Unified digital sliding mode control with inductor current ripple reconstruction for DC-DC converters

In this paper, a digital implementation of a unified sliding mode controller for DC-DC converters is presented. Although current information is used as a control variable, a pure voltage-mode implementation has been considered and the inductor current ripple is digitally reconstructed. The proposed universal control algorithm can be applied to different converter topologies and operating modes. In particular, experimental results are shown for a prototyping system of a Buck converter operating in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM), where only negligible transient effects are present when changing the operation mode. The presented measurements confirm that the proposed universal control algorithm is capable of achieving tight voltage regulation and excellent dynamic performance under different operating conditions. Additionally, a comparison to a state-of-the-art digital Proportional-Integral-Derivative (PID) controller illustrates the performance improvement of the proposed digital control scheme.