Method and apparatus of adaptively canceling a fundamental frequency of an analog signal

A method of canceling a fundamental frequency from an analog signal, said method comprising:

• inputting a first analog signal from a powered apparatus;
• outputting a second digital signal;
• employing a digital-to-analog converter comprising an input and an output;
• employing an analog-to-digital converter comprising an input and an output;
• outputting a third digital signal from an adaptive filter as a function of the second digital signal and a plurality of adaptive weights;
• inputting the third digital signal to and outputting a fourth analog signal representative of an estimate of a fundamental frequency component of the first analog signal from said digital-to-analog converter;
• inputting a fifth analog signal to said analog-to-digital converter and outputting from said analog-to-digital converter the second digital signal representative of the first analog signal with the fundamental frequency component removed;
• providing the fifth analog signal as a function of a difference between the first analog signal and the fourth analog signal;
• and
• providing load diagnostics or power quality assessment of said powered apparatus from said second digital signal.

A system comprising:

• a first apparatus including a first analog signal having a fundamental frequency;
• and
• a second apparatus comprising:
• an input structured to input the first analog signal,
• an output structured to output a second digital signal,
• a processor,
• a routine executed by the processor,
• a digital-to-analog converter comprising an input, an output and a delay between the input and the output of the digital-to-analog converter, and
• an analog-to-digital converter comprising an input, an output and a delay between the input and the output of the analog-to-digital converter,
• wherein said digital-to-analog converter is structured to input a third digital signal and output a fourth analog signal representative of an estimate of a fundamental frequency component of the first analog signal,
• wherein said analog-to-digital converter is structured to input a fifth analog signal and output the second digital signal representative of the first analog signal with the fundamental frequency component removed,
• wherein said routine is structured to provide the third digital signal being y(n)=ws(n)*sin(ωon)+wc(n)*cos(ωon),
• wherein said routine is further structured to provide a first adaptive weight being ws(n)=ws(n−1)+μcIF(n−1)xs(n−Δ−1),
• wherein said routine is further structured to provide a second adaptive weight being wc(n)=wc(n−1)+μcIF(n−1)xc(n−Δ−1),
• wherein ωo is frequency of the fundamental frequency component,
• wherein n is an integer representative of a sample number,
• wherein μc is a positive constant,
• wherein IF(n−1) is the second digital signal for the sample number represented by n−1,
• wherein xs(n−Δ−1)=sin(ωo(n−Δ−1)),
• wherein xc(n−Δ−1)=cos(ωo(n−Δ−1)),
• wherein Δ is a sum of the delay of the analog-to-digital converter and the delay of the digital-to-analog converter, and
• wherein said routine is further structured to provide the fifth analog signal being a function of a difference between the first analog signal and the fourth analog signal.

A fundamental frequency cancellation filter comprising:

• a processor comprising:
• an input structured to input a first analog signal,
• an output structured to output a second digital signal,
• a routine,
• a digital-to-analog converter comprising an input, an output and a delay between the input and the output of the digital-to-analog converter, and
• an analog-to-digital converter comprising an input, an output and a delay between the input and the output of the analog-to-digital converter,
• wherein said digital-to-analog converter is structured to input a third digital signal and output a fourth analog signal representative of an estimate of a fundamental frequency component of the first analog signal,
• wherein said analog-to-digital converter is structured to input a fifth analog signal and output the second digital signal representative of the first analog signal with the fundamental frequency component removed,
• wherein said routine is structured to provide the third digital signal being y(n)=ws(n)*sin(ωon)+wc(n)*cos(ωon),
• wherein said routine is further structured to provide a first adaptive weight being ws(n)=ws(n−1)+μcIF(n−1)xs(n−Δ−1),
• wherein said routine is further structured to provide a second adaptive weight being wc(n)=wc(n−1)+μcIF(n−1)xc(n−Δ−1),
• wherein ωo is frequency of the fundamental frequency component,
• wherein n is an integer representative of a sample number,
• wherein μc is a positive constant,
• wherein IF(n−1) is the second digital signal for the sample number represented by n−1,
• wherein xs(n−Δ−1)=sin(ωo(n−Δ−1)),
• wherein xc(n−Δ−1)=cos(ωo(n−Δ−1)),
• wherein Δ is a sum of the delay of the analog-to-digital converter and the delay of the digital-to-analog converter, and
• wherein said routine is further structured to provide the fifth analog signal being a function of a difference between the first analog signal and the fourth analog signal.

A method of canceling a fundamental frequency from an analog signal, said method comprising:

• inputting a first analog signal;
• outputting a second digital signal;
• employing a digital-to-analog converter comprising an input and an output;
• employing an analog-to-digital converter comprising an input and an output;
• inputting a third digital signal to and outputting a fourth analog signal representative of an estimate of a fundamental frequency component of the first analog signal from said digital-to-analog converter;
• inputting a fifth analog signal to said analog-to-digital converter and outputting from said analog-to-digital converter the second digital signal representative of the first analog signal with the fundamental frequency component removed;
• providing a first adaptive filter weight, ws(n), and a second adaptive filter weight, wc(n);
• providing a first digital sine signal, xs(n)=sin(ωon), and a second digital cosine signal, xc(n)=cos(ωon);
• providing the third digital signal being y(n)=ws(n)*sin(ωon)+wc(n)*cos(ωon);
• employing ωo as frequency of the fundamental frequency component;
• employing n as an integer representative of a sample number;
• and
• providing the fifth analog signal as a function of a difference between the first analog signal and the fourth analog signal.