CN1276262C - Current sensor - Google Patents
Current sensor Download PDFInfo
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- CN1276262C CN1276262C CN 03159359 CN03159359A CN1276262C CN 1276262 C CN1276262 C CN 1276262C CN 03159359 CN03159359 CN 03159359 CN 03159359 A CN03159359 A CN 03159359A CN 1276262 C CN1276262 C CN 1276262C
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Abstract
The sensor is provided with an air-core coil 1 for detecting a current under measurement, an A/D converter 2 for quantizing an output signal of the coil 1, and a digital processor 20 having an integrator 4 for integrating equalized data of the A/D converter 2 and a high-pass filter 3 for passing only high frequency components of output data of the integrator 4 to output an electric quantity proportional to the current under measurement. The processor 20 has a function for multiplying the difference value between the input and output signals of the high-pass filter 3 by a fixed factor and adding the result to the input of the integrator 4.
Description
Invention field
The present invention relates to the current sensor that test section uses air core coil.
Background technology
As this current sensor current sensor in non-patent literature 1 on the books.This current sensor adopts Rogowski coil (a kind of air core coil) as current detecting part.It is unshakable in one's determination as core that so-called Rogowski coil is that a kind of employing insulant replaces, again on this core around on the coil of secondary coil.And, in order to be varied to the signal that output voltage turns back to primary current is directly proportional of direct ratio with time primary current from the Rogowski coil is that obtain, to have adopted with DC skew and removed the formation that circuit and incomplete integrator carry out digital operation via the A/D transducer.Constant is 1 second during the discharge of this incomplete integration.
The value of primary current is when maximal value (phase place 90 degree), and air core coil is output as 0, after this Shu Chu sign-inverted.By it is carried out integration, recover the primary current waveform.
[non-patent literature]
Mitsubishi Electric's skill newspaper, Vol.75, No.8, calendar year 2001 (p.31～36).
Usually, when the input of integrator contains flip-flop, because with integrator this composition of addition continuously, the value in the integrator is just dull to be increased or dull the minimizing, can not carry out current measurement correctly because integrator is saturated.Here said DC composition has 2 classes, i.e. the DC composition of input signal follows the ON/OFF of primary current and phase change etc. to accumulate on DC composition in the integrator.
The DC composition of input signal is because the influence of the influence of the influence of power circuit, peripheral equipment, the mimic channel till from air core coil to the A/D transducer etc., and the earth potential of input signal changes and causes.
The DC composition of accumulation is because the phase place of primary current produces when sharply changing in the integrator.The phase place moment ground of primary current took place sharply to change when for example, load capacious inserted.As an example, when primary current was maximal value, the value in the integrator be maximum, but this state next time the phase change 180 of electric current spend, just be expressed as the situation of minimum value.
The sign-inverted of original air core coil output should be that the center changes with 0 by the value of subtracting each other in the integrator, but because the current phase of determination object changes, and the symbol of air core coil output is nonreversible, the value in the integrator increases.Value in the integrator when that is to say the phase change that becomes primary current is the change of benchmark.This with integrator in the accumulation equivalence of DC composition, arrives saturated nargin (scope of integrator and DC composition poor) and diminishes, often saturated owing to the value of primary current.
For taking countermeasure, adopt the DC skew to remove circuit and remove the contained DC composition of input signal in the prior art the DC composition.Yet under the situation that the DC of input signal composition changes, the DC skew remove circuit before arriving convergence between, the DC composition is input to incomplete integrating circuit by the DC off-centre circuit.For removing this DC composition, carry out incomplete integration in the prior art, be designed so that the signal of importing decays with the time, become 0 after 1 second kind.Saturated countermeasure as above integrator must 2 grades of treatment circuits.
In addition, constant ground discharge (owing to being incomplete integration) can not correctly apply Integral Processing when having owing to integrator, can not obtain the signal that precision is directly proportional with primary current well.Output waveform after the digital integration is continuously made in the output of A/D transducer, and its phase place by leading, but does not apply all countermeasures with respect to waveform in the above-mentioned prior art.
The present invention does for solving above problem, and its purpose is to obtain following the current sensor that primary current changes rapidly.In addition, its purpose is to obtain the current sensor little with respect to the phase deviation of primary current.
Summary of the invention
Current sensor of the present invention, comprise the air core coil of detection assay to image current, the A/D transducer that the output signal of this air core coil is quantized, and have quantized data to this A/D transducer and carry out the integrator of integration and the radio-frequency component of the output data by integrator only, the digital processes of the Hi-pass filter of output and the proportional electric weight of determination object electric current, described digital processes has the function that difference value with the input signal of Hi-pass filter and output signal multiply by certain coefficient and is added to the input end of integrator, and the certain coefficient value that multiply by described difference value is less than 1.
