Multiple fault diagnosis in variable speed drives through current measurements

In this paper, a signal-based method is proposed for the detection and isolation of open-switch faults in variable speed drives. The fault diagnosis algorithm relies only on the information of stator currents. Residuals and features are generated from the trajectory of Park´s current vector and symmetrical components of line currents. Fault detection is achieved by directly monitoring the magnitude of Park´s vector. Meanwhile, an isolation algorithm based on pattern recognition is proposed by applying a supervise classification technique. The proposed scheme is able to evaluate 18 single and simultaneous faults conditions under steady-state operation. Experimental data is evaluated from a test bench of 1 HP induction motor to validate the fault detection and isolation scheme presented in this work.