CN221039215U - Single power supply current detection circuit based on fluxgate principle - Google Patents
Single power supply current detection circuit based on fluxgate principle Download PDFInfo
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- CN221039215U CN221039215U CN202322614422.5U CN202322614422U CN221039215U CN 221039215 U CN221039215 U CN 221039215U CN 202322614422 U CN202322614422 U CN 202322614422U CN 221039215 U CN221039215 U CN 221039215U
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Abstract
The utility model discloses a single power supply current detection circuit based on a fluxgate principle, which comprises a midpoint constant voltage source circuit, an excitation oscillating circuit, a filtering amplifying circuit and a self-checking circuit, wherein the excitation oscillating circuit comprises two comparator circuits and a common collector push-pull circuit; the output ends of the two comparator circuits are respectively and correspondingly connected with the two bases of the common collector push-pull circuit, so that the common collector push-pull circuit continuously generates square waves under the alternate driving of the comparator circuits. The exciting oscillating circuit is simpler, the use of one amplifier unit is reduced, the problem of larger common emitter push-pull impedance is avoided, the quality of the generated square wave is better, and the phenomenon of voltage drop is avoided.
Description
Technical Field
The utility model relates to the technical field of current detection, in particular to a single power supply current detection circuit based on a fluxgate principle.
Background
The fluxgate sensor measures the weak magnetic field by utilizing the nonlinear relation between the magnetic induction intensity and the magnetic field intensity of a high-permeability magnetic core in the magnetic field to be measured under the saturated excitation of an alternating magnetic field. The magnetic field generated by the current is measured by utilizing the phenomenon, so that the purpose of measuring the current is indirectly achieved. The fluxgate sensor has the characteristics of high resolution, wide and reliable measuring weak magnetic field range, capability of directly measuring the component of the magnetic field, suitability for use in a rapid motion system and the like.
The existing fluxgate sensor circuit has two implementation schemes of dual power supply and single power supply. The circuit is usually composed of a self-checking circuit, an excitation circuit, a filtering amplifying circuit and the like. Under the single power supply scheme, a constant voltage source circuit is also required to be added to provide a midpoint voltage to be used as a virtual ground. Compared with a Hall principle sensor, the current sensor based on the fluxgate principle has higher sensitivity and measurement accuracy, and the fluxgate probe has better stability.
The exciting circuit of the existing fluxgate sensor is shown in fig. 1, and is composed of a comparator, an amplifier and a common emitter push-pull circuit. The scheme has good performance when power is supplied at a high voltage of +/-12V, but under a 5V power supply condition, the condition that square wave voltage slightly drops can occur due to lower exciting voltage and relatively higher output impedance of a common emitter circuit, so that detection accuracy is affected.
Disclosure of utility model
The utility model aims to provide a single power supply current detection circuit based on a fluxgate principle, and square wave excitation signals generated by an excitation oscillating circuit are high in quality.
In order to achieve the above purpose, the utility model adopts the following technical scheme: the single power supply current detection circuit based on the fluxgate principle comprises a midpoint constant voltage source circuit, an excitation oscillating circuit, a filtering amplifying circuit and a self-checking circuit, wherein the excitation oscillating circuit comprises two comparator circuits and a common collector push-pull circuit; the output ends of the two comparator circuits are respectively and correspondingly connected with the two bases of the common collector push-pull circuit, so that the common collector push-pull circuit continuously generates square waves under the drive of the comparator circuits.
Preferably, the common-collector push-pull circuit comprises a triode Q3 and a triode Q4 which are connected with each other through a common collector; the common collector electrodes of the triode Q3 and the triode Q4 are connected with the input ends of the two comparator circuits through an inductance circuit; the triode Q3 and the triode Q4 are both biased.
Preferably, the emitter and base of the transistor Q3 and the transistor Q4 are connected by a resistor-capacitor to form a bias.
Preferably, the resistive-capacitive element is a resistor and a capacitor.
