A Simple Variable Frequency and Single-Phase-Shifted Control for the Dual Active Bridge Series Resonant Converter

Abstract

Dual-active-bridge series-resonant-converter (DAB-SRC) is widely applied due to its simple circuit structure. A lot of literature has proposed variety kinds of control strategies to ensure the soft switching realization. However, problems such as complex control algorithms, intricate parameter design processes, and a high number of feedback control variables still persist. This article introduced a variable frequency and single-phase-shifted (VF&SPS) control strategy based on the time-domain analysis, which employs only two control variables (frequency and phase-shifted angle) and only two frequently-used feedback variables (output voltage and current). The soft switching region and the gain model are presented by visualization method so the converter's operating region is clear. By establishing a linear function between normalized frequency f _n and the quality factor Q ( f _n = k * Q + b ), the operating track of the converter is restricted and the soft-switching is also ensured even with a constant switching dead-band time. The output is finally regulated by the phase-shifted angle ϕ, which is generated by a proportional integral compensator. The correctness of the theoretical analysis is verified by a 1.2-kW bidirectional prototype with a maximum efficiency of 97.9%.