Adaptive repetitive control of PWM inverters for very low THD ac-voltage regulation with unknown loads

Abstract

An adaptive repetitive control scheme is proposed and applied to the control of a pulsewidth-modulated (PWM) inverter used in a high-performance ac power supply; The proposed control scheme can adaptively eliminate periodic distortions caused by unknown periodic load disturbances in an ac power supply, The proposed adaptive repetitive controller consists of a voltage regulator using state feedback control, a repetitive controller with tuning parameters, and an adaptive controller,vith a recursive least-squares estimator (LSE), This adaptive repetitive controller designed for ac-voltage regulation has been realized using a single-chip digital signal processor (DSP) TMS320C14 from Texas Instruments, Experimental verification has been carried out on a 2-kVA PWM inverter. Simulation and experimental results show that the DSP-based adaptive repetitive controller can achieve both good dynamic response and low total harmonic distortion (THD) under large-load disturbances and uncertainties.