A Load-Current-Estimating Scheme With Delay Compensation for the Dual-Active-Bridge DC–DC Converter

The dual-active-bridge (DAB) dc–dc converter is a promising candidate for the isolated dc–dc power transferred applications, such as in the dc distribution system, the solid-state transformer, and the energy storage system. In these applications, the fast-dynamic response is usually a core requirement, especially under load changes. To improve the dynamic performance of the DAB dc–dc converter, this article proposes a simple load-current-estimating (LCE) scheme with delay compensation for fast dynamic performance. Based on the current flowing model of the DAB dc–dc converter, the LCE strategy is proposed with single-phase-shift modulation method. Moreover, the inherent switching-period delay phenomenon of the LCE scheme is analyzed. Therefore, the corresponding delay compensation method is proposed for further boosting dynamic responses, and the dynamic limitation of the LCE scheme may be obtained for DAB dc–dc converter. Then, for the proposed LCE scheme, a damping coefficient is introduced to restrict the potential instability caused by the measurement noise, and the fast-dynamic response will be influenced a little when the load resistor is changed. In addition, the extended rule for the optimized triple-phase-shift modulation method is discussed. Finally, the simulation result and the experimental result both validate the fast-dynamic performance of this proposed LCE strategy without or with delay compensation.