Implementation of Soft-Switching Auxiliary Current Control for Faster Load Transient Response

Abstract

A control circuit for the auxiliary buck/boost converter was designed and implemented to improve the load transient response of the buck converter. The circuit shapes the auxiliary inductor current in the critical conduction mode through peak current mode control. The soft-switching operation of the auxiliary switches minimizes the power loss and thus increases the efficiency of the auxiliary converter. Along with the design guidelines and estimated power loss to improve the performance of the proposed control technique, the implementation of the control circuit is explained in detail. Simple analog ICs such as operational amplifiers and comparators, and a couple of logic gates suffices the realization of the proposed control. A prototype buck converter whose input voltage, output voltage, and switching frequency were 15 V, 3.3 V, and 200 kHz, respectively were tested with the implemented control circuit to verify the performance of the proposed control technique.

Keywords

• Buck converter
• load transient response
• capacitor charge balance
• critical conduction mode
• peak current mode
• soft switching