Patent ID: 7061777

Claim:
An input stage circuit of a three-level DC/DC converter, coupled to a primary side of a transformer, comprising: a positive input terminal and a negative input terminal, coupled to an input voltage; a first switch module, coupled between the positive input terminal and a first terminal of the primary side, controlling the connection and disconnection between the input voltage and the transformer; a second switch module, coupled to the negative input terminal and the first terminal of the primary side, controlling the connection and disconnection between the input voltage and the transformer; a first voltage-dividing capacitor, coupled between the positive input terminal and a second terminal of the primary side; a second voltage-dividing capacitor, coupled between the negative input terminal and the second terminal of the primary side; a flying capacitor, coupled between the first switch module and the second switch module; a pair of freewheeling diodes, respectively coupled between the two terminals of the flying capacitor, and the second terminal of the primary side; and a discharging module, coupled between the flying capacitor and the second terminal of the primary side, discharging the flying capacitor.