Eliminating Current Sensor Dependencies in DAB Converters Using a Luenberger Observer-Based Hybrid Approach

A robust and sensorless control strategy is presented for dual active bridge (DAB) converters for electric vehicle (EV) charging application. In this paper, the Luenberger Observer-based sliding mode control has been developed. The observer successfully estimated the load current, retaining the benefits of sliding-mode control. Moreover, the observer has been modified to suppress the double-line frequency ripple at the output of the DAB converter when integrated with a single-phase AC-DC converter. This paper delves into a detailed mathematical modeling of DAB converters utilizing reduced-order models to minimize computational complexity. The modeling is accompanied by a detailed stability analysis. This paper provides comprehensive guidelines for controller design and parameter selection. To validate the proposed theoretical framework, a hardware prototype was developed in the laboratory, which was subjected to various experimental scenarios, including load variations, parametric changes, and cascade architecture. The experimental results confirm the effectiveness and robustness of the proposed control strategy.