A Second Harmonic Voltage Suppression Strategy Based on the Novel Split-Capacitor Three Phase LCL Dual Active Bridge Converter in Single-Phase AC/DC System

It is well-known issue that the inherent double-line-frequency oscillation of DC bus has been occurred in the single-phase voltage source rectifier. To address this issue, bulk aluminum electrolytic capacitor or additional decoupling circuit are employed in conventional method. It will reduce the system lifetime, efficiency and power density. In this paper, a novel split-capacitor three phase LCL dual active bridge (split-capacitor 3ph-LCL-DAB) converter with corresponding second harmonic voltage suppression strategy has been proposed. This novel topology and control scheme divert the ripple power to the resonant split-capacitor branch without additional decoupling circuit. Tanks to the split-capacitor structure and novel control method, the DC link capacitor has no need for absorbing the massive double-line-frequency fluctuating power. The double-line-frequency oscillation of DC bus will be mitigated. The capacitance value of DC bus has been decreased significantly and power density improved greatly. The simulation results verify the effectiveness of proposed topology and scheme.