高速小功率永磁无刷直流电机铁心损耗研究

Research on Core Loss of High Speed and Low Power Permanent Magnet Brushless DC Motor

效率、力矩波动和成本问题一直是困扰高速小功率永磁无刷直流电机(BLDCM)在机床设备中应用的关键因素。为改善这些问题,文章主要就降低铁心损耗、提高电机效率的方面展开研究,利用数值计算方法和场路结合思想,针对硅钢片定子铁心在高频时铁损系数高的问题,提出了使用锰-锌(Mn-Zn)铁氧体材料和磁环无槽结构的设计方法,不但能有效降低电机铁损,还能降低绕组电感,缩短换相过程,显著提高效率、降低力矩波动和减少成本。文中对一款12000rpm/50W的高速小功率BLDCM进行改良,基于有限元分析软件得到改良后力矩波动率低至5%,并通过制作和测试样机得到定子铁心损耗降低8.121%,验证了方案的正确性和可行性。

Efficiency, torque fluctuation and cost have always been key factors impeding the application of permanent magnet brushless DC motors (BLDCM) with high speed and low power in machine tool equipment. This paper mainly studies the aspect of reducing core loss to improve motor efficiency. On the base of numerical calculation methods and field-path combination ideas, a method of using Mn-Zn ferrite material and adopting slotless structure with magnetic ring as iron core is proposed for the problem that silicon steel sheet core has a high iron loss coefficient at high frequencies. The scheme can not only effectively reduce the motor iron loss, but also reduce the winding inductance and shorten the process of commutation. As a result, the efficiency of the motor can be greatly improved and the cost can be cut down. In the end, take a high speed and low power BLDCM with speed of 12,000 rpm and power of 50W as an example to optimize. Based on the finite element analysis software, the torque fluctuation is as low as 5%, and the stator core loss is reduced by 8.121% by making and testing of the motor prototype, which verifies the correctness and feasibility of the scheme.