DC voltage balance control for three-level NPC power converters with even-order harmonic elimination scheme
First Claim
1. A three-level power conversion system, comprising:
- a DC connection for receiving or supplying DC electrical power, the DC connection comprising first and second DC terminals and first and second capacitors coupled in series between the first and second DC terminals, the capacitors being coupled at a common node;
a multi-phase AC connection for receiving or supplying multi-phase electrical power, the AC connection comprising first, second, and third AC terminals, anda three-level switching network comprising;
a first set of switching devices coupled with the DC connection and the first AC terminal, the first set operable in one of three states to selectively electrically couple the first AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a first set of switching control signals,a second set of switching devices coupled with the DC connection and the second AC terminal, the second set operable in one of three states to selectively electrically couple the second AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a second set of switching control signals, anda third set of switching devices coupled with the DC connection and the third AC terminal, the third set operable in one of three states to selectively electrically couple the third AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a third set of switching control signals; and
a switch control system providing the sets of switching control signals by space vector modulation to equalize the voltages across the capacitors in open-loop fashion during operation of the power conversion system;
wherein the switch control system comprises an even-order harmonic elimination space vector modulation system coupled with the three-level switching network, the space vector modulation system providing the sets of switching control signals by space vector modulation according to an even-order harmonic elimination vector switching sequence ensuring half-wave symmetry at all times to balance the voltage at the common node.
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Accused Products
Abstract
Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.
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Citations
19 Claims
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1. A three-level power conversion system, comprising:
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a DC connection for receiving or supplying DC electrical power, the DC connection comprising first and second DC terminals and first and second capacitors coupled in series between the first and second DC terminals, the capacitors being coupled at a common node; a multi-phase AC connection for receiving or supplying multi-phase electrical power, the AC connection comprising first, second, and third AC terminals, and a three-level switching network comprising; a first set of switching devices coupled with the DC connection and the first AC terminal, the first set operable in one of three states to selectively electrically couple the first AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a first set of switching control signals, a second set of switching devices coupled with the DC connection and the second AC terminal, the second set operable in one of three states to selectively electrically couple the second AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a second set of switching control signals, and a third set of switching devices coupled with the DC connection and the third AC terminal, the third set operable in one of three states to selectively electrically couple the third AC terminal to one of the first DC terminal, the second DC terminal, and the common node according to a third set of switching control signals; and a switch control system providing the sets of switching control signals by space vector modulation to equalize the voltages across the capacitors in open-loop fashion during operation of the power conversion system; wherein the switch control system comprises an even-order harmonic elimination space vector modulation system coupled with the three-level switching network, the space vector modulation system providing the sets of switching control signals by space vector modulation according to an even-order harmonic elimination vector switching sequence ensuring half-wave symmetry at all times to balance the voltage at the common node. - View Dependent Claims (2, 3, 4, 5)
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6. A space vector modulation control system for providing switching control signals to a three-level power conversion system having a DC connection with a pair of capacitors connected in series between first and second DC terminals and connected to one another at a common node, the control system comprising:
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driver means for selectively actuating individual switches or pairs of switches in a switching network of the power conversion system for selective coupling of individual AC terminals of the power conversion system to one of the first DC terminal, the second DC terminal, and the common node; and switch control means for controlling the driver means by space vector modulation to ensure half-wave symmetry at all times and to balance the voltages across the capacitors in open-loop operation of the power conversion system. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A vector switching sequence for space vector modulation of a switching network in a three-level power conversion system, the vector switching sequence comprising:
a machine readable medium comprising vector sequence listings for each segment of a space vector modulation diagram defining stationary space vectors representing switching states for the switching network and defining a plurality of sectors positioned around an origin of the space vector modulation diagram, the sectors each having a plurality of triangular segments, each segment defined by a unique set of three space vectors at the corners of the corresponding triangular segment, wherein the individual vector sequence listings define a sequence of switching states corresponding to the three space vectors defining each segment, with the vector switching sequences defined for diagram segments that are symmetrically opposite with respect to the diagram origin comprising symmetrically opposite switching states to ensure half-wave symmetry at all times. - View Dependent Claims (14, 15, 16, 17)
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18. A method for space vector modulation control of a three-level power conversion system, the method comprising:
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providing a space vector modulation vector switching sequence comprising vector sequence listings for each segment of the space vector modulation diagram, the individual vector sequence listings defining a sequence of switching states corresponding to the three space vectors defining each segment, wherein the vector switching sequences defined for diagram segments that are symmetrically opposite with respect to the diagram origin comprise symmetrically opposite switching states; obtaining a reference vector representative of a desired state of the power conversion system; determining a reference vector segment location in a space vector modulation diagram defining space vectors representing switching states for the switching network and defining a plurality of sectors positioned around an origin of the space vector modulation diagram, the sectors each having a plurality of triangular segments, each segment defined by a unique set of three space vectors at the corners of the corresponding triangular segment; and providing switching control signals to the power conversion system to ensure half-wave symmetry at all times according to the vector sequence listing for the reference vector segment location. - View Dependent Claims (19)
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Specification