CN210572699U - A Rogowski coil integrator DC error elimination circuit - Google Patents
A Rogowski coil integrator DC error elimination circuit Download PDFInfo
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- CN210572699U CN210572699U CN201920886409.6U CN201920886409U CN210572699U CN 210572699 U CN210572699 U CN 210572699U CN 201920886409 U CN201920886409 U CN 201920886409U CN 210572699 U CN210572699 U CN 210572699U
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- 239000003990 capacitor Substances 0.000 claims description 26
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- 238000005259 measurement Methods 0.000 abstract description 6
- 239000004743 Polypropylene Substances 0.000 description 3
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Abstract
本实用新型公开了一种罗氏线圈积分器直流误差消除电路，包括依次连接的罗氏线圈、前置放大器和第一积分器，前置放大器包括依次连接的反相放大器和同相放大器，第一积分器输出与罗氏线圈电流成正比的电压信号；还包括第二积分器和低通滤波器，罗氏线圈输出感应电动势信号至反相放大器的反相输入端，同相放大器的输出还连接至第二积分器的输入，第二积分器的输出连接至低通滤波器的输入，低通滤波器输出直流电平信号至反相放大器的同相输入端。本实用新型通过增加积分器和低通滤波器构成闭环控制电路，以消除罗氏线圈输出信号所含直流分量，提高电子式互感器测量的准确性和稳定性，拓展测量应用范围。
The utility model discloses a DC error elimination circuit of a Rogowski coil integrator, which comprises a Rogowski coil, a preamplifier and a first integrator which are connected in sequence. The preamplifier comprises an inverting amplifier and a non-inverting amplifier which are connected in sequence, and the first integrator It outputs a voltage signal proportional to the current of the Rogowski coil; it also includes a second integrator and a low-pass filter, the Rogowski coil outputs the induced electromotive force signal to the inverting input end of the inverting amplifier, and the output of the non-inverting amplifier is also connected to the second integrator The input of the second integrator is connected to the input of the low-pass filter, and the low-pass filter outputs a DC level signal to the non-inverting input terminal of the inverting amplifier. The utility model forms a closed-loop control circuit by adding an integrator and a low-pass filter, so as to eliminate the DC component contained in the output signal of the Rogowski coil, improve the accuracy and stability of the electronic transformer measurement, and expand the measurement application range.
Description
Technical Field
The utility model belongs to the luo shi coil integrator field, concretely relates to luo shi coil integrator direct current error cancelling circuit.
Background
In the field of modern electrical measurement, a novel electronic transformer based on a Rogowski coil replaces a traditional electromagnetic current transformer in many occasions, and overcomes the defects of magnetic saturation, ferromagnetic resonance, small dynamic range, narrow frequency band and the like of the electromagnetic current transformer. The novel electronic transformer mainly comprises a Rogowski coil, a preamplifier and an integrator; according to the Rogowski coil measurement principle, the induced electromotive force e (t) of the whole coil is as follows:
from the formula (1), when the coil frame material, size and winding coil wire are fixed, r, N and S are regarded as fixed values, i.e. the mutual inductance M is fixed value. From this it can be concluded that: the output e (t) of the rogowski coil is proportional to the derivative of the current i (t) through the coil, and the two are 90 ° out of phase. In order to truly acquire the measured current i (t), an integration link must be added, and the voltage u is output after integrationo(t) is:
wherein k is the preamplifier gain; from the formula (2), the output voltage uoThe amplitude of (t) is proportional to the measured current i (t), and the output voltage uoThe phase of (t) is the same as the measured current i (t), so that the aim of really obtaining the measured current i (t) is fulfilled. However, in practical engineering applications, the measured current i (t) is not an ideal sine wave signal, but contains higher harmonics and a direct current component signal, and after the direct current component is input to the integrator, an accumulative error is generated, the integrated current value gradually deviates from an accurate value, and finally, problems such as data overflow and malfunction of downstream protection equipment are caused.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to the problem that exists with not enough above-mentioned, provide a luo shi coil integrator direct current error cancelling circuit to eliminate the direct current component that luo shi coil signal contains, improve electronic transformer measuring accuracy and stability, extend and measure the range of application.
In order to realize the purpose, the utility model discloses a technical scheme is: a Rogowski coil integrator direct current error elimination circuit comprises a Rogowski coil, a preamplifier and a first integrator which are sequentially connected, wherein the preamplifier comprises an inverting amplifier and a non-inverting amplifier which are sequentially connected, and the first integrator outputs a voltage signal which is in direct proportion to the current of the Rogowski coil; the Rogowski coil outputs an induced electromotive force signal to the inverting input end of the inverting amplifier, the output of the non-inverting amplifier is also connected to the input of the second integrator, the output of the second integrator is connected to the input of the low-pass filter, and the low-pass filter outputs a direct-current level signal to the non-inverting input end of the inverting amplifier.
