Soft-Switching Auxiliary Current Control for Improving Load Transient Response of Buck Converter

Abstract

An auxiliary current control is proposed herein to improve the load transient response of the buck converter. The proposed technique increases the efficiency of the auxiliary converter by employing soft switching. The design guidelines for achieving a capacitor charge balance for the output capacitor during the transition are also presented. The simulation results revealed that the output voltage overshoot and settling time during the load step-down transient were 62 mV and 29.4  μ s, respectively; however, in the case of conventional time-optimal control, these values were 666 mV and 57.2  μ s, respectively, under the same condition. The estimated power loss of the proposed scheme was only 45%–60% of those of the conventional counterparts. The performance and effectiveness of the technique were experimentally verified using a prototype buck converter with a 15 V input, 3.3 V output, and 200 kHz switching frequency.