CN112630501A - DC current sensor circuit with arbitrary bias current output - Google Patents
DC current sensor circuit with arbitrary bias current output Download PDFInfo
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- CN112630501A CN112630501A CN202011532320.3A CN202011532320A CN112630501A CN 112630501 A CN112630501 A CN 112630501A CN 202011532320 A CN202011532320 A CN 202011532320A CN 112630501 A CN112630501 A CN 112630501A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/202—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
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Abstract
The invention discloses a direct current sensor circuit capable of outputting any bias current, which comprises a precise voltage stabilizing circuit, a magnetic-sensitive detection circuit, a voltage comparison and push-pull output circuit and a bias circuit which are connected in sequence, wherein: the precise voltage stabilizing circuit is used for converting the input voltage into the working voltage of the magnetic-sensing detection circuit; the magnetic-sensing detection circuit is used for detecting the magnetic field intensity in the open coil and generating a signal to be output to the voltage comparison and push-pull output circuit; the voltage comparison and push-pull output circuit is used for generating zero bias current; and the bias circuit is used for generating bias current, and the bias current and the zero bias current are superposed to be used as the output of the direct current sensor. The invention can detect the direct current signal of hundreds of amperes, solve the power consumption problem generated by the input current signal of hundreds of amperes, and isolate and output a current signal which can be set arbitrarily and is linear with the detection current.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a direct current sensor circuit with any bias current output.
Background
In recent years, hall current sensor products are widely applied to the military and civil goods fields of aviation, aerospace, communication, instruments, metallurgy, railways and the like due to the advantages of good precision and linearity, high isolation between detection signals and output signals, high reliability, low power consumption, convenience in maintenance and replacement and the like. In many applications, the zero output of the hall current sensor is required to be 0mA or 4mA of the reference, that is, when the detection current is zero, the output current of the sensor is 0mA or 4 mA; when the detection current is in a negative direction, the output current of the sensor is a current value smaller than a reference value (0mA or 4 mA); when the detection current is positive, the output current of the sensor is a current value larger than a reference value (0mA or 4mA), and the detection current and the output current change into a linear relation. At present, the zero output current of the conventional Hall current sensor on the market is mostly 0mA or 4mA, and the Hall current sensor is a product which is not output by other reference values. In application, however, products with other reference value current outputs are required, for example, the reference value is 30mA, namely when the detection current is zero, the output current of the sensor is 30 mA; when the detection current is in a negative direction, the output current of the sensor is a current value smaller than 30 mA; when the detection current is positive, the output current of the sensor is a current value larger than 30mA, and the detection current and the output current change into a linear relation. There is no sensor in the prior art that can output any bias current.
Disclosure of Invention
The invention aims to provide a direct current sensor circuit with any bias current output, which is used for solving the problem that the zero output reference of a Hall current sensor in the prior art is 0mA or 4mA, and bias currents with other numerical values cannot be output at will.
The invention solves the problems through the following technical scheme:
the utility model provides a direct current sensor circuit of arbitrary bias current output, includes the accurate voltage stabilizing circuit, the magnetic-sensitive detection circuit, voltage comparison and push-pull output circuit and the bias circuit that connect gradually, wherein:
the precise voltage stabilizing circuit is used for converting the input voltage into the working voltage of the magnetic-sensing detection circuit;
the power supply of a general sensor is not an accurate voltage value (such as +/-15V), but a voltage range (such as +/-12V to +/-15V), and the output voltage of the magnetic sensing detection circuit during zero magnetic flux is a positive power supply voltage and half of the power supply voltage, so that when the power supply voltage changes within an allowable range, the zero output of the magnetic sensing detection circuit is stable, and an accurate power supply voltage (such as +5V) needs to be provided for the magnetic sensing detection circuit, therefore, the power supply needs to be stabilized.
The magnetic-sensing detection circuit is used for detecting the magnetic field intensity in the open coil and generating a signal to be output to the voltage comparison and push-pull output circuit;
the magnetic-sensing detection circuit mainly comprises a Hall chip, when the detected current is zero, zero magnetic flux is in the open coil, and the zero output voltage of the Hall chip is reference voltage; when the detected current passes through the open coil, the Hall chip in the open coil detects the magnetic flux change of the magnetic ring, and a voltage value which is in direct proportion to the magnetic flux change is output on the basis of the zero output voltage, namely:
vout1 ═ reference voltage + K × Δ V
Where Vout1 is the output voltage of the hall chip, Δ V is the sensitivity of the hall chip, i.e., the amount of voltage change caused by unit magnetic flux change, and K is the amplification factor adjusted by the peripheral resistance.