Further perfecting the technical scheme, the inverting amplifier comprises an operational amplifier U1, a resistor R1 and a resistor R2, the output of the Rogowski coil is connected to the inverting input end of the operational amplifier U1 through the resistor R1, and the resistor R2 is arranged between the output end and the inverting input end of the operational amplifier U1.
Further, the non-inverting amplifier includes an operational amplifier U2, resistors R4 and R5, an output of the inverting amplifier is connected to a non-inverting input terminal of the operational amplifier U2, a resistor R4 is disposed between the inverting input terminal and a ground terminal of the operational amplifier U2, and a resistor R5 is disposed between an output terminal and the inverting input terminal of the operational amplifier U2.
Further, the first integrator comprises an operational amplifier U3, a resistor R6 and a capacitor C2, the output of the non-inverting amplifier is connected to the inverting input terminal of the operational amplifier U3 through the resistor R6, the non-inverting input terminal of the operational amplifier U3 is grounded, the capacitor C2 is arranged between the output terminal and the inverting input terminal of the operational amplifier U3, and the output terminal of the operational amplifier U3 outputs a voltage signal proportional to the current of the rogowski coil; the second integrator has the same structure as the first integrator, and includes an operational amplifier U4, a resistor R7, and a capacitor C3.
Further, the low-pass filter comprises a capacitor C1 and a resistor R3, the output of the second integrator is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the non-inverting input terminal of the operational amplifier U1 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded.
The utility model has the advantages that: the utility model discloses an increase two elementary circuits of integrator and low pass filter, establish a closed-loop control system, eliminate the direct current component that the Rogowski coil signal contains and operational amplifier's direct current offset VosThe accuracy and the stability of the measurement of the novel electronic transformer are improved, and the measurement application range is expanded; and, the utility model discloses circuit structure is simple, uses some general electron devices just can accomplish the design and the improvement of circuit, is favorable to reducing the running cost of enterprise.
Drawings
Fig. 1 is a block diagram of the circuit structure of the present invention;
FIG. 2 is a detailed circuit diagram of FIG. 1;
in the figure: 1. a Rogowski coil; 2. an inverting amplifier; 3. a non-inverting amplifier; 4. a first integrator; 5. a second integrator; 6. a low pass filter.
Detailed Description
In order to make the disclosure of the present invention clearer, the following detailed description of the embodiments of the present invention is made with reference to the accompanying drawings. It should be noted that for the sake of clarity, the figures and the description omit representation and description of parts not relevant to the present invention, known to a person skilled in the art.
Example 1:
the utility model provides a rogowski coil integrator direct current error cancelling circuit, as shown in figure 1, including rogowski coil 1, preamplifier and the first integrator 4 that connect gradually, preamplifier includes inverting amplifier 2 and cophase amplifier 3 that connect gradually, and the output of first integrator 4 is with the voltage signal of rogowski coil 1 electric current direct ratio; the high-voltage direct current power supply further comprises a second integrator 5 and a low-pass filter 6, the rogowski coil 1 outputs an induced electromotive force signal to the inverting input end of the inverting amplifier 2, the output of the non-inverting amplifier 3 is further connected to the input of the second integrator 5, the output of the second integrator 5 is connected to the input of the low-pass filter 6, and the low-pass filter 6 outputs a direct current level signal to the non-inverting input end of the inverting amplifier 2.
As shown in fig. 2, the inverting amplifier 2 includes an operational amplifier U1, resistors R1 and R2, the output of the rogowski coil 1 is connected to the inverting input terminal of the operational amplifier U1 via the resistor R1, and the resistor R2 is provided between the output terminal and the inverting input terminal of the operational amplifier U1. The model of the operational amplifier U1 is OP07, OP07 is a low noise amplifier, and the gain of the inverting amplifier 2 can be set by setting the values of the resistors R1 and R2.
The non-inverting amplifier 3 includes an operational amplifier U2, resistors R4 and R5, an output terminal of the operational amplifier U1 is connected to a non-inverting input terminal of the operational amplifier U2, a resistor R4 is provided between an inverting input terminal and a ground terminal of the operational amplifier U2, and a resistor R5 is provided between the output terminal and the inverting input terminal of the operational amplifier U2. The model of the operational amplifier U2 is OP07, and the gain of the non-inverting amplifier 3 can be set by setting the values of the resistors R4 and R5.
The first integrator 4 comprises an operational amplifier U3, a resistor R6 and a capacitor C2, wherein the output end of the operational amplifier U2 is connected to the inverting input end of the operational amplifier U3 through the resistor R6, the non-inverting input end of the operational amplifier U3 is grounded, the capacitor C2 is arranged between the output end and the inverting input end of the operational amplifier U3, and the output end of the operational amplifier U3 outputs a voltage signal proportional to the current of the rogowski coil 1. The model of the operational amplifier U3 is OP77, and the OP77 has ultra-low offset voltage Vos，VosIs 10 uV; the capacitor C2 is made of polypropylene with low temperature coefficient, and the time constant of the first integrator 4 can be set by setting the values of the resistor R6 and the capacitor C2.
