New approach to current control of AC-to-DC voltage-type convertors

A new phase- and amplitude-based current control strategy for a PWM AC-to-DC voltage-type convertor is presented which introduces state feedback control of an LC filter. The feedback of the state variables of the LC filter connected to the AC side of the convertor not only compensates a DC component of the AC input current but also eliminates the oscillations of the DC output current and voltage waveforms during transients. A mathematical model of the convertor system with proposed control strategy is developed to carry out computer simulation of the system under transient operating conditions. The simulation and the experimental results of the proposed system show that the transient waveforms of AC input and DC output currents are improved greatly, even for low damping effect. The simulated results also show that the dynamic response can be significantly improved even when the DC side capacitance is substantially reduced