A hybrid electric vehicle (HEV) powertrain combines an internal combustion engine (ICE) with an electric propulsion system to achieve improved fuel efficiency and reduced emissions. The main components of an HEV powertrain typically include:
Internal Combustion Engine (ICE): The ICE is a traditional gasoline or diesel engine that provides power to the vehicle by burning fuel. It is one of the primary sources of propulsion in the HEV.
Electric Motor(s): HEVs are equipped with one or more electric motors that provide additional power to assist the internal combustion engine during acceleration and other driving conditions. These electric motors can also act as generators during regenerative braking, converting kinetic energy into electrical energy to recharge the battery.
Battery Pack: The battery pack stores electrical energy for use by the electric motor(s) and other auxiliary systems in the vehicle. Typically, HEVs use high-voltage lithium-ion (Li-ion) batteries or other advanced battery technologies to provide power to the electric motors.
Power Electronics: The power electronics system manages the flow of electrical energy between the battery, electric motor(s), and other vehicle systems. It includes components like inverters and converters that convert direct current (DC) to alternating current (AC) and vice versa as needed.
Transmission: The transmission in an HEV can vary depending on the vehicle's configuration. Some HEVs use a traditional automatic transmission, while others may use a continuously variable transmission (CVT) or a dual-clutch transmission to optimize power delivery from the ICE and electric motor(s).
Regenerative Braking System: HEVs employ a regenerative braking system that captures and stores energy generated during braking. When the driver applies the brakes, the electric motor acts as a generator, converting kinetic energy into electrical energy and storing it in the battery.
Hybrid Control Unit (HCU): The hybrid control unit is the brain of the powertrain. It manages the coordination between the internal combustion engine, electric motor(s), battery pack, and power electronics. The HCU ensures that the powertrain operates efficiently and seamlessly transitions between the different power sources based on driving conditions and energy demands.
Engine Control Unit (ECU): The engine control unit is responsible for managing the operation of the internal combustion engine, optimizing fuel efficiency, and controlling emissions.
Accessory Drive: In some HEVs, the accessory drive is powered by the electric motor(s) rather than the engine. This design allows the engine to shut off during idle or low-power conditions, further enhancing fuel efficiency.
The combination of these components allows hybrid electric vehicles to optimize the use of both the internal combustion engine and electric propulsion system, providing better fuel economy and reduced environmental impact compared to conventional gasoline or diesel vehicles.