DC-bus voltage control of three-phase AC/DC PWM converters using feedback linearization

In this paper, a fast voltage control strategy of three-phase ac/dc pulsewi dth modulation (PWM) converters applying a feedback linearization technique is proposed, First, incorporating the power balance of the input and outpu t sides in system modeling, a nonlinear model of the PWM converter is deriv ed with state variables such as ac input currents and de output voltage. Th en, by input-output feedback linearization, the system is linearized and a state feedback control law is obtained by pole placement. With this control scheme, output voltage responses become faster than those in a conventiona l cascade control structure, For robust control to parameter variations, in tegrators are added to the exact feedback control law. Since the fast volta ge control is feasible for load changes, it is shown that the de electrolyt ic capacitor size can be reduced remarkably. In addition, the capacitor cur rent is analyzed for size reduction of the capacitor, As is usual with PWM converters, the input current is regulated to be sinusoidal and the source power factor can be controlled at unity, The experimental results are provi ded to verify the validity of the proposed control algorithm for a 1.5-kVA insulated gate bipolar transistor PWM converter system.