Sliding mode control of a closed-loop regulated PWM inverter under large load variations

Abstract

A discrete sliding mode control scheme is presented for the closed-loop regulation of a pulse-width-modulated (PWM) inverter in application of high-performance uninterruptible power supply (UPS) systems. Based on the dynamic model of the PWM inverter, the sliding condition of the concerned system can be obtained and the PWM pattern is determined at every sampling instant by the proposed sliding mode control algorithm. Time response behavior of the digitally controlled PWM inverter by using a sliding mode control scheme under large load variations has been analyzed and a systematic design procedure is also suggested. A digital signal processor (DSP)-based (TMS 320C25) PWM inverter controller with a sampling rate of 10 kHz is implemented to verify the proposed control scheme. The constructed DSP-based digitally controlled PWM inverter system has fast dynamic response and low total harmonic distortion (THD) for AC phase-controlled nonlinear load.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>