CN102664621B - Isolation method and circuit for signal acquisition of electronic mutual inductor - Google Patents
Isolation method and circuit for signal acquisition of electronic mutual inductor Download PDFInfo
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- CN102664621B CN102664621B CN201210165091.5A CN201210165091A CN102664621B CN 102664621 B CN102664621 B CN 102664621B CN 201210165091 A CN201210165091 A CN 201210165091A CN 102664621 B CN102664621 B CN 102664621B
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Abstract
The invention discloses an isolation method and circuit for the signal acquisition of an electronic mutual inductor, which aims to solve the technical problems of improving the linearity degree of the isolation circuit and lowering cost. The method comprises the following steps of: outputting direct-current voltage by a reference stabilized voltage power supply; overlapping with an input signal; amplifying or reducing the overlapped input signal; inputting into the second operational amplifier of a servo feedback isolation circuit to the input end of a photoelectric coupler; maintaining the potential of the reverse input end of the second operational amplifier to 0V by the feedback current generated by the photoelectric coupler; and outputting a signal from the output current generated by photocoupling via the reverse input end and the reverse output end of a fourth operational amplifier. The circuit is formed by connecting a reference direct-current power supply circuit and the servo feedback isolation circuit. Compared with the prior art, the isolation method and circuit have the characteristics that linear isolation is realized by the linear photocoupling and operational amplifier, and the isolation circuit has the advantages of simple structure, high precision, good linearity degree, low cost and good safety.
Description
Technical field
The present invention relates to a kind of signal acquisition method and circuit of electronic mutual inductor, particularly partition method and the buffer circuit in a kind of electronic mutual inductor signal acquisition process.
Background technology
The analog signal partition method of prior art has many types, utilize photoelectricity isolation method aspect cost, volume, antijamming capability and circuit complexity, thering is very large advantage, by appropriate design circuit, can realize 0.1% high-precision signal isolates, be a kind of very practical analog signal isolation method, be widely used.The object one of 0.1% high accuracy isolation is because earth point is different, to measurement, to bring error with output for fear of input (signal end), the 2nd, and in order to protect circuit of output terminal to avoid the impact of inlet circuit fault, the 3rd, in order to improve antijamming capability.The isolation that adopts photoelectricity isolation method to realize is divided into digital signal isolation and analog signal isolation, digital signal buffer circuit is simpler, analog signal will realize high accuracy and isolate that circuit is more complex, to reach isolation effect, guarantee again the high accuracy progress of disease of analog signal, guarantee the linear transfer of signal.
The greatest problem that application optocoupler transmission of analogue signal exists is nonlinear distortion, the physical essence that optocoupler is realized signal transmission is current delivery, in the current transmission characteristic of optocoupler, have a linearity range, the optocoupler to different size, the size of its linearity range is different with the linearity.The alleged linear optical coupling of industry refers in its transfer curve, the shared large percentage of linearity range of the ratio of output current and input current (current transfer ratio), the good optocoupler of the linearity.The linearity of optocoupler can easily obtain by actual measurement, the problem that solves the raising linearity in prior art generally can only realize by appropriate design circuit, causes high accuracy and linear good buffer circuit ubiquity circuit structure complexity and the high drawback of cost.
Summary of the invention
The partition method and the circuit that the object of this invention is to provide a kind of electric mutual inductor signals collecting, the technical problem that solve is to improve the linearity of buffer circuit, reduces costs.
The present invention is by the following technical solutions: a kind of partition method of electric mutual inductor signals collecting, comprise the following steps: one, peaked with reference to stabilized voltage power supply output dc voltage higher than applied signal voltage negative half period with output potential, with formation stack input signal after input signal stack; Two, stack input signal is zoomed in or out, to the working range of optical coupler; Three, the input signal after zooming in or out is input to the reverse input end of the second operational amplifier of servo feedback isolation circuit, the electric current of the second operational amplifier output terminal output is to the input of optical coupler, the feedback current that photoelectrical coupler produces makes the reverse input end current potential of the second operational amplifier maintain 0V, and the output current that photoelectric coupling produces is through reverse input end, the output output signal of four-operational amplifier.
Output signal of the present invention is converted to numerical quantities by modulus sampling A/D chip, then by single-chip microcomputer, the numerical quantities collecting is deducted to the DC component that fixed value removes stack.
Direct voltage with reference to stabilized voltage power supply output 2.5V of the present invention.
