Hybrid electric vehicles are generally classified according to the form of power transmission, which can be divided into series type, parallel type and hybrid type. Series hybrid electric vehicle is a method of driving the vehicle with electric motor by converting engine power into electricity. The power is transmitted from the engine to the drive motor through the serial transmission of generator and battery. The volt of Chevrolet and the extended range version of BMW I3 are series hybrid vehicles.
The main disadvantage is that the energy is converted several times and the efficiency of the mechanical system is relatively low. Parallel hybrid electric vehicle is a “parallel mode” in which the engine is the main power source and the motor is the auxiliary power. The power is transmitted to the drive shaft from the route starting from the engine and the route starting from the battery.
German Audi duoiii, American Ford, Daimler Chris, Honda Civic, BYD Qin, Chang’an Jiexun, Chery A5 BSG and others belong to parallel hybrid vehicles. Although the parallel structure composed of engine and motor in the system can provide power for the vehicle at the same time and improve the power performance. But the most obvious disadvantage is that the parallel structure can not realize the hybrid mode. The engine has the function of charging the power battery. When the power is exhausted, the vehicle can only be driven by the engine.
The hybrid electric vehicle has the advantage of integrating series and parallel connection. It transmits the engine driving force through the way of mechanical power and electric transmission at the same time, realizes the most effective combination of the two, effectively improves the transmission efficiency of the transmission system and improves the fuel economy. Japanese Toyota Prius, American general hybrid system, eq7200he hybrid car developed by domestic Dongfeng Electric Vehicle Co., Ltd. and FAW Pentium B70 all belong to hybrid hybrid vehicles.