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

随着人们对环境污染、全球变暖和能源短缺问题的日益关注，电动汽车被认为是清洁、可持续和环保的交通工具。由于灵活的可控性，电动汽车也更容易实现自动驾驶，因此在建立智慧城市方面很有前景。电动驱动系统（EDS）是电动汽车的关键部件之一，它要求具有高功率密度以方便启动和加速，并要求具有高效率以延长电动汽车的行驶里程。未来的EDS倾向于采用高度集成化的结构，为电池的安装留出更多空间，从而进一步延长电动汽车的行驶里程。特斯拉、博格华纳、宝马、Nidec等众多汽车公司都在大力开发集成EDS。然而，由于散热的关键要求，现有的EDS大多数只是部分集成，而具有通用外壳的高集成三合一EDS的开发仍处于起步阶段。该研究项目的全球目标是探索用于电动汽车推进的高度集成EDS的使能技术。长期目标是：a)推进EDS系统级设计优化领域的知识，b)开发集成EDS热管理方面的关键新知识和研发能力，c)开拓技术，使未来分布式直驱电动汽车的集成EDS成为可能。更具体地说，在未来5年，该项目将重点开发一种新型的高度集成的三合一EDS，其中电机，逆变器和变速箱组装在一个共同的外壳中。为了实现这一目标，我们将提出一种新的永磁（PM）电机拓扑结构，其磁场谐波含量较少，因此具有高转矩密度。同时，将探索一种创新的系统级设计优化工具，以实现EDS的最佳整体系统性能。由于其紧凑的结构，热管理是开发三合一EDS的最大挑战，我们打算研究一种新的混合冷却系统，既可以控制整体温升，又可以冷却内部热点。此外，该研究项目将培养包括本科生、硕士和博士在内的高素质人才。这些学生将成为新型EDS研发过程的关键驱动力，将该研究项目的进展整合到工业创新和商业应用中。本研究计划的独创性在于开发一种新型永磁电机，一种创新的系统级优化工具和一种新的混合冷却系统。随着这些研究目标的实现，该研究项目将率先开发下一代高度集成的三合一EDS，其紧凑的结构，高功率密度和高效率的特点将引领未来电动汽车的革命。

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.