Preferably, the emitter of the triode Q3 is connected to the power supply VCC, the emitter of the triode Q4 is connected to GND, and the collector of the triode Q3 and the collector of the triode Q4 are connected to the a end of the inductance circuit through a resistor-capacitor element.
Preferably, the two comparator circuits are respectively connected with the base electrode of the triode Q3 and the base electrode of the triode Q4, and a power supply is also connected between the comparator circuits and the common collector push-pull circuit through a resistor-capacitor element.
As one preferable, the inductance circuit includes an inductance L1, the inductance L1 is connected with the common collector of the common collector push-pull circuit through an a terminal, and meanwhile, the a terminal voltage of the inductance L1 is used as an input reference of the comparator; the common collector voltage of the common collector push-pull circuit is used as an input reference of the comparator at the end B after passing through the inductor L1.
Preferably, the filtering amplifying circuit includes a plurality of second-order active filters, so as to perform filtering processing on the signal generated by the B end of the inductance circuit.
Preferably, the filter amplifying circuit includes two second-order active filters, and performs a filtering process.
Preferably, the two second-order active filters include a front-stage filter circuit and a rear-stage filter circuit, and the filters of the rear-stage filter circuits are connected to GND.
Compared with the prior art, the utility model has the beneficial effects that:
(1) The circuit is simpler, the use of one amplifier unit is reduced, the problem of larger output impedance of the common emitter push-pull circuit is avoided, the quality of the generated square wave is better, and the phenomenon of square wave voltage drop is avoided;
(2) The scheme of separating and connecting different reference grounds by adopting the multistage filter avoids the interference on the output signal when the peak of the constant-voltage source in the point of the traditional filter amplifying circuit is used as the reference ground, improves the quality of the output signal and improves the signal-to-noise ratio.
Drawings
FIG. 1 is a schematic diagram of a conventional exciting oscillating circuit of a single power supply current detecting circuit;
FIG. 2 is a schematic diagram of a square wave generated by an excitation oscillating circuit of a single power supply current detection circuit according to the prior art;
FIG. 3 is a schematic diagram of a conventional filtering amplifier circuit of a single power supply current detection circuit;
FIG. 4 is a schematic diagram of a single power supply current detection circuit excitation oscillating circuit based on fluxgate principle according to the present application;
FIG. 5 is a schematic diagram of a square wave generated by an excitation oscillator circuit of a single supply current detection circuit based on the fluxgate principle of the present application;
Fig. 6 is a schematic diagram of a filtering amplifier circuit of a single power supply current detection circuit based on the fluxgate principle according to the present application.
In the figure: 10. an excitation oscillating circuit; 101. a comparator circuit; 102. an amplifier circuit; 103. a common emitter push-pull circuit; 104. an inductance circuit; 105. a common collector push-pull circuit; 20. a filter amplifying circuit; 201. a stage filter circuit; 202. and a post-stage filter circuit.
Detailed Description
The present utility model will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below.
It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
The terms "comprises" and "comprising," along with any variations thereof, in the description and claims, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1, an exciting oscillating circuit 10 of a conventional single power supply current detection circuit mainly includes a comparator circuit 101, an amplifier circuit 102 and a common emitter push-pull circuit 103. An output terminal of the comparator circuit 101 is connected to an input terminal of the amplifier circuit 102, an output terminal of the amplifier circuit 102 is connected to an input terminal of the common-emitter push-pull circuit 103, one terminal of the inductance circuit 104 is connected to a common-emitter of the common-emitter push-pull circuit 103 through the a terminal, an emitter voltage of the common-emitter push-pull circuit 103 is used as an input reference of the comparator circuit 101 and an input reference of the amplifier circuit 102 through the a terminal, and an emitter voltage of the common-emitter push-pull circuit 103 is used as an input reference of the comparator at the B terminal after passing through the inductance L1.
