Hybrid Backstepping Control for DC–DC Buck Converters

Abstract

This paper presents a backstepping control technique in combination with the sliding-mode mechanism for simultaneous control of the capacitor voltage and inductor current in a DC–DC buck converter. The proposed hybrid controller is capable of tackling both the matched and mismatched types of uncertainties like input voltage change and load current variation. The backstepping control can reject both matched and mismatched types of uncertainties, whereas the sliding-mode control is robust against matched uncertainties only. The systematic controller design procedure of backstepping and invariance property of SMC for matched uncertainty have been utilized for robust tracking of both the capacitor voltage and inductor current simultaneously. It is found that by switching between these two different control structures, one exclusively for the matched and the other for the mismatched uncertainties, excellent transient and steady-state performances can be ensured. In the case of backstepping control, performance of the buck converter is largely dependent on design parameters. Hence, these design parameters are judiciously selected to assure optimum performance. Simulation studies have been carried out to verify the effectiveness of proposed hybrid control structure. Transient performances like peak overshoot, peak undershoot, settling time, and also steady-state error have been measured under widely varying changes in input voltage and load current. Simulation results demonstrate that as compared to existing controllers, the proposed hybrid control strategy offers superior transient and steady-state performances.