Comprehensive GSSA and D-Q frame dynamic modeling of dual-active-bridge DC-DC converters

Dynamic modeling and control of DC–DC power converters require formulations capable of capturing nonlinearity, harmonic interaction, and control sensitivity under fast-switching and bidirectional power flow. The two-level dual-active-bridge (2L-DAB) converter exemplifies such challenges, especially under phase-shift modulation schemes used for galvanically isolated energy transfer. To address these issues, three complementary modeling frameworks are developed: a switching model in the time domain, a rotating-frame formulation based on the DQ transformation, and a generalized state-space averaging (GSSA) model that incorporates fundamental and harmonic components through frequency-domain decomposition. Each formulation enables a different perspective—ranging from intuitive time-domain dynamics to harmonic coupling behavior—while providing a foundation for control system design. Small-signal linearizations yield control-to-output transfer functions used for loop-shaping via proportional-integral (PI) compensators. A modified phase margin criterion is employed to guarantee dynamic stability and robustness. Comparative simulation results under reference and load disturbances demonstrate the distinct advantages of each model, with the GSSA approach excelling in harmonic accuracy and the DQ-based model offering streamlined controller implementation. These tools offer a robust methodology for high-fidelity analysis and design of high-performance DAB-based systems.