Fast Integral Terminal Sliding Mode Control Based Current Sensorless Scheme of DAB Converter

Dual active bridge (DAB) converters are essential in applications such as EV charging and DC microgrids, yet they are prone to output voltage instability caused by changes in input voltage and loading conditions. To counter these issues, this paper introduces a Fast Integral Terminal Sliding Mode Control (FITSMC) that enhances the dynamic performance of DAB converters. This control strategy uses a FITSM surface to ensure fast error convergence and high tracking accuracy despite parameter uncertainties and significant disturbances. Additionally, a higher-order sliding mode observer (SMO) with adaptive observer gain is developed to precisely estimate the varying load current for a wide range. The estimated load current is considered as disturbance and compensated in proposed control law. Furthermore, The paper demonstrates closed-loop stability and finite-time convergence through Lyapunov stability theory. Experimental results confirm the superior performance of the proposed control against output and input voltage disturbances, sudden load shifts, and parametric variations. A comparative analysis is also included to highlight the advancements over existing sliding mode controls of DAB converter.