Analysis and Implementation of Three-Level Neutral Point Clamped Inverter Fed Induction Motor Drive

Multi-level inverters have found wider scope of applications in medium as well as high-power adjustable-speed drives (ASDs) due to their capability of handling high powers and power quality friendly approach. For efficient control of ASDs, indirect vector control is used which has advantages like; elimination of retrofitting of shaft encoder, faster dynamic response, and low torque pulsations. Carrier less modulation techniques (e.g., space vector pulse width modulation) provide more maximum peak fundamental output voltage in linear range of modulation for multi-level inverters. However, carrier based control schemes provide simpler control and more flexibility in operation of the control, especially for dc-link capacitor voltage balancing. This paper focuses on analyzing performance of indirect vector control of induction motor, for phase disposition type of multi-carrier technique. Steady-state as well as dynamic performance of the three-level inverter based drive is analyzed by simulation studies. For experimental validation, hardware set-up of three-level neutral point clamped inverter controlled induction motor drive is developed using Arm Cortex ST32F4 in open-loop configuration. Experimental results depicting satisfactory operation of the developed drive in steady state are presented in this paper.