CN109782074B - Low-frequency sine wave fast response full-parameter estimation method and device - Google Patents
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Abstract
The invention discloses a low-frequency sine wave fast response full parameter estimation method and a device, wherein the method comprises the following steps: at a sampling frequency f0Sampling an original waveform; 4 continuous sampling points from any time are used as input, and the direct current component, the amplitude, the frequency and the phase of the original waveform are calculated and output; and each time a new sampling point is obtained, performing rolling updating on the new sampling point in a first-in first-out mode, and calculating and outputting a new round of direct-current component, amplitude, frequency and phase of the original waveform by taking the updated 4 continuous sampling points as input. The invention uses continuous 4 sampling points at any moment as input to carry out full parameter estimation, and has less parameters to be set and low application requirement.
Description
Technical Field
The invention relates to the technical field of industrial control automation, in particular to a low-frequency sine wave fast response full-parameter estimation method and device.
Background
In the fields of power frequency signal detection, vibration table feedback, vibrated object monitoring, engine monitoring and the like, parameter estimation needs to be carried out on a low-frequency sinusoidal signal, in order to carry out feedback adjustment in time, sometimes the response of the parameter estimation is expected to quickly reflect the real situation of the original signal at the moment rather than being influenced by a plurality of historical waveforms, and meanwhile, due to the consideration of cost and response speed, the addition of pre-processing links such as a filter is also not expected.
The sine wave full parameters comprise 4 parameters of direct current component, amplitude, frequency and phase, and the premise assumptions of the parameter estimation method are different because the focus points concerned by different parameter estimation devices are different.
The separate dc component estimation is usually implemented with a filter. The filter needs to remove all frequencies above 0 hz, leaving 0 hz and is therefore a low pass filter. An ideal dc component measuring device is a low-pass filter with a cutoff frequency infinitely close to 0, but the response speed of the low-pass filter becomes slower as the cutoff frequency approaches 0. The filters used in engineering cannot tolerate too long a response time and therefore only a relatively low empirical value can be selected, resulting in the device not being usable for lower frequency sine wave measurements.
Separate amplitude estimation is typically achieved by measuring peak-to-peak or effective values. The key of peak-to-peak value measurement is to find the position of a peak, before the next peak does not appear, the measuring device can always send the result of the last measurement to an upper computer, the response speed cannot be higher than the frequency of a measured signal, even after the peak appears, because a digital sampling system carries out discrete sampling, the device cannot ensure that the point just sampled is just the peak point, so that discrete sampling errors are caused, the amplitude precision is reflected in the final measurement result, namely, the amplitude precision fluctuates periodically along with time, in addition, the identification of the peak point is difficult, the peak point can be usually identified according to the minimum point of the local maximum value, but under the condition that the waveform period is not obtained, the local definition is unknown; the peak point can also be identified by using the slope turning point, but if the sine wave contains a certain amount of noise, a plurality of small peaks appear near the real peak point, which results in inaccurate identification.
The estimation of the frequency alone is difficult for an arbitrary waveform, and usually, the frequency is obtained by detecting a zero-crossing point on the assumption that the waveform has two sections of monotone rising and monotone falling. Sine waves conform to the assumption, so the method is suitable, but discrete sampling errors can also occur when a digital system performs zero-crossing detection, real zero-crossing time cannot be obtained, for high-frequency sine waves, a method of averaging a plurality of waveforms can be adopted, and high-precision measurement can also be realized by dividing total time by the number of zero-crossing times, but for low-frequency sine waves, enough cycles cannot be obtained within reasonable response time for error averaging.
The phase estimation alone, which can be performed by zero-crossing time method, also faces the same discrete sampling error as the frequency estimation.
In addition to estimating each parameter individually, there is a method capable of estimating a plurality of parameters. For example, 3 parameters except for frequency can be estimated simultaneously by using a least square method, since the frequency cannot be estimated directly, the range of the frequency needs to be known, segmented scanning is performed in the range, the number of segments influences the final calculation accuracy, the least square method is a statistical method, more data needs to be stored and calculated, the method is more suitable for high-accuracy estimation of time-invariant signals, and the response speed is inferior to that of a single algorithm.
