A Hybrid Twenty Five-level Inverter for an Open-End Winding Induction Motor (OEWIM) Drive

Abstract

In this paper, a hybrid twenty five-level inverter topology for an OEWIM (Open-End Winding Induction Motor) drive is proposed. In this topology, one end of OEWIM is fed by a FC based hybrid five-level inverter and other end is connected to a symmetrical five-level inverter. The hybrid five-level inverter is achieved by cascading a three-level flying capacitor inverter with capacitor fed H-bridge. The symmetrical five-level inverter is obtained by cascade connection of four 2-level inverters with equal DC-link voltages. The combined effect of five-level hybrid and five-level symmetrical inverters generate twenty five distinct levels in the phase voltage. In this proposed topology, a total of 3,43,000 space phasor combinations are accessible; hence using switching redundancies, the capacitor voltages can be maintained at desired levels. The proposed topology requires only 48 switching devices, as compared to conventional topologies that require 144 switches and fully eliminates the requirement of clamping diodes, which are required in NPC inverter. It, also, requires only 6 capacitors unlike to 828 capacitors required in twenty five-level FC inverter and 5 DC power supply sources as compared to twenty five-level CHB inverter that require 36 DC power supply sources. Simulation study is carried out to evaluate the performance of the proposed inverter and results are presented.