AC-DC-DC isolated converter with bidirectional power flow capability

A novel AC-DC-DC isolated converter with bidirectional power flow capability is proposed and studied. The proposed structure consists of a three-phase current source converter and a special DC-DC isolated converter. In this DC-DC converter, the primary side of the high-frequency transformer is a current source converter and the secondary side is a voltage source converter. Based on this novel topology, a simple and efficient control strategy using the voltage of the inductor in the DC-side to control the current of the AC-side is presented. The feature of the bidirectional power flow allows the converter to provide energy as a power source or to regenerate power back to the AC power grid with high overall energy efficiency. Another feature of this converter is that the DC-side current and voltage can be regulated in a wide range from zero to the rating value. Furthermore, the AC-side current and voltage have low total harmonic distortion and unit power factor in a wide output power range. The operation of the proposed topology and control scheme are confirmed by the experimental results on a 10-kW design example.