CN110824221A - Isolation sampling circuit of direct-current voltage - Google Patents

Isolation sampling circuit of direct-current voltage Download PDF

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Publication number
CN110824221A
CN110824221A CN201911116929.XA CN201911116929A CN110824221A CN 110824221 A CN110824221 A CN 110824221A CN 201911116929 A CN201911116929 A CN 201911116929A CN 110824221 A CN110824221 A CN 110824221A
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China
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current
voltage
output
conversion circuit
resistor
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CN201911116929.XA
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Inventor
汤能文
鲁忠渝
王修
洪瑞德
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HUIZHOU JINHU INDUSTRIAL DEVELOPMENT Co Ltd
Ten Pao Electronics Huizhou Co Ltd
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HUIZHOU JINHU INDUSTRIAL DEVELOPMENT Co Ltd
Ten Pao Electronics Huizhou Co Ltd
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Priority to CN201911116929.XA priority Critical patent/CN110824221A/en
Publication of CN110824221A publication Critical patent/CN110824221A/en
Pending legal-status Critical Current

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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
    • G01R15/22—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-emitting devices, e.g. LED, optocouplers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

The invention relates to the technical field of voltage sampling, in particular to an isolated sampling circuit of direct current voltage, which is built only by conventional components such as an optical coupler, an operational amplifier, a resistor, a capacitor and the like, is provided with an input voltage-current conversion circuit (1), a first current transmission optical coupler (OP1), an output current-voltage conversion circuit (2) for voltage conversion and output, and is also provided with an output voltage-current conversion circuit (3), a second current transmission optical coupler (OP2) and a thermistor (RT) in the input voltage-current conversion circuit (1) for linear regulation of output voltage, the circuit integrally solves the problems of expensive devices, large temperature drift and unobvious performance improvement of the existing isolated sampling circuit, realizes voltage sampling and isolated transmission with higher precision, and achieves the purposes of reducing cost and improving reliability, has high cost performance.

