混合式永磁同步电机弱磁性能的研究

针对传统永磁同步电机弱磁性能不佳的问题,提出了应用混合式结构来改善永磁同步电机弱磁性能。研究了传统永磁同步电机的结构,得出了传统永磁同步电机弱磁困难的原因是电枢磁势和转子励磁磁势的不对等。分析了混合式永磁同步电机的结构,得出了其转子永磁体用量少,励磁磁势较小;气隙很小同步电感大,短路电流与额定电流的比值小。介绍了应用短路电流与额定电流的比值来判断永磁同步电机弱磁性能的方法,分析得出了混合式结构弱磁性能要好于传统永磁同步电机。采用了基于直轴电流负向控制的附加闭环方法进行弱磁控制,对传统永磁同步电机和混合式永磁同步电机的弱磁性能进行了对比实验,混合式结构的弱磁扩速倍数为传统式结构的2.63倍。研究结果表明,混合式结构可以有效提升永磁同步电机弱磁性能。

Field weakening performance of hybrid permanent magnet synchronous motor

Aiming at solving the problem of the poor field weakening performance of traditional permanent magnet synchronous motor, hybrid permanent magnet synchronous motor was presented. Through studying structure of traditional permanent magnet synchronous motor, the cause of field weakening difficult of traditional permanent magnet synchronous motor was armature potential far less than rotor excitation mag-netic potential was obtained. Permanent magnet expenditure of hybrid permanent magnet synchronous motor was less, so its rotor excitation magnetic potential was smaller. The air gap of hybrid permanent magnet synchronous motor was smaller and synchronous inductance was big-ger, so the ratio of short circuit current and rated current was smaller. Judging field weakening performance of permanent magnet synchronous motor by the ratio of short circuit current and rated current was introduced, and better field weakening performance using hybrid structure was obtained. Additional closed loop method based on direct axis current negative control was adopt to conduct field weakening experiment of tra-ditional permanent magnet synchronous motor and hybrid permanent magnet synchronous motor. The field weakening speed expansion ratio of hybrid structure motor was 2. 63 times that of the traditional structure. The results indicate that the field weakening performance of permanent magnet synchronous motor can be effectively improved by using hybrid structure.