Fault-tolerant multi-level inverter topologies for open-end winding induction motor drive

Abstract

This paper presents two nine-level inverter topologies for open-end winding induction motor drive with fault-tolerance for all possible switch faults. The proposed topologies are designed with three voltage-source inverters each with eight switches, an isolated DC source and a capacitor. The number of compo nents and the scheme of connection employed for phase windings in both the topologies are identical. The voltage across the capacitors is controlled using the phase currents and hence does not require any additional pre-charging cir cuit. The direction of phase currents flowing through the capacitors deter mines their charging and discharging states. Hence the proposed topologies are categorized as flying-capacitor leg based topology (FCLBT) and switched capacitor based topology (SCBT) considering the technique employed for gen erating intermittent voltages. Although these topologies require three sources, the output voltage peak across each phase winding would be twice the source voltage, hence lower rating renewable energy sources can be employed as input sources. Conventional level-shifted carrier sinusoidal pulse width modu lation technique (SPWM) is employed for generating switching pulses. The proposed topologies employ reduced number of devices compared to existing similar nine-level topologies and also exhibit fault-tolerance for switch faults. The post-fault operation of the proposed topologies does not require any addi tional hardware but necessitates the modifications of switching pulses. Simula tions are performed in the MATLAB/Simulink environment and results are presented. A prototype is constructed to validate the performance of the pro posed topologies and experimental results are presented.