Digital PWM-based boundary control for boost converter with exact feedback linearisation modelling

Abstract

ABSTRACT In this paper, a digital pulse width modulation (PWM)-based boundary control (BC) for boost converter is proposed. Compared to existing BC methods for boost converter, the proposed method utilises the exact feedback linearisation model and employs PWM technique to realise a fixed switching frequency and a low sampling rate simultaneously. Firstly, based on the linearised model of boost converter, we derive a near-time-optimal switching surface (SS) and verify the existence of sliding-mode motion on this SS. It means that the reaching law method can be used to derive the discrete-time BC. Then, by combining the first-order and near-time-optimal SS, a practical digital BC is derived. Due to the employment of PWM technique, a fixed switching frequency and a low sampling rate are realised. Moreover, the effects of model mismatch and the problems in starting process are discussed. An integral compensation method for eliminating steady-state errors and a current-limiting control are proposed accordingly. Experimental results are given to verify the effectiveness and high dynamic performance of the proposed BC method.