Motor Torque Analysis for diagnosis in PMSMs under non-stationary conditions

The field of Permanent Magnet Synchronous Motors (PMSMs) diagnosis is of research interest because widely used both in the Industrial environment and in electric vehicles. Amongst various Fault Detection (FD) techniques, the Motor Current Signature Analysis (MCSA) received lots of attention because some defecting frequencies may be monitored through the motor currents in case of steady-state functioning. This latter assumption is not always fulfilled, such e.g. in robotic systems driven by PMSMs, where constant speed assumption is unrealistic in most of the cases. Furthermore, MCSA in not suitable for systems working under non-stationary conditions without using advanced processing techniques. This work investigates the use of load torque information for motor diagnostic purposes under not constant speed assumption. Simulations and experimental results are presented regarding the use of the proposed Motor Torque Analysis (MTA) to overcome these limits