Multi-Time Scale Mixed System Modeling and Stability Prediction of Phase-shifted Single-phase Dual Active Bridge DC-DC Converter

A discrete-time model based on the time-scale methodology considering the system losses, including output capacitor equivalent series resistance (ESR) and delay due to the digital control, is established to accurately study the nonlinear dynamics and stability of a DAB converter. Extensive analyses are performed to study the effect of the converter equivalent resistance, transformer leakage inductance, and the output capacitor ESR on the stability boundaries of the control parameters. The proposed model of the digitally controlled DAB converter can accurately predict the stability boundaries, which can be effectively applied to the design of the system parameters and guarantee the stable operation of the converter. The accuracy of the model and the theoretical analyses are validated by simulation and experimental results. The stability analysis is then later verified using simulation and experimental setup.