Robust voltage-mode control of DC-DC switching converters based on a two-controller scheme

Abstract

The purpose of this paper is to present an analog and robust voltage-mode control loop of buck derived converters, which maintains the crossover frequency and the phase margin of the loop gain much closer to the design goals than the conventional loop, even with large variations of the power stage elements. Furthermore, the proposed scheme can achieve that the power stage seen by the voltage regulator becomes a first order system like current-mode controls do. A 5 V-5 A, 50 kHz buck prototype operating from an input voltage ranging from 15 V to 25 V has been experimentally tested with different LC output filters and load conditions, including discontinuous conduction mode. Small-signal and large signal measurements on the prototype have been carried out, showing the robustness properties achieved by the proposed loop.