Research on Closed-Loop Control of Single-Stage Hybrid Three-Level DAB Type Resonant AC-DC Converter

In order to expand the application of single-stage isolated AC-DC converter and improve its current characteristics, a new topology with half-bridge three-level structure on the AC side is proposed, the working principle and steady-state characteristics of the converter are analyzed in detail based on the three-phase shift modulation strategy, the rms value of the minimum resonant current is realized through the relationship of the three phase-shifting angles. The converter reduces the voltage stress of the AC-side switch to half the AC voltage, helping to reduce power loss and cost. Furthermore, a closed-loop control strategy of grid-side current for proportional resonant complex odd-harmonic repetitive control is proposed., and the grid-side current fundamental component is realized by the proportional resonance controller to achieve static difference closed-loop control of the fundamental component of the grid-side., and the odd-order harmonics of the grid-side current caused by grid voltage harmonics are eliminated by the odd-harmonic repetitive controller. Detailed experimental results verify the correctness and feasibility of the proposed topology and closed-loop control strategy.