The amplitude-frequency characteristic and the phase-frequency characteristic of the sinusoidal signal can be obtained simultaneously by utilizing a discrete Fourier transform method, but because the result obtained by the calculation is related to frequency dispersion, the discrete frequency with the maximum amplitude can only be obtained by scanning as output, the precision is limited by the number of transform points, if the distributed Fourier transform of a classical algorithm is adopted, the precise frequency can be further searched by adopting a bisection method after the maximum frequency is obtained preliminarily, but the performance is limited by a single chip microcomputer, when the single chip microcomputer is realized, the fast Fourier transform is generally adopted, the result on the fixed frequency points of the power of 2 to the power of N can only be obtained, and the further refinement can not be realized.
By analyzing the prior art, a parameter estimation mode based on a digital sampling mode, a single parameter estimation method and the like which do not need peripheral devices are generally not specially designed for sine waves, the universality is strong but the precision is poor, a multi-parameter estimation method needs to measure the frequency in advance, a multi-parameter estimation method needs to scan the frequency, a large number of sampling points need to be obtained, full parameter estimation is obtained in a longer time window through a statistical method, and a method for performing full parameter estimation with quick response capability on low-frequency sine signals is lacked.
Disclosure of Invention
Based on the above problems, the present invention aims to provide a full parameter estimation method and device that does not require a preprocessing process such as scanning, adding dc removal, aligning zero crossing points, etc., which may increase discrete sampling errors or add peripheral devices, or obtain a time window containing multiple waveforms, do not require successive approximation, and have low storage requirements.
The embodiment of the invention provides a low-frequency sine wave fast response full-parameter estimation method, which comprises the following steps: at a sampling frequency f0Sampling an original waveform; 4 continuous sampling points from any time are used as input, and the direct current component, the amplitude, the frequency and the phase of the original waveform are calculated and output; and each time a new sampling point is obtained, performing rolling updating on the new sampling point in a first-in first-out mode, and calculating and outputting a new round of direct current component, amplitude, frequency and phase by taking the updated 4 continuous sampling points as input.
Preferably, the method for calculating the direct current component, the amplitude, the frequency and the phase of the original waveform comprises the following steps:
calculating the direct current component of the original waveform:
let the 4 consecutive sample points input be y1,y2,y3,y4The following equation can be obtained
Solving an equation to obtain a direct current component DC of the original waveform;
wherein DC is the DC component of the original waveform, A is the amplitude of the original waveform, ph is the phase, w is the angular frequency, t0＝1/f0，t0Is the sampling point time interval;
calculating the amplitude of the original waveform:
translating the original waveform to form a first waveform according to a sampling point y1,y2,y3,y4Of arbitrary 3 sampling points yi,yj,ykThe following equation can be obtained
Solving the equation to obtain the amplitude A of the original waveform;
calculating the phase ph and frequency f of the original waveform:
scaling the first waveform to form a second waveform according to a sampling point y1,y2,y3,y4Any 2 sampling points y inl,ymThe following equation can be obtained
Solving the equation to obtain the phase ph of ph1 or ph2, wherein ph1+ ph2 is pi, and the angular frequency w is w1Or w2；
The phases ph1 and ph2 are respectively related to the angular frequency w1、w2Forming 4 combinations, substituting the direct current component DC, the amplitude A, the middle phase ph and the angular frequency w of the 4 combinations into an equation (1), and calculating to obtain 4 groups of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44Selection and sampling point y1,y2,y3,y4Deducing a group of sampling points with the minimum error as an optimal group;
and taking the phase corresponding to the optimal group as the phase ph of the original waveform, and converting the angular frequency corresponding to the optimal group into frequency as the frequency f of the original waveform.
