Generalized Control Technique for Three-Level Inverter Fed Six-Phase Permanent Magnet Synchronous Machines Under Fault Conditions

This paper presents a control technique of a GaN-based Three-Level (3L) Active Neutral Point Clamped (ANPC) inverter fed high-speed six-phase Permanent Magnet Synchronous Machine (PMSM) under both Open Circuit Fault (OCF) and Short Circuit Fault (SCF) conditions. The loss of one or more phases due to OCF or SCF in PMSMs can generate a high torque ripple. A high torque ripple can disrupt the operation of electric drives and even bring the drive to a standstill. Smooth operation under any fault conditions is becoming necessary to increase the reliability of the electric drives. This paper discusses an optimization method that calculates the operating points in different fault conditions while maximizing the torque without exceeding the rated line current rating of the inverter/ motor. The optimization method also provides the torque limit in post-fault conditions without compromising the speed for both one and two isolated neutral point configurations. The post-fault operating points are implemented using a control technique that can be achieved seamlessly from the state-of-the-art vector control method. The proposed control technique is verified in simulation, and the results are presented in this paper.