ADAPTIVE HARMONIC REDUCTION APPARATUS AND METHODS
First Claim
Patent Images
1. A power conversion system, comprising:
- an active rectifier including an AC input circuit with a rectifier input filter, a DC output with first and second DC output nodes, and a plurality of rectifier switching devices coupled between the AC input circuit and the DC output, the rectifier switching devices individually operative according to a corresponding rectifier switching control signal to selectively couple a corresponding AC input node with a corresponding DC output node;
a DC circuit including first and second DC current paths coupled with the first and second DC output nodes of the rectifier;
a PWM controller operative to provide pulse width modulated rectifier switching control signals to the rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; and
a switching angle generator operative to provide the set of rectifier switching angles to the PWM controller, the switching angle generator being operative in a first mode to provide the set of rectifier switching angles to the PWM controller as a set of selective harmonic elimination rectifier switching angles defining a quarter-wave symmetrical selective harmonic elimination switching pattern, the switching angle generator being operative in a second mode to provide the set of rectifier switching angles to the PWM controller as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern based at least partially on source harmonics associated with AC input power received by the rectifier and load harmonics associated with a load driven by the power conversion system, wherein the adaptive harmonic mitigation switching pattern does not have quarter-wave symmetry.
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Abstract
Power conversion systems with active front end converters for example motor drives and power generation systems for distributed energy sources are presented with adaptive harmonic minimization for grid-tie converters for minimized or reduced total harmonic distortion in the line current spectrum including the source harmonic current, the load harmonics and the PWM harmonics.
50 Citations
22 Claims
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1. A power conversion system, comprising:
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an active rectifier including an AC input circuit with a rectifier input filter, a DC output with first and second DC output nodes, and a plurality of rectifier switching devices coupled between the AC input circuit and the DC output, the rectifier switching devices individually operative according to a corresponding rectifier switching control signal to selectively couple a corresponding AC input node with a corresponding DC output node; a DC circuit including first and second DC current paths coupled with the first and second DC output nodes of the rectifier; a PWM controller operative to provide pulse width modulated rectifier switching control signals to the rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; and a switching angle generator operative to provide the set of rectifier switching angles to the PWM controller, the switching angle generator being operative in a first mode to provide the set of rectifier switching angles to the PWM controller as a set of selective harmonic elimination rectifier switching angles defining a quarter-wave symmetrical selective harmonic elimination switching pattern, the switching angle generator being operative in a second mode to provide the set of rectifier switching angles to the PWM controller as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern based at least partially on source harmonics associated with AC input power received by the rectifier and load harmonics associated with a load driven by the power conversion system, wherein the adaptive harmonic mitigation switching pattern does not have quarter-wave symmetry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating an active rectifier in a power conversion system, the method comprising:
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providing pulse width modulated rectifier switching control signals to the active rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; in a first operating mode, providing the set of rectifier switching angles as a set of selective harmonic elimination rectifier switching angles defining a quarter-wave symmetrical selective harmonic elimination switching pattern; and in a second operating mode, providing the set of rectifier switching angles as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern based at least partially on source harmonics associated with AC input power received by the active rectifier and load harmonics associated with a load driven by the power conversion system, wherein the adaptive harmonic mitigation switching pattern does not have quarter-wave symmetry. - View Dependent Claims (15, 16)
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17. A non-transitory computer readable medium with computer executable instructions for operating an active rectifier in a power conversion system, the computer readable medium comprising computer executable instructions for:
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providing pulse width modulated rectifier switching control signals to the active rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; in a first operating mode, providing the set of rectifier switching angles as a set of selective harmonic elimination rectifier switching angles defining a quarter-wave symmetrical selective harmonic elimination switching pattern; and in a second operating mode, providing the set of rectifier switching angles as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern based at least partially on source harmonics associated with AC input power received by the active rectifier and load harmonics associated with a load driven by the power conversion system, wherein the adaptive harmonic mitigation switching pattern does not have quarter-wave symmetry.
