永磁体端部长度对永磁无刷直流电机性能影响的分析

Analysis of influence of permanent magnet end length on the performance of BLDC motors

在永磁无刷直流电机中,通常使用霍尔传感器对转子的位置进行实时检测。电机设计中普遍采用永磁体长度大于定子铁芯长度的方式,以使霍尔传感器能利用永磁铁的端部漏磁来检测转子的位置。但永磁体端部漏磁通常会引起电机的振动、噪音等问题,其对电机性能的影响难以得到精确的评估。本文以KMB-T140永磁无刷直流电机为例,利用Ansoft有限元分析软件进行三维建模,并对不同磁钢长度所引起的电机性能的改变进行分析,得到永磁体端部长度对电机反电势、反电势谐波、齿槽转矩的影响。该研究对高精度、高功率密度永磁无刷直流电机的设计和优化具有一定的参考意义。

Generally,hall sensors are employed to detect the rotor＇s real-time position in a permanent magnet brushless direct current（ BLDC） motor. In motor design,the permanent magnet length is usually longer than the length of stator core so that the rotor real-time position can be detected real-timely by hall sensors through the end leakage flux. However,the performance of the motor is degraded due to the vibration and noise resulted from the end leakage flux. This paper takes a BLDC motor KMB-T140 as example,3D modeling was constructed using Ansoft software of finite element analysis,and the impact of motor performance including back EMF,EMF harmonics and cogging torque caused by the vibration of the end length of the magnet was checked. The research provides valuable reference for the design and optimization of high precision and high power density permanent magnet BLDC motors.