Control of a bidirectional dual active bridge converter for charge and discharge of a Li-Ion Battery

This work investigates current control of an isolated bidirectional Phase-Shifted (PS) Dual Active Bridge (DAB) DC-DC converter (270V/28V, 5kW), for an energy storage application based on a 28V Li-Ion Battery. Two control strategies are investigated. First, a nonlinear average-model-based Sliding Mode Controller (SMC) is developed. Then, a model-less Fuzzy Control (FC) is presented and proven to be more suitable for the application. There is two main contributions in this work: (i) No small-signal model is needed in SMC design, neither a DAB model at all is needed for FC, which guarantees the closed-loop system robustness. (ii) Stability analysis has been carried out using Lyapunov´s method for both SMC and FC, in order to derive stability conditions to properly choose FC parameters. Simulation results are presented for both control strategies in order to highlight the advantages and compare the proposed approaches.