Preferably, after the original waveform is translated to form the first waveform, the original waveform is translated according to a sampling point y1,y2,y3The following equation can be obtained
Solving the equation results in the amplitude a,
preferably, after the first waveform is scaled to form the second waveform, the second waveform is scaled according to the sampling point y1,y2The following equation can be obtained
Solving the equation can obtain the phase ph of ph1 or ph2 and the angular frequency w of w1Or w2Wherein, in the step (A),
preferably, the selection and sampling point y1,y2,y3,y4The method for deriving the optimal set of sample points with the smallest error specifically includes: respectively calculating each group of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44And the sampling point y1,y2,y3,y4To obtain 4 sets of distances d11,d21,d31,d41、d12,d22,d32,d42、d13,d23,d33,d43、d14,d24,d34,d44(ii) a And calculating the sum of squares of each group of distances, and taking the derived sampling points corresponding to the group of distances with the minimum sum of squares as the optimal group.
Preferably, before the outputting the dc component, the amplitude, the frequency and the phase of the original waveform, the dc component, the amplitude, the frequency and the phase of the original waveform are subjected to a smoothing filtering process.
The invention also provides a low-frequency sine wave fast response full-parameter estimation device which comprises a microprocessor and a communication chip, wherein the microprocessor adopts the sampling frequency f0Sampling an original waveform, taking 4 continuous sampling points from any time as input, and calculating and outputting a direct current component, an amplitude value, a frequency and a phase of the original waveform; when a new sampling point is obtained, the new sampling point is updated in a first-in first-out mode in a rolling mode, and the updated 4 new continuous sampling points are used as input to calculate and output the direct current component, the amplitude, the frequency and the phase of the original waveform of a new round;
the method for calculating the direct current component, the amplitude, the frequency and the phase of the original waveform comprises the following steps:
calculating the direct current component of the original waveform:
let the 4 consecutive sample points input be y1,y2,y3,y4The following equation can be obtained
Solving an equation to obtain a direct current component DC of the original waveform;
wherein DC is the DC component of the original waveform, A is the amplitude of the original waveform, ph is the phase, w is the angular frequency, t0＝1/f0，t0Is the sampling point time interval;
calculating the amplitude of the original waveform:
translating the original waveform to form a first waveform according to a sampling point y1,y2,y3,y4Of arbitrary 3 sampling points yi,yj,ykThe following equation can be obtained
Solving the equation to obtain the amplitude A of the original waveform;
calculating the phase ph and frequency f of the original waveform:
scaling the first waveform to form a second waveform according to a sampling point y1,y2,y3,y4Any 2 sampling points y inl,ymThe following equation can be obtained
Solving the equation to obtain the phase ph of ph1 or ph2, wherein ph1+ ph2 is pi, and the angular frequency w is w1Or w2；
The phases ph1 and ph2 are respectively related to the frequency w1、w2Forming 4 combinations, substituting the direct current component DC, the amplitude A, the middle phase ph and the angular frequency w of the 4 combinations into an equation (1), and calculating to obtain 4 groups of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44Selection and sampling point y1,y2,y3,y4Deducing a group of sampling points with the minimum error as an optimal group;
taking the phase corresponding to the optimal group as the phase ph of the original waveform, and converting the angular frequency corresponding to the optimal group into frequency as the frequency f of the original waveform;
the communication chip is electrically connected with the microprocessor and outputs the direct current component, the amplitude, the frequency and the phase of the original waveform calculated by the microprocessor.
Preferably, the digital signal processing device further comprises a digital filter, the digital filter is respectively electrically connected with the microprocessor and the communication chip, and the direct current component, the amplitude, the frequency and the phase of the original waveform calculated by the microprocessor are output by the microprocessor after being filtered by the digital filter.
Preferably, the microprocessor is a single chip microcomputer with the model number of PIC24HJ64GP 506.
Preferably, the communication chip model is ET 1200.
Compared with the prior art, the invention has the following technical effects:
1. the embodiment of the invention utilizes continuous 4 sampling points at any moment as input to carry out full parameter estimation, all parameter estimation is from forward calculation, iteration is not needed, scanning at preset intervals is not needed, the waveform is insensitive to the initial position, special points such as zero crossing points and peak points do not need to be scanned and searched on a time axis, the parameters needed to be set are few, and the application requirement is low.
