Hybrid green uninterruptible power system and bi-directional converter module and power conversion method thereof

A hybrid green uninterruptible power system including an input port, a boost module, a secondary battery, a bi-directional converter module, and an inverter module is provided. The boost module converts an AC utility power into a high voltage DC power. The bi-directional converter module includes a multi-winding transformer for either converting the high-voltage DC power into a low-voltage DC power for charging the secondary battery, or for releasing and boosting the power stored in the secondary battery. The multi-winding transformer further induces an additional DC power when converting the power. Whereby, the hybrid green uninterruptible power system is able to generate the additional DC power all the time and optimizes its energy converting efficiency between the secondary battery and an external device consuming DC power.