The signal generated by the magnetic-sensing detection circuit is amplified in the voltage comparison and push-pull output circuit, the power tube in the push-pull circuit in the voltage comparison and push-pull output circuit is driven to be conducted, compensation current is generated, the compensation current generates magnetic induction intensity in a magnetic field, when the compensation current is increased to a certain degree, the compensation is balanced, and namely zero-point bias current is generated.
And the bias circuit is used for generating bias current, and the bias current and the zero bias current are superposed to be used as the output of the direct current sensor. By changing the bias current of the bias circuit, the output current of the direct current sensor can be changed, and any bias current output can be achieved.
The bias circuit comprises a primary side bias current adjusting resistor connected with an input voltage, the primary side bias current adjusting resistor is connected with a first end of a primary side winding of a transformer T1 after being connected with an anti-reverse diode D2 in series, and a second end of the primary side winding of the transformer T1 is grounded; the first end of the secondary winding of the transformer T1 is connected with the output end of the voltage comparison and push-pull output circuit, and the second end of the secondary winding of the transformer T1 is used as the output end of the direct current sensor.
The voltage comparison and push-pull output circuit comprises an operational amplifier, a power tube Q1 and a power tube Q2, wherein the positive input end and the negative input end of the operational amplifier are respectively connected with the two output ends of the magnetic-sensing detection circuit, and the positive voltage input end of the operational amplifier is connected to a voltage VCC through an anti-reverse diode D1; the output end of the operational amplifier is connected with one end of a secondary winding of the transformer T1 through a resistor R11, and the voltage input negative end of the operational amplifier is connected with the output end of the direct current sensor through an anti-reverse diode D3; the power tube Q1 is connected with the power tube Q2 in a push-pull mode, a resistor R12 is connected between an emitter of the power tube Q1 and an emitter of the power tube Q2 in series, a collector of the power tube Q1 is connected with the positive voltage input end of the operational amplifier, and a collector of the power tube Q2 is connected with the negative voltage input end of the operational amplifier after being connected with a resistor R13 in series; the base of the power tube Q1 and the base of the power tube Q2 are connected with the node between the operational amplifier and the resistor R11. The operational amplifier adopts a rail-to-rail (rail-to-rail) operational amplifier with double power supplies.
The power supply voltage of the operational amplifier is supplied with power after passing through the anti-reverse diode D1, the resistor R12 and the resistor R13 are push-pull output current adjusting resistors, the output currents of the power tube Q1 and the power tube Q2 are guaranteed to be balanced, and damage caused by overlarge current of the power tube is avoided.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention can detect the direct current signal of hundreds of amperes, solve the power consumption problem generated by the input current signal of hundreds of amperes, and isolate and output a current signal which can be set arbitrarily and is linear with the detection current.
(2) The invention has simple circuit, low cost and small volume.
Drawings
FIG. 1 is a functional block diagram of the present invention;
FIG. 2 is a schematic diagram of the circuit of the present invention;
FIG. 3 is a schematic diagram of the power dissipation of the SOT89 power tube;
wherein, 1-a precision voltage stabilizing circuit; 2-a magnetic sensitive detection circuit; 3-a voltage comparison and push-pull output circuit; 4-a bias circuit; U1B-Hall chip; u3-precision voltage-stabilizing power chip; U2A — operational amplifier.
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
Example (b):
referring to fig. 1, a dc current sensor circuit with any bias current output includes a precise voltage stabilizing circuit 1, a magnetic sensing detection circuit 2, a voltage comparison and push-pull output circuit 3 and a bias circuit 4, which are connected in sequence, wherein:
the precise voltage stabilizing circuit 1 is used for converting input voltage into working voltage of the magnetic-sensing detection circuit 2; the power supply of the general sensor is not an accurate voltage value (e.g., +/-15V), but a voltage range (e.g., +/-12V- +/-15V), and the output voltage of the magnetic sensing detection circuit 2 at zero magnetic flux is a positive power supply voltage and is half of the power supply voltage, so as to ensure that the zero output of the magnetic sensing detection circuit 2 is stable when the power supply voltage changes within an allowable range, and an accurate power supply voltage (e.g., +5V) needs to be provided for the magnetic sensing detection circuit 2, therefore, the power supply voltage stabilization is needed.
