Dual-Active Bridge Sequential Pareto Optimization for Fast Pre-Design and Final Component Selection

A challenge in designing a dual-active bridge (DAB) converter is achieving zero-voltage switching (ZVS) operation and minimal RMS current at all converter operating points together with optimizing all components for identifying the best possible tradeoffs between minimal loss and volume designs. Hence, a sequential Pareto dimensioning of a DAB converter is proposed. In the first Pareto plane, the circuit parameters are optimized for a maximum coverage of ZVS events (considering parasitic nonlinear MOSFET capacitance effects) and minimum RMS bridge currents in the whole operating range. In a second step, the magnetic components are optimized w.r.t. volume and losses and the heat sink is optimized in a third step w.r.t. volume, thermal resistance and surface area using a Pareto plane. This sequential workflow delivers a Pareto plane as a summery of all components to choose the final converter design. The evaluated analytical results are verified by detailed open-source numerical simulations, containing nonlinear SiC-MOSFET output capacitances, nonlinear MOSFET forward characteristics, as well as FEM simulations to verify the magnetic components' properties.