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18. A power conversion system, comprising:
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an active rectifier including an AC input circuit with a rectifier input filter, a DC output with first and second DC output nodes, and a plurality of rectifier switching devices coupled between the AC input circuit and the DC output, the rectifier switching devices individually operative according to a corresponding rectifier switching control signal to selectively couple a corresponding AC input node with a corresponding DC output node; a DC circuit including first and second DC current paths coupled with the first and second DC output nodes of the rectifier; a PWM controller operative to provide pulse width modulated rectifier switching control signals to the rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; and a switching angle generator operative to provide the set of rectifier switching angles to the PWM controller as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern that does not have quarter-wave symmetry based at least partially on source harmonics associated with AC input power received by the rectifier and load harmonics associated with a load driven by the power conversion system, the switching angle generator being operative to provide the set of adaptive harmonic mitigation rectifier switching angles in discrete steps using a measured line current hth harmonic component associated with AC current received by the rectifier in a given current step and a switching pattern hth harmonic component associated with switching operation of the active rectifier in an immediately preceding step. - View Dependent Claims (19)
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20. A method of operating an active rectifier in a power conversion system, the method comprising:
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providing pulse width modulated rectifier switching control signals to the active rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; and providing the set of rectifier switching angles as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern that does not have quarter-wave symmetry based at least partially on source harmonics associated with AC input power received by the rectifier and load harmonics associated with a load driven by the power conversion system, wherein the set of adaptive harmonic mitigation rectifier switching angles is provided in discrete steps using a measured line current hth harmonic component associated with AC current received by the rectifier in a given current step and a switching pattern hth harmonic component associated with switching operation of the active rectifier in an immediately preceding step.
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21. A non-transitory computer readable medium with computer executable instructions for operating an active rectifier in a power conversion system, the computer readable medium comprising computer executable instructions for:
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providing pulse width modulated rectifier switching control signals to the active rectifier to cause the rectifier to convert AC electrical input power to provide DC power to the DC circuit according to a set of rectifier switching angles; and providing the set of rectifier switching angles as a set of adaptive harmonic mitigation rectifier switching angles defining a half-wave symmetrical adaptive harmonic mitigation switching pattern that does not have quarter-wave symmetry based at least partially on source harmonics associated with AC input power received by the rectifier and load harmonics associated with a load driven by the power conversion system, wherein the set of adaptive harmonic mitigation rectifier switching angles is provided in discrete steps using a measured line current hth harmonic component associated with AC current received by the rectifier in a given current step and a switching pattern hth harmonic component associated with switching operation of the active rectifier in an immediately preceding step.
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22. A power conversion system, comprising:
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a rectifier comprising an AC input circuit with a rectifier input filter and a plurality of AC input nodes to receive AC electrical input power, a DC output with first and second DC output nodes, and a plurality of rectifier switching devices individually coupled between one of the AC input nodes and one of the first and second DC output nodes, the rectifier switching devices individually operative to selectively couple the corresponding AC input node with the corresponding DC output node according to a corresponding rectifier switching control signal; an intermediate DC circuit comprising first and second DC current paths coupled with the first and second DC output nodes of the rectifier; an inverter comprising an AC output with a plurality of AC output nodes for supplying power to a load, the inverter operative to convert DC power from the intermediate circuit to provide AC electrical output power to the load; a calculator component operative to calculate at least one computed source harmonic value indicative of source harmonics at the AC input of the rectifier based at least partially on a measured power conversion system operating signal or value; and a switch control system with a rectifier control component comprising; a switching angle generator operative to compute a set of rectifier switching angles substantially in real time based at least partially on the at least one computed source harmonic value and on a transfer function of the rectifier input filter, and a PWM controller receiving the set of rectifier switching angles from the switching angle generator and operative to provide pulse width modulated rectifier switching control signals to the rectifier according to the set of rectifier switching angles to cause the rectifier to convert AC electrical input power to provide regulated DC power to the intermediate DC circuit.
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Specification