Abstract: The dq synchronous system was built by constructing virtual orthogonal voltage and current based on second order generalized integrator. The predictive power model was derived to construct main control system of cascaded H-bridge rectifier combining the instantaneous power theory, which took the duty cycle of active and reactive power as control object. Then, a new voltage balancing control strategy was proposed dealing with the problem of DC voltage imbalance in cascaded H-bridge rectifier. The modification of active power was obtained by the voltage balance controller when the objective function of coupling effect achieves minimum and the active power was distributed by reconstructing the duty cycle of active power in each modular, which eliminated the coupling effect between the voltage balance controller and the main control system on the basis of ensuring the DC voltage balance. The correctness and effectiveness of the proposed method was verified by simulation and experimental results.

Key words: cascaded H-bridge, predictive power, voltage balance, second order generalized integrator, coupling effect