The magnetic-sensing detection circuit 2 is used for detecting the magnetic field intensity in the split coil and generating a signal to be output to the voltage comparison and push-pull output circuit 3; the magnetic sensitive detection circuit 2 mainly comprises a Hall chip (HALL) U1B, the reference voltage of the Hall chip U1B is 2.5V, when the detected current is zero, zero magnetic flux is in the open coil, the zero output power of the Hall chip U1B is 2.5V, when the detected current passes through the open coil, the Hall chip U1B in the open coil detects the magnetic flux change of the magnetic ring, and a voltage value which is in direct proportion to the magnetic flux change is superposed and output on the basis of the zero output voltage, namely:
Vout1＝2.5V+K*ΔV
vout1 is the output voltage of the Hall chip U1B, Δ V is the sensitivity of the Hall chip, namely the voltage change caused by unit magnetic flux change, and K is the amplification factor regulated by the peripheral resistance.
The signal generated by the magnetic-sensing detection circuit 2 is amplified in the voltage comparison and push-pull output circuit 3, and then the power tube in the push-pull circuit in the voltage comparison and push-pull output circuit 3 is driven to be conducted to generate compensation current, the compensation current generates magnetic induction intensity in a magnetic field, and when the compensation current is increased to a certain degree, the compensation reaches balance, namely zero bias current is generated.
And the bias circuit 4 is used for generating bias current, and the bias current and the zero bias current are superposed to be used as the output of the direct current sensor. By changing the bias current of the bias circuit 4, the output current of the direct current sensor can be changed, and any bias current output can be achieved.
Example 2:
on the basis of the embodiment 1, with reference to fig. 2, after passing through the anti-reverse diode D1, the input voltage VCC is stabilized by the precision voltage stabilizing circuit 1 and then converted into +5V voltage to supply power to the magnetic sensing detection circuit 2, and the precision voltage stabilizing circuit 1 is composed of a precision voltage stabilizing power chip U3, a bypass capacitor C1 and a bypass capacitor C2, and is used for stabilizing the input and output voltages of the chip. The magnetic-sensing detection circuit 2 comprises a Hall chip U1B and a peripheral resistor, when a detected current passes through the open coil, the Hall chip U1B in the air gap of the open coil detects the magnetic flux change of the magnetic ring, and a voltage value in direct proportion to the magnetic flux change is superposed on the basis of a zero-point output voltage. When the magnetic force line vertically passes through the front side of the hall chip U1B, the hall chip U1B outputs a forward variation voltage, i.e., Δ V > 0; otherwise, the negative voltage variation is output, namely delta V < 0. The Hall chip is a linear output magnetic-sensing chip, the inner part of the Hall chip is provided with an adjustable temperature compensation function, the maximum output voltage is clamped at 93 percent of the power supply voltage, and the minimum output voltage is 5 percent of the power supply voltage. The peripheral resistors (resistor R3, resistor R4, resistor R5, resistor R1, resistor R2 and resistor R3) function to adjust the amplification.
The voltage comparison and push-pull output circuit 3 comprises an operational amplifier U2A, a power tube Q1 and a power tube Q2, wherein a positive input end and a negative input end of the operational amplifier U2A are respectively connected with two output ends of the magnetic-sensing detection circuit 2, and a voltage input positive end of the operational amplifier U2A is connected to an input voltage VCC through an anti-reverse diode D1; the output end of the operational amplifier U2A is connected with one end of a secondary winding of the transformer T1 through a resistor R11, and the voltage input negative end of the operational amplifier U2A is connected with the output end of the direct current sensor through an anti-reverse diode D3; the power tube Q1 is connected with the power tube Q2 in a push-pull mode, a resistor R12 is connected between an emitter of the power tube Q1 and an emitter of the power tube Q2 in series, a collector of the power tube Q1 is connected with the positive voltage input end of the operational amplifier, and a collector of the power tube Q2 is connected with the negative voltage input end of the operational amplifier after being connected with a resistor R13 in series; the base of the power tube Q1 and the base of the power tube Q2 are connected with the node between the operational amplifier and the resistor R11. The operational amplifier U2A employs a dual power supply rail-to-rail (rail-to-rail) operational amplifier. The resistor R12 and the resistor R13 are push-pull output current adjusting resistors, so that the output currents of the power tube Q1 and the power tube Q2 are kept balanced, and damage caused by overlarge current of the power tube is avoided.
