CN113447704A - Electronic sensor alternating current signal sampling circuit based on optical coupling isolation - Google Patents
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Abstract
本发明提供一种基于光耦隔离的电子传感器交流信号采样电路，包括电压输入端VIN、电压输出端VOUT、光耦电路和运放芯片，所述运放芯片包括通道U1A、U1B、U1C和U1D，所述光耦电路包括线性光耦合器U2和U3，电压输入端VIN连接通道U1A的输入端，通道U1A的输出端分别通过通道U1B和U1C连接线性光耦合器U2和U3，线性光耦合器U2和U3连接通道U1D的输入端，通道U1D的输出端连接电压输出端VOUT，通道U1A以及线性光耦合器U2和U3分别连接一个±5V电源。本发明利用电子式互感器采样电路具备较强的信号隔离和抗干扰能力，使用线性光耦对模拟信号隔离，通过反馈通路的非线性来抵消直通通路的非线性，实现线性隔离的目的。
The present invention provides an electronic sensor AC signal sampling circuit based on optocoupler isolation, comprising a voltage input terminal V IN , a voltage output terminal V OUT , an optocoupler circuit and an operational amplifier chip, wherein the operational amplifier chip includes channels U1A, U1B, U1C and U1D, the optocoupler circuit includes linear optocouplers U2 and U3, the voltage input terminal V IN is connected to the input terminal of the channel U1A, and the output terminal of the channel U1A is connected to the linear optocouplers U2 and U3 through the channels U1B and U1C respectively. The optical couplers U2 and U3 are connected to the input terminal of the channel U1D, the output terminal of the channel U1D is connected to the voltage output terminal V OUT , and the channel U1A and the linear optical couplers U2 and U3 are respectively connected to a ±5V power supply. The invention utilizes the electronic transformer sampling circuit with strong signal isolation and anti-interference ability, uses linear optocoupler to isolate the analog signal, offsets the nonlinearity of the straight-through path through the nonlinearity of the feedback path, and realizes the purpose of linear isolation.
Description
Technical Field
The invention belongs to the technical field of electronics, and particularly relates to an electronic sensor alternating-current signal sampling circuit based on optical coupling isolation.
Background
With the acceleration of the primary and secondary fusion process of the power distribution network, the traditional electromagnetic mutual inductor has been gradually replaced by the electronic mutual inductor (ECT/EVT), and compared with the traditional electromagnetic mutual inductor, the electronic mutual inductor has the advantages of high measurement precision, wide transient response range, simple insulation structure, smaller volume and no magnetic saturation phenomenon. However, compared with the conventional electromagnetic transformer, the analog signal output by the electronic transformer has a small magnitude, is easily subjected to electromagnetic interference of the surrounding environment and the switch body, and has a more prominent signal attenuation problem in the signal transmission process. Therefore, the stability and sampling precision of the sampling circuit applied to the electronic transformer are difficult to ensure at present.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides an electronic sensor alternating-current signal sampling circuit based on optical coupling isolation.
The invention adopts the following technical scheme for solving the technical problems:
the invention provides an electronic sensor alternating current signal sampling circuit based on optical coupling isolation, which comprises a voltage input end VINVoltage output terminal VOUTChip is put to opto-coupler circuit and fortune, the chip is put to fortune includes passageway U1A, U1B, U1C and U1D, the opto-coupler circuit includes linear optical coupler U2 and U3, voltage input VINThe input end of a channel U1A is connected, the output end of the channel U1A is connected with the input end of a linear optical coupler U2 through a channel U1B, the output end of the channel U1A is connected with the input end of a linear optical coupler U3 through a channel U1C, the output ends of the linear optical couplers U2 and U3 are connected with the input end of a channel U1D, and the output end of the channel U1D is connected with a voltage output end VOUTThe channel U1A and the linear optical couplers U2 and U3 are connected to a +/-5V power supply respectively.
Further, the operational amplifier chip is an OP4177AR four-channel integrated chip.
Further, the linear optical couplers U2 and U3 are HCNR200 type linear optical couplers.
Further, AlGaAs type light emitting diodes and photodiodes PD1 and PD2 are respectively provided inside the linear photo-couplers U2 and U3.
