The isolated multilevel inverter using common-arm scheme for 3-phase system

For 3-phase applications, an isolated multilevel inverter employing 3-phase transformers can reduce the number of transformers compared with that of using single- phase transformers. However it needs a large number of switches. To solve this problem, we propose a modified 3-phase isolated multilevel inverter adopting common-arm scheme. Phase angle control based on equal-area method is presented to obtain optimal switching functions identified with fundamental frequency of output voltage. Thanks to this control strategy, harmonic components of output voltage and switching losses can be diminished considerably. To verify performance of the proposed multilevel inverter, we implemented computer-aided simulations.