When the current I is detected1When the magnetic induction intensity is changed within the range of 0A-200A, the open magnetic ring generates the magnetic induction intensity B1, the Hall chip U1B outputs different voltages, the operational amplifier U2A outputs a voltage close to a positive power supply or a negative power supply, and then a power tube Q1 or a power tube Q2 in a subsequent push-pull output circuit is conducted, so that a secondary coil generates a compensation current I2And generating a compensation magnetic induction B2 on the magnetic ring, when the compensation current increases to a certain degree, the compensation reaches balance, I2No longer increasing, according to the law of full current N1I1＝N2I2，I2Is proportional to I1。
The following are examples of measurements:
since the maximum operating temperature is 95 ℃, the power tube in the invention is selected from an SOT89 triode, and the dissipated power is shown in fig. 3. When the ambient temperature is 95 ℃, the dissipation power is slightly larger than 0.2W. According to the circuit parameters, the formula of the dissipated power of the push-pull circuit can be listed as follows:
P＝IOUT×(14-IOUT×R)
＝-67IOUT 2+14IOUT
wherein 67 is the measured sensor output current IOUTThe total resistance passed, 14, is the measured voltage of the input voltage after passing through the anti-flyback diode, and is an estimate. Calculated to be proper toOUTWhen the power consumption reaches 104mA, the power consumption is 0.73W, and the allowance is sufficient.
The bias circuit comprises a primary side bias current adjusting resistor connected with an input voltage, the primary side bias current adjusting resistor is connected with a first end of a primary side winding of a transformer T1 after being connected with an anti-reverse diode D2 in series, and a second end of the primary side winding of the transformer T1 is grounded; the first end of the secondary winding of the transformer T1 is connected with the output end of the voltage comparison and push-pull output circuit, and the second end of the secondary winding of the transformer T1 is used as the output end of the direct current sensor.
When the magnetic sensor works normally, the direct current supply voltage VCC within the range of +/-12V to +/-15V is converted into accurate +5V through the precise voltage stabilizing circuit 1 so as to supply power to the magnetic sensor detection circuit 2. The magnetic-sensing detection circuit 2 detects the magnetic field intensity in the open coil, and generates a reference 0mA zero-point bias current Io1 after the voltage comparison and the amplification of a power tube of the push-pull output circuit 3. The +5V voltage drives the power tube Q1 or the power tube Q2 to be conducted at the same time, then a bias current Io2 is generated through the bias circuit 4, and after the zero bias current Io1 and the bias current Io2 are superposed, the output Iout of the direct current linear Hall current sensor with any bias current output is finally realized.
The bias circuit is connected to the +5V power supply end and is connected in series with a diode D2, so that the product damage caused by the fact that a current flows backward to the voltage stabilizing chip when a primary side current is reversely led in can be prevented, and the resistor R14, the resistor R15 and the resistor R16 are resistors for adjusting the primary side bias current. Assuming that the output current of the primary winding is I1The output current of the secondary winding is I2According to the law of conservation of ampere-turn ratioThe method comprises the following steps:
N1I1+N3I3＝N2I2
wherein N is1The number of turns of the current to be measured is usually 1; i is1Is the primary side current; n is a radical of3The number of turns of the primary winding; i is3Is a primary side bias current; n is a radical of2The number of turns of the secondary winding is; i is2The output current of the secondary side, namely the bias current Io2, is superposed with the zero bias current Io1 to be used as the output of the sensor.
It can be seen that the bias circuit can change the primary and secondary side turn ratio of the coil according to the requirement to obtain any required bias current output.
The DC200A direct current Hall current sensor designed based on the invention linearly outputs 30 mA-80 mA direct current after detection. The test results are shown in table 1:
TABLE 1DC200A DC Hall Current sensor test results
According to the results, the zero point deviation of the Hall current sensor is 0.05mA, the maximum deviation in the rated current range is 0.05mA, and the nonlinear error is less than 0.18%.
