A novel DC-link voltages balancing control method for cascaded H-bridge rectifier

DC-link voltages balancing is very important for cascaded H-bridge rectifier (CHBR). A new control method for voltages balancing is proposed in this paper. The relationship between the modulation index increment and the output voltage error is deduced. Therefore the modulation indexes of the cells are rearranged according to the measured dc voltages and the DC voltages are regulated to be the same value. The implement method for the proposed strategy is discussed in detail and the final method is derived. Simulations and experiments were carried out with the presented method. All of them approve that the proposed method is effective for such cascaded topology. The good performance is achieved when the CHBR is operating on the different conditions.