Current Sensorless Variable Frequency Modulation for Synchronous Buck Converter

Abstract

This paper introduces a current sensorless variable frequency modulation for synchronous Buck converter. The proposed control method realizes zero voltage switching (ZVS) without any zero-crossing detection (ZCD) circuit. The digital control is used in this paper to reduce the complexity of the converter and the sensitivity of sampling noise. In addition, compared with the existing digital variable frequency method with current sensor, the proposed method estimates the inductor current through current observer which can be used in wide load range applications. The expensive current sensors and sampling circuits can be saved, further reducing the cost of the converter. Finally, an experimental prototype with 4SV input and 24V output is built. The experimental results prove the effectiveness and feasibility of the proposed method.