THREE-PHASE MULTI-LEVEL VOLTAGE SOURCE CONVERTER

摘要

PURPOSE: A three-phase multi-level voltage source converter is provided to reduce a harmonic wave of an input current applied to three-phase diode rectification circuit by adding a level converting auxiliary circuit thereto. CONSTITUTION: A three-phase multi-level voltage source converter comprises a main circuit and a level converting auxiliary circuit. The main circuit includes three-phase diode bridge rectification circuits(D1-D6). The level converting auxiliary circuit includes single-phase self-excited converters(G11,G12) and three AC(alternating current) switches(Sa-Sc). The single-phase self-excited converters(G11,G12) operate at a frequency higher than a power source frequency in three times. The three AC switches(Sa-Sc) direct a current toward an opposite direction to a single-phase transformer(TX1). The single-phase self-excited converters(G11,G12) and three AC(alternating current) switches(Sa-Sc) are controlled to produce a square wave of 12 levels.