What is a hybrid-electric bus?
Simply speaking, a hybrid-electric bus is defined as carrying two sources of motive energy, with an electric drive motor to provide partial or complete power to the drive wheels. In most cases the two sources of motive energy will be an electrical energy storage device, such as a battery pack and a fossil fuel power unit, such as a diesel or CNG engine and generator. In a conventional bus, the engine generates mechanical power that is transferred to the wheels through the transmission and differential. In a series hybrid-electric vehicle, this motive power is supplied or assisted by an electric traction motor. The hybrid-electric vehicles tested under this project were series hybrid-electric buses. Series configuration. The series designation means that the engine is only electrically (not mechanically) connected to the drive wheels of the vehicle, and the path of energy from engine to wheels is series in layout (one single energy path). In a parallel hybrid there are two separate ener
