Hybrid Vehicle: A hybrid vehicle is one that uses two different methods to propel the vehicle. A hybrid electric vehicle, abbreviated HEV uses both an internal combustion engine and an electric motor to propel the vehicle. Most hybrid vehicles use a high-voltage battery pack and a combination electric motor and generator to help or assist a gasoline engine. The types of hybrid electric vehicles include series, parallel, and series-parallel designs.
Series-Hybrid vehicle
In Series Hybrid vehicles, the Internal Combustion Engine (ICE) drives a generator, which charges the battery and supplies current to the electronically controlled motor. The electric motor propels the car. In this system, Internal Combustion Engine operates at constant speed with maximum efficiency, It causes low exhaust emissions. The vehicle is controlled electronically. The electric control simplifies the mechanical gears and the differential. Both Internal combustion engine and electric drive have to be rated to the maximum power. It has low overall system efficiency.