Development and Demonstration of a New Range-Extension Hybrid Powertrain Concept 2020-01-0845

A new range-extension hybrid powertrain concept, namely the Tongji Extended-range Hybrid Technology (TJEHT) was developed and demonstrated in this study. This hybrid system is composed of a direct-injection gasoline engine, a traction motor, an Integrated Starter-Generator (ISG) motor, and a transmission. In addition, an electronically controlled clutch between the ISG motor and engine, and an electronically controlled synchronizer between the ISG motor and transmission are also employed in the transmission case. Hence, this system can provide six basic operating modes including the single-motor driving, dual-motor driving, serial driving, parallel driving, engine-only driving and regeneration mode depending on the engagement status of the clutch and synchronizer. Importantly, the unique dual-motor operation mode can improve vehicle acceleration performance and the overall operating efficiency. The hybrid system controls and energy management strategy based on equivalent fuel consumption minimization were developed and validated. The choice of an operating mode is optimized according to the drivers’ demand, actual vehicle state, operation conditions, and other boundary conditions. In this paper, the powertrain architecture and operating modes are firstly described. Secondly, the hybrid control strategy is introduced, which includes the control architecture, energy management strategy, torque structure and coordination, and controls of the engine, clutch, and synchronizer. Thirdly, the development of a prototype vehicle with the use of the TJEHT system is discussed. Based on the simulation analysis, the key specifications of the major components such as the motors’ peak powers and torques are defined. The vehicle performance is compared in the simulations between using the TJEHT system and the one without the dual-motor driving mode to show the advantages of the TJEHT system. Finally, the results of the powertrain dyno experiments and vehicle road tests are reported. The functional requirements and operating modes of the hybrid powertrain were demonstrated and validated.