DC power transmission system of voltage source converter using pulse-interleaving auxiliary circuit

A converter system comprising:

• an IGBT converter for converting an AC power to a DC power or the DC power to the AC power;
• an open Y-Y transformer and a Y-Δ transformer for stepping up or stepping down the AC power having a predetermined magnitude;
• a capacitor for dividing a DC voltage;
• and
• a DC auxiliary circuit comprising a normal transformer and a half-bridge for overlapping a pulse type input voltage to increase the number of pulses of an output waveform,
• wherein the IGBT converter comprises a first converter connected to the Y-Y transformer and a second converter connected to the Y-Δ transformer,
• the capacitor comprises a first DC capacitor connected between a primary side terminal of the transformer of the DC auxiliary circuit and a positive terminal of the first converter, and a second DC capacitor connected between the primary side terminal of the transformer of the DC auxiliary circuit and a negative terminal of the second converter, and
• the half-bridge of the DC auxiliary circuit comprises a 3-level half-bridge consisting of first through fourth switching elements connected to the first DC capacitor and the second DC capacitor in parallel and connected to secondary side terminals of the transformer.