CN210142143U - High-precision current sampling circuit - Google Patents
High-precision current sampling circuit Download PDFInfo
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- CN210142143U CN210142143U CN201920371626.1U CN201920371626U CN210142143U CN 210142143 U CN210142143 U CN 210142143U CN 201920371626 U CN201920371626 U CN 201920371626U CN 210142143 U CN210142143 U CN 210142143U
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Abstract
The utility model relates to an industrial motor control technical field especially relates to a current sampling circuit of high accuracy, specifically includes RC filter circuit, difference amplifier circuit and integrating circuit, through adding the direct current offset voltage reference source in difference amplifier circuit, has enlarged the dynamic range of the output signal undistorted after the input signal enlargies, when the electric current was the negative value promptly, amplifier circuit still can amplify the signal for positive value voltage signal. In the integrating circuit, the voltage signal is subjected to voltage-frequency conversion through the integrating circuit to generate a triangular wave signal and is transmitted to a post-stage digital signal processing chip, and data acquisition is performed through the post-stage digital signal processing chip to enhance sampling precision and stability, so that the problems that a current sampling circuit is seriously interfered by noise and has low resolution are solved.
Description
Technical Field
The utility model relates to an industrial motor control technical field especially relates to a current sampling circuit of high accuracy.
Background
In many circuit systems, we involve current sampling, such as in the field of motor control. The common methods in the prior art comprise: 1. the Hall sensor is used for sampling current, the Hall sensor directly outputs a voltage value suitable for a DSP sampling voltage range, the DSP reads a corresponding voltage value and converts the voltage value into a corresponding current value through a certain conversion relation, and the method is generally poor in acquisition precision and suitable for large current acquisition; 2. the method of adding the sampling resistor by the single-ended amplifying circuit is used, and the voltage drop on the sampling resistor is amplified by the single-ended amplifying circuit and then input into the single chip microcomputer for sampling and conversion to obtain a corresponding current value; the single-ended amplification circuit has poor precision and stability and is suitable for occasions with low precision requirements.
Patent document No. 201721163339.9 discloses a current sampling circuit for filtering out harmonics, but the following disadvantages still exist: 1. the current sampled by the sampling circuit can only be a positive value, and when the current is a negative value, the amplifying circuit can not normally amplify the current; 2. the sampling circuit is a traditional A/D sampling amplifying circuit, the sampling precision of the sampling circuit can still be influenced by the sampling precision of the sampler, and the requirement on the sampler is high.
Patent No. 201821212397.0 discloses a current sampling circuit with improved driving capability, but the sampling circuit is inferior in both sampling accuracy and stability and is only suitable for use in cases where accuracy is not high.
Therefore, how to solve the problems of serious noise interference and low resolution of the current sampling circuit becomes a technical problem to be solved urgently by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a current sampling circuit of high accuracy to solve current sampling circuit and receive the serious and lower problem of resolution ratio of noise interference.
In order to achieve the above object, the utility model provides a current sampling circuit of high accuracy, a serial communication port, include:
the input end of the RC filter circuit receives a voltage signal obtained by collecting current by a sampling resistor, and the voltage signal is filtered by the RC filter circuit;
the input end of the differential amplification circuit is connected with the output end of the RC filter circuit so as to receive the voltage signal filtered by the RC filter circuit; the differential amplification circuit comprises an amplification factor adjusting module and a reference source for generating bias voltage, wherein the amplification factor adjusting module is used for controlling, amplifying and adjusting the voltage value of the received voltage, and the reference source for generating the bias voltage is used for giving a certain direct current bias to the voltage signal so that the amplification circuit amplifies the alternating current signal into a positive voltage signal;
and the input end of the integrating circuit is connected with the output end of the differential amplifying circuit and is used for converting the amplified and adjusted voltage signal into a triangular wave signal and transmitting the integrated triangular wave signal to the digital signal processing chip.
Preferably, the RC filter circuit includes:
the input end of the first resistor is connected with the positive end of the sampling resistor;
the input end of the second resistor is connected with the negative end of the sampling resistor;
the input end of the third resistor is connected with the first resistor;
the input end of the fourth resistor is connected with the second resistor;
the two ends of the first capacitor are connected with the first resistor and the second resistor;
one end of the second capacitor is connected with the third resistor, and the other end of the second capacitor is connected with the ground;
and one end of the third capacitor is connected with the fourth resistor, and the other end of the third capacitor is connected with the ground.
