Neutral-point voltage balancing of three-level EV traction inverter using modified carrier-based SVM and THD comparison with a two-level inverter

Abstract

This paper concentrates on the application of a three-level Neutral-Point Clamped (NPC) inverter in a Permanent Magnet Synchronous Motor (PMSM) driven electric vehicle. Carrier-Based Space Vector Modulation (CB-SVM) strategy allows a simple technique for inverter switching. A split-capacitor dc bus voltage balancing strategy using a simple PI controller has been presented for the entire speed range of operation of the PMSM. For the same current Total Harmonic Distortion (THD), three-level NPC inverter provides a 65% reduction in switching frequency when compared to a conventional two-level inverter while driving the PMSM with the same parameters. Torque and speed dual loop controllers have been developed using the Field-oriented Control technique to have a wider range of operation beyond the base speed of the PMSM.