The exciting oscillating circuit 10 performs well when the high voltage of ±12v is supplied, but under the condition of 5V supply, the square wave voltage slightly drops due to the low exciting voltage and the relatively high output impedance of the common emitter push-pull circuit 103. Additionally, since the transistor Q1 and the transistor Q2 of the common-emitter push-pull circuit 103 inevitably enter the amplifying region at the same time during the process of inverting the exciting current of the exciting oscillating circuit 10, a large current change rate is generated. A higher voltage spike is generated at the moment of switching of the excitation current, as shown in fig. 2.
As shown in fig. 3, in the conventional filtering and amplifying circuit 20 of the single-power current detection circuit, a bias adjustment circuit and a gain adjustment circuit are generally added on the basis of the conventional filtering and amplifying circuit, and only a simplified schematic diagram of the filtering and amplifying circuit 20 is provided, which mainly includes a front stage filtering circuit 201 and a rear stage filtering circuit 202, wherein the filters of the front stage filtering circuit 201 and the rear stage filtering circuit 202 are connected to a reference ground VREF.
It will be appreciated that, due to the limited input/output capability of the midpoint constant voltage source circuit, voltage spikes generated at the moment of commutation of the inductor L1 will inevitably affect other circuits, and in particular, when the voltage of the midpoint constant voltage source circuit is adopted as the reference ground VREF by the filter amplifying circuit 20, the output signal will overlap with the signal spikes of the reference ground VREF, and pollute the signal output quality of the single power current detection circuit.
Based on the above, in order to avoid slight drop of square wave voltage on the basis of the existing single power supply current detection circuit, the square wave quality is improved. In one preferred embodiment of the present application, a single power current detection circuit based on the fluxgate principle is provided, which includes a midpoint constant voltage source circuit, an excitation oscillating circuit 10, a filter amplifying circuit 20 and a self-checking circuit, wherein the midpoint constant voltage source circuit and the self-checking circuit are not different from the existing scheme, and therefore are not described herein. The exciting oscillating circuit 10 comprises two comparator circuits 101 and a common collector push-pull circuit 105; the output ends of the two comparator circuits 101 are respectively connected with the two bases of the common-collector push-pull circuit 105 correspondingly, so that the common-collector push-pull circuit 105 continuously generates square waves under the drive of the comparator circuits 101, and the situation that the square wave voltage slightly drops is further avoided. It will be appreciated that the reduction of the amplifier circuit 102 simplifies the circuit.
Specifically, the common-collector push-pull circuit 105 includes a triode Q3 and a triode Q4 connected to each other by a common collector, where the common collectors of the triode Q3 and the triode Q4 are respectively connected to the input ends of the two comparator circuits 101 through the inductance circuit 104, so as to be used as input references of the two comparators; the triode Q3 and the triode Q4 are biased, so that the closing speed of the triode Q3 and the triode Q4 can be improved.
It can be appreciated that the emitter and the base of the triode Q3 and the emitter and the base of the triode Q4 are connected through the resistor-capacitor element, so that the voltages between the emitter and the base of the triode Q3 and the triode Q4 are respectively kept in a proper range to form bias, and the closing speed of the triode Q3 and the triode Q4 is further improved, so that the triode Q3 and the triode Q4 work normally.
In an alternative embodiment, the resistive-capacitive element is a resistor. It will be appreciated that the resistor-capacitor element may be other components or circuits that increase the turn-off speed of transistor Q3 and transistor Q4.
Further, the emitter of the triode Q3 is connected with the power VCC, the emitter of the triode Q4 is connected with GND, the collector of the triode Q3 and the collector of the triode Q4 are connected with the a end of the inductor 104 through series resistor-capacitor elements, it is understood that the series resistor-capacitor elements between the collector and the base form bias, so that the triode Q3 and the triode Q4 are turned off under the condition of extremely high resistance of the base is ensured, and the turn-off speed of the triode Q3 and the triode Q4 is further improved.
