Nonsmooth Current-Constrained Control for a DC–DC Synchronous Buck Converter with Disturbances via Finite-Time-Convergent Extended State Observers

• Main Authors: Qiqing Miao, Zhenxing Sun, Xinghua Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Electronics
• Subjects: dc–dc synchronous buck converter; nonsmooth control; current-constrained control; finite-time extended state observer
• Online Access: https://www.mdpi.com/2079-9292/9/1/16

This study investigates the problem of overlarge current protection for a DC−DC synchronous buck converter with the existence of uncertainties and disturbances. Aiming to deal with the hardware damage in the electric circuit of a DC−DC buck that may be caused by overlarge transient current, a new nonsmooth current-constrained control (NCC) algorithm is proposed to replace the traditional ones, which use conservative coefficients to satisfy current constraint, leading to a sacrifice of dynamic performance. Based on the homogeneous system technique, a nonsmooth state feedback controller is improved by adding a penalty term that prompts the adaptive gain of the controller according to the inductor current and current constraint. Then by using two finite-time extended state observers (FTESO), the unmatched disturbances and matched disturbances can be compensated to enhance the robustness of the DC−DC synchronous buck converter. The effect of proposed scheme has been verified by experimental results.