Patent ID: 9190924
Filing Date: 2015-11-17
Classification: H02M

Abstract:
1. An indirect matrix converter comprising: a converter comprising three series circuits connected in parallel, each of said three series circuits being formed of serially connected bidirectional switch means connected in upper and lower arms, a three-phase AC power supply being connected to the junctions between the upper and lower arms of said three series circuits through input filters each including a reactor and parallel capacitors; DC buses including a positive polarity bus provided by an upper arm end of a parallel circuit formed of said three series circuits, and a negative polarity bus provided by a lower arm end of said parallel circuit; and an inverter comprising three series circuits each including upper and lower arms of switch devices connected in such a manner that current flows in the same direction, said three series circuits being connected in parallel with each other between said DC buses, a three-phase load being connected to the junctions between said upper and lower arms of said three series circuits; wherein said indirect matrix converter further comprises: positive polarity voltage-drop means having its one end connected to said positive polarity bus; negative polarity voltage-drop means having its one end connected to said negative polarity bus; a capacitor connected between the other end of said positive polarity voltage-drop means and the other end of said negative polarity voltage-drop means; an upper discharge preventing snubber circuit provided in association with each of said switch devices of said upper arm of said inverter; and a lower discharge preventing snubber circuit provided in association with each of said switch devices of said lower arm of said inverter; a discharge resistor of each of said upper discharge preventing snubber circuits being connected to said other end of said negative polarity voltage-drop means, a discharge resistor of each of said lower discharge preventing snubber circuits being connected to said other end of said positive polarity voltage-drop means.