It should be noted that, the two comparator circuits 101 are respectively connected with the base electrode of the triode Q3 and the base electrode of the triode Q4, so as to respectively drive the triode Q3 and the triode Q4 to generate continuous square waves, and a power source VCC is further connected between the comparator circuits and the common collector push-pull circuit through a resistor-capacitor element, so that the phenomenon that the triode Q3 and the triode Q4 of the common collector push-pull circuit 105 are directly connected in an amplifying region due to the fact that the common collector push-pull circuit 105 is driven by the pull resistor and the open drain output of the comparator circuits 101 is avoided.
Further, the inductance circuit 104 includes an inductance L1, one end of the inductance L1 is connected to the common collector of the common collector push-pull circuit 105 through the a terminal, and meanwhile, the a terminal voltage of the inductance L1 is used as an input reference of the comparator; the other end of the inductor L1 is connected to the input end of the comparator circuit 101 through the B end, and the common collector voltage of the common collector push-pull circuit 105 is used as an input reference of the comparator at the B end after passing through the inductor L1, so that the voltages at the a end and the B end can be compared through the comparator. Specifically, when the voltage at the a end is maintained before the inductor L1 is saturated, the voltage at the a end is inverted after the inductor L1 is saturated, so that the inductor L1 is repeatedly excited.
The exciting oscillating circuit 10 of the single power supply current detection circuit based on the fluxgate principle generates square waves as shown in fig. 5, and compared with the square waves in fig. 2, the square waves in fig. 5 avoid the phenomena of slight voltage drop and voltage spike, and the quality of the square waves is obviously improved.
The filtering and amplifying circuit 20 of the single power supply current detection circuit based on the fluxgate principle provided by the application, as shown in fig. 6, is characterized in that the filtering and amplifying circuit 20 comprises two second-order active filters, so that the signal generated at the end B of the inductance circuit 104 can be filtered.
Specifically, the filter amplifier circuit 20 includes a front stage filter circuit 201 and a rear stage filter circuit 202, and the filter of the rear stage filter circuit 202 is connected to GND. It will be appreciated that if the pre-stage filter circuit 201 and the post-stage filter circuit 202 use the same reference ground VREF, the voltage spike of the reference ground VREF will be superimposed on the output signal of the filter amplifier circuit 20 to pollute the output signal, since the exciting oscillating circuit 10 introduces the voltage spike to the reference ground VREF. The reference ground of the filter of the post-stage filter circuit 202 is replaced by the more stable GND, so that the voltage spike of the reference ground VREF is prevented from being introduced into the post-stage filter circuit 202, the influence of the voltage spike of the reference ground VREF on the filter amplifying circuit 20 is reduced, and the quality of the output signal of the single power supply current detecting circuit is further improved.
In some alternative embodiments, the filter of the pre-stage filtering circuit 201 is connected to the reference ground VREF, so that the circuit gain is fully placed in the first stage, the peak of the output signal overlapping the reference ground VREF is further avoided, and meanwhile, the signal-to-noise ratio of the filter is improved, and the quality of the output signal is improved. It will be appreciated that the filter amplifier circuit 20 may also comprise a plurality of second order active filters, and that the amplifier circuit filtering GND must be placed after the amplifier circuit filtering VREF with reference to ground and must include a first order filter circuit filtering GND.
The working process of the single power supply current detection circuit based on the fluxgate principle of the application is specifically as follows, the exciting oscillating circuit 10 repeatedly excites the magnetic core of the inductor L1, so that the magnetic core of the inductor L1 is in the process of repeated saturation magnetization, and the current signal is extracted and used as an output signal through the filtering amplifying circuit 20. When the current passing through the magnetic ring is 0, the current magnetized in the forward and reverse directions is equal in magnitude and opposite in direction, and the output signal is a midpoint signal after passing through the filter amplification circuit 20; when the current passing through the magnetic ring is not 0, the hysteresis curve of the magnetic core of the inductor L1 is biased due to the current magnetic field, and the exciting current is further biased, so that the output signal generates bias voltage on the basis of the midpoint signal, and the bias voltage is in direct proportion to the measured current, thereby indirectly detecting the measured current.