After the test circuit is built, the following table shows the test results of input DC +/-50A and output 50mA bias current as shown in table 2:
table 250 mA bias current output and input comparison table
In conclusion, the direct current sensor circuit with any bias current output can be realized in both theoretical and practical tests.
Although the present invention has been described herein with reference to the illustrated embodiments thereof, which are intended to be preferred embodiments of the present invention, it is to be understood that the invention is not limited thereto, and that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.
Claims (4)
1. The utility model provides a direct current sensor circuit of arbitrary bias current output which characterized in that, including the accurate voltage stabilizing circuit, the magnetic-sensitive detection circuit, voltage comparison and push-pull output circuit and the bias circuit that connect gradually, wherein:
the precise voltage stabilizing circuit is used for converting the input voltage into the working voltage of the magnetic-sensing detection circuit;
the magnetic-sensing detection circuit is used for detecting the magnetic field intensity in the open coil and generating a signal to be output to the voltage comparison and push-pull output circuit;
the voltage comparison and push-pull output circuit is used for generating zero bias current;
and the bias circuit is used for generating bias current, and the bias current and the zero bias current are superposed to be used as the output of the direct current sensor.
2. The direct current sensor circuit with any bias current output according to claim 1, wherein the bias circuit comprises a primary bias current adjusting resistor connected with the input voltage, the primary bias current adjusting resistor is connected with a first end of a primary winding of a transformer T1 after being connected with an anti-reverse diode D2 in series, and a second end of the primary winding of the transformer T1 is grounded; the first end of the secondary winding of the transformer T1 is connected with the output end of the voltage comparison and push-pull output circuit, and the second end of the secondary winding of the transformer T1 is used as the output end of the direct current sensor.
3. The direct current sensor circuit with any bias current output according to claim 2, wherein the voltage comparison and push-pull output circuit comprises an operational amplifier, a power tube Q1 and a power tube Q2, a positive input end and a negative input end of the operational amplifier are respectively connected with two output ends of the magnetic sensing detection circuit, and a positive voltage input end of the operational amplifier is connected to the voltage VCC through an anti-reverse diode D1; the output end of the operational amplifier is connected with one end of a secondary winding of the transformer T1 through a resistor R11, and the voltage input negative end of the operational amplifier is connected with the output end of the direct current sensor through an anti-reverse diode D3; the power tube Q1 is connected with the power tube Q2 in a push-pull mode, a resistor R12 is connected between an emitter of the power tube Q1 and an emitter of the power tube Q2 in series, a collector of the power tube Q1 is connected with the positive voltage input end of the operational amplifier, and a collector of the power tube Q2 is connected with the negative voltage input end of the operational amplifier after being connected with a resistor R13 in series; the base of the power tube Q1 and the base of the power tube Q2 are connected with the node between the operational amplifier and the resistor R11.
4. The arbitrary bias current output direct current sensor circuit as claimed in claim 3, wherein said operational amplifier employs a dual power supply rail to rail operational amplifier.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011532320.3A CN112630501A (en) | 2020-12-22 | 2020-12-22 | DC current sensor circuit with arbitrary bias current output |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011532320.3A CN112630501A (en) | 2020-12-22 | 2020-12-22 | DC current sensor circuit with arbitrary bias current output |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114264864A (en) * | 2022-03-01 | 2022-04-01 | 北京智芯微电子科技有限公司 | Current detector and circuit |
| CN117519397A (en) * | 2024-01-05 | 2024-02-06 | 成都新欣神风电子科技有限公司 | Zero bias adjustable circuit based on magnetic balance current sensor |
-
2020
- 2020-12-22 CN CN202011532320.3A patent/CN112630501A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114264864A (en) * | 2022-03-01 | 2022-04-01 | 北京智芯微电子科技有限公司 | Current detector and circuit |
| CN117519397A (en) * | 2024-01-05 | 2024-02-06 | 成都新欣神风电子科技有限公司 | Zero bias adjustable circuit based on magnetic balance current sensor |
| CN117519397B (en) * | 2024-01-05 | 2024-04-12 | 成都新欣神风电子科技有限公司 | Zero bias adjustable circuit based on magnetic balance current sensor |
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