A multilevel inverter system for an induction motor with open-end windings

In this paper, a multilevel inverter system for an open-end winding induction motor drive is described. Multilevel inversion is achieved by feeding an open-end winding induction motor with two 2-level inverters in cascade (equivalent to a 3-level inverter) from one end and a single 2-level inverter, from the other end of the motor. The combined inverter system with open-end winding induction motor produces voltage space phasor locations identical to a 6-level inverter. A total of 512 space phasor combinations are available in the proposed scheme, distributed over 91 space vector locations. The proposed inverter drive scheme is capable of producing a multilevel PWM waveform for the phase voltage ranging from a 2-level waveform to a 6-level waveform depending on the speed range. A space vector PWM scheme for the proposed drive is implemented using a 1-HP induction motor with open-end winding structure.