Preferably, the differential amplifier circuit includes:
the input end of the fifth resistor is connected with the third resistor;
the input end of the sixth resistor is connected with the fourth resistor;
the input end of the seventh resistor is connected with the sixth resistor;
an input end of the eighth resistor is connected with the fifth resistor;
the reference source for generating the bias voltage is connected with the output end of the seventh resistor;
a fourth capacitor connected in parallel with the seventh resistor;
the fifth capacitor is connected with the eighth resistor in parallel;
and the input end of the first operational amplifier is connected with the fifth resistor and the sixth resistor, and the output end of the first operational amplifier is connected with the eighth resistor.
Preferably, the amplification factor of the first operational amplifier is adjusted according to the resistance values of the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor and a reference source for generating the bias voltage.
Preferably, the integration circuit includes:
the input end of the ninth resistor is connected with the eighth resistor;
the input end of the tenth resistor is connected with the ninth resistor, and the output end of the tenth resistor is connected with the wire grounding end;
one end of the sixth capacitor is connected with the ninth resistor;
the input end of the second operational amplifier is connected with a ninth resistor and voltage, and the output end of the second operational amplifier is connected with the sixth capacitor;
the eleventh resistor is connected with the output end of the second operational amplifier;
and the twelfth resistor is connected with the input end of the tenth resistor.
Preferably, the triangular wave signal is adjusted by adjusting the charging and discharging speed of the sixth capacitor according to the resistance values of the ninth resistor, the tenth resistor, the eleventh resistor and the twelfth resistor, the capacitance value of the sixth capacitor and the voltage value of the digital signal processing chip.
Preferably, the current sampling circuit further comprises a clamping diode, an input end of the clamping diode is connected with the eleventh resistor, an output end of the clamping diode is connected with the digital signal processing chip, and the clamping diode is used for limiting and protecting the voltage of the corresponding counting pin.
Preferably, the voltage limiting range of the clamping diode is configured according to the rated voltage value of the digital signal processing chip.
The utility model provides a current sampling circuit of high accuracy is through adding the DC offset voltage reference source in difference amplifier circuit for the dynamic range of the output signal distortionless after the input signal enlargies is bigger, and when the electric current was the negative value, amplifier circuit still can carry out amplifier circuit with the signal and still can amplify the signal for positive voltage signal. In the integrating circuit, the voltage signal is subjected to voltage-frequency conversion through the integrating circuit to generate a triangular wave signal and is transmitted to a post-stage digital signal processing chip, and data acquisition is performed through the post-stage digital signal processing chip to enhance sampling precision and stability, so that the problems that a current sampling circuit is seriously interfered by noise and has low resolution are solved.
Drawings
The accompanying drawings, which form a part hereof, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without undue limitation. In the drawings:
fig. 1 is the schematic diagram of the high-precision current sampling circuit provided by the present invention.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings.
In order to make the technical solution of the present invention better understood, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged under appropriate circumstances for purposes of describing the embodiments of the invention herein.
As shown in fig. 1, fig. 1 is a schematic diagram of a high-precision current sampling circuit provided by the present invention.
The utility model provides a current sampling circuit of high accuracy, include: an RC filter circuit 100, a differential amplifier circuit 200, and an integrator circuit 300; the input end of the RC filter circuit 100 receives a voltage signal obtained by collecting current by a sampling resistor R033, and the voltage signal is filtered by the RC filter circuit 100 to filter higher harmonics which reduce sampling precision; the input end of the differential amplification circuit 200 is connected with the output end of the RC filter circuit 100 to receive the voltage signal filtered by the RC filter circuit 100, the differential amplification circuit 200 includes an amplification factor adjustment module and a reference source generating a bias voltage, the amplification factor adjustment module is used for controlling, amplifying and adjusting the voltage value of the received voltage, and the reference source generating the bias voltage is used for providing a certain direct current bias to the voltage signal, so that the amplification circuit amplifies the alternating current signal into a positive voltage signal; the input end of the integrating circuit 300 is connected to the output end of the differential amplifying circuit 200, and is configured to convert the amplified and adjusted voltage signal into a triangular wave signal, and transmit the integrated triangular wave signal to a digital signal processing chip (hereinafter referred to as DSP). The current sequentially passes through the RC filter circuit 100, the differential amplifier circuit 200 and the integrating circuit 300 to form a low-noise high-resolution current sampling circuit.
