由于超高速电机可以直接驱动高速负载，具有体积小、重量轻、响应快、功率密度高等特点，目前已广泛应用于压缩机、真空泵、微型燃气轮机、飞轮储能、机床以及吸尘器、吹风机等设备中。超高速电机的设计需要进行多场域耦合迭代，才能保证电机的性能满足要求。本文针对应用于吸尘器的超高速单相无刷直流电机，从电机的电磁设计、控制和温升三个方面进行深入研究，其主要内容包括：针对单相无刷直流电机存在启动死点问题，通过采用非对称气隙结构来消除启动死点，设计并对比分析不同非对称气隙结构对单相无刷直流电机齿槽转矩和感应电动势的影响。由于小功率超高转速的电机转矩较小，与齿槽转矩为同一数量级，分析齿槽转矩对电机转矩产生的影响。此外，对高频下电机的铁心损耗进行分析，通过优化定子结构来降低电机的铁心损耗，最终设计出性能较优的超高速单相无刷直流电机。对单相无刷直流电机的方波控制策略进行分析，提出超高速单相无刷直流电机方波控制的最优控制角及其计算公式，对比分析各种方波控制策略的电流和转矩特性。由于电机在加速和稳态时性能要求不同，提出适用于超高速单相无刷直流电机的控制策略。在Simulink中搭建单相无刷直流电机的仿真模型，并设计实验测试平台，对提出的控制策略进行仿真与实验验证。通过有限元软件分析电机内各部分产生的电磁损耗，实验测试风机系统在不同空气流量下的效率，通过电机内的空气流量间接计算得到强迫风冷的风速并将其作为热仿真的边界条件。采用磁场和温度场仿真软件进行磁热耦合仿真，得到轴向强迫风冷的电机运行于超高速下的温升情况。
Ultra-high-speed motors have small size, light weight, fast response, high power density, and can be directly connected to high-speed loads. At present, ultra-high-speed motors are mainly used in compressors, vacuum pumps, micro gas turbines, flywheel energy storage, machine tools, vacuum cleaner and hair dryer. The design of ultra-high-speed motor needs multi field coupling iteration to meet the performance requirements. In this dissertation, the ultra-high-speed single-phase brushless direct-current (BLDC) motor applied to vacuum cleaners is studied and analyzed from three aspects: electromagnetic design, control and temperature rise. The main contents include:Because the single-phase BLDC motor has the problem of starting dead point, the asymmetric air gap structure is adopted to eliminate the starting dead point. The effect of different asymmetric air gap structures on cogging torque and induction electromotive force of ultra-high-speed single-phase BLDC motor is compared and analyzed. Because the torque of the motor with small power and high speed is small, the influence of cogging torque on the motor torque is analyzed. The core loss of ultra-high-speed single-phase BLDC motor is analyzed and reduced by optimizing the structure of the stator. Finally, an ultra-high-speed single-phase BLDC motor with better performance is designed.The square wave control strategy of single-phase BLDC motor is analyzed. The optimal control angle and its calculation formula for square wave control of ultra-high-speed single-phase BLDC motor are proposed. The current and torque characteristics of various square wave control strategies are compared. Due to different requirements of motor performance in steady state and acceleration, the control strategy suitable for ultra-high-speed single-phase BLDC motor is proposed. The Simulink simulation model of single-phase BLDC motor is built, and the experimental platform is set up to test the motor performance using the proposed control method.The electromagnetic loss of each part of the motor is analyzed by the finite element analysis software. As the motor is used in the fan system, the efficiency of the fan system under different air flow is tested through experiments. The speed of forced air cooling wind is calculated indirectly by the air flow in the motor, which is regarded as the boundary condition of thermal simulation. The temperature rise of the motor with axial forced air cooling at super high speed is obtained by the finite element simulation of magneto-thermal coupling with the simulation software of magnetic field and thermal field.