The foregoing has outlined the basic principles, features, and advantages of the present utility model. It will be understood by those skilled in the art that the present utility model is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present utility model, and various changes and modifications may be made therein without departing from the spirit and scope of the utility model, which is defined by the appended claims. The scope of the utility model is defined by the appended claims and equivalents thereof.
Claims (10)
1. The single power supply current detection circuit based on the fluxgate principle comprises a midpoint constant voltage source circuit, an excitation oscillating circuit, a filtering amplifying circuit and a self-checking circuit, and is characterized in that the excitation oscillating circuit comprises two comparator circuits and a common collector push-pull circuit; the output ends of the two comparator circuits are respectively and correspondingly connected with the two bases of the common collector push-pull circuit, so that the common collector push-pull circuit continuously generates square waves under the drive of the comparator circuits.
2. The single power supply current detection circuit based on the fluxgate principle according to claim 1, wherein the common collector push-pull circuit comprises a triode Q3 and a triode Q4 connected by a common collector; the common collector electrodes of the triode Q3 and the triode Q4 are connected with the input ends of the two comparator circuits through an inductance circuit; the triode Q3 and the triode Q4 are both biased.
3. The single supply current detection circuit based on the fluxgate principle according to claim 2, wherein the emitter and base of the transistor Q3 and the transistor Q4 are connected by a resistor-capacitor element to form a bias.
4. The single power supply current detection circuit based on the fluxgate principle according to claim 3, wherein the resistance-capacitance element is a resistor and a capacitor.
5. The single power supply current detection circuit based on the fluxgate principle according to claim 2, wherein the emitter of the triode Q3 is connected with the power supply VCC, the emitter of the triode Q4 is connected with GND, and the collector of the triode Q3 and the collector of the triode Q4 are connected with the a end of the inductance circuit through series resistance-capacitance elements.
6. The single power supply current detection circuit based on the fluxgate principle according to claim 2, wherein two comparator circuits are respectively connected with the base of the triode Q3 and the base of the triode Q4, and a power supply is further connected between the comparator circuits and the common collector push-pull circuit through a resistor-capacitor element.
7. The single power supply current detection circuit based on the fluxgate principle according to claim 2, wherein the inductance circuit comprises an inductance L1, the inductance L1 is connected with a common collector of the common collector push-pull circuit through an a terminal, and the a terminal voltage of the inductance L1 is used as an input reference of a comparator; the common collector voltage of the common collector push-pull circuit is used as an input reference of the comparator at the end B after passing through the inductor L1.
8. The single power supply current detection circuit according to any one of claims 1 to 6, wherein the filter amplifier circuit includes a plurality of second order active filters for filtering the signal generated at the B terminal of the inductor circuit.
9. The single power supply current detection circuit based on the fluxgate principle according to claim 8, wherein the filter amplifying circuit includes two second order active filters for performing a filtering process.
10. The fluxgate principle-based single power supply current detection circuit according to claim 8, wherein the two second-order active filters include a front-stage filter circuit and a rear-stage filter circuit, and the filters of the rear-stage filter circuits are connected to GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322614422.5U CN221039215U (en) | 2023-09-26 | 2023-09-26 | Single power supply current detection circuit based on fluxgate principle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322614422.5U CN221039215U (en) | 2023-09-26 | 2023-09-26 | Single power supply current detection circuit based on fluxgate principle |
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| Publication Number | Publication Date |
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| CN221039215U true CN221039215U (en) | 2024-05-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322614422.5U Active CN221039215U (en) | 2023-09-26 | 2023-09-26 | Single power supply current detection circuit based on fluxgate principle |
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| Country | Link |
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| CN (1) | CN221039215U (en) |
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2023
- 2023-09-26 CN CN202322614422.5U patent/CN221039215U/en active Active
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