Analysis and experimentation of a new three-phase multilevel current-source inverter

Multilevel converter technology has been mainly used for voltage-source inverters (VSI) by now. But with the development of the superconducting magnetic energy storage (SMES) technology, superconducting inductors can be used as higher efficiency energy storage elements, the application of current source multilevel inverters (CSI's) in power systems will be more and more popular. A new kind of three-phase multilevel CSI topology is presented in this paper. The new multilevel CSI's synthesize the staircase current wave from several levels of balance inductor currents. The switching strategy that can ensure equal current division among the branches and current harmonics reduction is presented. A three-phase 6-level CSI and a three-phase CSI using the new topology are discussed by the simulations. An experimental prototype of a three-phase 6-level CSI has been built to practise the proposition in the paper.