Complex wavelet filter based power measurement and calibration system
First Claim
1. A power measurement system comprising:
- a current measurement circuit for measuring a current through a load;
a voltage measurement circuit for measuring a voltage across terminals of the load, wherein the voltage is an AC voltage;
a complex wavelet filter for filtering an output of the current measurement circuit and an output of the voltage measurement circuit to provide complex current output components and complex voltage output components; and
a processor for receiving the complex current output components and the complex voltage output components and generating a load power measurement value, wherein the processor further determines a line frequency calibration value from the complex voltage output components, wherein the line frequency calibration value is indicative of a line frequency of the AC voltage across the terminals of the load.
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Abstract
A power measurement and calibration system provides power and line frequency measurements by using a bandpass filter having complex voltage and current outputs from which real and imaginary power components can be determined. Calibration of the filter may be omitted if a complex wavelet filter is used to implement the bandpass filter and a determination of line frequency can also be provided for downstream use. A processor receiving data from the output of the filter can compute real and imaginary power, power factor and the line frequency. The filter may be implemented by a processor executing program instructions, or a digital circuit implementing the filter and optionally a CORDIC rotator for computing the current-to-voltage phase relationship can provide input to the processor for power measurement and calibration of the sample rate to line frequency relationship and for other uses.
24 Citations
28 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 voltage measurement circuit for measuring a voltage across terminals of the load, wherein the voltage is an AC voltage; a complex wavelet filter for filtering an output of the current measurement circuit and an output of the voltage measurement circuit to provide complex current output components and complex voltage output components; and a processor for receiving the complex current output components and the complex voltage output components and generating a load power measurement value, wherein the processor further determines a line frequency calibration value from the complex voltage output components, wherein the line frequency calibration value is indicative of a line frequency of the AC voltage across the terminals of the load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. 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 complex wavelet filter response to provide complex current output components indicative of real and imaginary portions of the current; second measuring an AC voltage across terminals of the load; second filtering a result of the second measuring with the complex wavelet filter response, to provide complex voltage output components indicative of real and imaginary portions of the AC voltage; and first processing the complex current output components and the complex voltage output components to generate a load power measurement value; and second processing the complex voltage output components to determine a line frequency calibration value indicative of a line frequency of the AC voltage across the terminals of the load. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. An integrated circuit, comprising:
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a current measurement circuit for measuring a current through a load; a voltage measurement circuit for measuring an AC voltage across terminals of the load; a complex wavelet filter for processing an output of the current measurement circuit and an output of the voltage measurement circuit to provide complex current output components and complex voltage output components; and a processor for receiving the complex current output components and the complex voltage output components and generating a load power measurement value, and for processing to the complex voltage output components to determine a line frequency calibration value from the complex voltage output components, wherein the line frequency calibration value is indicative of a line frequency of the AC voltage across the terminals of the load. - View Dependent Claims (27, 28)
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Specification