Description of drawings
Fig. 1 illustrates the pie graph of the current sensor of example 1 of the present invention.
Fig. 2 illustrates the processing flow chart of example 1.
Fig. 3 illustrates the pie graph of major part of the current sensor of example 2 of the present invention.
Fig. 4 illustrates the graph of a relation of the primary current phase place and the phase place behind the integration of example 2.
Fig. 5 illustrates the pie graph of major part of the current sensor of example 3 of the present invention.
Fig. 6 illustrates the processing flow chart of example 3.
Specific implementation method
Example 1
Fig. 1 illustrates the current sensor of example 1 of the present invention, the output signal of the air core coil 1 of the voltage that is directly proportional with the variable quantity of its time is also exported in detection as the primary current of determination object, by the sample quantization of A/D transducer 2, offer the digital processes 20 that the data after quantizing are carried out digital processing.
By above-mentioned formation, specifically, detect the variable quantity of primary current with air core coil.The analog voltage signal of this air core coil output is input to the A/D transducer, the transducer digital value.Numerical data after the conversion is handled by digital processes 20, obtains and the proportional electric weight of the primary current of said determination object as output.
A/D transducer 2 is the digital processing of being undertaken by software later.The flow process of processing is described with reference to Fig. 2.The electric weight (S1) that utilizes air core coil 1 to detect to be directly proportional with primary current quantizes by the sampled analog signal with A/D transducer 2, is transformed into digital signal (S2).At this moment, in simulating signal output, during overlapping DC composition, when merely carrying out continuous integration, will exceed integrator 4 treatable scopes (saturated), can not obtain correct signal.For remove this DC composition from integrator 4, apply the processing (S6) of the difference value of feedback input signal of Hi-pass filter 3 and output signal.The initial value of the difference value of feedback is set to 0, will be worth with the output signal of A/D transducer 2 by adder 7 and carry out addition (S3).
Secondly, the processing of multiply by certain coefficient by the difference value of the input signal of 6 pairs of Hi-pass filters 3 of coefficient times quadrupler and output signal.Like this, the DC composition in the integrator 4 little by little is removed, and makes the DC composition converge on 0.
Secondly, carry out continuous integration by integrator 4 and handle (S4).Specifically, the initial value of establishing integrator is 0, adds that successively the input data (detecting data+differential data) of each sampling obtain output.
Secondly, keep the output of integrator 4, calculate the difference value (S6) of the output of described output and Hi-pass filter 3.
Secondly, by applying Hi-pass filter 3, from the output (integral result) of integrator 4, remove DC composition (S5).
Secondly, from the result who obtains by Hi-pass filter 3, deduct the value that output kept as described integrator 4.This difference result be multiply by value behind certain coefficient (S7) by the output addition (S3) of addition process device 7 with the A/D transducer 2 of prime.
But certain coefficient settings that will multiply each other with described difference value is than 1 little value.Be preferably the value of using less than 0.5.By using the value less than 1 to be used as coefficient, the DC compositions in the integrator 4 little by little converge on 0.
This is a few hours, and the DC composition in the integrator 4 is longer to the time that converges on 0.Otherwise coefficient approached 1 o'clock, and convergence is fast, if but too big (being in close proximity to 1 numeral), then the DC compositions do not converge on 0 and vibrate in the integrator 4.
Current sensor of the present invention is to apply sub-Hi-pass filter 3 to the output of integrator 4, or applies the value of the processing of some.
The shown feature of the present invention of this example is that whole processing of the back level of A/D transducer are all carried out in the digital processing mode by digital processes 10, but also can consider by the whole function of analog circuitry processes in addition.Also can consider to change the position of inserting A/D transducer 2 in addition, use analog circuitry processes before the A/D transducer 2, the back level of A/D transducer 2 is handled and is carried out digital processing.
Hi-pass filter 3 then also can be such formation if any the function of removing the DC composition.
According to the prime Hi-pass filter that can remove in the prior art necessary integrator 4 of the present invention, there is not any problem certainly but Hi-pass filter is set in the prime of integrator 4 yet.
In this example, the A/D transducer is directly imported in the output of air core coil 1, but also can insert the low-pass filter that is used for tackling surge betwixt.That is, this example 1 not delimit the scope of the invention, and except test section adopts the air core coil function later with having above-mentioned A/D transducer 2, can consider various distortion.
Example 2
Example 2 is by the current sensor shown in the example 1 being managed improve the corresponding to technology of phase place that the method for sampling makes the integral result and the primary current waveform of integrator 4.
