Multilevel inverter with series connection of H-bridge cells

A novel AC/DC/AC converter topology, a three-phase switching mode rectifier (SMR) and a three-phase multilevel inverter with separate DC power supplies, is proposed in this paper. To improve the power quality, three-phase SMR is adopted to supply sinusoidal wave with high power factor and current distortion. The separate DC bus voltages are provided by switching mode DC-DC converters. The full-bridge cells are adopted to provide multilevel line voltage. The control schemes of three-phase multilevel inverter are based on look-up table with sine-triangular PWM method. The voltage unbalance problem between the separate DC bus voltages is improved by using the proposed control scheme. The proposed AC/DC/AC converter is verified by computer simulations.