Detection and Localization of Stator Resistance Dissymmetry Based on Multiple Reference Frame Controllers in Multiphase Induction Motor Drives

Multiphase drives are receiving increasing attention by the research community in high-power applications. In this paper, the behavior of multiphase induction machines with an odd number of phases is investigated under the assumption that the resistances of the stator winding are unbalanced owing to poor connections. A high-resistance connection can cause overheating and supply voltage unbalance, which may reduce the efficiency and increase the fire hazard. The main contribution of this paper is a control scheme that can detect the stator resistance unbalance, that can localize the faulty phase, and, at the same time, that can keep the drive behavior unchanged, both in transient and steady-state operating conditions. The control scheme is based on an analytical model that shows the effect of the unbalance on the current components related to the high-order spatial harmonics of the air-gap magnetic field. The theoretical analysis and the feasibility of the control scheme are confirmed by experimental tests.