Fig. 3 illustrates the major part of the current sensor of example 2, have: the A/D transducer 2 that will quantize with the analog voltage signal that the variable quantity of primary current is directly proportional, selection treating apparatus 8 with function of the data of only selecting desired timing data or calculate desired timing from the data through quantizing has the downsampling device 9 that changes to the function in desired sampling period by the approximate processing that waits from sampling period of A/D transducer 2.It shown in Fig. 3 the minimum function that obtains effect of the present invention.In the reality, the prime of A/D transducer 2 connects air core coil 1, and the back level of downsampling device 9 connects digital processes 20.Again, digital processes also can and be selected between the treating apparatus at the A/D transducer.
Specify it with reference to Fig. 4,4 couples of voltage signal V that are directly proportional with the variable quantity of the primary current signal I of determination object carry out Euler's integral by integrator, and the waveform of integral result R has had leading with respect to the waveform phase of primary current signal I.This phase lead amount D complies with and is become in the sampling period, always 1/2 sampling period of leading.By proofreading and correct this phase lead amount the mensuration precision is improved.
At first, the sampling of A/D transducer 2 is exported the sampling period more than 2 times in the sampling period that requires and is carried out so-called over-sampling with current sensor.From the data that sample, select the data of desired timing with selecting treating apparatus 8.The result data of integration since with the data of the phase place in primary current 1/2 sampling period that was leading relatively, so the The data of being extracted makes the data in 1/2 sampling period of delay from desired sampling.Only extract the previous data of selecting by downsampling device 9, data are passed to next function with the sampling period identical with the sampling period of current sensor output.
When the sample frequency of A/D transducer 2 is the 2N (N is an integer) of current sensor output frequency, because the data after existing 1/2 to sample, so merely select it just can.
The sample frequency of A/D transducer 2 be the current sensor output frequency 2N doubly beyond the time, then carry out the approximate of straight-line interpolation, or carry out the match etc. of primary voltage waveform generation, the output of timing of 1/2 sampling of having calculated the current sensor output delay is extracted it.
Only extract the previous data of selecting by downsampling device 9, data are passed to next function with the timing identical with the cycle of current sensor output.
Above-mentioned processing is identical with 1/2 sampling period of the constant time lag current sensor that makes sampling.
In this example, the sample frequency of establishing A/D transducer 2 is more than 2 times, even but carrying out phase calibration below 2 times too, can carry out high-acruracy survey of current sensor output.But, the sample frequency of A/D transducer 2 is below 2 times the time, utilizes the down-sampling can the deterioration radio-frequency component, so the mensuration precision of high-frequency region descends on the contrary.
By above-mentioned sample waveform is postponed, can make the phase place of output waveform of integrator consistent with the phase place of the current waveform of determination object, can constitute more current with high accuracy sensor.
Example 3
This example 3 is by example 1 described current sensor is improved the corresponding to technology of phase place that integrator makes the integral result and the primary current of integrator.As shown in Figure 5, current sensor has analog voltage signal A/D transducer 2 that quantizes and the platform shape integrator 10 that the data after quantizing is carried out platform shape integration that the variable quantity to primary current is directly proportional.It shown in Fig. 5 the minimum function that obtains effect of the present invention.In the reality, at the prime connection air core coil 1 of A/D transducer 2, the input side connection adder at platform shape integrator 10 connects Hi-pass filter etc. at outgoing side.
As implement as described in the form 2, the waveform of integral result is compared with the waveform of a waveform, always phase lead 1/2 sampling period.For proofreading and correct this phase place, adopt the platform shape integrator 10 of 1/2 sampling period of the waveform delay phase place that makes integral result.Platform shape integrator 10 is made up of integrator 4, maintenance data and the equalization data of example 1.
Fig. 6 illustrates concrete treatment scheme.At first, keep data 1. (S10) with 0 initialization.1. so-called maintenance data are the data to averaging of the sampled data usefulness of A/D transducer 2.Secondly, with 2 samplings (S11) of A/D transducer to sampled data be stored in and keep data 2. (S12).
Secondly, get sampled data with keep data 1. and, do 1/2 and calculate (equalization) (S13).Data after the equalization (equalization data) are by integrator 4 addition successively in the platform shape integrator 10.But the initial value of establishing integrator 4 is 0.To keep data 2. to copy to and keep data 1. (S14).Below carry out platform shape integration by repeating same order.
In this example, distinguish and keep data 1. to reach keeping data 2., and 2. the so-called data that keep are that the sampled data substitution is kept the 1. device of usefulness of data, also available other method.
In this example, averaging processing before as the integrator 4 of platform shape integration is handled and is also obtained identical effect yet apply equalization after integrator 4.
By to preceding sampled data and current averaging of sampled data, or, can make the integrator output waveform consistent, can constitute more current with high accuracy sensor with the phase place of primary current waveform to preceding integrator output and current averaging of integrator output.