Description

Isolation sampling circuit of direct-current voltage
Technical Field
The invention relates to the technical field of voltage sampling, in particular to an isolation sampling circuit for direct-current voltage.
Background
It is often necessary to sample the circuit voltage in power electronic systems. The sampling topology of the common ground system is relatively simple, but voltage sampling has great difficulty for mutually isolated systems. The traditional voltage isolation sampling mainly comprises the modes of transformer isolation, capacitance isolation, optical coupling isolation and the like. The transformer isolation and the capacitor isolation are suitable for being used as an isolation sampling mode of alternating voltage and digital signal voltage, if the direct voltage is to be sampled by the transformer isolation and the capacitor isolation, voltage signals changing along with input voltage need to be obtained through processing of circuits such as voltage frequency conversion, rectification filtering and the like, the circuits are complex, the cost is high, and the voltage precision is influenced by a plurality of factors and is not high.
The opto-coupler isolation is compared with the transformer isolation and the capacitor isolation, and is small in size, the mutual anti-interference capacity between the two isolated ends is strong, but the linearity of the common opto-coupler is not high, the temperature stability is poor, and although the linearity of the analog opto-coupler with high linearity is better, the discreteness of the Current Transmission Ratio (CTR) is still larger, the temperature stability is also general, the price is more expensive, and the cost performance is not high.
Disclosure of Invention
The invention provides an isolation sampling circuit for direct-current voltage, and solves the technical problems that the existing sampling circuit for isolation by adopting an optical coupler has the common cost of the optical coupler but low linearity and poor temperature stability, and a high-linearity analog optical coupler has the disadvantages of high cost, poor temperature stability and large discreteness of current transmission ratio.
In order to solve the technical problem, the invention provides an isolated sampling circuit for direct-current voltage, which comprises an input voltage-current conversion circuit (1), a first current transmission optocoupler (OP1), an output current-voltage conversion circuit (2), an output voltage-current conversion circuit (3) and a second current transmission optocoupler (OP2) which are sequentially connected in a closed loop manner; the power supply circuit also comprises an input voltage, an input power supply (VCC1) and an input ground (GND1) which are connected with the input voltage-current conversion circuit (1), an output power supply (VCC2) and an output ground (GND2) which are connected with the output current-voltage conversion circuit (2) and the output voltage-current conversion circuit (3), wherein the input voltage is converted and then is output from the output current-voltage conversion circuit (2) as an output voltage;
the input voltage-current conversion circuit (1) is electrically connected with the transmitting end of the first current transmission optocoupler (OP1) and the receiving end of the second current transmission optocoupler (OP2), the receiving end of the first current transmission optocoupler (OP1) is electrically connected with the output current-voltage conversion circuit (2), and the transmitting end of the second current transmission optocoupler (OP2) is electrically connected with the output voltage-current conversion circuit (3).
Preferably, the input voltage-current conversion circuit (1) is provided with a resistor, a capacitor and an operational amplifier, and is used for converting the input voltage into a corresponding sampling current and transmitting the sampling current to the input voltage-current conversion circuit (1) through the first current transmission optical coupler (OP 1).
Preferably, the output current-voltage conversion circuit (2) is provided with a resistor and a capacitor for converting the sampling current into the output voltage output.
Preferably, the output voltage-current conversion circuit (3) is provided with a resistor and an operational amplifier, and is used for converting the output voltage into a feedback current and transmitting the feedback current to the output current-voltage conversion circuit (2) through the second current transmission optocoupler (OP2) to adjust the sampling current, so as to adjust the output voltage.
Preferably, the input voltage-current conversion circuit (1) is provided with a current regulation resistance network provided with a thermistor (RT) and a first operational amplifier (U1).
Preferably, the current regulation resistor network is further provided with first to sixth resistors (R1 to R6), and the input voltage-current conversion circuit (1) is further provided with a first capacitor (C1);
one end of the first resistor (R1) is connected with the input voltage, and the other end of the first resistor (R1) is connected with a same-direction input end (PIN1) of the first operational amplifier (U1), one end of the first capacitor (C1) and one end of the second resistor (R2); a power supply end (PIN4) of the first operational amplifier (U1) is connected with the input power supply (VCC1), a reverse input end of the first operational amplifier is connected with an E pole of a receiving end of the second current transmission optocoupler (OP2), one end of the fourth resistor (R4) and one end of the thermistor (RT) are connected after the third resistor (R3) is connected, and an output end of the first operational amplifier is connected with a positive pole of a transmitting end of the first current transmission optocoupler (OP 1); the fifth resistor (R5) and the sixth resistor (R6) are respectively connected between the positive pole of the emitting end of the first current transmission optocoupler (OP1) and the C pole of the receiving end of the second current transmission optocoupler (OP2) and between the negative pole of the emitting end of the first current transmission optocoupler (OP1) and the E pole of the receiving end of the second current transmission optocoupler (OP 2);