The RC filter circuit 100 includes a sampling resistor and three low-pass filters, the sampling resistor converts the input current signal at the input end into a voltage signal, and the three low-pass filters are used for filtering out higher harmonics of the voltage signal and transmitting the higher harmonics to the differential amplifier circuit. The differential amplification circuit 200 comprises an input end, an amplification factor adjusting part with direct current bias and an output end, wherein the input end is used for receiving the voltage signal filtered by the RC filter circuit; the reference source for generating bias voltage is used for providing certain direct current bias for the voltage signal and amplifying the alternating current signal into a positive voltage signal; the amplification factor adjusting module is used for controlling, amplifying and adjusting the voltage value of the received voltage; the output end is used for outputting the amplified and adjusted voltage signal. The integrator circuit 300 includes an input terminal, a charge/discharge part of the capacitor, and an output terminal, the input terminal includes a voltage signal transmitted from the differential amplifier circuit and an output voltage signal transmitted from the DSP, the charge/discharge part of the capacitor controls charge/discharge of the capacitor to form a triangular wave signal by outputting a high level or a low level through the DSP, and the output terminal outputs the triangular wave signal to the DSP.
Wherein, the sampling resistor R033 performs current collection by using a milliohm level.
Specifically, the current sequentially passes through the RC filter circuit 100, the differential amplifier circuit 200, and the integrator circuit 300 to form a unidirectional current sampling circuit to complete low-noise high-precision acquisition of the current signal. The current flows through the sampling resistor R033 from top to bottom, a voltage value is generated on the sampling resistor R033, the voltage value is used as the input voltage of the differential amplification circuit, is amplified and adjusted to a preset voltage value through the differential amplification circuit 200 in a high-precision mode, and is subjected to voltage-frequency conversion through the integration circuit 300, so that the noise of the circuit is further reduced. The differential amplifier circuit 200 amplifies the received voltage and outputs the amplified voltage as:
wherein:
R11＝R12,R13＝R14,R15＝R16,R17＝R18
the charging and discharging currents of an integrating capacitor C16 of the integrating circuit are respectively as follows:
charging current, i.e. when the input voltage at IN is VDDAt this time, the input current at the left end of the capacitor C16 is:
the discharging current, i.e. when the input voltage at the IN terminal is 0V, the output current at the left terminal of the capacitor C16 is:
wherein iinIn the same direction as the current direction shown; i.e. ioutIn a direction opposite to the current direction shown in the figure, i is enabled to be a certain resistance value and a certain voltage valueinAnd ioutThe current is positive, and the voltage output by the integrating capacitor is (0, V)DD) And a certain margin is reserved in the interval range.
Specifically, the RC filter circuit 100 in this embodiment includes a first resistor R11, a second resistor R12, a third resistor R13, a fourth resistor R14, a first capacitor C11, a second capacitor C12, and a third capacitor C13; the input end of the first resistor R11 is connected with the positive end of the sampling resistor R033; the input end of the second resistor R12 is connected with the negative end of the sampling resistor R033; the input end of the third resistor R13 is connected with the first resistor R11; the input end of the fourth resistor R14 is connected with the second resistor R12; the two ends of the first capacitor C11 are connected with a first resistor R11 and a second resistor R12; one end of the second capacitor C12 is connected with the third resistor R13, and the other end is connected with the ground; one end of the third capacitor C13 is connected to the fourth resistor R14, and the other end is connected to ground.
Specifically, the differential amplifier circuit 200 in this embodiment includes a fifth resistor R15, a sixth resistor R16, a seventh resistor R17, an eighth resistor R18, and a dc bias voltage reference source Ui1A fourth capacitor C14, a fifth capacitor C15, a first operational amplifier; the input end of the fifth resistor R15 is connected with the third resistor R13; the input end of the sixth resistor R16 is connected with the fourth resistor R14; the input end of the seventh resistor R17 is connected with the sixth resistor R16; the input end of the eighth resistor R18 is connected with the fifth resistor R15; DC bias voltage reference source Ui1The output end of the seventh resistor R17 is connected; fourth capacitor C14 and seventh capacitorThe resistors R17 are connected in parallel; the fifth capacitor C15 is connected in parallel with the eighth resistor R18; the input end of the first operational amplifier is connected with the fifth resistor and the sixth resistor, and the output end of the first operational amplifier is connected with the eighth resistor R18. Preferably, the bias voltage is generated according to the resistance values of the fifth resistor R15, the sixth resistor R16, the seventh resistor R16 and the eighth resistor R18 and the reference source U for generating the bias voltagei1And adjusting the amplification factor of the first operational amplifier.
