BI-DIRECTIONAL POWER CONVERTER

A bi-directional power converter, a control unit, a charging device and a method for transferring power between an EV and a power grid are provided. The bi-directional power converter includes an isolated DC-DC converter having a first stage converting a DC voltage into a high frequency AC voltage, a second stage capable of converting a high frequency AC voltage having an amplitude V2 into the DC voltage having an amplitude of V2 or 2V2, and converting the DC voltage into a multi-level high frequency AC voltage, and an intermediary stage electrically coupled to the first and the second stages, having a high frequency transformer of a turns ratio V1:V2.