Research on cascaded three-phase-bridge multilevel converter based on CPS-PWM

Cascaded multilevel converters are emerging as a new breed of power converter options for high-voltage and high-power applications. A cascaded three-phase-bridge (C3PB) multilevel topology is proposed in this study. The new multilevel converter topology is derived from an optimum combination of three-phase voltage source converter modules and it needs fewer switches and dc capacitors than Δ-connected cascaded H-bridge converter under the similar operation condition. The characteristics of the C3PB converter are presented through analysing its current relationship, voltage relationship and power allocation in detail; the analysis results show that all the converter modules equally share the output power. Based on carrier phase-shifted pulse-width modulation (CPS-PWM) technique, simulation results of two-level and three-level inverter are given to verify the theoretical analysis; meanwhile, CPS-PWM and power decoupling control method are employed to validate the three-level C3PB rectifier. Finally, based on Digital Signal Processor (DSP) + Field Programmable Gate Array (FPGA) control board, a lab prototype is built to verify the validity and feasibility of the proposed C3PB converter along with the proposed control method.