多相永磁推进电机的外部短路分析

为了定量评估短路电流对多相永磁推进电机转子磁钢的危害,并为短路保护提供依据,建立了该类电机基于场路耦合的非线性电磁暂态数学模型。据此以一台50kW极18相永磁无刷直流电机为例,计算了发生外部单相对地和两相对地突然短路故障时的短路电流波形,并分析了发生短路时阻尼绕组对电磁暂态过程的影响,其仿真结果与实验结果吻合较好。研究结果表明,该方法可以有效地计算该类电机的暂态短路电流,可用于设计阻尼绕组和校核永磁磁钢的最大退磁工作点。

External faults in poly-phase permanent magnet propulsion motors

The damage caused by short-circuit currents to magnets in poly-phase permanent magnet propulsion motors was analyzed using an FEM circuit coupled nonlinear transient model. The objective is to develop a method to provide fault protection during short circuits. Simulations of a 50 kW 4-pole 18-phase permanent magnet brushless machine predicted the single phase to ground fault currents and the two phase to ground fault currents. The model was also used to investigate the effect of damping winding on the transient process. The calculated currents agree well with measured values which shows that the method can effectively calculate short circuit currents in permanent magnet machines with damping windings. The method can be used to design damping windings and determine the most serious transient demagnetization point.