Three-phase power supply with three-phase three-level DC/DC converter

A three-phase power supply with a three-phase three-level DC/DC converter receiving a three-phase AC voltage, each phase of the three-phase power supply comprising:

• a full-bridge thyristor converter having two thyristors electrically connected in series to each other to convert the AC voltage into a DC voltage;
• a full-bridge rectifier having two power switch elements electrically connected in series to each other to receive and rectify the DC voltage outputted from the full-bridge thyristor converter;
• a full-bridge switching circuit with four series switches including an upper arm and a lower arm, the upper arm having a first power switch element and a second power switch element and the lower arm having a third power switch element and a fourth power switch element to switch the DC voltage into a rectangular voltage, respectively;
• wherein each of the power switch elements has an anti-parallel diode and a parasitic capacitance, respectively;
• an isolated transformer having a primary-side winding and a secondary-side winding, and the primary-side winding electrically connected to the full-bridge switching circuit to receive the rectangular voltage and vary the magnitude of the rectangular voltage according to a turn ratio between the primary-side winding and the secondary-side winding;
• a rectifying circuit electrically connected to the secondary-side winding of the isolated transformer to rectify an output voltage produced from the secondary-side winding;
• and
• a low-pass filtering circuit electrically connected to the rectifying circuit to filter out high-frequency harmonic components of the rectified output voltage of the rectifying circuit and output a DC output voltage;
• whereby the three-level power supply is provided to reduce withstanding voltage of the power switch elements, further zero-voltage switching (ZVS) is achieved by the isolated transformer and the power switch elements to increase the efficiency of the DC/DC converter.