Specifically, the integrating circuit 300 in this embodiment includes a ninth resistor R19, a tenth resistor R20, a sixth capacitor C16, a second operational amplifier, an eleventh resistor R21, and a twelfth resistor R22; the input end of the ninth resistor R19 is connected with the eighth resistor R18; the input end of the tenth resistor R20 is connected with the ninth resistor R19, and the output end of the tenth resistor R20 is connected with the wire ground end; one end of the sixth capacitor C16 is connected with the ninth resistor R19; the input terminal of the second operational amplifier, the ninth resistor R19 and the voltage Ui2, and the output end of the second operational amplifier is connected with a sixth capacitor C16; the eleventh resistor R21 is connected with the output end of the second operational amplifier; the twelfth resistor R22 is connected to the input of the tenth resistor R20. Preferably, the triangular wave signal is adjusted by adjusting the charging and discharging speed of the sixth capacitor C16 according to the resistance values of the ninth resistor R19, the tenth resistor R20, the eleventh resistor R21, the twelfth resistor R22, the capacitance value of the sixth capacitor C16 and the voltage value of the DSP.
In addition, the current sampling circuit in this embodiment further includes a clamping diode, an input end of the clamping diode is connected to the eleventh resistor, an output end of the clamping diode is connected to the DSP, and a counting pin of the clamping diode is used for voltage limiting and protection. Preferably, the voltage limiting range of the clamping diode is configured according to the rated voltage value of the DSP.
The utility model discloses a high frequency signal that first order RC filter circuit 100 filtering sampling signal is unnecessary, differential mode signal is enlargied to second level difference amplifier circuit 200, restrain common mode signal, the magnification adjustment portion that has direct current biasing through the addition makes the dynamic range of the undistorted of output signal after the input signal enlargies bigger, when the electric current is the negative value, amplifier circuit still can normally enlarge the signal, third level integrator circuit 300 converts voltage analog signal into triangular wave signal and spreads into in DSP, the precision of having avoided traditional AD sampling is not high and the relatively poor problem of stability, cooperate with the DSP of back level simultaneously, control integrator circuit's charge-discharge, form the closed-loop control of AD conversion.
The structure, features and effects of the present invention have been described in detail above according to the embodiment shown in the drawings, and the above description is only the preferred embodiment of the present invention, but the present invention is not limited to the implementation scope shown in the drawings, and all changes made according to the idea of the present invention or equivalent embodiments modified to the same changes should be considered within the protection scope of the present invention when not exceeding the spirit covered by the description and drawings.
Claims (8)
1. A high precision current sampling circuit, comprising:
the input end of the RC filter circuit receives a voltage signal obtained by collecting current by a sampling resistor, and the voltage signal is filtered by the RC filter circuit;
the input end of the differential amplification circuit is connected with the output end of the RC filter circuit so as to receive the voltage signal filtered by the RC filter circuit; the differential amplification circuit comprises an amplification factor adjusting module and a reference source for generating bias voltage, wherein the amplification factor adjusting module is used for controlling and amplifying the received voltage to adjust the voltage value, and the reference source for generating the bias voltage is used for carrying out direct current bias on a voltage signal so that the amplification circuit amplifies the alternating current signal into a positive voltage signal;
and the input end of the integrating circuit is connected with the output end of the differential amplifying circuit and is used for converting the amplified and adjusted voltage signal into a triangular wave signal and transmitting the integrated triangular wave signal to the digital signal processing chip.
2. The high precision current sampling circuit of claim 1, wherein the RC filter circuit comprises:
the input end of the first resistor is connected with the positive end of the sampling resistor;
the input end of the second resistor is connected with the negative end of the sampling resistor;
the input end of the third resistor is connected with the first resistor;
the input end of the fourth resistor is connected with the second resistor;
the two ends of the first capacitor are connected with the first resistor and the second resistor;
one end of the second capacitor is connected with the third resistor, and the other end of the second capacitor is connected with the ground;
and one end of the third capacitor is connected with the fourth resistor, and the other end of the third capacitor is connected with the ground.
