Modeling, Analysis, and Design of 48/12V Digitally Controlled Non-Isolated DAB-Type Converters for Automotive and Data Center Applications

In this paper, a discrete-time (DT) framework is proposed in a non-isolated DAB-type two-stage 48-to-12 V converter, which is useful for automotive and data center applications. Using the proposed framework, both DT large-signal and small-signal models are derived. Using SIMPLIS switch simulation, the accuracy of the large-signal DT models is validated at every sampling instants, including the behavior after large-step transients. The DT small-signal is used to analyze the closed-loop stability analysis under digital control. The digital voltage controller is designed using DT small-signal transfer functions. Simulation case studies are presented for a single-stage 24 V to 12 V converter. Further, a simulated load transient case study of the complete two-stage 48 V to 12 V, 48 W is shown to demonstrate a fast dynamic response. Closed-loop steady-state hardware results are presented for a 24 V to 12 V non-isolated DAB-type converter, which shows stable cycle-by-cycle behavior.