Further, the operational amplifier circuit further includes resistors R1, R2, R5, R6, R7, R8, R9, and capacitors C1, C2, C3, and C4, the voltage input VIN is connected to the forward input terminal of the channel U1A through the resistor R8, the forward input terminal of the channel U1A is grounded through the resistor R7, the inverting input terminal of the channel U1A is grounded through the resistor R9, the resistor R6 and the capacitor C1 are respectively connected in parallel between the output terminal and the inverting input terminal of the channel U1A, the output terminal of the channel U1A is connected to the inverting input terminal of the channel U1B through the resistor R1, the inverting input terminal of the channel U1C is connected through the resistor R5, the forward input terminal of the channel U1B is grounded, the input terminal of the channel U1C is grounded, the capacitor C2 is connected in parallel between the output terminal and the inverting input terminal of the channel U1B, the capacitor C3 is connected in parallel between the output terminal of the channel U1 and the inverting input terminal 1B, and the inverting input terminal of the channel U4, the positive input of channel U1D is connected to ground.
Further, the optical coupling circuit further comprises resistors R3 and R4, one end of the resistor R3 is connected with the output end of the channel U1B, the other end of the resistor R3 is connected with the linear optical coupler U2, one end of the resistor R4 is connected with the output end of the channel U1C, and the other end of the resistor R4 is connected with the linear optical coupler U3.
Further, the operational amplifier circuit further comprises diodes V1 and V2, wherein a cathode of the diode V1 is connected to an output end of the channel U1B, an anode of the diode V1 is connected to a reverse input end of the channel U1B, a cathode of the diode V2 is connected to a reverse input end of the channel U1C, and an anode of the diode V2 is connected to an output end of the channel U1C.
Further, the diodes V1 and V2 are IN4148WS diodes.
The invention has the following beneficial effects:
the invention utilizes the sampling circuit of the electronic mutual inductor to have stronger signal isolation and anti-interference capability, uses the linear optical coupling to isolate the analog signal, and counteracts the nonlinearity of the through passage through the nonlinearity of the feedback passage, thereby realizing the purpose of linear isolation.
Drawings
FIG. 1 is a schematic structural view of a preferred embodiment of the present invention;
fig. 2 is a schematic diagram of the internal structure of a linear optical coupler according to a preferred embodiment of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in FIG. 1, the electronic sensor alternating current signal sampling circuit based on optical coupling isolation provided by the invention comprises a voltage input end VINVoltage output terminal VOUTChip is put to opto-coupler circuit and fortune, the chip is put to fortune includes passageway U1A, U1B, U1C and U1D, the opto-coupler circuit includes linear optical coupler U2 and U3, voltage input VINThe input of channel U1A is connected, the output of channel U1A is connected to linear optocouplers U2 and U3 through channels U1B and U1C, respectively, linear optocouplers U2 and U3 are connected to the input of channel U1D,the output end of the channel U1D is connected with a voltage output end VOUTThe channel U1A and the linear optical couplers U2 and U3 are connected to a +/-5V power supply respectively. The operational amplifier chip is an OP4177AR four-channel integrated chip. The linear optical couplers U2 and U3 are HCNR200 type linear optical couplers. The operational amplifier circuit also comprises resistors R, R and capacitors C, C and C, wherein a voltage input end VIN is connected with a forward input end of a channel U1 through the resistor R, the forward input end of the channel U1 is grounded through the resistor R, a reverse input end of the channel U1 is grounded through the resistor R, the resistor R and the capacitor C are respectively connected between an output end and a reverse input end of the channel U1 in parallel, an output end of the channel U1 is respectively connected with the reverse input end of the channel U1 through the resistor R, the reverse input end of the channel U1 is connected through the resistor R, the forward input end of the channel U1 is grounded, the capacitor C is connected between the output end and the reverse input end of the channel U1 in parallel, and the capacitor C and the resistor R are connected between the output end and the reverse input end of the channel U1 in parallel, the positive input of channel U1D is connected to ground. The operational amplifier circuit further comprises diodes V1 and V2, wherein the negative electrode of the diode V1 is connected with the output end of the channel U1B, the positive electrode of the diode V1 is connected with the reverse input end of the channel U1B, the negative electrode of the diode V2 is connected with the reverse input end of the channel U1C, and the positive electrode of the diode V2 is connected with the output end of the channel U1C. Diodes V1 and V2 are IN4148WS diodes for selecting and distinguishing between positive and negative voltages, such as for the U1B channel, where diode V1 can only pass positive voltages and not negative voltages. And V2 in the U1C channel can only pass negative voltage and can not pass positive voltage. .