2. After the direct current component and the amplitude are calculated, the original waveform is translated and zoomed for one time respectively, so that the subsequent calculation is simplified, and the tedious calculation process of directly solving the original equation is avoided.
3. The embodiment of the invention updates the 4 continuous sampling points as input point by point, has small calculation amount and can be realized by a common processor.
Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts. In the drawings:
FIG. 1 is a flow chart of a low-frequency sine wave fast response full parameter estimation method according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating a low-frequency sine wave fast response full parameter estimation process according to an embodiment of the present invention;
FIG. 3 is a diagram of a low frequency sine wave fast response full parameter estimation apparatus according to the present invention.
Detailed Description
The present invention is implemented on the premise of the technical solution of the present invention, and a detailed implementation and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments, and those skilled in the art can modify and revise the method and apparatus without changing the spirit and content of the present invention.
Example 1
Referring to fig. 1, a method for estimating full parameters of fast response of low-frequency sine wave includes the following steps:
s100, sampling frequency f0Sampling an original waveform;
s101, taking 4 continuous sampling points from any time as input, and calculating and outputting a direct current component, an amplitude value, a frequency and a phase of the original waveform;
s102: and each time a new sampling point is obtained, performing rolling updating on the new sampling point in a first-in first-out mode, and calculating and outputting a new round of direct-current component, amplitude, frequency and phase of the original waveform by taking the updated 4 new continuous sampling points as input.
In particular, 4 consecutive sampling points y starting at a certain time1,y2,y3,y4Calculating and outputting the direct current component, amplitude, frequency and phase of the original waveform as input; obtain new sampling point y5Then, the continuous 4 sampling points are updated to be y2,y3,y4,y5And with y2,y3,y4,y5Calculating and outputting the direct current component, amplitude, frequency and phase of the original waveform of the new round as input; and updating 4 continuous sampling points in the same way every time a new sampling point is obtained subsequently, and calculating and outputting the direct current component, the amplitude, the frequency and the phase of the original waveform in a new round by taking the updated continuous sampling points as input.
The input 4 continuous sampling points are refreshed in a rolling mode in real time, the sampling points are insensitive to the initial position on the waveform, special points such as zero crossing points and peak points do not need to be scanned and searched on a time axis, output data are updated and uploaded to an upper computer immediately when a new sampling point is obtained, and the upper computer can obtain parameter estimation with the fastest updating speed theoretically.
As an embodiment, referring to fig. 2, the method for calculating the dc component, the amplitude, the frequency and the phase of the original waveform includes the following steps:
s1011: calculating the direct current component of the original waveform:
let the 4 consecutive sample points input be y1,y2,y3,y4The following equation can be obtained
Solving the equation can obtain the DC component of the original waveform
Wherein DC is the DC component of the original waveform, A is the amplitude of the original waveform, ph is the phase, w is the angular frequency, t0＝1/f0，t0Is the sampling point time interval;
s1012: calculating the amplitude of the original waveform:
translating the original waveform to form a first waveform according to a sampling point y1,y2,y3,y4Of arbitrary 3 sampling points yi,yj,ykThe following equation can be obtained
Solving the equation to obtain the amplitude A of the original waveform;
in this embodiment, the sampling point y1,y2,y3Substituting equation (2) can give the following equation
Namely, it is
Solving the equation to obtain the amplitude
S1013: calculating the phase and frequency of the original waveform:
scaling the first waveform to form a second waveform according to a sampling point y1,y2,y3,y4Any 2 sampling points y inl,ymThe following equation can be obtained
Solving the equation to obtain the phase ph of ph1 or ph2, wherein ph1+ ph2 is pi, and the angular frequency w is w1Or w2(ii) a In this embodiment, the sampling point y1,y2Substituting equation (3) can give the following equation
Namely, it is
Solving the equation can obtain the phase ph of ph1 or ph2 and the angular frequency w of w1Or w2Wherein, in the step (A),