the other end of the first capacitor (C1), the other end of the second resistor (R2), the other end of the fourth resistor (R4), the other end of the thermistor (RT) and the grounding end of the first operational amplifier (U1) are all connected with the input ground (GND 1).
Preferably, the output current-voltage conversion circuit (2) is provided with a seventh resistor (R7), an eighth resistor (R8) and a second capacitor (C2), the output power supply (VCC2) is connected with the C pole of the receiving end of the first current transmission optocoupler (OP1), and the output voltage is output from the E pole of the receiving end of the first current transmission optocoupler (OP 1);
the seventh resistor (R7) and the second capacitor (C2) are connected in series between the E pole of the receiving end of the first current transmission optocoupler (OP1) and the output ground (GND2), and the eighth resistor (R8) is connected in parallel at two ends of the second capacitor (C2).
Preferably, the output voltage-current conversion circuit (3) is provided with a ninth resistor (R9) and a second operational amplifier (U2); the equidirectional input end, the reverse input end, the output end, the power supply end, the ground terminal of second operational amplifier (U2) are connected respectively the E utmost point of first current transmission opto-coupler (OP1) receiving end, the negative pole of second current transmission opto-coupler (OP2) transmitting end, the positive pole of second current transmission opto-coupler (OP2) transmitting end output power supply (VCC2), export ground (GND2), ninth resistance (R9) are connected between the reverse input end of second operational amplifier (U2) and export ground (GND 2).
Specifically, the input voltage is a direct current voltage.
The isolation sampling circuit of the direct-current voltage is built only by conventional components such as an optical coupler, an operational amplifier, a resistor and a capacitor, is provided with an input voltage-current conversion circuit (1), a first current transmission optical coupler (OP1) and an output current-voltage conversion circuit (2) for voltage conversion and output, and is further provided with an output voltage-current conversion circuit (3), a second current transmission optical coupler (OP2) and a thermistor (RT) in the input voltage-current conversion circuit (1) for linear regulation of output voltage.
Drawings
Fig. 1 is a block diagram of an isolated sampling circuit for dc voltage according to an embodiment of the present invention;
fig. 2 is an electrical connection diagram of an isolated sampling circuit for dc voltage according to an embodiment of the present invention.
And (3) graphic labeling: an input voltage-current conversion circuit 1 (a first operational amplifier U1, first to sixth resistors R1 to R6, and a first capacitor C1); a first current-carrying optocoupler OP 1; the output current-voltage conversion circuit 2 (a seventh resistor R7, an eighth resistor R8, a second capacitor C2); an output voltage-current conversion circuit 3 (a ninth resistor R9, a second operational amplifier U2); a second current-carrying optocoupler OP 2; input power supply VCC1, input ground GND1, output power supply VCC2, and output ground GND 2.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are given for illustrative purposes only and are not to be construed as limiting the invention, and the embodiments and the dimensions of the components and the drawings are merely preferred embodiments, which are provided for reference and illustrative purposes only and do not limit the scope of the invention, since many changes may be made therein without departing from the spirit and scope thereof.
An isolated sampling circuit for a direct current voltage provided by an embodiment of the present invention is, for example, a module structure diagram shown in fig. 1, and includes an input voltage-current conversion circuit 1, a first current transmission optocoupler OP1, an output current-voltage conversion circuit 2, an output voltage-current conversion circuit 3, and a second current transmission optocoupler OP2, which are sequentially connected in a closed loop manner; the power supply circuit further comprises an input voltage, an input power supply VCC1 and an input ground GND1 which are connected with the input voltage-current conversion circuit 1, an output power supply VCC2 and an output ground GND2 which are connected with the output current-voltage conversion circuit 2 and the output voltage-current conversion circuit 3, wherein the input voltage is converted and then is output from the output current-voltage conversion circuit 2 as an output voltage;
the input voltage-current conversion circuit 1 is electrically connected with the transmitting end of the first current transmission optocoupler OP1 and the receiving end of the second current transmission optocoupler OP2, the receiving end of the first current transmission optocoupler OP1 is electrically connected with the output current-voltage conversion circuit 2, and the transmitting end of the second current transmission optocoupler OP2 is electrically connected with the output voltage-current conversion circuit 3.
Specifically, the input voltage is a direct current voltage.
In this embodiment, the input voltage-current conversion circuit 1 is provided with a resistor, a capacitor and an operational amplifier, and is configured to convert the input voltage into a corresponding sampling current and transmit the sampling current to the input voltage-current conversion circuit 1 through the first current transmission optocoupler OP 1. The output current-voltage conversion circuit 2 is provided with a resistor and a capacitor, and is used for converting the sampling current into the output voltage to be output. The output voltage-current conversion circuit 3 is provided with a resistor and an operational amplifier, and is configured to convert the output voltage into a feedback current, and transmit the feedback current to the output current-voltage conversion circuit 2 through the second current transmission optocoupler OP2 to adjust the sampling current, so as to adjust the output voltage.
