A simple switching frequency regulated sliding mode controller for a VSI with a full digital implementation

Abstract

This paper describes the design of a first order sliding mode controller for a VSI operating at 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 THD. The implementation methodology using a micro controller preserves all the benefits of a continuous time implementation. Moreover, the paper analyses 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.