Peak Current Minimization-Based Optimal Nonlinear Control of a Dual Active Bridge DC-DC Converter

This paper presents the dynamic analysis coupled with the peak-current-minimization-based control of the Dual Active Bridge DC-DC converters (DAB). First, using the first harmonic approximation (FHA) model, the DAB system's zero dynamics, and stability analyses are conducted. The effect of these analyses on the closed-loop controller design is discussed. Based on the results from the zero-dynamic analysis, the input-output feedback linearization approach is employed to design the converter's output voltage controller. Furthermore, an optimal control algorithm is developed using the Lagrange and Karush-Kuhn-Tucker (KKT) conditions to minimize the DAB's inductor peak current. The zero voltage switching (ZVS) analysis of the converter is conducted to determine the ZVS region of the converter based on the results obtained from the optimization analysis. Finally, a 1 kW DAB prototype is built to verify the optimization and control algorithms experimentally.