An 18-Pulse Extended Delta Configured Multi-Winding Transformer to Improve the Power Quality of MLI Based Induction Motor Drives

This paper deals with a new structure of induction motor drive (IMD). A novel multi-winding transformer structure with an extended delta configuration is presented to obtain an 18-pulse AC-DC converter for medium voltage IMD applications. A multilevel inverter (MLI) topology is utilized to drive an induction motor (IM). The 3-level neutral point clamped (NPC) inverter used in this paper requires fewer DC sources and helps to improve the power quality and dynamic response of the IMD. The proposed multi-winding transformer meets the DC voltage requirements of the 3-level NPC inverter while also reducing total harmonic distortion (THD) of supply current to less than 5%, as required by IEEE-519. The power factor of the proposed IMD remains over 0.96. Indirect vector control scheme is deployed to operate the 7.5 kW IM. The level shifted pulse width modulation (LSPWM) technique is utilized to control the multilevel NPC inverter, which enhances the efficiency of the drive. The presented IMD is designed and its performance is validated in the MATLAB/Simulink environment under different operating conditions.