High Bandwidth Inductor Current Estimator for Digitally Controlled DC–DC Converters for Light Load Applications

This article presents a digital current estimator designed for switching converters operating under light load conditions. The proposed technique can estimate the inductor current for continuous and discontinuous conduction modes of operation with independent gain control for average and ripple components. The impact of inductor parameter tolerance, MOSFET ON-state resistance, and diode forward voltage drop on the estimation are analyzed. The theory of estimation and its implementation on field programmable gate array is detailed. The proposed theory is validated experimentally on a buck converter prototype with an accuracy of 5% on average and 1% on the ripple component. The applicability of the estimation method is verified on a digital current hysteresis-controlled buck converter and unity power factor boost rectifier.