Extended State Observer Based Second Order Sliding Mode Control Strategy for DC-DC Buck Converters

The parametric uncertainties and external disturbances in the buck converter would cause degradation of the control performance. In this paper, a disturbance observer based second order sliding mode (SOSM) control strategy for buck converter is proposed to solve this problem. The double-loop control strategy is set up to force the output voltage and inductor current to their references. The load variation which significantly influences the control performance can be considered as the external disturbance. The parametric uncertainty of the capacitor and the load variation are estimated by an extended state observer (ESO), and the parametric uncertainty of the inductor is dealt by the SOSM controller. The strategy has good tracking performance and disturbance rejection ability against parametric uncertainties and external disturbances. Simulation results verifies the performance of the presented control strategy.