Based on short circuit and open circuit electro-magnetic transient analysis of 3-phase stator of inductive motor, the short-circuit feedback current in the medium voltage variable frequency drives ( VFD) are calculated quantitatively. 基于异步电动机三相输入开路及三相输入短路的电磁暂态过程,结合大容量异步电动机的特点,数学上计算了定子短路反馈电流。