Fault diagnosis scheme for open‐circuit faults in field‐oriented control induction motor drives

Abstract

In this study, a new model‐based fault detection and isolation (FDI) strategy is proposed for field‐oriented control (FOC) induction motor (IM) drives. Actuator faults are addressed, and specifically, single open‐circuit faults are considered in this study. The residual signals are synthesised by taking the resulting closed‐loop dynamics when a FOC strategy is applied, that is, the residuals are referenced to the synchronous reference frame ( dq e ‐coordinates), which are generated by using a bank of variable structure observers to obtain a robust FDI scheme. Thus, subsystems sensitive to a specific fault, but decoupled from other faults are obtained in a natural way, where only two stator currents and the mechanical position are required for fault isolation purposes. Residual evaluation is carried out in the stator reference frame ( dq ‐coordinates) for the IM model, where the residual direction (angle) is employed to isolate a fault in each one of the six power switches in a voltage source inverter. In addition, the observer FDI scheme can be combined with a fault re‐configuration strategy in order to improve the reliability of the motor drive. Experimental results are illustrated for a three‐phase 3/4 HP IM drive at different reference frequencies and load torques with single open‐circuit faults that verify the ideas presented in this work.