Detection of coupling inductor faults in three-phase adjustable speed drives with direct power control-based active front-end rectifiers

Inductors are utilized as the typical filtering option in three-phase adjustable speed drives (ASDs) with an active front-end rectifier (AFE) controlled by the so-called direct power control (DPC) method. Faults in the coupling inductors are one of the possible causes of failure in those systems. In this paper, a new algorithm for the early detection of coupling inductor faults in DPC-based AFEs of ASDs is presented. Most of these faults involve variations of the coil inductance value, as in the case of inter-turn short circuits. The proposed algorithm estimates and tracks the coupling inductance value to achieve a correct diagnosis. Therefore, a major system breakdown can be avoided. The algorithm also provides the identification of the winding where the fault occurs.