCEVs primarily utilizes the battery for energy recuperation during braking, providing supplemental power for quick acceleration, and managing power delivery from the fuel cell. The battery smooths out power fluctuations and allows the fuel cell to idle or shut down during periods of low power demand. The vehicle’s energy storage capacity is determined by the size of the hydrogen fuel tank. This contrasts with all-electric vehicles, where both power and energy capacity are directly linked to battery size. To delve deeper into the workings of fuel cell electric vehicles, explore this resource.
Key Components of a Hydrogen Fuel Cell Electric Car Explained
To understand how hydrogen fuel cell cars operate, it’s essential to know the function of their main components:
Auxiliary Battery: Similar to conventional gasoline cars, FCEVs include a low-voltage auxiliary battery. This battery provides the initial power to start the vehicle’s systems before the high-voltage traction battery engages and also powers the car’s accessories.
Battery Pack: The high-voltage battery pack is crucial for energy storage in an FCEV. It stores electricity captured through regenerative braking, converting kinetic energy back into electrical energy when the vehicle decelerates. This stored energy also supplements the fuel cell by providing extra power to the electric traction motor when needed, particularly during acceleration.
DC/DC Converter: This component plays a vital role in managing electrical power within the FCEV. The DC/DC converter steps down the high-voltage DC power from the traction battery pack to a lower voltage. This lower voltage DC power is required to operate the vehicle’s various accessories and to recharge the auxiliary battery.
Electric Traction Motor (FCEV): The electric traction motor is what propels the FCEV. It draws power from both the fuel cell and the traction battery pack to drive the vehicle’s wheels. Some advanced designs integrate motor generators that combine both driving and energy regeneration functionalities into a single unit.
Fuel Cell Stack: At the heart of an FCEV is the fuel cell stack. This assembly comprises multiple individual membrane electrode assemblies (MEAs). Within these MEAs, a chemical reaction occurs where hydrogen from the fuel tank and oxygen from the air combine to produce electricity. This electrochemical process is clean, with water and heat as the primary byproducts.
Fuel Filler: Refueling an FCEV is similar to refueling a gasoline car. A nozzle from a hydrogen fuel dispenser connects to the vehicle’s receptacle to fill the hydrogen fuel tank with pressurized hydrogen gas.
Fuel Tank (Hydrogen): This high-pressure tank is designed to safely store hydrogen gas onboard the vehicle. It holds the hydrogen fuel until it is required by the fuel cell to generate electricity. The size of the tank dictates the vehicle’s driving range.
Power Electronics Controller (FCEV): This sophisticated unit acts as the brain of the FCEV’s powertrain. The power electronics controller manages the flow of electrical energy from both the fuel cell and the traction battery. It precisely controls the speed of the electric traction motor and the torque it delivers, optimizing performance and efficiency.
Thermal System (Cooling) – (FCEV): Maintaining the correct operating temperature is critical for the efficiency and longevity of an FCEV’s components. The thermal management system, or cooling system, ensures that the fuel cell stack, electric motor, power electronics, and other components operate within their optimal temperature ranges.
Transmission (Electric): The transmission in an FCEV transfers the mechanical power generated by the electric traction motor to the vehicle’s wheels, enabling it to move. Electric vehicle transmissions are typically simpler than those in gasoline cars, often being single-speed transmissions due to the electric motor’s broad torque curve.
