Design methodology of drive train for a series-parallel hybrid electric vehicle (SP-HEV) and its power flow control strategy

Hybrid electric vehicles (HEVs) are emerging as one of the most viable alternative to conventional automobiles. They can improve the fuel economy and pollutant emissions significantly. Furthermore, series-parallel hybrid electric vehicles (SP-HEV) have excellent advantages to other types of HEV. However, HEV drive train design and control are more complex than conventional automobiles. This paper explains a systematic design methodology of the drive train for a SP-HEV and explores the power flow control (PFC) strategy in it. Sizing methodology of power for electric motor, electric generator, electrochemical battery and battery weight and capacity in a SP-HEV are investigated and shown in the paper. Then efficiency optimization of the vehicle via electric generator and electric motor in different operation modes is described and also the power flow control strategy in the proposed SP-HEV is explored in details. Finally a design example is implemented for a given vehicle and desired driving performance.