Patent ID: 8750004
Filing Date: 2014-06-10
Classification: H02M

Abstract:
1. A three-phase inverter device, comprising: a DC voltage source series circuit, formed by series connection of a first DC voltage source and a second DC voltage source; a first terminal connected to a positive-side terminal of the DC voltage source series circuit, a second terminal connected to a negative-side terminal of the DC voltage source series circuit, and a third terminal connected to a connection point of the first DC voltage source and the second DC voltage source; and three switching element series circuits groups, each formed by series connection of positive-side and negative-side semiconductor switching elements, to each of which a diode is antiparallel-connected, one end of each of the switching element series circuits is connected to the first terminal and another end being connected to the second terminal, and each connection point of the positive-side semiconductor switching element and the negative-side semiconductor switching element being a three-phase AC output terminal; wherein the AC output terminal for each phase of the three-phase inverter device is connected via a bidirectional switch to the third terminal; wherein, when the voltage across the first and second terminals of the DC voltage source series circuit is higher than a first prescribed value, the positive-side and negative-side semiconductor switching elements of one of the phases are made non-conducting, the bidirectional switch connecting the AC output terminal for the one phase and the third terminal is made conducting, and the positive-side and negative-side semiconductor switching elements of the other two phases and the bidirectional switches connected to the other two phases are caused to perform switching operation; wherein, when the voltage across the first and second terminals of the DC voltage source series circuit is lower than a second prescribed value, the positive-side and negative-side semiconductor switching elements and bidirectional switches of all phases of the three-phase inverter device are caused to perform a switching operation; and wherein, when the voltage across the first and second terminals of the DC voltage source series circuit is higher than a third prescribed value, the positive-side and negative-side semiconductor switching elements of two phases for which an absolute value of the voltage across the AC output terminals is highest and the bidirectional switches connected to the two phases are caused to perform a switching operation, the positive-side and negative-side semiconductor switching elements of the remaining one phase are made non-conducting, and the bidirectional switch connected to the remaining phase are made conducting.