what are HEVs?

Hybrid-electric vehicles (HEVs) combine the benefits of gasoline engines and electric motors and can be configured to obtain different objectives, such as improved fuel economy, increased power, or additional auxiliary power for electronic devices and power tools, also known as HEVs or hybrids. Present-day hybrids are equipped with ICEs and electric motors. A hybrid's ICE engine, as in any ICE-powered car, produces power through continuous, controlled explosions that push down pistons connected to a rotating crankshaft. That rotating force (torque) is ultimately transmitted to the vehicle's wheels.

A hybrid's electric motor is energized by a battery, which produces power through a chemical reaction. The battery is continuously recharged by a generator that—like the alternator of a conventional car—is driven by the ICE.

Hybrids can have a parallel design, a series design, or a combination of both:

• In a parallel design, the energy conversion unit and electric propulsion system are connected directly to the vehicle's wheels. The primary engine is used for highway driving; the electric motor provides added power during hill climbs, acceleration, and other periods of high demand.
  
• In a series design, the primary engine is connected to a generator that produces electricity. The electricity charges the batteries, which drive an electric motor that powers the wheels. HEVs can also be built to use the series configuration at low speeds and the parallel configuration for highway driving and acceleration.

Some of the advanced technologies typically used by hybrids include

• Regenerative BrakingThe electric motor applies resistance to the drivetrain causing the wheels to slow down. In return, the energy from the wheels turns the motor, which functions as a generator, converting energy normally wasted during coasting and braking into electricity, which is stored in a battery until needed by the electric motor.
  
• Electric Motor Drive/Assist
  The electric motor provides additional power to assist the engine in accelerating, passing, or hill climbing. This allows a smaller, more efficient engine to be used. In some vehicles, the motor alone provides power for low-speed driving conditions where internal combustion engines are least efficient.
  
• Automatic Start/Shutoff
  Automatically shuts off the engine when the vehicle comes to a stop and restarts it when the accelerator is pressed. This prevents wasted energy from idling.