the phases ph1 and ph2 are respectively related to the angular frequency w1、w24 combinations (ph1, w)1)、(ph1，w2)、(ph2，w1)、(ph2，w2) Respectively substituting the DC component DC, the amplitude A and the middle phase ph and the angular frequency w of the 4 combinations into equation (1) based on the combination (ph1, w)1) Calculating to obtain a first set of derived sampling points y11,y21,y31,y41Based on the combination (ph1, w)2) Calculating to obtain a second set of derived sample points y12,y22,y32,y42Based on the combination (ph2, w)1) Calculating to obtain a third group of derived sampling points y13,y23,y33,y43Based on the combination (ph2, w)2) Calculating to obtain a fourth groupDeriving sample points y14,y24,y34,y44Selection and sampling point y1,y2,y3,y4Deducing a group of sampling points with the minimum error as an optimal group;
in this embodiment, each set of derived sampling points y is calculated separately11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44And the sampling point y1,y2,y3,y4To obtain a first set of distances d11,d21,d31,d41A second set of distances d12,d22,d32,d42A third set of distances d13,d23,d33,d43And a fourth set of distances d14,d24,d34,d44Wherein d is11Is a sampling point y11And y1Distance of d21Is a sampling point y21And y2Distance of d31Is a sampling point y31And y3Distance of d41Is a sampling point y41And y4And so on; finally, the sum of the squares of the distances of each group is calculated, taking the first group as an example, the sum of the squares of the distances is
And taking the derived sampling points corresponding to the group of distances with the smallest sum of squares as the optimal group.
And taking the phase corresponding to the optimal group as the phase ph of the original waveform, and converting the angular frequency corresponding to the optimal group into frequency as the frequency f of the original waveform.
As an embodiment, before the outputting the dc component, the amplitude, the frequency and the phase of the original waveform, the dc component, the amplitude, the frequency and the phase of the original waveform are subjected to a smoothing filtering process.
Generally, the direct current component, amplitude, frequency and phase of each calculation output are only related to four corresponding input sampling points, and are not influenced by previous sampling data, and meanwhile, since four independent parameters are estimated theoretically at least four sampling points are needed, a parameter estimation mode which is faster in response than the method cannot exist; when the noise is large and the requirement on the response speed is not high, the output filter is accessed, and the parameters of the output filter are adjusted to carry out smooth filtering processing on the direct current component, the amplitude, the frequency and the phase of the original waveform, so that the response speed and the anti-noise capacity are dynamically and smoothly changed.
All parameters of the embodiment of the invention come from forward calculation of an original waveform, no iteration, no scanning of an artificial preset interval, no addition of a prefilter and no setting of a width window, namely, the number of iterations, the iteration precision, the scanning interval, the prefilter parameters and the windowing width are not required to be preset, and the less the parameters are required to be set, the lower the application difficulty is, and the closer the performances obtained under different occasions are correspondingly.
Example 2
Referring to fig. 3, a low frequency sine wave fast response full parameter estimation device includes a microprocessor and a communication chip, wherein,
the microprocessor sampling frequency f0Sampling an original waveform, taking 4 continuous sampling points from any time as input, and calculating and outputting a direct current component, an amplitude value, a frequency and a phase of the original waveform; when a new sampling point is obtained, the new sampling point is updated in a first-in first-out mode in a rolling mode, and the updated 4 new continuous sampling points are used as input to calculate and output the direct current component, the amplitude, the frequency and the phase of the original waveform of a new round;
the microprocessor is a single chip microcomputer or a digital signal processor, in the embodiment, the microprocessor samples the single chip microcomputer with the model of PIC24HJ64GP506 and is provided with an on-chip ADC (analog-to-digital converter), when the original waveform is sampled, equal-interval sampling is realized by using a timer in the single chip microcomputer, parameter estimation is carried out after conventional calibration calculation is carried out, and the direct current component, the amplitude, the frequency and the phase of the original waveform are calculated;
the communication chip is electrically connected with the microprocessor, outputs the direct current component, the amplitude, the frequency and the phase of the original waveform calculated by the microprocessor, and uploads the direct current component, the amplitude, the frequency and the phase to an upper computer through an Ethercat bus.