Input signal after of the present invention zooming in or out is input to the reverse input end of the second operational amplifier through current-limiting resistance.
The electric current of the second operational amplifier output terminal output of the present invention is to input first light-emitting diode of optical coupler, the irradiation that the first light-emitting diode sends is on second photoelectric diode and the 3rd photoelectric diode of optical coupler, the reverse input end that the feedback current that the second photoelectric diode produces flow back into the second operational amplifier makes its voltage maintain 0V, and the output current that the 3rd photoelectric diode produces is through reverse input end, the output output signal of four-operational amplifier.
A buffer circuit for electric mutual inductor signals collecting, by connecting and composing with reference to DC power supply circuit and servo feedback isolation circuit; Describedly with reference to DC power supply circuit, be provided with power supply chip, the inverting input of power supply chip output termination the 3rd computing discharger, the inverting input of input signal to the three computing dischargers, is connected with the resistance that the current signal of input signal is converted to voltage signal between input signal end and power supply chip output; Described servo feedback isolation circuit is watched and is provided with optical coupler, input termination second operational amplifier of optical coupler, and output termination four-operational amplifier, the feedback signal of optical coupler is inputted the input of the second operational amplifier.
Between the inverting input of the 3rd computing discharger of the present invention and input signal end, be serially connected with the first resistance, input signal is through the inverting input of the first electricity to the three computing dischargers, between input signal end and power supply chip output, is connected with the 3rd resistance in parallel and the 5th resistance.
The first light-emitting diode negative terminal of the output termination optical coupler of the second operational amplifier of the present invention, the positive termination of the first Light-Emitting Diode; The second photodiode negative terminal of described optical coupler connects the input of the second operational amplifier, positive ending grounding; The 3rd photodiode negative terminal of described optical coupler connects the inverting input of four-operational amplifier, just terminates to the normal phase input end of four-operational amplifier.
Optical coupler of the present invention adopts HCNR201 or HCNR200, and the second operational amplifier and four-operational amplifier adopt AD8607, and power supply chip adopts ADR441, and the 3rd operational amplifier adopts AD8607.
The reverse input end of the second operational amplifier of the present invention and output cross-over connection have the second filter capacitor, and the reverse input end of four-operational amplifier and output cross-over connection have the 5th filter capacitor.
The present invention compared with prior art, utilizes linear optical coupling and operational amplifier to realize linear isolation, has circuit structure simple, and precision is high, the advantage that the linearity is good, cost is low and safe.
Accompanying drawing explanation
Fig. 1 is circuit theory diagrams of the present invention.
Fig. 2 is the equivalent circuit theory figure of optical coupler.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in further details.The partition method of electric mutual inductor signals collecting of the present invention, comprises the following steps:
One, at the signal input part of electronic mutual inductor, with output potential higher than the peaked direct voltage VREF with reference to stabilized voltage power supply U1 output 2.5V of applied signal voltage negative half period, with formation stack input signal after input signal IN stack, to raise the input current potential of AC signal, the voltage that makes input signal be all on the occasion of.
Two, by the 3rd operational amplifier U3A, the stack input signal after raising is zoomed in or out, to the working range of optical coupler U5, make input voltage signal within can the scope of linear transform.
Three, input signal after zooming in or out is input to the reverse input end of the second operational amplifier U2A through current-limiting resistance R4, the electric current of U2A output output is to input the first light-emitting diode D1 of the U5 of optical coupler, the light intensity that D1 sends increases with the increase of the reverse input end input voltage of U2, the irradiation of D1 is on the second photoelectric diode D2 of U5, make D2 conducting, the positive ending grounding IGND of D2, the negative terminal of D2 is connected with the reverse input end of U2A, therefore the reverse input end current potential of U2A maintains 0V, the light of D1 is radiated on the 3rd photoelectric diode D3 of U5 simultaneously, make D3 conducting, thereby make output output signal.
Four, output signal is converted to numerical quantities by modulus AD sampling A/D chip, and then the single-chip microcomputer by subsequent conditioning circuit deducts by the numerical quantities collecting the DC component that a fixed value removes stack.
As shown in Figure 1, the buffer circuit of electric mutual inductor signals collecting of the present invention, by connecting and composing with reference to DC power supply circuit and servo feedback isolation circuit.
