三电平变频调速系统中直流预励磁试验研究

在交流电机变频调速系统中，电机起动时往往输出转矩不足却经常出现较大的冲击电流，严重时甚至可能造成变频器中开关器件的损坏，尤其在二极管钳位的三电平变频器中，起动时的瞬时冲击电流往往造成中性点偏移而使得变频器无法正常起动。该文在探究上述情况产生原因的同时，提出了一种应用于三电平变频器-电机系统的直流预励磁方案，在电机起动前预先建立起电机磁场，有效地遏制过大的起动电流。通过系统性试验对比，结果表明此方法在380V/160kW三电平变频调速系统中取得了良好的应用效果，同时探讨了此直流预励磁方案在中高压三电平变频器中应用的可能性。

The Experimental Analysis of DC Pre-excitation for 3-Level Inverter-motor System

In the AC adjusting speed system,the significant current impulse frequently occurs in the starting process while the output torque is sufficient.This would damage the power electronics device,cause the unbalance of neutral point in three-level NPC topology,and deteriorate the starting performance.In this paper,a DC pre-excitation strategy,which limits the starting current and enhances the electromagnetic torque via establishing the flux linkage before starting process,is proposed to the three-level inverter under analysis on the mechanism of the above large current.The relevant experiments present its eminent effect on the 380V/160kW inverter-motor system.Also this paper discuss the feasibility of its application in high voltage high power inverter.