Fractional proportional integral controller applied into two parallel 3-phase PWM rectifiers

With the ever-increasing requirements in industrial manufacturing as well as in the daily life activities of modern society, the control systems equipped with two or more parallel PWM rectifiers rather than solely with a PWM rectifier are widely used to meet the system demands of higher productivity, reliability and safety. Although the control result of the system using conventional PI controller in PWM rectifier is relatively ideal, the design parameters are the relative ones and they are sensitive to the changes of system parameters when conducting more than one PWM rectifier in parallel. For instance, higher overshoot of output voltage and difficulty in the choice of controller parameters. The Fractional Proportional Integral controller rather than the conventional PI controller is proposed in this paper to overcome the drawbacks above. The ideal control results and obviously improved control quality are illustrated by both simulations and experiments of Fractional Proportional Integral controller applied in two parallel PWM rectifiers.