CN215340049U - Electronic circuit for open-loop single-power-supply current output Hall current sensor - Google Patents
Electronic circuit for open-loop single-power-supply current output Hall current sensor Download PDFInfo
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- CN215340049U CN215340049U CN202120814872.7U CN202120814872U CN215340049U CN 215340049 U CN215340049 U CN 215340049U CN 202120814872 U CN202120814872 U CN 202120814872U CN 215340049 U CN215340049 U CN 215340049U
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Abstract
The utility model relates to the field of Hall current sensor electronic circuits, in particular to an electronic circuit for an open-loop type single-power-supply current output Hall current sensor, which comprises an instrument amplifier consisting of double operational amplifiers, one or 2n Hall elements connected in parallel, a linear positive temperature coefficient constant current source, a voltage bias circuit and a zero current bias and voltage-to-current conversion circuit. The temperature tracking compensation of the full-temperature region is realized by using a linear positive temperature coefficient constant current source to the sensitivity negative temperature coefficient of one or 2n Hall elements; 2n Hall elements are connected in parallel, so that the measurement precision of the detachable open-loop Hall current sensor is improved, and the application field of the detachable open-loop Hall current sensor is expanded; the demand that the detachable current sensor with single power supply working current output is greatly needed in the fields of wind power generation, communication power supplies, electric power internet of things and the like is met, the cost is lower, and the applicability is better.
Description
Technical Field
The utility model particularly relates to the field of Hall current sensor electronic circuits, in particular to an electronic circuit for an open-loop type single-power-supply current output Hall current sensor.
Background
The Hall current sensor is a novel current sensor, has the characteristics of high sensitivity, low power consumption, electric isolation, high cost performance, convenient use and the like, and is widely applied to the automatic control field of various current conversion technologies, alternating current numerical control devices and the like which take current as a measurement and monitoring object.
The Hall current sensor usually has two working modes of open loop and closed loop, the open loop type Hall current sensor is composed of an annular magnetic core with an air gap made of soft magnetic materials, a Hall element and a proper amplifying circuit, wherein the Hall element directly detects the magnetic induction intensity of current to be detected in the air gap of the magnetic core, the sensitivity is moderate, the temperature stability is the most important factor, an ion injection type or molecular beam epitaxy type Hall element made of GaAs materials is generally selected, and the ion injection type Hall element is easy to have defects of unevenness, faults or dislocation and the like in the process of ion injection, annealing and the like; the molecular beam epitaxy type hall element is a physical process, and the probability of generating defects such as unevenness, stacking faults or dislocation is much lower, so that the molecular beam epitaxy type GaAs hall element is selected, and the relevant characteristics of the molecular beam epitaxy type Hall element are shown in figure 1.
As can be seen from fig. 1, the offset voltage of the hall element in fig. 2 increases linearly with the increasing operating current, which illustrates that the cause of the offset voltage is purely resistive, and the equivalent diagram of the hall element is shown in fig. 3; as can be seen from fig. 1, the output voltage of the hall element decreases approximately linearly with the increase of the operating temperature, and can be compensated by a linear temperature compensation method.
An electronic circuit of a ring-shaped Hall current sensor is opened at home and abroad as shown in figure 4, and the circuit has the following problems:
1. from the input of the differential amplifier, the output resistance R of the Hall element becomes a part of the input impedance of the amplifier, the amplification factor of the amplifier is changed from AV-R6/R4-R7/R5 to AV-R6/(R4 + R) -R7/(R5 + R), R increases with the temperature, AV decreases in a nonlinear way, and the full-temperature-zone linear tracking compensation cannot be carried out;
2. the temperature characteristics of PN junction voltages of Tr1 and Tr2 are utilized to carry out tracking compensation on the sensitivity temperature drift of the Hall element; the output amplitude of the current sensor is adjusted by adjusting the working current of the Hall element, so that the output amplitude and the sensitivity temperature drift of the Hall element cannot be simultaneously considered during tracking compensation;
3. the voltage is led out from the input end of the Hall element to carry out proportion adjustment on the zero voltage of the sensor, so that the proportion adjustment on the zero voltage and the tracking compensation on the offset voltage temperature drift of the Hall element cannot be simultaneously considered;
4. when the T-type network at the output end of the amplifier drives a large load, the output voltage of the sensor can be attenuated due to the voltage drop on the resistor in the T-type network.
5. When the output voltage of the open-loop Hall current sensor is transmitted in a long distance, particularly wind power generation, when the output voltage is output in a long distance, the signal transmission line reaches 30-100 meters, and the output voltage is attenuated!
