Cascade controller for DC∕DC buck convertor

Abstract

In order to deal with the increasing demand for good load and supply-voltage regulation of DC/DC convertors, a new cascade controller is proposed. The control of DC/DC buck convertor is first decomposed into a primary voltage-control loop and a secondary current-control loop. The cascade controller is then implemented based on the buck-converter settings with the dynamics of the secondary loop much faster than these of the primary loop. A robustness analysis of the cascade controller against load changes and supply changes is presented. Experimental results are included to demonstrate the effectiveness of the proposed control scheme over a conventional single-loop PI controller. The proposed controller can be implemented as a low-cost addon to a conventional single-loop controller. Detail design equations are presented.