Fuzzy logic based open-circuit fault diagnosis in IGBT for CMLI fed PMSM drive

For the objective of enhancing the reliability in power electronics, a fault diagnosis technique has been reported for a three-phase cascaded multilevel inverter (CMLI). This paper presents a fuzzy based fault diagnosis technique based on the average current Parks vector technique for the three-phase CMLI fed permanent-magnet synchronous motor (PMSM) drive. The three-phase normalized currents divided into positive (E-q(+)) and negative groups(E-q(-)). Then the average current Park's vector technique is used to measure the fault symptom variables by using the phase current information. The proposed fault diagnosis technique can detect and locate the single or multiple open-circuit faults, and also the intermittent faults in IGBT's at any condition (ex., change in mechanical speed, change in load torque and change in system parameters), which can improve the reliability of the motor drive system. The effectiveness of the proposed method is validated by the simulation and experimental results.