Three-level NPC inverter based SVM-VCIMD with feed-forward active PFC rectifier for enhanced AC mains power quality

This paper presents a Scott-transformer based Power Factor Correction (PFC) rectifier for a three-level Neutral-Point-Clamped (NPC) inverter fed Induction Motor Drive (HMD) for enhanced power quality at AC mains. Here, the Scott-transformer based PFC rectifier is digitally controlled by a current feed-forward control. The torque component of the stator current is added to the output of the DC bus voltage Proportional plus Integral (PI) controller as a feed-forward term which enhances the dynamic performance of the DC bus voltage regulation. The three-level NPC inverter is controlled by a Space Vector Modulated (SVM) indirect vector control scheme. The performance of the proposed DC bus voltage loop with feedforward control is compared with the conventional one and found to offer faster response with less overshoot and undershoot. The proposed IMD system is simulated using MATLAB/Simulink and the same is validated experimentally. The proposed drive system is analyzed for a wide variation in reference speed and load torques demonstrating significant improvement in the performance indices.