Model-Based Dynamic Control of Two Degrees-Of-Freedom Modulation for Dual Active Half-Bridge Converter

This paper proposes a model-based dynamic control for dual active half-bridge converters to satisfy both a loss-minimizing operation and a high-dynamic response. First, the loss-minimizing operation is analyzed based on a two degrees-of-freedom (DOF) modulation scheme, where two variables, a phase shift and a duty ratio, are determined to minimize a transformer rms current. The 2-DOF modulation could be changed to the 1-DOF modulation according to operating conditions, where a smooth transition between the modulation schemes is required. Moreover, the output voltage control should be designed to provide fast dynamic performance under source and load variations. Therefore, the voltage controller is unified with the modulation schemes where a model-based control is adopted to lessen the burden of an error compensation part. A model-based calculation part improves the dynamics of the 2-DOF modulation with a load current feedforward. Lastly, the effectiveness of the proposed method is verified by the simulation and experimental results.