3. The high-precision current sampling circuit according to claim 2, wherein the differential amplification circuit comprises:
the input end of the fifth resistor is connected with the third resistor;
the input end of the sixth resistor is connected with the fourth resistor;
the input end of the seventh resistor is connected with the sixth resistor;
an input end of the eighth resistor is connected with the fifth resistor;
the reference source for generating the bias voltage is connected with the output end of the seventh resistor;
a fourth capacitor connected in parallel with the seventh resistor;
the fifth capacitor is connected with the eighth resistor in parallel;
and the input end of the first operational amplifier is connected with the fifth resistor and the sixth resistor, and the output end of the first operational amplifier is connected with the eighth resistor.
4. The high-precision current sampling circuit according to claim 3, wherein the amplification factor of the first operational amplifier is adjusted according to the resistance values of a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor and a reference source for generating a bias voltage.
5. The high precision current sampling circuit of claim 3, wherein the integrating circuit comprises:
the input end of the ninth resistor is connected with the eighth resistor;
the input end of the tenth resistor is connected with the ninth resistor, and the output end of the tenth resistor is connected with the wire grounding end;
one end of the sixth capacitor is connected with the ninth resistor;
the input end of the second operational amplifier is connected with a ninth resistor and voltage, and the output end of the second operational amplifier is connected with the sixth capacitor;
the eleventh resistor is connected with the output end of the second operational amplifier;
and the twelfth resistor is connected with the input end of the tenth resistor.
6. The high-precision current sampling circuit according to claim 5, wherein the triangular wave signal is adjusted by adjusting the charging and discharging speed of the sixth capacitor according to the resistance values of the ninth resistor, the tenth resistor, the eleventh resistor and the twelfth resistor, the capacitance value of the sixth capacitor and the voltage value of the digital signal processing chip.
7. The high-precision current sampling circuit according to claim 1, wherein the current sampling circuit further comprises a clamping diode, an input end of the clamping diode is connected with the eleventh resistor, an output end of the clamping diode is connected with the digital signal processing chip, and the clamping diode limits voltage and protects a corresponding counting pin.
8. The high-precision current sampling circuit according to claim 7, wherein the voltage limiting range of the clamping diode is configured according to the rated voltage value of the digital signal processing chip.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112379162A (en) * | 2020-08-21 | 2021-02-19 | 中国电力科学研究院有限公司 | Differential-to-single-ended sampling device and method for station area topology identification |
| CN112630516A (en) * | 2020-12-05 | 2021-04-09 | 西安翔腾微电子科技有限公司 | High-precision sensor current signal sampling method and circuit |
| CN112858756A (en) * | 2021-03-02 | 2021-05-28 | 广州小鹏汽车科技有限公司 | Current testing device, current testing method and electronic equipment |
| CN114113745A (en) * | 2021-11-12 | 2022-03-01 | 天津航空机电有限公司 | High-precision circuit capable of acquiring large current and small current |
| CN114759278A (en) * | 2022-06-16 | 2022-07-15 | 广东高斯宝电气技术有限公司 | Battery charging method controlled by MCU |
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2019
- 2019-03-22 CN CN201920371626.1U patent/CN210142143U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112379162A (en) * | 2020-08-21 | 2021-02-19 | 中国电力科学研究院有限公司 | Differential-to-single-ended sampling device and method for station area topology identification |
| CN112630516A (en) * | 2020-12-05 | 2021-04-09 | 西安翔腾微电子科技有限公司 | High-precision sensor current signal sampling method and circuit |
| CN112858756A (en) * | 2021-03-02 | 2021-05-28 | 广州小鹏汽车科技有限公司 | Current testing device, current testing method and electronic equipment |
| CN112858756B (en) * | 2021-03-02 | 2024-03-08 | 广州小鹏汽车科技有限公司 | Current testing device, current testing method and electronic equipment |
| CN114113745A (en) * | 2021-11-12 | 2022-03-01 | 天津航空机电有限公司 | High-precision circuit capable of acquiring large current and small current |
| CN114759278A (en) * | 2022-06-16 | 2022-07-15 | 广东高斯宝电气技术有限公司 | Battery charging method controlled by MCU |
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