As implement shown in the form 1～3, test section uses the current sensor of the present invention of air core coil, can prevent the saturated phenomenon of primary current, and owing to can detect instantaneous value, so be suitable for using, be specially adapted to calculate the circuit and the equipment of the phase effect electric power (comprising no electric power, higher-order wave electric power) or the amount of electrical power (comprising useless quantity of power, higher-order wave amount of electrical power) of electric current and voltage as current sensor.
The present invention is because as consist of above-mentionedly, so can receive following effect.
Multiply by amount behind certain coefficient in integrator by the difference value with the input signal of high-pass filter Flip-flop is removed in addition lenitively, so even contain excessive direct current in the output signal of air core coil The situation of composition, primary current carry out the situation that the phase generate of situation, the primary current of ON/OFF changes, Also can avoid saturated phenomenon and carry out correct current detecting.
Again, formation of the present invention only go up to increase the function that difference value with the input signal of Hi-pass filter feeds back to integrator at basic comprising (integrator and Hi-pass filter) to be implemented, so can simply constitute the saturated countermeasure of realization.
Again, constitute simplification, so can constitute the current sensor that test section is held the air core coil of simple and double valency formation owing to can make DC remove circuit.
Claims (3)
1. a current sensor is characterized in that, comprises
Detection assay is to the air core coil of image current,
The A/D transducer that the output signal of this air core coil is quantized, and
Have quantized data to this A/D transducer and carry out the integrator of integration and the digital processes of the Hi-pass filter of radio-frequency component, output and the proportional electric weight of determination object electric current of the output data by integrator only,
Described digital processes has the function that difference value with the input signal of Hi-pass filter and output signal multiply by certain coefficient and is added to the input end of integrator, and the certain coefficient value that multiply by described difference value is less than 1.
2. current sensor as claimed in claim 1 is characterized in that,
Described integrator is Euler (Eulr) integrator, by to the sampled result of the over-sampling that carries out with described A/D transducer through a certain amount of delay and carry out down-sampling, make the phase place between the output of determination object electric current and described digital processes consistent.
3. current sensor as claimed in claim 1 is characterized in that,
Described integrator is a platform shape integrator.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003068801 | 2003-03-13 | ||
| US2003068801 | 2003-03-13 | ||
| JP2003068801A JP4156412B2 (en) | 2003-03-13 | 2003-03-13 | Current sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1530661A CN1530661A (en) | 2004-09-22 |
| CN1276262C true CN1276262C (en) | 2006-09-20 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03159359 Expired - Fee Related CN1276262C (en) | 2003-03-13 | 2003-09-09 | Current sensor |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP4156412B2 (en) |
| CN (1) | CN1276262C (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100724101B1 (en) | 2005-10-27 | 2007-06-04 | 한국표준과학연구원 | AC current sensor using air core |
| EP1958310A2 (en) * | 2005-11-25 | 2008-08-20 | Nxp B.V. | Charging control device for supplying electronic equipment application(s) and battery with compensated current |
| CN101331402B (en) * | 2005-12-15 | 2011-06-08 | 奇美电子股份有限公司 | Current measurement circuit and method |
| US8232758B2 (en) * | 2009-08-28 | 2012-07-31 | Fanuc Ltd | Controller of electric motor having function of estimating inertia and friction simultaneously |
| JP5439696B2 (en) * | 2010-04-20 | 2014-03-12 | 株式会社ミツトヨ | Integrator |
| US8836525B2 (en) * | 2011-06-06 | 2014-09-16 | Lear Corporation | Isolated resistive current sensor |
| CN103235172B (en) * | 2013-04-24 | 2015-05-20 | 常熟开关制造有限公司(原常熟开关厂） | Current measuring method and measuring device |
| US9588147B2 (en) * | 2015-02-04 | 2017-03-07 | 3M Innovative Properties Company | Electronic integrator for Rogowski coil sensors |
| CN107702813A (en) * | 2017-11-01 | 2018-02-16 | 厦门傅里叶电子有限公司 | Microspeaker controls thermometric integrating apparatus and method |
| CN107748289A (en) * | 2017-11-28 | 2018-03-02 | 嘉兴伏尔电子科技有限公司 | A kind of follow-on inverter phase detectors |
| CN110118891B (en) * | 2019-05-31 | 2021-03-16 | 四川英杰电气股份有限公司 | Current detection method, device terminal and readable storage medium |
-
2003
- 2003-03-13 JP JP2003068801A patent/JP4156412B2/en not_active Expired - Lifetime
- 2003-09-09 CN CN 03159359 patent/CN1276262C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004279139A (en) | 2004-10-07 |
| CN1530661A (en) | 2004-09-22 |
| JP4156412B2 (en) | 2008-09-24 |
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