A four level rectifier-inverter system for drive applications

Multilevel converter technology has been receiving increased attention, especially for high power applications. In particular, three level drive systems have been extensively reported. In this paper, a four level rectifier-inverter system is investigated for drive applications. A dynamic control algorithm is described which balances the voltages on a 4 level rectifier-inverter drive system primarily from the rectifier. The proposed control method can also generate unity power factor currents at the utility interface. The inverter modulation is relatively unconstrained and modified to implement a zero sequence compensation for added voltage balancing. Simulation results are used to verify the efficacy of the control algorithm.