Analytical Prediction of the Short-Circuit Current in Fault-Tolerant Permanent-Magnet Machines

This paper describes an analytical technique that can be utilized to predict the short-circuit current in a fault-tolerant permanent-magnet machine under partial-turn short-circuit fault conditions. It has been shown that the current in partially short-circuited turns is dependent on their relative position in the slot where the phase winding is accommodated, and the slot-leakage flux associated with these turns has a significant influence on the short-circuit current when a remedial action has been applied. An analytical model that quantifies the variation of the slot-leakage flux as a function of the relative position of partially short-circuited turns has been developed. Both finite-element analysis and experimental results demonstrate the effectiveness of the proposed technique for predicting the short-circuit current.