6. In an industrial automatic control system, a current sensor is generally powered by a switching power supply, the switching power supply generally transforms voltage, rectifies the voltage and filters the voltage into direct current voltage to supply power to a control system by a transformer, the rectification and the filtering are generally completed by a large-capacity aluminum electrolytic capacitor, the electrolyte of the aluminum electrolytic capacitor is continuously volatilized along with the increase of time and working temperature, the equivalent impedance of the aluminum electrolytic capacitor is continuously increased, the filtering effect is reduced, the ripple voltage amplitude in the direct current voltage for supplying power to the control system is continuously increased to more than plus or minus 18V, and the power supply continuously impacts an operational amplifier in the current sensor along with the increase of the switching times of the system power supply, so that the amplifier damages the current sensor and is failed!
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide an electronic circuit for an open-loop single-power-supply current output Hall current sensor, which solves the problems in the prior art.
In order to achieve the purpose, the utility model provides the following technical scheme:
the device comprises an instrument amplifier consisting of double operational amplifiers, one or 2n Hall elements connected in parallel, a linear positive temperature coefficient constant current source, a voltage bias circuit and a zero current bias and voltage-to-current conversion circuit; the input end of one or 2n parallel Hall elements is connected with a linear positive temperature coefficient constant current source, the output end of the Hall elements is connected with the input end of an instrument amplifier, a voltage bias circuit biases an electronic circuit, the output end of the instrument amplifier is connected with the input end of a zero current bias and voltage-to-current conversion circuit, and the zero voltage of the electronic circuit is adjusted by adjusting parallel resistors from two output ends of the Hall elements respectively; and adjusting the amplification factor of the instrument amplifier to adjust the output amplitude of the electronic circuit, wherein the resistor R14 of the RC filter is positioned in the negative feedback of the instrument amplifier, and a polarity protection diode and a limiting voltage stabilizing diode or a bidirectional TVS (transient voltage suppressor) and a polarity protection diode are respectively added at the power supply end of the open-loop Hall current sensor.
Preferably: the linear positive temperature coefficient constant current source consists of a PNP and NPN complementary pair transistor, resistors R1, R2, R3, R4, R5 and an adjustable voltage reference VZ 1; an emitter of the NPN triode is connected with a reference end of the adjustable voltage reference VZ1 and then is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with a cathode end of the adjustable voltage reference; the anode end of the adjustable voltage reference is connected with the base electrode of the NPN triode and then connected with the collector electrode of the PNP triode; the collector of the NPN triode is connected with the base of the PNP triode and then connected with one end of a resistor R2, and the other end of the resistor R2 is connected with a positive power supply; an emitting electrode of the PNP triode is connected with one end of a resistor R5, the other end of a resistor R4 is connected with one end of a resistor R5 in series, the other end of the resistor R5 is connected with a positive power supply, after the resistor R3 and a capacitor C1 are connected in parallel, one end of the resistor R5 is connected with an anode of an adjustable voltage reference, and the other end of the resistor R4 is connected with the positive power supply.
Preferably: a voltage bias circuit is composed of a variable voltage reference VZ2, bias voltages generated by resistors R15, R16 and R17, and a voltage driving circuit generated by an amplifier A2, a resistor R18, capacitors C12 and C13.
Preferably: a zero current bias and voltage-to-current conversion circuit; the circuit consists of a zero current bias voltage generated by a variable voltage reference VZ3, a resistor R19, an amplifier A3, resistors R20-R27, a capacitor C14 and triodes Q3-Q5, and a circuit for generating the zero current bias and voltage-to-current conversion.
Preferably: and 2n parallel Hall elements are arranged along the annular magnetic core in the same direction.
Compared with the prior art, the utility model has the beneficial effects that:
1. the internal resistance of the Hall element becomes the input balance resistance of the instrumentation amplifier, the influence of the temperature drift of the output resistance of the Hall element on the amplification factor of the dual operational amplifier is effectively eliminated, and the linear positive temperature coefficient constant current source realizes the full-temperature-zone linear temperature tracking compensation of the sensitivity temperature drift of one or 2n Hall elements; the better the temperature stability of the sensor output, the wider the working temperature range; the lower the manufacturing cost is, the lower the price is, the better the quality is really achieved, and the zero temperature drift is 50 ppm/DEG C-300 ppm/DEG C; the working temperature zone reaches-40 to 85 ℃; -40 to 105 ℃; greatly improves the current measurement precision of the open-loop Hall current sensor, expands the application field of the open-loop Hall current sensor,
particularly, the detachable open-loop Hall current sensor realizes single-current work and current output, and meets the requirements of large-scale single-power work, current output, detachability, large current and ultra-long distance transmission in the fields of wind power generation, communication power supply, power internet of things and the like.