More specifically, as a preferred embodiment, the input voltage-current conversion circuit 1 is provided with a current adjusting resistance network provided with a thermistor RT and a first operational amplifier U1, as shown in the electrical connection diagram of fig. 2. The current regulation resistor network is further provided with first to sixth resistors R1 to R6, and the input voltage-current conversion circuit 1 is further provided with a first capacitor C1. One end of the first resistor R1 is connected to the input voltage, and the other end is connected to a PIN1(PIN represents a PIN number, the same below) which is a same-direction input end of the first operational amplifier U1, one end of the first capacitor C1, and one end of the second resistor R2; a power supply end PIN4 of the first operational amplifier U1 is connected with the input power supply VCC1, a reverse input end PIN2 is connected with an E pole PIN11 at the receiving end of the second current transmission optocoupler OP2, and is connected with one end of the fourth resistor R4 and one end of the thermistor RT after being connected with the third resistor R3, and an output end PIN3 is connected with a positive pole PIN7 at the transmitting end of the first current transmission optocoupler OP 1; the fifth resistor R5 and the sixth resistor R6 are respectively connected between a positive pole PIN7 at the emitting end of the first current transmission optocoupler OP1 and a C pole PIN10 at the receiving end of the second current transmission optocoupler OP2 and between a negative pole PIN6 at the emitting end of the first current transmission optocoupler OP1 and an E pole PIN11 at the receiving end of the second current transmission optocoupler OP 2. The other end of the first capacitor C1, the other end of the second resistor R2, the other end of the fourth resistor R4, the other end of the thermistor RT, and the ground PIN5 of the first operational amplifier U1 are all connected to the input ground GND 1.
The output current-voltage conversion circuit 2 is provided with a seventh resistor R7, an eighth resistor R8 and a second capacitor C2, the output power supply VCC2 is connected with a C-pole PIN8 at the receiving end of the first current transmission optocoupler OP1, and the output voltage is output from an E-pole PIN9 at the receiving end of the first current transmission optocoupler OP 1. The seventh resistor R7 and the second capacitor C2 are connected in series between the E-pole PIN9 at the receiving end of the first current transmission optocoupler OP1 and the output ground GND2, and the eighth resistor R8 is connected in parallel at two ends of the second capacitor C2.
The output voltage-current conversion circuit 3 is provided with a ninth resistor R9 and a second operational amplifier U2. The same-direction input terminal PIN17, the reverse-direction input terminal PIN18, the output terminal PIN14, the power terminal PIN15 and the ground terminal PIN16 of the second operational amplifier U2 are respectively connected with the E-pole PIN9 at the receiving terminal of the first current-transmission optocoupler OP1, the negative pole PIN13 at the transmitting terminal of the second current-transmission optocoupler OP2, the positive pole PIN12 at the transmitting terminal of the second current-transmission optocoupler OP2, the output power supply VCC2 and the output ground GND2, and the ninth resistor R9 is connected between the reverse-direction input terminal PIN18 of the second operational amplifier U2 and the output ground GND 2.
The embodiment of the invention provides an isolation sampling circuit of direct current voltage, which comprises the following working procedures:
the input voltage which is firstly accessed is sampled by a first resistor R1, a second resistor R2 and a first capacitor C1, and then the output voltage of the input voltage is converted into a current signal by a first operational amplifier U1, a fourth resistor R4, a third resistor R3 and a thermistor RT according to the total resistance value of temperature change. Then the transmitting end of the first current transmission optocoupler OP1 transmits a current signal to the receiving end, the seventh resistor R7, the eighth resistor R8 and the second capacitor C2 convert the received current signal into an output voltage, the output voltage is converted into a current through the second operational amplifier U2 and the ninth resistor R9 and transmitted to the receiving end through the transmitting end of the second current transmission optocoupler OP2 to form negative feedback, the transmission current of a passage where the transmitting end of the sixth resistor R6 and the transmitting end of the first current transmission optocoupler OP1 are located is adjusted, the transmission current of the first current transmission optocoupler OP1 is adjusted in reverse to adjust the output voltage, and finally the voltage of a sampling point is linearly changed along with the input voltage.
The isolation sampling circuit of the direct-current voltage provided by the embodiment of the invention is built only by adopting conventional components such as an optical coupler, an operational amplifier, a resistor, a capacitor and the like, is provided with an input voltage-current conversion circuit 1, a first current transmission optical coupler OP1 and an output current-voltage conversion circuit 2 for voltage conversion and output, and is also provided with an output voltage-current conversion circuit 3, a second current transmission optical coupler OP2 and a thermistor RT in the input voltage-current conversion circuit 1 for linear regulation of output voltage.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (9)

