Active Clamp Boost Converter with Blanking Time Tuning Considered

Abstract

An active clamp boost converter with blanking time auto-tuned is presented herein, and this is implemented by an additional auxiliary switch, an additional resonant inductor, and an additional active clamp capacitor as compared with the conventional boost converter. In this structure, both the main and auxiliary switches have zero voltage switching (ZVS) turn-on as well as the output diode has zero current switching (ZCS) turn-off, causing the overall efficiency of the converter to be upgraded. Moreover, as the active clamp circuit is adopted, the voltage spike on the main switch can be suppressed to some extent whereas, because of this structure, although the input inductor is designed in the continuous conduction mode (CCM), the output diode can operate with ZCS turn-off, leading to the resonant inductor operating in the discontinuous conduction mode (DCM), hence there is no reverse recovery current during the turn-off period of the output diode. Furthermore, unlike the existing soft switching circuits, the auto-tuning technique based on a given look-up table is added to adjust the cut-off time point of the auxiliary switch to reduce the current flowing through the output diode, so that the overall efficiency is upgraded further. In this paper, basic operating principles, mathematic deductions, potential designs, and some experimental results are given. To sum up, the novelty of this paper is ZCS turn-off of the output diode, DCM operation of the resonant inductor, and auto-tuning of cut-off time point of the auxiliary switch. In addition, the efficiency of the proposed converter can be up to 96.9%.