Development of a highly integrated 3-in-1 electric drive system for electric vehicle propulsion

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With increasing concerns regarding environmental pollution, global warming and energy shortage, electric vehicles (EVs) are considered as clean, sustainable and environmentally friendly transportation tools. Because of the flexible controllability, EVs also make it easier to achieve autonomous drive and therefore are promising in establishing a smart city. The electric drive system (EDS) is one of the key components of an EV, which is required to have a high-power density to facilitate starting up and accelerating, and a high efficiency to extend EV mileage. The future EDS tends to have a highly integrated structure to leave more space for battery installation and further extend EV mileage accordingly. Many automotive companies such as Tesla, BorgWarner, BMW and Nidec are devoting extensive efforts to the development of integrated EDS. However, because of the critical requirement of heat dissipation, the majority of existing EDS is only partially integrated, while the development of highly integrated 3-in-1 EDS with a common enclosure is still in its infancy. The global objective of this research program is to explore enabling technologies for the highly integrated EDS for EV propulsion. The long-term objectives are: a) advance knowledge in the field of system-level design optimization of EDS, b) develop key new knowledge and R&D capability in the thermal management of integrated EDS, c) pioneer technologies enabling the future integrated EDS for distributed direct-drive EVs. More specifically, in the next 5 years, this program will focus on developing a novel highly integrated 3-in-1 EDS, in which the motor, inverter and gearbox are assembled in a common enclosure. To achieve this goal, we will propose a new permanent magnet (PM) motor topology with less field harmonic contents and, consequently, a high torque density. Meanwhile, an innovative system-level design optimization tool will be explored to achieve the best overall system performance of the EDS. Thermal management is the most significant challenge in developing 3-in-1 EDS due to its compact structure, and we intend to investigate a novel hybrid cooling system to both control the overall temperature rise and cool the internal hot spots. Furthermore, this research program will train highly qualified personnel including undergraduate, master's and Ph.D. students. These students will be key drivers of the R&D process for new EDS integrating advances from this research program into industrial innovation and commercial applications. The originality of this research proposal lies in the development of a novel PM motor, an innovative system-level optimization tool, and a new hybrid cooling system. With the accomplishment of these research objectives, this research program will pioneer enabling technologies to develop the next-generation highly integrated 3-in-1 EDS, whose compact structure, high-power density and high efficiency features will lead the revolution of the future EVs.