Servo feedback isolation circuit is provided with an optical coupler U5, input termination the second operational amplifier U2A of optical coupler U5, output termination four-operational amplifier U4A, the input of the feedback signal input U2A of optical coupler U5.U5 adopts HCNR201, and the representative value of its direct current nonlinearity is 0.01%, and maximum is 0.05%, and bandwidth is up to 1MHz, and be low to moderate-65 * 10-6/ ℃ of temperature coefficient gains.
Reverse input end at U2A is serially connected with current-limiting resistance R4, guarantees that the electric current that flows through optical coupler U5 is in the range of linearity of linear optocoupler.Output 1 pin of U2A connects the first light-emitting diode D1 negative terminal 1 pin of U5, and anode 2 pin of the first Light-Emitting Diode D1 of U5 meet power supply IVCC through the 6th resistance R 6, and the output current of U2A is controlled the light intensity of D1.
The reverse input end of U2A and output cross-over connection have the second filter capacitor C2, and the reverse input end of U4A and output cross-over connection have the 5th filter capacitor C5, improve the antijamming capability of buffer circuit, in order to avoid there is self-oscillation.
With reference to DC power supply circuit, being provided with a temperature drift is the power supply chip U1 of 0.005mV/ ℃, U1 output termination the 3rd computing discharger U3A.Between the inverting input of U3A and input signal end, be serially connected with the first resistance R 1, input signal IN is through the inverting input of R1 to U3A.Between input signal end and U1 output, be connected with the 3rd resistance R 3 in parallel and the 5th resistance R 5, for the voltage of U1 output is added in to input signal, raise the current potential of input signal.Between the inverting input of U3A and output, be parallel with the second resistance R 2 and the first filter capacitor C1, R2 is used for coordinating U3A to carry out convergent-divergent to input signal, input signal is zoomed between the linear zone of U5 in, C1 plays low-pass filtering.
R3 and R5 are converted to voltage signal by the current signal of input signal IN, if do not need R3 and R5 resistance when IN is input as voltage signal.Then the reverse amplification circuit consisting of U3A zooms in or out in the working range of optical coupler to voltage signal, the output signal zooming in or out after processing is input to the second photodiode D2 negative terminal 3 pin of U5, the anode 4 pin ground connection of D2 through the current-limiting resistance R4 of 100k.
As shown in Figure 2, the second photodiode D2 in U5 and the similar voltage generator of the effect of the 3rd photodiode D3, the electric current flowing through on the electric current flowing through on D2 and D3 and D1 is linear.Negative terminal 1 pin of D1 is connected to output 1 pin of U2A, and anode 2 pin of D1 meet power supply IVCC through R6.D3 negative terminal 6 pin in U5 are connected to the inverting input of U4A, and D3 anode 5 pin are connected to the normal phase input end of U4A.The increase of the reverse input end input voltage of U2, the electric current that flows through D1 increases, luminous quantity also can increase, the irradiation of D1 light source is on D2, make D2 conducting, due to anode and the ground connection IGND of D2, the negative terminal of D2 is connected with the reverse input end of U2A, so just can make the current potential of U2A inverting input maintain 0V.
The light producing due to D1 impinges upon on the D3 of the input that connects U4A simultaneously, on D3, also produce photoelectric current, first this electric current can flow out from the inverting input of U4A, and then by the output of U4A, flow into one electric current and replace gradually the electric current being flowed out by U4A inverting input, the voltage of U4A output will raise to produce output voltage gradually simultaneously.The reverse input end of U4A and output cross-over connection have the 7th resistance R 7, for limiting the electric current that flows through U5, make in U5 is operated between linear zone.
In the present embodiment, if required precision is very high, and require Low Drift Temperature, optical coupler U5 selects HCNR201, generally can select HCNR200, the second operational amplifier U2A and four-operational amplifier U4A adopt AD8607, and power supply chip U1 adopts ADR441, the 2.5V voltage of output, the 3rd operational amplifier U3A adopts AD8607.R3 and R5 are 1 Europe, and R1 is 10K, and R2 is 56K, and R4 is 100K, and R6 is 51 Europe, and R7 is 100K, and R1, R2, R3, R4, R5, R6, R7 are that precision is ± 0.10%, and temperature is floated for ± 5PPM/ ℃ a High Precision Low Temperature floats resistance, and C1 is 100p, and C2 is 100p, and C5 is 100p.Guaranteed the high accuracy of whole circuit, Low Drift Temperature, the linearity is good.
