无刷直流电动机动态性能分析

Analysis on Dynamic Property of Brushless DC Motor

针对无刷直流电动机实际运行过程中存在的脉动和非平滑现象,基于内部结构特征和工作原理,研究了无刷直流电动机的运动特征和动态特性。从电机齿槽结构、绕组形式、转子位置、换相过程等方面分析了气隙磁场分布特征和对相电流、反电动势波形的关联作用,阐述了造成转速变化和产生脉动转矩的影响机理,讨论了单闭环控制与双闭环控制方式下的电机运行特性。通过搭建系统仿真模型,获得了空载启动、突加负载、变转速等控制要求下电机转速、定子电流和转矩的运行曲线和变化规律。理论分析和仿真实验均有效地阐明了无刷直流电动机的动态性能。

In order to eliminate the phenomenons of torque ripple and unsmooth, the motion feature and dynam- ical property of brushless DC motor are studied based on the inner structure characteristic and working princi- ple. From the aspects of the motor stator cogging structure, form of armature winding, position of rotor and process of phase change, the magnetic field distribution characteristics in the air gap of motor are analyzed, and the effects of above factors on the phase current and counter electromotive force waveform are also studied. The mechanism of the change of rotational speed and torque ripple is elaborated. The operation characteristics of brushless DC motor under single closed-loop control and double closed-loop control are discussed. Through the construction of the simulation model of brushless DC motor control system, the running curves of motor speed, stator current and torque are obtained in the process of motor starting, loading and speed governing. Dynamic change regularity of brushless DC motor is confirmed. The dynamic performance of brushless DC motor is dem- onstrated effectively by both results of theoretical analysis and simulation.