Multiwinding Transformer Fed CHB Inverter With On-Line Switching Angle Calculation Based SHE Technique for Vector Controlled Induction Motor Drive

A multiwinding transformer for ac–dc converter with multilevel inverter fed induction motor drive (IMD) is presented in this article. An 18 pulse ac–dc conversion is used on input side of the IMD, to meet the power quality requirement as per the IEEE-519 standard. At IM side, a ternary configured nine-level cascaded H-bridge (CHB)-inverter is used to enhance the response of the IMD. A simple online calculation of switching angles and its implementation of selective harmonic elimination strategy, are proposed to control a nine-level CHB-inverter. In this article, a nine-level CHB-inverter is operated at fundamental frequency switching for reducing the losses and suppressing the lower order harmonics (fifth, seventh, and eleventh) to a negligible value and to enhance the torque profile of the IMD. The performances of IMD are evaluated in MATLAB-Simulink environment and then simulated results are verified by test results taken from developed prototype in the laboratory to show its effectiveness for medium power applications.