In this embodiment, the communication chip is ET 1200.
As an embodiment, the digital filter is respectively electrically connected with the microprocessor and the communication chip, and the direct current component, the amplitude, the frequency and the phase of the original waveform calculated by the microprocessor are output by the microprocessor after being filtered by the digital filter. The digital filter may be selected based on the noise content and response time requirements of a particular application and is not limited to a particular type.
The communication port of the low-frequency sine wave quick response full parameter estimation device CAN be an Ethernet interface, a CAN interface, an RS485 interface and other interfaces which CAN receive and transmit data frames.
The parameter estimation method in the embodiment of the invention does not need pretreatment processes such as direct current removal, zero crossing point alignment and the like, does not need to obtain a time window containing a plurality of waveforms, but directly utilizes results of continuous four-time sampling to calculate to obtain full parameters, the response speed of parameter estimation can be much higher than the frequency of a measured signal, meanwhile, through reasonably selecting the sequence of parameter calculation, the calculated parameters are utilized to carry out simplified transformation on the waveforms, the whole process has no successive approximation, no scanning and small storage requirement, and the whole function can be realized by using a low-cost singlechip and an on-chip ADC.
The disclosure above is only one specific embodiment of the present application, but the present application is not limited thereto, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present application.
Claims (9)
1. A low-frequency sine wave fast response full parameter estimation method is characterized by comprising the following steps:
at a sampling frequency f0To the originalSampling the initial waveform;
4 continuous sampling points from any time are used as input, and the direct current component, the amplitude, the frequency and the phase of the original waveform are calculated and output;
when a new sampling point is obtained, the new sampling point is updated in a first-in first-out mode in a rolling mode, and 4 updated continuous sampling points are used as input to calculate and output a new round of direct current component, amplitude, frequency and phase;
the method for calculating the direct current component, the amplitude, the frequency and the phase of the original waveform comprises the following steps:
calculating the direct current component of the original waveform:
let the 4 consecutive sample points input be y1,y2,y3,y4The following equation can be obtained
Solving an equation to obtain a direct current component DC of the original waveform;
wherein DC is the DC component of the original waveform, A is the amplitude of the original waveform, ph is the phase, w is the angular frequency, t0＝1/f0，t0Is the sampling point time interval;
calculating the amplitude of the original waveform:
translating the original waveform to form a first waveform according to a sampling point y1,y2,y3,y4Of arbitrary 3 sampling points yi,yj,ykThe following equation can be obtained
Solving the equation to obtain the amplitude A of the original waveform;
calculating the phase ph and frequency f of the original waveform:
scaling the first waveform to form a second waveform according to a sampling point y1,y2,y3,y4Any 2 sampling points y inl,ymThe following equation can be obtained
Solving the equation to obtain the phase ph of ph1 or ph2, wherein ph1+ ph2 is pi, and the angular frequency w is w1Or w2；
The phases ph1 and ph2 are respectively related to the angular frequency w1、w2Forming 4 combinations, substituting the direct current component DC, the amplitude A, the middle phase ph and the angular frequency w of the 4 combinations into an equation (1), and calculating to obtain 4 groups of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44Selection and sampling point y1,y2,y3,y4Deducing a group of sampling points with the minimum error as an optimal group;
and taking the phase corresponding to the optimal group as the phase ph of the original waveform, and converting the angular frequency corresponding to the optimal group into frequency as the frequency f of the original waveform.
