| Abstract |
The DC microgird system is one of the potential candidates for future power systems. It could be easily connected with the renewable energies, and further, reduced the power consumptions without additional AC/DC conversion. In addition, the autonomous active distribution DC grid system by using triple-active-bridge (TAB) converter is considered as a high reliable and energy manageable network system. In high DC voltage applications, the pre-charging of DC capacitors in TAB converter is a preliminary mode which limits the inrush current during the power start-up procedure because the semiconductors in TAB are exposed to high surge current during the procedure. In conventional pre-charging method, a simple external circuit consisting of a resistor and a switch is used as a current limiter. However, it consumes additional power due to the resistor In this paper, a smart self-charging method without additional current limiter is proposed for TAB converter in high DC voltage application. The charging current of DC capacitor is programmable to control and shorten the capacitor charging time. Furthermore, the proposed method can smoothly switch the TAB converter from preliminary pre-charging mode to a constant voltage control mode. A 10 kW-TAB converter was made to demonstrate the feasibility. The validity of the method was verified by using the TAB converter under 400 V-input conditions. |
