Power conversion system
First Claim
1. A power conversion system comprising:
- a power converter for performing power conversion between plural-phase AC and DC, the power converter including a plurality of legs each having a positive arm and a negative arm connected in series, with a connection point therebetween connected to each phase AC line, the plurality of legs being connected in parallel between positive and negative DC buses; and
a control device for controlling the power converter, whereineach of the positive arm and the negative arm of each leg is composed of at least one converter cells connected in series and including;
a series unit of a plurality of semiconductor switching elements connected in series to each other; and
a DC capacitor connected in parallel to the series unit, a terminal of the semiconductor switching element being used as an output terminal,the control device includes a voltage command generating unit for generating a first voltage command for the positive arm and a second voltage command for the negative arm, to perform output control for each converter cell in the positive arm and the negative arm, andthe voltage command generating unit includes;
a current control unit for calculating control commands for controlling an AC current component flowing through each phase AC line, and a circulating current component for each phase which circulates between the legs; and
a command distributing unit for, on the basis of the control commands and a DC voltage command value for voltage between the DC buses, subtracting voltage drop portions due to inductance values in the positive arm and the negative arm from voltages assigned as outputs of the positive arm and the negative arm, to determine the first voltage command and the second voltage command.
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Accused Products
Abstract
In a power conversion system in which one or more converter cells are connected in series to form an arm for each phase, a control device includes a voltage command generating unit for generating a positive arm voltage command and a negative arm voltage command for each phase. The voltage command generating unit includes an AC current control unit, a circulating current control unit, and a command distributing unit. On the basis of inputted voltage commands, the command distributing unit subtracts voltage drop portions due to inductance values in the arms from respective voltages assigned as outputs of the positive arm and the negative arm, to distribute voltage components, thereby determining the positive arm voltage command and the negative arm voltage command.
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Citations
11 Claims
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1. A power conversion system comprising:
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a power converter for performing power conversion between plural-phase AC and DC, the power converter including a plurality of legs each having a positive arm and a negative arm connected in series, with a connection point therebetween connected to each phase AC line, the plurality of legs being connected in parallel between positive and negative DC buses; and a control device for controlling the power converter, wherein each of the positive arm and the negative arm of each leg is composed of at least one converter cells connected in series and including;
a series unit of a plurality of semiconductor switching elements connected in series to each other; and
a DC capacitor connected in parallel to the series unit, a terminal of the semiconductor switching element being used as an output terminal,the control device includes a voltage command generating unit for generating a first voltage command for the positive arm and a second voltage command for the negative arm, to perform output control for each converter cell in the positive arm and the negative arm, and the voltage command generating unit includes; a current control unit for calculating control commands for controlling an AC current component flowing through each phase AC line, and a circulating current component for each phase which circulates between the legs; and a command distributing unit for, on the basis of the control commands and a DC voltage command value for voltage between the DC buses, subtracting voltage drop portions due to inductance values in the positive arm and the negative arm from voltages assigned as outputs of the positive arm and the negative arm, to determine the first voltage command and the second voltage command. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification