A Digital Dual-state-variable Predictive Controller for High Switching Frequency Buck Converter with Improved Sigma-Delta DPWM
Résumé
This paper presents a novel digital controller for the high switching frequency buck converter based on the principle of predictive control. Compared to traditional current-mode predictive controller, the prediction of the inductor current and the output voltage are performed at the same time by adding a control variable to the DPWM signal that can dynamically adjust the time of voltage jump. It accelerates the convergence rate during transient states, while inherently preserving the rejection of power and reference perturbations. The analysis of controllers operation illustrates the dual-state-variable predictive attributes that lead to the digital implementation. To further enhance the power efficiency of the controller, an 1-1 MASH - DPWM with a feasible dither generation module is proposed to restrain the idle-tone effects without deteriorating the closed-loop stability as well as to preserve reasonable cost in silicon area. Experimental results verify closed-loop operations at switching frequency up to 4 MHz only limited by the discrete buck converter. The converter is well regulated over a large output range with excellent dynamic performances.