A voltage-based approach for open-circuit fault diagnosis in voltage-fed SVM motor drives without extra hardware

The widespread use of electric drives has led to an increasing interest in their condition monitoring and fault diagnostics. Regarding power switch open-circuit fault diagnosis, the proposed voltage-based approaches require additional hardware, increasing the system cost. Thus, the industry acceptance may be low. Therefore, this paper proposes a new voltage-based approach for open-circuit faults diagnosis in voltage source inverters with space vector modulation (SVM) feeding permanent magnet synchronous motors (PMSM) without additional sensors, by employing a flux observer based on the machine current model, which allows to estimate the motor terminal voltages. The diagnostic method uses the average values of the errors between the reference and the estimated voltages. Its implementation in a direct torque controlled (DTC) PMSM drive implies a minimum additional computational effort, because the flux observer is usually already available. Several experimental results are presented for a DTC as well as for a vector controlled PMSM drive.