永磁无刷直流电机消除逆变环流的弱磁性能研究

Analysis of Flux-Weakening by Eliminating Circulating Current in PM BLDCM

分析了造成永磁无刷直流电机弱磁运行区间过窄的一个关键因素——逆变电路环流;提出了一种新型驱动拓扑电路,此新型电路结构在传统三相逆变桥的基础上,在每个半桥臂下方反向串联一个相同的功率器件,同步控制其通断,达到消除逆变环流的效果。通过与传统逆变电路拓扑的对比,分析了此新型电路拓扑消除环流的原理,并对传统驱动拓扑电路和新型驱动拓扑电路进行了对比实验研究。结果表明,此拓扑电路消除了环流,进而消除了弱磁区间环流引起的负转矩。实验中永磁无刷直流电机的弱磁调速比从传统电路的1.22增大到2.58,有效地扩展了永磁无刷直流电机的弱磁调速范围。

Permanent magnet brushless DC motors （PM BLDCM）have narrow flux-weakening operation region,which restrict to use for high speed applications and traction systems. The performance of PM BLDCM flux-weakening operation considering inverter is investigated by analyzing the inverter circulating current. A novel inverter topology is suggested. The new topology adds a same power thyristor to anti-series connect to every inverter half-bridge and controls them synchronously. Compared with the traditional inverter topology,the reason of why the circulating current can be eliminated is analyzed. Both of traditional inverter and the novel inverter are tested with the same PM BLDCM and the same condition. Experimental result shows that the novel inverter topology can eliminate the circulating current in flux-weakening operation region,and the flux-weakening operation region ratio extends from 1.22 with the traditional inverter topology to 2.58 with the novel topology. The flux-weakening operation performance is improved evidently.