As shown in fig. 1, the linear photo couplers U2 and U3 are respectively composed of AlGaAs type light emitting diodes and photodiodes PD1 and PD2, specifically, the cathode of the AlGaAs type light emitting diode is connected to pin 1, anode connection pin 2, cathode connection pin 3, anode connection pin 4 of photodiode PD1, cathode connection pin 6 of photodiode PD2, and anode connection pin 5. As shown in fig. 2, the optical coupler circuit further includes resistors R3 and R4, one end of the resistor R3 is connected to the output end of the channel U1B, the other end of the resistor R3 is connected to the pin 1 of the linear optical coupler U2, one end of the resistor R4 is connected to the output end of the channel U1C, and the other end of the resistor R4 is connected to the pin 2 of the linear optical coupler U3. Pins 4 and 5 of the linear optical coupler U2 are grounded respectively, pin 2 is connected with a +/-5V power supply, pin 3 is connected with the reverse input end of the channel U1B, and pin 6 is connected with the reverse input end of the channel U1D; pins 3 and 6 of the linear optocoupler U3 are grounded, pin 1 is connected to a + -5V power supply, pin 5 is connected to the inverting input of channel U1D, and pin 4 is connected to the inverting input of channel U1C, respectively.
As shown in fig. 1, the present invention selects an HCNR200 type linear optical coupler as an optical coupler element with high linearity, and has the advantages of ultra-low linearity (0.01%), low gain temperature coefficient (65 ppm/deg.c), high voltage withstand level (5 kV), high isolation voltage (8 kV maximum isolation), unidirectional transmission, strong common-mode interference resistance, one-to-one linear high-speed signal transmission, etc. The LED is composed of 3 photoelectric elements, wherein the LED is a high-performance AlGaAs type light emitting diode, and the PD1 and the PD2 are two photodiodes which are manufactured by the same process and have strict proportion relation. When a current I flows in the LEDFThe emitted light induces photocurrents IPD1 and IPD2 in PD1 and PD2, which are proportional to the LED light intensity. The alternating voltage signal is connected into the optical coupler after being conditioned, various interference pulses mixed in the input quantity are filtered by the optical coupler on the input side, and the optical coupler has high electrical isolation and anti-interference capacity and ensures the sampling precision of the signal.
OP4177AR is a four-channel integrated channel, 5V power supply. The channel U1A is used as a non-inverting amplifier, the gain of the output voltage is (1 + R6/R9), the non-inverting input terminal R7 and R8 form a voltage dividing circuit, the voltage of the input operational amplifier is the divided value of the resistor R7, the final gain of the circuit is 1 according to the specific parameter setting in fig. 2, and therefore the input voltage and the output voltage are the same after passing through the non-inverting amplifier circuit. The voltage is output from the U1A and enters the U1B/U1C, and the U1B/U1C form a negative feedback circuit. Since the input signal is an ac voltage signal, it needs to process the positive and negative signals separately, the U1B channel is responsible for processing the positive voltage signal, and the U1C channel is responsible for processing the negative voltage signal. Take U1B channel as an example, by adjusting the current I flowing through the LED in the optical couplerFAnd further controls the current flowing through the photodiode PD1Stream IPD1Easy availability of IPD1=VIN/R1，VINIn order that the input voltage of the channel U1B is also equal to the input voltage of the channel U1A, the PD1 is connected to the input end of the U1B, the detection of the output optical signal of the LED is completed, and the current passing through the LED is automatically adjusted to compensate the nonlinearity of the LED light intensity caused by the temperature change, so that the feedback circuit is mainly used for stabilizing and linearizing the LED light output. The output voltages of the U1B and U1C channels are respectively passed through the optical coupler U2、U3To the U1D channel.
U1D is a voltage-current conversion circuit for converting current IPD2Converted back to output voltage VOUTAnd V isOUT= IPD2*R2Then there is VOUT/VIN=（IPD2*R2）/（IPD1*R1） =K3*（R2/R1）,K3For gain setting, the standard value of K3 is 1 according to the HCNR200 type optocoupler work manual. Thus VINAnd VOUTThe relation between the two is linear and independent of the luminous flux of the LED, and the gain can be adjusted by adjusting R1And R2The value of (c) is implemented. The specifically set gain value is related to the amplitude of the signal and the input amplitude of the later-stage AD chip, and the set value in the schematic diagram of fig. 2 is 1. Capacitor C1、C2、C3The circuit can be prevented from generating oscillation, the high-frequency characteristic of the circuit is improved, the stability of the circuit is improved, and the capacitance value can be specifically selected according to the working frequency. In addition, the optical coupler can generate high-frequency noise, so that the output resistor R2Is connected with a capacitor C in parallel4The low pass filter is constructed, and the value of the specific capacitor is determined by the input frequency and the noise frequency. R3、R4The current flowing through the LED is limited, so that the luminous intensity of the LED is controlled, and the LED can be prevented from being damaged accidentally. R3、R4Resistance value of and IFRelated, there are R = VCC/IF，IFThe operating current is recommended for the LED.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are intended to further illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is also intended to be covered by the appended claims. The scope of the invention is defined by the claims and their equivalents.
