Electric Vehicle Powertrains

A battery-electric vehicle (BEV) is propelled exclusively by electric motor power drawn from an onboard battery and has no internal combustion engine. A hybrid-electric vehicle (HEV) combines an internal combustion engine with an electric motor and battery, so propulsion energy ultimately comes from both fuel and electricity generated or recovered within the vehicle.

Propulsion source and energy flow

• In a BEV, only the electric motor supplies tractive power; its battery is principally recharged from an external electricity source and also receives energy through regenerative braking.
• In an HEV, the engine, electric motor, or both can contribute to propulsion, depending on the powertrain design.
• A conventional HEV usually charges its battery through the internal combustion engine and regenerative braking, rather than through external plug-in charging.

Hybrid powertrain configurations

The defining feature of a hybrid is the presence of both a fuel-based engine and an electrical drive system, although their connection to the wheels varies.

• In a parallel hybrid, the engine and electric motor can both transmit mechanical power to the wheels.
• In a series hybrid, only the electric motor drives the wheels, while the engine generates electricity.
• A plug-in hybrid electric vehicle is externally chargeable but retains an engine, unlike a battery-electric vehicle.

Energy-infrastructure significance

A BEV shifts vehicle energy demand towards electricity and therefore depends on charging infrastructure and the power system. An HEV improves fuel use through electric assistance and energy recovery, but it continues to depend on transport fuel.