Patent ID: 9136775
Filing Date: 2015-09-15
Classification: H02M

Abstract:
1. A control method for controlling a multilevel power conversion circuit for converting DC power to AC power or AC power to DC power, one phase portion of the power conversion circuit including: a first semiconductor switch series circuit that is connected between a positive terminal and a negative terminal of a DC power supply system having the positive terminal, the negative terminal, and a middle terminal, and composed of at least series-connected six semiconductor switches each having an anti-parallel-connected diode; a first capacitor that is connected in parallel to a series circuit of two semiconductor switches connected to a middle point of the first semiconductor switch series circuit; a second capacitor that is connected in parallel to a series circuit of four semiconductor switches, two of which are in a one side of a middle point of the first semiconductor switch series circuit and two of which are in the other side of the middle point of the first semiconductor switch series circuit; a second semiconductor switch series circuit that is connected in parallel to the second capacitor and composed of at least series-connected four semiconductor switches each having an anti-parallel connected diode; a third capacitor that is connected in parallel to a series circuit of two semiconductor switches each connected to a middle point of the second semiconductor switch series circuit; and a bidirectional switch that is connected between the middle point of the second semiconductor switch series circuit and the middle terminal of the DC power supply system and is capable of bidirectional switching, the method comprising: delivering a predetermined switching pattern of semiconductor switches when a potential at the middle point of the first semiconductor switch series circuit, the middle point being an AC terminal, changes from a positive side potential through a middle point potential to a negative side potential of the DC power supply system, or from the negative side potential through the middle point potential to the positive side potential, wherein a period of time for delivering the predetermined switching pattern is shorter than one carrier period of pulse width modulation control.