2. The amplitude limiting voltage stabilizing diode is added at the power supply end of the current sensor, the influence of the sharp pulse voltage in the power supply end of the current sensor on the current sensor is greatly reduced, the failure rate is reduced from 3000PPM to below 100PPM, and the quality of the current sensor is greatly improved! (FIG. 8, FIG. 9)
3. The utility model is an electronic circuit for an open-loop type single-power-supply current output Hall current sensor, which has low cost, high reliability and better applicability.
Drawings
FIG. 1 is a graph showing the output voltage characteristic and offset voltage characteristic of a molecular beam epitaxy GaAs Hall element;
FIG. 2 is a circuit schematic diagram of a GaAs Hall element;
FIG. 3 is an equivalent circuit diagram of a GaAs Hall element;
FIG. 4 is an electronic circuit diagram of an open loop type Hall current sensor at home and abroad;
FIG. 5 is a circuit diagram of an open-loop single supply current output Hall current sensor for a trimmer potentiometer;
FIG. 6 is a circuit diagram of a linear positive temperature coefficient constant current source;
FIG. 7 is a graph of measured temperature for a linear positive temperature coefficient constant current source;
FIG. 8 is a waveform diagram of the output DC voltage when the switching power supply is switched on and off;
fig. 9 is a waveform diagram of the power supply terminal after the current sensor power supply terminal is added with a limiting voltage stabilizing diode.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 5 to 7, an electronic circuit for measuring a detachable hall current sensor with 5000 ampere open-loop single power supply 24V working and current output of 12mA ± 8 mA: an instrumentation amplifier composed of two dual operational amplifiers a1, A2BA4580RFSOP8, R8 ═ R9 ═ 3.0K, C5 ═ C6 ═ 3PF, R7 ═ 470, C8 ═ C9 ═ 150PF, R10 ═ R11 ═ 10K Ω, R12 ═ R13 ═ 51K Ω, C10 ═ 33PF, 6 hall elements (HG302C, SIP 4); the linear positive temperature coefficient constant current source comprises a PNP (MMBT3906SOT-23), an NPN (MMBT3904SOT-23) complementary pair tube, a resistor R1 (910), a resistor R2 (1.0K, C1) 0.01UF, a resistor R3 (200K, R4) 51, a resistor R5 (750) and an adjustable voltage reference VZ (CZ431, SOT-23). A polarity protection diode D1/D2(BAT54W, SOD-23) and a voltage-limiting 30V voltage-stabilizing diode (BZT52B30T1G, SOD-123) are respectively added at a power supply end of the current sensor, or a 400W bidirectional TVS tube (WS30P4SMA-BSMA) and a polarity protection diode D (BAT54W, SOD-23) are respectively added. The zero voltage of the whole circuit is adjusted by connecting two output ends of the Hall element in parallel in a resistance mode, wherein R6-R8-R9-R357-R7-R9-R4.7K; the resistor of the RC filter is positioned in the negative feedback of the differential amplifier in the instrument amplifier, R17 is 200, C10 is 4700PF, RW1 and RW2 are trimmer potentiometers.
The voltage bias circuit comprises a bias voltage 7.5V generated by a variable voltage reference VZ2(CZ431, SOT-23), a resistor R15-3K, R16-20K, R17-10K, an amplifier A2, a resistor R18-200, and a capacitor C12-C13-1000 PF generation voltage driving circuit.
A zero current bias and voltage-to-current conversion circuit. The circuit is composed of a variable voltage reference VZ3(CZ432, SOT-23), a zero current bias voltage 1.25V generated by a resistor R19 ═ 3.3K, an amplifier A3(LF253SOP8), a resistor R20 ═ 30K, a resistor R21 ═ 1.2K, a capacitor C14 ═ 100PF, a triode Q3(MMBT3904 SOT23), a Q4(MMBT3906SOT23), a Q5(MMBTSOT89), a zero current bias voltage and a voltage-to-current conversion circuit.
The 6 parallel Hall elements are arranged along the annular magnetic core in the same orientation. Under the condition that the IC of the Hall element is 5mA, the Hall element is graded with the same polarity with each difference of 0.5mV according to the positive value and the negative value of offset voltage; for 6 Hall elements, according to the fact that offset voltage values of the Hall elements are in the same gear and are paired one by one with opposite polarities, the Hall elements are arranged and installed along the same direction of the annular magnetic core under the drive of the same linear positive temperature coefficient constant current source, offset voltages of the Hall elements are eliminated in a paired mode with opposite polarities, at the moment, the range of the zero voltage of the Hall current sensor is small, time is saved during adjustment, production efficiency is high, and full-automatic flow production is achieved during production of the whole Hall current sensor.