1. An isolation sampling circuit for direct-current voltage is characterized by comprising an input voltage-current conversion circuit (1), a first current transmission optocoupler (OP1), an output current-voltage conversion circuit (2), an output voltage-current conversion circuit (3) and a second current transmission optocoupler (OP2) which are sequentially connected in a closed loop manner; the power supply circuit also comprises an input voltage, an input power supply (VCC1) and an input ground (GND1) which are connected with the input voltage-current conversion circuit (1), an output power supply (VCC2) and an output ground (GND2) which are connected with the output current-voltage conversion circuit (2) and the output voltage-current conversion circuit (3), wherein the input voltage is converted and then is output from the output current-voltage conversion circuit (2) as an output voltage;
the input voltage-current conversion circuit (1) is electrically connected with the transmitting end of the first current transmission optocoupler (OP1) and the receiving end of the second current transmission optocoupler (OP2), the receiving end of the first current transmission optocoupler (OP1) is electrically connected with the output current-voltage conversion circuit (2), and the transmitting end of the second current transmission optocoupler (OP2) is electrically connected with the output voltage-current conversion circuit (3).
2. The isolated sampling circuit of claim 1, wherein: the input voltage-current conversion circuit (1) is provided with a resistor, a capacitor and an operational amplifier, and is used for converting the input voltage into corresponding sampling current and transmitting the sampling current to the input voltage-current conversion circuit (1) through the first current transmission optocoupler (OP 1).
3. The isolated sampling circuit of claim 1, wherein: the output current-voltage conversion circuit (2) is provided with a resistor and a capacitor and is used for converting the sampling current into the output voltage to be output.
4. The isolated sampling circuit of claim 1, wherein: the output voltage-current conversion circuit (3) is provided with a resistor and an operational amplifier, and is used for converting the output voltage into feedback current and transmitting the feedback current to the output current-voltage conversion circuit (2) through the second current transmission optocoupler (OP2) to adjust the sampling current, so that the output voltage is adjusted.
5. The isolated sampling circuit of claim 2, wherein: the input voltage-current conversion circuit (1) is provided with a current regulation resistance network and a first operational amplifier (U1), and the current regulation resistance network is provided with a thermistor (RT).
6. The isolated sampling circuit of claim 5, wherein: the current regulation resistor network is also provided with first to sixth resistors (R1 to R6), and the input voltage-current conversion circuit (1) is also provided with a first capacitor (C1);
one end of the first resistor (R1) is connected with the input voltage, and the other end of the first resistor (R1) is connected with a same-direction input end (PIN1) of the first operational amplifier (U1), one end of the first capacitor (C1) and one end of the second resistor (R2); a power supply end (PIN4) of the first operational amplifier (U1) is connected with the input power supply (VCC1), a reverse input end of the first operational amplifier is connected with an E pole of a receiving end of the second current transmission optocoupler (OP2), one end of the fourth resistor (R4) and one end of the thermistor (RT) are connected after the third resistor (R3) is connected, and an output end of the first operational amplifier is connected with a positive pole of a transmitting end of the first current transmission optocoupler (OP 1); the fifth resistor (R5) and the sixth resistor (R6) are respectively connected between the positive pole of the emitting end of the first current transmission optocoupler (OP1) and the C pole of the receiving end of the second current transmission optocoupler (OP2) and between the negative pole of the emitting end of the first current transmission optocoupler (OP1) and the E pole of the receiving end of the second current transmission optocoupler (OP 2);
the other end of the first capacitor (C1), the other end of the second resistor (R2), the other end of the fourth resistor (R4), the other end of the thermistor (RT) and the grounding end of the first operational amplifier (U1) are all connected with the input ground (GND 1).
7. The isolated sampling circuit of claim 6, wherein: the output current-voltage conversion circuit (2) is provided with a seventh resistor (R7), an eighth resistor (R8) and a second capacitor (C2), the output power supply (VCC2) is connected with the C pole of the receiving end of the first current transmission optocoupler (OP1), and the output voltage is output from the E pole of the receiving end of the first current transmission optocoupler (OP 1);
the seventh resistor (R7) and the second capacitor (C2) are connected in series between the E pole of the receiving end of the first current transmission optocoupler (OP1) and the output ground (GND2), and the eighth resistor (R8) is connected in parallel at two ends of the second capacitor (C2).
8. An isolated sampling circuit for a dc voltage as claimed in claim 7, wherein: the output voltage-current conversion circuit (3) is provided with a ninth resistor (R9) and a second operational amplifier (U2); the equidirectional input end, the reverse input end, the output end, the power supply end, the ground terminal of second operational amplifier (U2) are connected respectively the E utmost point of first current transmission opto-coupler (OP1) receiving end, the negative pole of second current transmission opto-coupler (OP2) transmitting end, the positive pole of second current transmission opto-coupler (OP2) transmitting end output power supply (VCC2), export ground (GND2), ninth resistance (R9) are connected between the reverse input end of second operational amplifier (U2) and export ground (GND 2).
9. An isolated sampling circuit for dc voltage as claimed in any preceding claim, wherein: the input voltage is a direct current voltage.
CN201911116929.XA 2019-11-15 2019-11-15 Isolation sampling circuit of direct-current voltage Pending CN110824221A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911116929.XA CN110824221A (en) 2019-11-15 2019-11-15 Isolation sampling circuit of direct-current voltage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911116929.XA CN110824221A (en) 2019-11-15 2019-11-15 Isolation sampling circuit of direct-current voltage

Publications (1)

Publication Number Publication Date
CN110824221A true CN110824221A (en) 2020-02-21

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CN201911116929.XA Pending CN110824221A (en) 2019-11-15 2019-11-15 Isolation sampling circuit of direct-current voltage

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