Sliding mode control with inductor current observer for interleaved DC-DC converters

Due to their switching behavior, DC-DC converters are inherently variable structure systems. Control laws based on sliding mode theory are therefore widely used, because of their discontinuous nature. Although offering good performance, the downsides of sliding mode control are the requirement of full state information and a variable switching frequency. This paper presents a digital sliding mode controller for a two-phase interleaved buck converter. Rather than a direct current measurement, a sliding mode observer is proposed to digitally reconstruct the inductor currents. Moreover, a constant switching frequency is achieved by synchronizing the pulse-width modulation (PWM) signals to a clock. Simulation and experimental results are provided to demonstrate the functionality and performance of the proposed control scheme and observer.