2. The low frequency sine wave fast response full parameter estimation method of claim 1, wherein after said translating the original waveform to form a first waveform, according to sampling point y1,y2,y3The following equation can be obtained
Solving the equation results in the amplitude a,
3. the method of claim 1, wherein the scaling of the first waveform to form a second waveform is followed by y sampling points1,y2The following equation can be obtained
Solving the equation can obtain the phase ph of ph1 or ph2 and the angular frequency w of w1Or w2Wherein, in the step (A),
4. the low frequency sine wave fast response full parameter estimation method of claim 1, wherein the selection and sampling point y1,y2,y3,y4The method for deriving the optimal set of sample points with the smallest error specifically includes: respectively calculating each group of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44And the sampling point y1,y2,y3,y4To obtain 4 sets of distances d11,d21,d31,d41、d12,d22,d32,d42、d13,d23,d33,d43、d14,d24,d34,d44(ii) a And calculating the sum of squares of each group of distances, and taking the derived sampling points corresponding to the group of distances with the minimum sum of squares as the optimal group.
5. The low-frequency sine wave fast response full parameter estimation method according to claim 1, wherein the dc component, amplitude, frequency and phase of the original waveform are smoothed before outputting the dc component, amplitude, frequency and phase of the original waveform.
6. A low-frequency sine wave fast response full parameter estimation device is characterized by comprising a microprocessor and a communication chip, wherein,
the microprocessor sampling frequency f0Sampling an original waveform, taking 4 continuous sampling points from any time as input, and calculating and outputting a direct current component, an amplitude value, a frequency and a phase of the original waveform; when a new sampling point is obtained, the new sampling point is updated in a first-in first-out mode in a rolling mode, and the updated 4 new continuous sampling points are used as input to calculate and output the direct current component, the amplitude, the frequency and the phase of the original waveform of a new round;
the method for calculating the direct current component, the amplitude, the frequency and the phase of the original waveform comprises the following steps:
calculating the direct current component of the original waveform:
let the 4 consecutive sample points input be y1,y2,y3,y4The following equation can be obtained
Solving an equation to obtain a direct current component DC of the original waveform;
wherein DC is the DC component of the original waveform, A is the amplitude of the original waveform, ph is the phase, w is the angular frequency, t0＝1/f0，t0Is the sampling point time interval;
calculating the amplitude of the original waveform:
translating the original waveform to form a first waveform according to a sampling point y1,y2,y3,y4Of arbitrary 3 sampling points yi,yj,ykThe following equation can be obtained
Solving the equation to obtain the amplitude A of the original waveform;
calculating the phase ph and frequency f of the original waveform:
scaling the first waveform to form a second waveform according to a sampling point y1,y2,y3,y4Any 2 sampling points y inl,ymThe following equation can be obtained
Solving the equation to obtain the phase ph of ph1 or ph2, wherein ph1+ ph2 is pi, and the angular frequency w is w1Or w2；
The phases ph1 and ph2 are respectively related to the frequency w1、w2Forming 4 combinations, substituting the direct current component DC, the amplitude A, the middle phase ph and the angular frequency w of the 4 combinations into an equation (1), and calculating to obtain 4 groups of derived sampling points y11,y21,y31,y41、y12,y22,y32,y42、y13,y23,y33,y43、y14,y24,y34,y44Selection and sampling point y1,y2,y3,y4Deducing a group of sampling points with the minimum error as an optimal group;
taking the phase corresponding to the optimal group as the phase ph of the original waveform, and converting the angular frequency corresponding to the optimal group into frequency as the frequency f of the original waveform;
the communication chip is electrically connected with the microprocessor and outputs the direct current component, the amplitude, the frequency and the phase of the original waveform calculated by the microprocessor.
7. The low-frequency sine wave fast response full parameter estimation device according to claim 6, further comprising a digital filter, wherein the digital filter is electrically connected to the microprocessor and the communication chip, respectively, and the microprocessor outputs the dc component, amplitude, frequency and phase of the original waveform calculated by the microprocessor after the dc component, amplitude, frequency and phase are filtered by the digital filter.
8. The low-frequency sine wave fast response full parameter estimation device according to claim 6, wherein the microprocessor is a single chip microcomputer with model number PIC24HJ64GP 506.
9. The full parameter estimation device of fast response of low frequency sine wave according to claim 6, wherein the communication chip model is ET 1200.
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