Detection of Trailing-Edge Demagnetization for Six-Phase Permanent Magnet Motors

The trailing edge demagnetization in Surface-Mounted Permanent-Magnet Synchronous Motors (SMPMSMs) is commonly the result of an excessive torque overload. This fault irreversibly reduces the torque constant and motor efficiency, and it is often difficult to diagnose in three-phase machines for small demagnetization angles. Conversely, multiphase drives providing additional degrees of freedom make it possible to develop new potential diagnostic algorithms that are more accurate and robustThis paper proposes a diagnostic algorithm for the online detection of rotor demagnetization faults for six-phase machines with parallel magnetized rotor magnets. The proposed technique directly quantifies the demagnetization angle and actively corrects the angular position of the control system to ensure maximum motor performance in post-fault conditions. Experimental tests have been carried out on two identical six-phase PMSMs differing only in the size of the rotor magnets to emulate the effect of a trailing edge demagnetization. The experimental results confirm the effectiveness and robustness of the proposed solution.