Decoupling Control Method for Single-phase Cascade H-bridge Rectifiers

In this paper, a decoupling control method is presented for single-phase cascaded H-bridge (CHB) rectifier, to eliminate the coupling effect of the capacitor voltage balancing controllers on the outer-loop voltage controller and inner-loop current controllers. Firstly, the coupling effect is analyzed according to the mathematical model of CHB rectifier. Then, the outer-loop reference voltage is redesigned to eliminate the coupling effect of the capacitor voltage balancing controllers on the outer-loop voltage controller. The active and reactive duty cycle components are designed to realize the decoupling of the voltage balancing control and the inner-loop current control, and the even distribution of the reactive powers among H-bridges. Finally, simulation results have verified the effectiveness of the proposed method.