Power meter having complex quadrature output current and voltage filters
First Claim
1. A power measurement system comprising:
- a current measurement circuit for measuring a current through a load;
a first bandpass filter having a bandpass filter response formed by two or more filter stages each having a single complex pole, wherein the poles of each of the stages have a frequency relationship in the complex plane other than a conjugate frequency relationship, wherein the first bandpass filter has an input coupled to an output of the current measurement circuit and provides complex current output components having a substantially quadrature phase relationship throughout a pass-band of the first bandpass filter, and wherein the first bandpass filter response rejects one of a positive or a negative half of a complex frequency spectrum;
a voltage measurement circuit for measuring a voltage across terminals of the load;
a second bandpass filter having a response substantially identical to the bandpass filter response, wherein the second bandpass filter has an input coupled to an output of the voltage measurement circuit and provides complex voltage output components having a substantially quadrature phase relationship throughout a pass-band of the second bandpass filter; and
a processing system for receiving the complex current output components and the complex voltage output components and providing at least one indication of a power provided to the load.
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Accused Products
Abstract
A power meter having complex quadrature output current and voltage filters provides power measurements in high amplitude and frequency variation and/or high jitter environments without requiring high computational overhead. A pair of filters, one for voltage and one for current each have a response determined by complex non-conjugate poles. The response of the filters is such that only the positive or negative half plane of the complex frequency spectrum is passed and provide complex outputs representing the real and imaginary parts of both the current and voltage. At least one indication of a power delivered to a load is computed from the complex current and voltage outputs, which may be the real and/or reactive power.
26 Citations
21 Claims
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1. A power measurement system comprising:
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a current measurement circuit for measuring a current through a load; a first bandpass filter having a bandpass filter response formed by two or more filter stages each having a single complex pole, wherein the poles of each of the stages have a frequency relationship in the complex plane other than a conjugate frequency relationship, wherein the first bandpass filter has an input coupled to an output of the current measurement circuit and provides complex current output components having a substantially quadrature phase relationship throughout a pass-band of the first bandpass filter, and wherein the first bandpass filter response rejects one of a positive or a negative half of a complex frequency spectrum; a voltage measurement circuit for measuring a voltage across terminals of the load; a second bandpass filter having a response substantially identical to the bandpass filter response, wherein the second bandpass filter has an input coupled to an output of the voltage measurement circuit and provides complex voltage output components having a substantially quadrature phase relationship throughout a pass-band of the second bandpass filter; and a processing system for receiving the complex current output components and the complex voltage output components and providing at least one indication of a power provided to the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of measuring electrical power supplied to a load, comprising:
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first measuring a current through the load; first filtering a result of the first measuring with a bandpass filter response formed by two or more filter stages each having a single complex pole, wherein the poles of each of the stages have a frequency relationship in the complex plane other than a conjugate frequency relationship, to provide complex current output components having a substantially quadrature phase relationship throughout a pass-band of the first bandpass filter; second measuring a voltage across terminals of the load; second filtering a result of the second measuring with the bandpass filter response, to provide complex voltage output components having a substantially quadrature phase relationship throughout a pass-band of the second bandpass filter; and processing the complex current output components and the complex voltage output components to compute at least one indication of a power provided to the load. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A power measurement system comprising:
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a current measurement circuit for measuring a current through a load; a first analog-to-digital converter for converting an output of the current measurement circuit to a digital current value; a voltage measurement circuit for measuring a voltage across terminals of the load; a second analog-to-digital converter for converting an output of the voltage measurement circuit to a digital voltage value; and a digital signal processing system that receives the digital current value and the digital voltage values and filters each of the digital current value and the digital voltage value with a bandpass filter response formed by two or more filter stages each having a single complex pole, wherein the poles of each of the stages have a frequency relationship in the complex plane other than a conjugate frequency relationship, wherein the bandpass filter response rejects one of a positive or a negative half of a complex frequency spectrum, and generates complex output components having a substantially quadrature phase relationship throughout a pass-band of the filtering and wherein the digital signal processing system combines a result of the filtering of the digital current value and a result of the filtering of the digital voltage value to determine an indication of a power provided to the load.
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21. A computer program product comprising computer readable storage media containing program instructions for execution by a digital signal processing core, the program instructions including program instructions for:
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first receiving a representation of a current through a load; first filtering a result of the first measuring with a a bandpass filter response formed by two or more filter stages each having a single complex pole, wherein the poles of each of the stages have a frequency relationship in the complex plane other than a conjugate frequency relationship, to provide complex current output components having a substantially quadrature phase relationship throughout a pass-band of the first filtering; second receiving a representation of a voltage across terminals of the load; second filtering a result of the second measuring with the bandpass filter response, to provide complex voltage output components having a substantially quadrature phase relationship throughout a pass-band of the second filtering; and processing the complex current output components and the complex voltage output components to compute at least one indication of a power provided to the load.
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Specification