A novel voltage balance method for cascaded H-bridge rectifier

In this paper, a novel algorithm is introduced for DC-link voltage balancing in cascaded H-bridge rectifier. With this method, the modulation index of each cell can be regulated by surveying not only the total DC voltage but also each cell´s DC voltage, therefore the modulation index of each cell can match their individual actual active power respectively and achieve the DC voltages balance. Furthermore, the steady area of such cascaded converter is discussed and the relationship of the active power ratio of two cells and the modulation index is given. Simulation and experimental results show the proper operation of the proposed topology and the corresponding control strategy.