Fast super twisting multi-quasi resonant sliding mode control of cascaded H bridge rectifier

In order to solve the problems of large overshoot in the DC-side voltage and low-order harmonic pollution in the grid-side current of the cascaded H bridge rectifier when the load changes suddenly, a fast super-twisting multi-quasi-resonant sliding mode algorithm is proposed. First, a mathematical model of the cascaded H bridge rectifier in the dq rotating coordinate system was established, the law of the grid-side current harmonic distribution of the cascaded H bridge rectifier was deduced, and its dynamic characteristics were analyzed. Secondly, a fast super-twisting multi-quasi-resonance sliding mode inner-loop controller is designed by combining fast super-twisting sliding mode control and multi-quasi-resonance control. Then the design equation of fast super-twisting multi-quasi-resonance sliding mode is derived, and the Lyapunov function is used to check its stability. Experimental results show that the proposed control strategy has smaller voltage overshoot and shorter dynamic response time and significantly reduces the grid-side current distortion rate.