Proportional and Integral Variable Structure Controller (PI –VSC) for Grid Connected PWM Voltage Source Converter

This paper introduces an improved method for DC link voltage regulation in pulse width modulation rectifier (PWMR) applications. The mathematical model of PWMR in synchronous reference frame is introduced. This model is used to investigate and design of DC voltage and current control loops. The current controller is designed based on modulus optimum, magnitude optimum, (MO) criteria while the voltage controller is designed based on Proportional Integral (PI) with variable structure control (VSC) concept, which is denoted as PI-VSC. In PI-VSC, the control system switches between PI and pure I controllers according to pre-defined switching function. The PI-VSC has three tuning parameters, which are the PI-controllers gains and the switching function. The PI controller gains are tuned using Symmetrical Optimum (SO) criterion, while the switching function based on the absolute error signal. To verify the validity