电动汽车用双转子混合励磁轴向磁通切换电机设计与效率优化控制研究

Considering the requirements for the drive system of electric vehicles such as low speed large torque and wide speed-regulation range with high efficiency, a novel double-rotor hybrid excited axial switched-flux (DR-HEASF) machine with both the permanent magnets and windings in the stator is presented. The proposed machine consists of single stator and double rotors with the disc hybrid excitation structure, which exhibits more advantages including the short axial length, simple and compact structure. Owing to the design of unique magnetic structure and the hybrid excitation in parallel, the speed-regulation range is broadened while keeping the high power and torque density. The fault-tolerant performance of the machine is greatly improved due to the specific structure design. In this project, the theoretical analysis, simulation calculation, and experimental research are implemented to investigate the new topology, design approach, electromagnetic performance analysis, electromagnetic parameters computation, losses and temperature-rise calculation, as well as control method of the DR-HEASF machine. An optimal efficiency control strategy considering the copper and iron loss of the machine is proposed according to the aims of improving the efficiency of machine and broadening the speed-regulation range. The fault-tolerance operation is realized at the different fault condition. The key technique problems such as the optimization design, efficiency optimization on-line, wide speed-regulation range in flux-weakening mode, and fault-tolerance performance of the DR-HEASF machine with stator-excitation will be solved. The operating mechanism of the DR-HEASF machine, such as the high efficient, wide speed-regulation, and fault-tolerance, will be completely revealed. The general method including the design, analysis, and control of the hybrid excited switched-flux machine will be explored. The scientific questions will be put forward, and lay the foundation for the future study and application of the DR-HEASF machine in the drive system of electric vehicles. Therefore, the investigation of this project has important theoretical significance and practical value.

针对电动汽车电驱动系统用电机应具有低速大扭矩和高效宽调速等要求，本项目提出一种新型定子励磁型双转子混合励磁轴向磁通切换电机。该电机采用单定子/双转子盘式混合励磁拓扑，轴向长度短，结构简单、紧凑，并联式混合励磁与独特的磁路结构设计，保持电机高功率/转矩密度的同时有效拓宽调速范围，特殊的容错结构设计提高电机容错性能。采用理论分析、仿真计算和实验研究相结合的方法，对电机新型结构、设计方法、电磁性能分析、电磁参数计算、损耗和温升计算、控制方法等展开研究。提出计及电机铜耗和铁耗的最优效率控制策略，实现不同故障状态下的容错控制，解决定子励磁型混合励磁轴向磁通切换电机优化设计、在线效率优化、宽调速弱磁和容错性能等关键技术问题，揭示电机高效率、宽调速和容错的机理，探求混合励磁磁通切换电机设计、分析和控制的普遍方法，凝练科学问题，为该电机在电动汽车电驱动系统领域的应用奠定基础，具有重要的理论意义和实用价值。

本项目针对电动汽车电驱动系统，研究了新型双转子混合励磁轴向磁通切换永磁电机设计方法与控制技术。从理论分析、仿真计算和实验研究三方面验证了电机设计及其控制方法的正确性。取得了如下成果：(1) 提出了新型合理的具有调磁能力的双转子混合励磁轴向磁通切换永磁电机结构。注入正向励磁电流，电机运行在增磁模式；通入反向励磁电流，电机运行在弱磁模式。建立了该电机的功率尺寸方程，提出了通用设计方法。(2) 基于三维有限元方法，分析了该电机电磁性能，包括磁场分布、气隙磁密、永磁磁链、反电动势、绕组电感、转矩性能和调磁性能，验证了设计方案的正确性。(3) 分析了该电机的齿槽转矩，提出了三种不同的齿槽转矩缩减方法，计算并验证了三种方法对齿槽转矩和调磁性能的影响。(4) 提出了一种虚拟定子磁通定向控制方法，建立了该电机的数学模型，并进行了仿真建模，验证数学模型的正确性和有效性。构建了该电机的矢量控制系统，提出了id=0控制、弱磁控制、铜耗最小控制与效率优化控制等策略，基于MATLAB/Simulink对控制策略进行了仿真分析，验证了所提出的控制策略的正确性。(5) 研制了一台600W实验样机，构建了以半实物仿真器MicroLabBox为核心的系统实验平台，测试了样机的特性。结果表明，在额定转速以下，当励磁电流为6 A时，电磁转矩增大了15%；在额定转速以上，当励磁电流为6 A时，调速范围扩大了10%，相同转速下带负载能力明显强。对比研究了id = 0控制、铜耗最小控制及效率优化控制策略和基于这三种控制策略下电机的转矩转速特性、输出功率及损耗。结果表明：基于效率优化控制策略的电机控制系统具有更强的带载能力、更宽的调速范围、更低的损耗和更高的运行效率、更大的输出功率，验证了所研究的混合励磁控制策略的有效性。