Control of three-phase single-stage isolated buck+boost unity power factor rectifier for unbalanced input voltages

A single-stage structure is proposed for realizing a unity power factor three-phase isolated AC-DC converter for telecommunication power supply modules. This structure is composed by integrating a boost converter to the isolated three-phase three-switch buck rectifier. Modified space vector modulation method is applied to the three-phase three-switch isolated unity power factor input buck rectifier based on the space vector modulation for non-isolated buck. The output boost switch operates during heavily unbalanced mains conditions. Input currents are sinusoidal and in phase with the input voltages even for heavily unbalanced input voltages, e.g. loss of one phase. The converter is modeled by a DC-DC equivalent circuit. This model is used for controller design in a multi-loop control structure. The structure is verified by numerical simulation of a 6kW, 380V/48Vdc designed example.