Modelling and Control of three-phase ac/dc converter including Phase Locked Loop

In this chapter, a mathematical model of the power circuit of a three-phase AC/DC converter is developed in the stationary and synchronous reference frames. Then, the operation principle of the phasor locked loop is addressed to exact the angle information of the power grid to realize the accurate control synchronized with the power grid. Afterward, based on the modeling of the three-phase grid-tied converter, the controller design of the PI (Proportion + Integral) and PR (Proportion + Resonant) is implemented under the synchronous reference frame and stationary reference frame, respectively. It is realized by the desired bandwidth and its corresponding phase margin with the aid of Bode plot. It is simulation proven that the step response of the inner grid current and outer DC voltage matches their desired bandwidth.