Fault Tolerant Control by Asymmetric Operation of Double Three-Phase PMSMs with Inter-Turn Faults

Abstract

Inter-turn faults are most likely the initial stator winding fault in variable speed drive systems with Voltage Source Inverters. The machine must stay within its thermal requirements locally at the fault to prevent its propagation. In this paper, we present a fault tolerant control scheme for a double three-phase Permanent Magnet Synchronous Machine which minimizes the propagation of the fault by adapting the operating points of both systems independently. We estimate the generated heat by the inter-turn fault with a machine learning regression. If the estimated heat of the faulty system is greater than a definite value, the operating point of this system is adapted until the estimated heat is below the limit. The healthy system is used to compensate the torque reduction of the faulty system. We validated the concept of the control scheme with a Finite Element Analysis simulation. The presented double threephase machine can compensate 13.9 W at nominal torque, which is an improvement of 74% compared to the equivalent single three-phase machine with the same heat limitation strategy. This heat reduction equals a temperature reduction of 111.2 K at fault locally.