Evaluation of driving performance and energy efficiency for a novel full hybrid system with dual-motor electric drive and integrated input- and output-split e-CVT

This paper presents a novel full hybrid electric vehicle (HEV) with power split electronic-continuously variable transmission (e-CVT) capable of providing dual-motor drive at purely electric drive and operating under either the input-split or output-split mode at hybrid drive. This powertrain consists of one engine, one motor, and one generator with a specific mechanical link among two planetary gearsets, one controllable clutch, and two one-way clutches. The corresponding kinematic architecture and operating modes are described, and analyzed in view of the characteristics of electric circulation. Then, the driving performance is simulated and compared with that of the baseline system with the original specifications of Toyota Prius. The results show that, with the significant 18% reduction of total power capacity of the motor and generator, the dual-motor electric drive can still satisfy the requirement of driving performance at low speed. The maximum percentage of improvement of driving performance for electric drive, circulation, and boost modes compared with those of the baseline system are 24%, 80%, and 48% respectively. Furthermore, the simulation on driving performance as well as energy efficiency shows that the input-split and output-split modes are preferably operated at low and high end of vehicle speed respectively. Therefore, the integrated input- and output-split e-CVT operation can provide superior performance covering the entire range of driving speed. As a result, the outstanding feature of the proposed system offers promising potential of further development especially for plug-in and sport hybrid application.