The second integrator 5 has the same structure as the first integrator 4, the second integrator 5 includes an operational amplifier U4, a resistor R7 and a capacitor C3, the output terminal of the operational amplifier U2 is connected to the inverting input terminal of the operational amplifier U4 through the resistor R7, the non-inverting input terminal of the operational amplifier U4 is grounded, and the capacitor C3 is disposed between the output terminal and the inverting input terminal of the operational amplifier U4. The model of the operational amplifier U4 is OP77, the capacitor C3 is a polypropylene capacitor with a low temperature coefficient, and the time constant of the second integrator 5 can be set by setting the values of the resistor R7 and the capacitor C3.
The low-pass filter 6 comprises a capacitor C1 and a resistor R3, the output end of the operational amplifier U4 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the non-inverting input end of the operational amplifier U1 and one end of a capacitor C1, and the other end of the capacitor C1 is grounded. Wherein, the capacitor C1 is a polypropylene capacitor with low temperature coefficient.
The utility model discloses a theory of operation: the utility model adds the second integrator 5 and the low pass filter 6 compensation link on the basis of the original preamplifier, and constructs a closed loop control system to compensate the DC level of the input end of the preamplifier, thereby eliminating the DC level in the AC signal; more specifically, the dc level component at the output terminal of the preamplifier is fed back to the non-inverting input terminal of the inverting amplifier 2, so as to force the dc level at the non-inverting input terminal of the inverting amplifier 2 to be equal to the dc level at the inverting input terminal, thereby achieving that the output dc level of the preamplifier is 0.
The above description is only intended to illustrate embodiments of the present invention, and the description is specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (5)
1. A Rogowski coil integrator direct current error elimination circuit comprises a Rogowski coil, a preamplifier and a first integrator which are sequentially connected, wherein the preamplifier comprises an inverting amplifier and a non-inverting amplifier which are sequentially connected, and the first integrator outputs a voltage signal which is in direct proportion to the current of the Rogowski coil; the method is characterized in that: the Rogowski coil outputs an induced electromotive force signal to the inverting input end of the inverting amplifier, the output of the non-inverting amplifier is also connected to the input of the second integrator, the output of the second integrator is connected to the input of the low-pass filter, and the low-pass filter outputs a direct-current level signal to the non-inverting input end of the inverting amplifier.
2. The rogowski coil integrator dc error cancellation circuit of claim 1, wherein: the inverting amplifier comprises an operational amplifier U1, a resistor R1 and a resistor R2, the output of the Rogowski coil is connected to the inverting input terminal of the operational amplifier U1 through the resistor R1, and a resistor R2 is arranged between the output terminal and the inverting input terminal of the operational amplifier U1.
3. The rogowski coil integrator dc error cancellation circuit of claim 1, wherein: the non-inverting amplifier comprises an operational amplifier U2, a resistor R4 and a resistor R5, wherein the output of the inverting amplifier is connected to the non-inverting input end of the operational amplifier U2, the resistor R4 is arranged between the inverting input end and the grounding end of the operational amplifier U2, and the resistor R5 is arranged between the output end and the inverting input end of the operational amplifier U2.
4. The rogowski coil integrator dc error cancellation circuit of claim 1, wherein: the first integrator comprises an operational amplifier U3, a resistor R6 and a capacitor C2, the output of a non-inverting amplifier is connected to the inverting input end of the operational amplifier U3 through the resistor R6, the non-inverting input end of the operational amplifier U3 is grounded, the capacitor C2 is arranged between the output end and the inverting input end of the operational amplifier U3, and the output end of the operational amplifier U3 outputs a voltage signal which is in direct proportion to the current of the Rogowski coil; the second integrator has the same structure as the first integrator, and includes an operational amplifier U4, a resistor R7, and a capacitor C3.
5. The rogowski coil integrator dc error cancellation circuit of claim 2, wherein: the low-pass filter comprises a capacitor C1 and a resistor R3, the output of the second integrator is connected to one end of a resistor R3, the other end of the resistor R3 is connected to the non-inverting input end of the operational amplifier U1 and one end of a capacitor C1, and the other end of the capacitor C1 is grounded.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920886409.6U CN210572699U (en) | 2019-06-13 | 2019-06-13 | A Rogowski coil integrator DC error elimination circuit |
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| CN201920886409.6U CN210572699U (en) | 2019-06-13 | 2019-06-13 | A Rogowski coil integrator DC error elimination circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT202000019285A1 (en) * | 2020-08-05 | 2022-02-05 | Areti S P A | CONDITIONER CIRCUIT, GROUP AND SYSTEM FOR THE MEASUREMENT OF AN ELECTRIC SIGNAL |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT202000019285A1 (en) * | 2020-08-05 | 2022-02-05 | Areti S P A | CONDITIONER CIRCUIT, GROUP AND SYSTEM FOR THE MEASUREMENT OF AN ELECTRIC SIGNAL |
| WO2022029644A1 (en) * | 2020-08-05 | 2022-02-10 | Areti S.P.A. | Conditioning circuit, group and system for the measurement of one electrical signal |
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