Switched-Resistance Method for Inductor DCR and Switch Parameter Estimation of DC-DC Converter

The estimate of inductor dc resistance (DCR) is required for different aspects of dc-dc converter operation such as power sharing among parallel converters, current-sensorless sensing, and controller tuning. The dc resistance of the inductor within a dc-dc converter also includes trace resistance of the circuit path and switch on-state resistance (
$r_{dson}$
). The latter parameters are intrinsic characteristics of the power converter layout, and hence, a different approach has to be considered to evaluate these parameter's values after fabrication. Due to application-specific constraints (e.g., measuring point accessibility, and variation in operating conditions), the value of non-ideal parameters needs to be estimated indirectly in situ rather than directly measured using a meter. This work presents a generalized method for estimating DCR in dc-dc converters using a series combination of a measuring resistor and a switch (R-Sw). This R-Sw arrangement can be either part of the converter or within a separate meter. Furthermore, it can be used with the existing closed-loop control system to determine not only the inductor DCR but also the switch
$r_{dson}$
and the diode voltage drop, current sharing between parallel connected converter, and multiport converter. The theory of operation, design, and digital implementation aspects of the proposed approach has been presented with respect to single-order dc-dc converter topologies. Experimental results validate the proposed concept of operation.