On the Design of a Novel Series-parallel Hybrid Transmission with a Compound Planetary Gear Train

This paper presents a systematic process to design a novel series-parallel hybrid transmission. Firstly, the general characteristics of a desired hybrid transmission system are concluded based on a study of numerous existing designs of hybrid transmission systems and the characteristics of provided input/output powers. Then, a systematic design procedure, including four main steps, is presented to synthesize a novel hybrid transmission system. The compound planetary gear trains (PGTs) are used to synthesize clutchless hybrid transmission by assigning input/output powers in the second step. Thirdly, clutches are added to control the operation modes of the synthesized systems. And, system parameters are addressed in the fourth step to get the most suitable series-parallel hybrid transmission that satisfies the design specifications. Finally, the designed system is analyzed for transmission efficiencies, kinematics and power flows in each operation mode, and vehicle performances. It is shown that the designed system satisfies all the design requirements and specifications.