In the series of hybrid vehiclevehicles shown in the Figure \ref{series}, the vehicle is primarily propelled by an electric motor. Hence, it requires a large electric motor to meet the maximum power requirements of the vehicle. ICE acts as a range extender for a purely electric vehicle. ICE and the generator can together can either power the motor, or charge the battery through an inverter. Regenerative braking is achieved when the motor acts as a generator to charge the battery. Thus, the large motor in Seriesthe hybrid series offers an advantage of high regeneration capacity. Since, the ICE does not propel the vehicle directly, it can be operated independentindependently to the power requirements of the vehicle. This allows ICE to be operated in the region of maximum efficiency. This, in turn, reduces emissions and allows downsizing of ICE. The major disadvantage of Seriesthis series configuration is that it required three machines - an engine, an electric motor, and a generator, thereby adding to the cost.