A Simple Switching-Frequency-Regulated Sliding-Mode Controller for a VSI With a Full Digital Implementation

Abstract

This article describes the design of a first-order sliding-mode controller for a voltage source inverter (VSI) operating at a fixed switching frequency. The proposal is simple, as it does not include any integral or resonant action in the switching function, and good results are obtained in terms of robustness, steady-state tracking error, fast transient response, and low total-harmonic distortion (THD). The implementation methodology using a microcontroller preserves all the benefits of a continuous-time implementation. Moreover, the article analyzes the sliding motion dynamics, and stability conditions are derived. Experimental results obtained with a 2.2-kW inverter show that fixed switching-frequency operation and robust output-voltage regulation with good performance indexes are achieved.