Design of robust direct current control for three-level pulse-width modulated rectifier

Considering a variety of three-phase three-level PWM rectifier's uncertainties, detailed analyses have been conducted to explain why the feed-forward decoupling methods are unable to fully achieve decoupling control of multivariable systems, singular values treated as measurement of system performance and stability analysis. High-power PWM rectifier has lower switching frequency, the system's effective bandwidth decreases, so that the decoupling effect will be influenced seriously. A robust H∞ control strategy for inner current loop of three-level PWM rectifier is proposed in this paper. The model uncertainties are taken into account for designing the controller of the system. Weighting functions' selection of robust H∞ controller is the most important and difficult problem in the design process. Usually, the problem is solved by manual calculation which costs too much time, and can't always get a good result. To overcome this drawback, the particle swarm optimization (PSO) algorithm is adopted to solve that problem. An augmented controlled object is constructed to synthesize robust H controller for PWM rectifier. The robust stability and performance are verified by simulation and experimental results. Copyright © 2016 American Scientific Publishers All rights reserved.