Advanced control scheme for a single-phase PWM rectifier in traction applications

This work presents an advanced control scheme for a single-phase PWM rectifier. The controller consists of a PR (proportional-resonant) controller using the double sampling strategy, namely, a dual update scheme, a delayless feed-forward compensator, and a fast phase angle estimator. The PR controller is capable of regulating a sinusoidal line current without an additional prediction or an extremely high control gain under a medium switching frequency (0.5-5 kHz). The dual update scheme is the method that performs the sampling and control calculation twice in a switching period, which reduces the control time delay significantly and enables us to extend the maximum allowable control bandwidth. The proposed feed-forward compensator uses the estimated one-step predicted value of the source voltage and the source current to avoid adverse effects caused by the one-step delay, measurement noise, and harmonic component of the source voltage in the feedforward compensation process. A fast phase angle estimator is also presented, which is capable of estimating the phase angle and the frequency of the source voltage even under a highly distorted source voltage condition or a sudden amplitude, phase angle, or frequency changing condition. The feasibility of the proposed control scheme is confirmed by experiments.