Robust Controller Design for Sinusoidal PWM Inverters

Abstract

This paper proposes a robust controller for sinusoidal PWM inverters, which can track a sinusoidal reference with zero steady-state error. A closed-loop system for single-phase full-bridge inverters is constructed on the basis of the internal model principle. The appropriate control gains of the constructed closed-loop system are determined using a state-feedback controller design method via linear matrix inequalities. The proposed controller can adapt to the uncertain variations in the load conditions. It is also shown that the pole-placement constraints and control performance indexes based on the H² and H^∞ norms as well as a standard quadric performance index in optimal control can be applied to the proposed robust controller. Digital computer simulation is implemented to confirm the validity of the proposed robust controller with the internal model principle. A prototype experimental model is constructed and tested. Experimental results demonstrate that an excellent and practical robust controller for sinusoidal PWM inverters is realized under uncertain and fluctuating load conditions, including the nonlinear loads such as diode rectifiers.