高转矩密度轴向磁场无刷记忆电机及其控制系统研究

The basic characteristics which are required by in-wheel motor of electric vehicle should include high torque density and wide speed range. The flat structure of an axial-flux permanent magnet (AFPM) machine is especially suitable for the in-wheel motor. However, due to the nearly constant air-gap field produced by magnets, it is difficult to regulate the flux and the speed range is limited. The project proposes a high torque density and flux-weakening axial-flux brushless memory machine (AFBLMM) which combines memory machine principle and AFPM machine structure and makes full use of neodymium iron boron (NdFeB) PM with excellent natural characteristics and aluminum nickel cobalt (AlNiCo) PM with intrinsical low coercivity and high remanence. The project aims to investigate the machine structure characteristics, design theory and the computation method of electromagnetic performances. The field-control physics of AFBLMM will be studied in-depth. PM flux density and field strength, as well as armature magnetic field, will be analyzed under different magnetization currents. Moreover, simulation models of AFBLMM and control system will be established. Some prototypes will be designed and manufactured. The motor drive and control system will be built and implemented according to appropriate control strategy, where the relationship between the flux controllability and the drive performances will be investigated. The project will achieve the goal that the proposed machine can operate over a wide speed range, and at the same time, the shortages of narrow speed range and low efficiency in constant power region can be effectively avoided. The results will lay the foundation for the further research and application in the electric in-wheel direct drive occasion.

电动汽车轮毂电机应具有较高出力和较宽调速范围，轴向磁场电机的扁平结构特别适用于电动汽车轮毂电机。常规的轴向磁场永磁电机气隙磁场基本保持恒定，限制了其在电动汽车宽调速直驱场合的应用。本项目将记忆电机原理与轴向磁场永磁电机结构有机结合，充分利用钕铁硼的优异固有特性及铝镍钴的易充、去磁特性，提出了一种具有高转矩密度并能弱磁扩速的轴向磁场无刷记忆电机（axial-flux brushless memory machine, AFBLMM）。本项目研究该类电机的结构特点、设计规律，掌握其参数计算以及性能分析方法；研究该电机的运行机理，包括三种磁场相互渗透情况和规律；建立该电机及控制系统的仿真模型；研制样机，并搭建电机控制实验平台，研究电机磁场在线调节与控制策略。本项目的研究，将有效改善轴向磁场电机调速范围窄的不足，实现电机宽调速范围运行，为该类电机在电动汽车轮毂直驱场合的应用提供理论基础和技术支持。

轴向磁场无刷记忆电机融合了轴向磁场电机和记忆电机的各自优势，不仅具有记忆电机的气隙磁通灵活可调的特点，又具有轴向磁场电机轴向尺寸小、效率高的特点。作为一种新概念电机，轴向磁场无刷记忆电机在电动汽车、工业制造、航空航天等领域都有着广阔的应用前景。本项目提出了一种该类电机的拓扑结构，分析了电机的运行原理，通过有限元仿真软件研究了其电磁特性并进行结构参数的优化，绘制了CAD图纸并试制了样机，对样机展开实验研究与分析，验证了理论的正确性；同时，建立了该电机及控制系统的仿真模型，并正在搭建电机的控制实验平台，电机磁场在线调节与控制策略也正在研究当中。本项目的研究，有效地改善了轴向磁场电机调速范围窄的不足，实现电机宽调速范围运行，为该类电机在电动汽车轮毂直驱场合的应用提供理论基础和技术支持。