A Comprehensive Performance Study of Three-Level NPC VSI with Induction Motor Load in Closed-loop

This paper presents a comprehensive performance study of three-phase three-level neutral point clamped (NPC) VSI using the carrier-based sine PWM (SPWM) technique in a closed loop with an induction motor load. The line current THD, torque ripple, and dynamic response are considered as the performance parameters and compared with two-level VSI. The mathematical modeling of field-oriented control (FOC) of the induction motor is explained. Design implementation of level shifted carrier-based PWM (LSC-SPWM) technique for three-phase three level NPC VSI in a closed loop with FOC based induction motor load is carried out in MATLAB/Simulink environment. Simulation results are illustrated for 4-kW induction motor drive under steady-state and with the load and speed transients. THD% of line voltage is found to be 44.93% and stator current THD% 3.94%, which is approximately 50% lesser than the two-level inverter.