Multiphase Converter with Currentless Sensing Technique

Abstract

This paper proposes an improved current sensing technique for a four-phase buck converter. The proposed technique is based on the conventional parallel voltage sensing with resistor-capacitor (RC) circuit. This technique requires a voltage sensor to be placed in parallel to the phase inductor. In this way, an inductor voltage which consists of high-frequency harmonics is obtained. By using RC circuit, the inductor voltage can be converted into the phase inductor current which is a requirement for the balancing current controller in a four-phase buck converter. The salient points of the proposed sensing technique are no external RC circuit is required, improving the efficiency of the converter and can be used for integrated circuit (IC) in which the conventional RC technique is not capable of. The proposed system is designed using MATLAB/SIMULINK simulation software and verified by a laboratory prototype with a TMS320F28335 as the main controller. The comparison is carried out between the proposed digital RC sensing, the conventional RC filtering sensing and series current sensing technique. Simulation and experimental results are provided to validate the system performance.