Claims (8)
1. The utility model provides an electronic sensor alternating current signal sampling circuit based on opto-coupler isolation which characterized in that: comprising a voltage input terminal VINVoltage output terminal VOUTChip is put to opto-coupler circuit and fortune, the chip is put to fortune includes passageway U1A, U1B, U1C and U1D, the opto-coupler circuit includes linear optical coupler U2 and U3, voltage input VINThe input end of a channel U1A is connected, the output end of the channel U1A is connected with the input end of a linear optical coupler U2 through a channel U1B, the output end of the channel U1A is connected with the input end of a linear optical coupler U3 through a channel U1C, the output ends of the linear optical couplers U2 and U3 are connected with the input end of a channel U1D, and the output end of the channel U1D is connected with a voltage output end VOUTThe channel U1A and the linear optical couplers U2 and U3 are connected to a +/-5V power supply respectively.
2. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: the operational amplifier chip is an OP4177AR four-channel integrated chip.
3. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: the linear optical couplers U2 and U3 are HCNR200 type linear optical couplers.
4. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: AlGaAs type light emitting diodes and photodiodes PD1 and PD2 are respectively provided inside the linear photo-couplers U2 and U3.
5. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: the operational amplifier circuit also comprises resistors R, R and capacitors C, C and C, wherein a voltage input end VIN is connected with a forward input end of a channel U1 through the resistor R, the forward input end of the channel U1 is grounded through the resistor R, a reverse input end of the channel U1 is grounded through the resistor R, the resistor R and the capacitor C are respectively connected between an output end and a reverse input end of the channel U1 in parallel, an output end of the channel U1 is respectively connected with the reverse input end of the channel U1 through the resistor R, the reverse input end of the channel U1 is connected through the resistor R, the forward input end of the channel U1 is grounded, the capacitor C is connected between the output end and the reverse input end of the channel U1 in parallel, and the capacitor C and the resistor R are respectively connected between the output end and the reverse input end of the channel U1 in parallel, the positive input of channel U1D is connected to ground.
6. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: the optical coupling circuit further comprises resistors R3 and R4, one end of the resistor R3 is connected with the output end of the channel U1B, the other end of the resistor R3 is connected with the linear optical coupler U2, one end of the resistor R4 is connected with the output end of the channel U1C, and the other end of the resistor R4 is connected with the linear optical coupler U3.
7. The electronic sensor alternating current signal sampling circuit based on optical coupling isolation according to claim 1, characterized in that: the operational amplifier circuit further comprises diodes V1 and V2, wherein the negative electrode of the diode V1 is connected with the output end of the channel U1B, the positive electrode of the diode V1 is connected with the reverse input end of the channel U1B, the negative electrode of the diode V2 is connected with the reverse input end of the channel U1C, and the positive electrode of the diode V2 is connected with the output end of the channel U1C.
8. The optical coupling isolation-based electronic sensor alternating current signal sampling circuit according to claim 7, wherein: the diodes V1 and V2 are IN4148WS diodes.
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| CN202110600006.2A CN113447704A (en) | 2021-05-31 | 2021-05-31 | Electronic sensor alternating current signal sampling circuit based on optical coupling isolation |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102664621A (en) * | 2012-05-25 | 2012-09-12 | 长园深瑞继保自动化有限公司 | Isolation method and circuit for signal acquisition of electronic mutual inductor |
| CN203084068U (en) * | 2012-12-19 | 2013-07-24 | 宁波伟吉电力科技有限公司 | Analog voltage acquisition circuit with isolation function |
| CN110824220A (en) * | 2019-11-05 | 2020-02-21 | 上海置信电气股份有限公司 | Novel signal acquisition circuit of electronic sensor |
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- 2021-05-31 CN CN202110600006.2A patent/CN113447704A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102664621A (en) * | 2012-05-25 | 2012-09-12 | 长园深瑞继保自动化有限公司 | Isolation method and circuit for signal acquisition of electronic mutual inductor |
| CN203084068U (en) * | 2012-12-19 | 2013-07-24 | 宁波伟吉电力科技有限公司 | Analog voltage acquisition circuit with isolation function |
| CN110824220A (en) * | 2019-11-05 | 2020-02-21 | 上海置信电气股份有限公司 | Novel signal acquisition circuit of electronic sensor |
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Application publication date: 20210928 |