Power conversion device

摘要

A power conversion device includes: a DC current calculation unit for calculating a circulating current component for each phase which circulates between the phases through first arms and/or second arms not via an AC power supply and a DC power supply; and a circulating current control unit for controlling the circulating current component for each phase so as to follow a predetermined circulating current command value, thereby reliably suppressing variation in voltages of DC capacitors of unit cells among the phases even in such a case where an impedance is additionally inserted in a DC circuit.

主权项

1. A power conversion device which is connected between an AC circuit for plural phases and a DC circuit and performs power conversion between the AC circuit and the DC circuit, the power conversion device comprising:
a first arm and a second arm provided for each phase and having one ends connected in series to each other, wherein the first arm and the second arm are each composed of one or a plurality of unit cells connected in series to each other, each unit cell being composed of: a series unit including a plurality of semiconductor switches connected in series to each other; and a DC capacitor connected in parallel to the series unit, a terminal of the semiconductor switch serving as an output end of the unit cell, a connection point between the first arm and the second arm for each phase is connected to a corresponding phase of the AC circuit, another one end of the first arm for each phase is connected to a positive side of the DC circuit, and another one end of the second arm for each phase is connected to a negative side of the DC circuit, the power conversion device further comprising:
circulating current calculation means for calculating a circulating current component for each phase which circulates between the respective phases not via the AC circuit and the DC circuit; anda circulating current control unit for controlling the circulating current component for each phase so as to follow a predetermined circulating current command value, the power conversion device thereby suppressing variation in voltages of the DC capacitors among the phases.