6 Hall elements are connected in parallel, the arithmetic mean of the output of the 6 Hall elements is realized, and the offset voltage, the temperature drift, the noise voltage and the like of the 6 Hall elements are equal
The multiple is reduced, so that the temperature characteristic of the sensor is more stable, and the lower limit of measurement is lower. The current measurement precision of the open-loop Hall current sensor is enabled to reach within 0.2% FS, the temperature drift of zero point and amplitude reaches 50 ppm/DEG C-200 ppm/DEG C, the working temperature zone reaches-40-105 ℃, the current measurement precision of the detachable open-loop Hall current sensor is greatly improved, and the application field of the detachable open-loop Hall current sensor is expanded.
Measured temperature of positive temperature coefficient constant current source
The actually measured temperature curve of the linear positive temperature coefficient constant current source is shown in fig. 7, and it can be seen that the linear positive temperature coefficient of the linear positive temperature coefficient constant current source is almost the same as the linear negative temperature coefficient of the output voltage of the hall element, so that the full-temperature-zone linear temperature tracking compensation of the sensitivity temperature drift of the hall element is realized.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.
Claims (5)
1. An open-loop type single-power-supply current output electronic circuit for a Hall current sensor is characterized in that: the device comprises an instrument amplifier consisting of double operational amplifiers, one or 2n Hall elements connected in parallel, a linear positive temperature coefficient constant current source, a voltage bias circuit and a zero current bias and voltage-to-current conversion circuit; the input end of the Hall element or the input ends of the Hall elements with 2n parallel connection are connected with a linear positive temperature coefficient constant current source, the output end of the Hall element or the input ends of the Hall elements with 2n parallel connection are connected with the input end of the instrument amplifier, the voltage bias circuit biases the electronic circuit, the output end of the instrument amplifier is connected with the input end of the zero current bias and voltage-to-current conversion circuit, and the zero voltage of the electronic circuit is adjusted by respectively adjusting the parallel resistance from the two output ends of the Hall element; and adjusting the amplification factor of the instrument amplifier to adjust the output amplitude of the electronic circuit, wherein a resistor R14 of an RC filter is positioned in the negative feedback of the instrument amplifier, and a polarity protection diode and a limiting voltage stabilizing diode or a bidirectional TVS (transient voltage suppressor) and a polarity protection diode are added at the power supply end of the open-loop Hall current sensor.
2. The electronic circuit for an open-loop single-supply current output hall current sensor according to claim 1, wherein: the linear positive temperature coefficient constant current source consists of a PNP and NPN complementary pair transistor, resistors R1, R2, R3, R4, R5 and an adjustable voltage reference VZ 1; an emitter of the NPN triode is connected with a reference end of the adjustable voltage reference VZ1 and then is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with a cathode end of the adjustable voltage reference; the anode end of the adjustable voltage reference is connected with the base electrode of the NPN triode and then connected with the collector electrode of the PNP triode; the collector of the NPN triode is connected with the base of the PNP triode and then connected with one end of a resistor R2, and the other end of the resistor R2 is connected with a positive power supply; an emitting electrode of the PNP triode is connected with one end of a resistor R5, the other end of a resistor R4 is connected with one end of a resistor R5 in series, the other end of the resistor R5 is connected with a positive power supply, after the resistor R3 and a capacitor C1 are connected in parallel, one end of the resistor R5 is connected with an anode of an adjustable voltage reference, and the other end of the resistor R4 is connected with the positive power supply.
3. The electronic circuit for an open-loop single-supply current output hall current sensor according to claim 1, wherein: a voltage bias circuit is composed of a variable voltage reference VZ2, bias voltages generated by resistors R15, R16 and R17, and a voltage driving circuit generated by an amplifier A2, a resistor R18, capacitors C12 and C13.
4. The electronic circuit for an open-loop single-supply current output hall current sensor according to claim 1, wherein: a zero current bias and voltage-to-current conversion circuit; the circuit consists of a zero current bias voltage generated by a variable voltage reference VZ3, a resistor R19, an amplifier A3, resistors R20-R27, a capacitor C14 and triodes Q3-Q5, and a circuit for generating the zero current bias and voltage-to-current conversion.
5. The electronic circuit for an open-loop single-supply current output hall current sensor according to claim 1, wherein: and 2n parallel Hall elements are arranged along the annular magnetic core in the same direction.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115542203A (en) * | 2022-11-02 | 2022-12-30 | 深圳市晶扬电子有限公司 | Magnetic field detection circuit based on Hall effect and current sensor |
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2021
- 2021-04-20 CN CN202120814872.7U patent/CN215340049U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115542203A (en) * | 2022-11-02 | 2022-12-30 | 深圳市晶扬电子有限公司 | Magnetic field detection circuit based on Hall effect and current sensor |
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