The buffer circuit operation principle of electric mutual inductor signals collecting of the present invention: U2A, U3A, U4A are by 5V DC power supply.Stabilized voltage power supply U1 output 2.5V reference voltage, alternating voltage stack with input signal, the alternating voltage of input signal after reference voltage is raised between 0 to 5V, input signal after stack zooms in or out in the linear working range of linear optocoupler by U3A, again through R4, the reverse input end of U2A, the output of U2A is to the D1 of U5, the electric current that flows through R4 is linear with the electric current that flows through D1, like this along with the increase through R4 input U2A voltage, the electric current of D1 of flowing through increases, the luminous quantity producing also increases, the irradiation of D1 light source is on the D2 of U5, make D2 conducting, because the anode of D2 is connected with ground IGND, and the negative terminal of D2 and the reverse input end of U2A are connected, so just can make the current potential of the inverting input of U2A maintain 0V.The illumination producing due to D1 produces photoelectric current on D3, first this electric current can flow out from the inverting input of U4A, the electric current of U4A output output replaces the electric current being flowed out by U4A inverting input gradually, and the voltage of U4A exit point will raise to produce output voltage gradually simultaneously.U2A front-end circuit has been raised 2.5V by signal, and buffer circuit signal processing circuit below, when exchanging AD signal sampling, deducts DC component with single-chip microcomputer, makes the actual value of numerical quantities reaction input signal.The advantages such as it is simple that circuit of the present invention has circuit structure, and precision is high, and the linearity is good, the low and fail safe height of cost.Experiment shows, 0, arrives in the input range of 5V, and output accuracy can reach 0.1%.The servo feedback isolation circuit consisting of U2A, U5 and U4A reaches high accuracy, the Low Drift Temperature progress of disease of analog signal.
Claims (10)
1. a partition method for electric mutual inductor signals collecting, comprises the following steps: one, use output potential peaked with reference to stabilized voltage power supply output dc voltage higher than applied signal voltage negative half period, with formation stack input signal after input signal stack; Two, stack input signal is zoomed in or out, to the working range of optical coupler; Three, the input signal after zooming in or out is input to the reverse input end of the second operational amplifier of servo feedback isolation circuit, the electric current of the second operational amplifier output terminal output is to the input of optical coupler, the feedback current that photoelectrical coupler produces makes the reverse input end current potential of the second operational amplifier maintain 0V, and the output current that photoelectric coupling produces is through reverse input end, the output output signal of four-operational amplifier.
2. the partition method of electric mutual inductor signals collecting according to claim 1, it is characterized in that: described output signal is converted to numerical quantities by modulus sampling A/D chip, then by single-chip microcomputer, the numerical quantities collecting is deducted to the DC component that fixed value removes stack.
3. the partition method of electric mutual inductor signals collecting according to claim 1, is characterized in that: the described direct voltage with reference to stabilized voltage power supply output 2.5V.
4. the partition method of electric mutual inductor signals collecting according to claim 1, is characterized in that: described in input signal after zooming in or out through current-limiting resistance, be input to the reverse input end of the second operational amplifier.
5. the partition method of electric mutual inductor signals collecting according to claim 1, it is characterized in that: the electric current of described the second operational amplifier output terminal output is to input first light-emitting diode of optical coupler, the irradiation that the first light-emitting diode sends is on second photoelectric diode and the 3rd photoelectric diode of optical coupler, the reverse input end that the feedback current that the second photoelectric diode produces flow back into the second operational amplifier makes its voltage maintain 0V, the output current that the 3rd photoelectric diode produces is through the reverse input end of four-operational amplifier, output output signal.
6. a buffer circuit for electric mutual inductor signals collecting, is characterized in that: the buffer circuit of described electric mutual inductor signals collecting is by connecting and composing with reference to DC power supply circuit and servo feedback isolation circuit; Describedly with reference to DC power supply circuit, be provided with power supply chip (U1), the normal phase input end of power supply chip (U1) output termination the 3rd computing discharger (U3A), the inverting input of input signal to the three computing dischargers (U3A), is connected with the resistance that the current signal of input signal is converted to voltage signal between input signal end and power supply chip (U1) output; Described servo feedback isolation circuit is watched and is provided with optical coupler (U5), the output of input termination second operational amplifier (U2A) of optical coupler (U5), the reverse input end of output termination four-operational amplifier (U4A), the feedback signal of optical coupler (U5) is inputted the reverse input end of the second operational amplifier (U2A).
7. the buffer circuit of electric mutual inductor signals collecting according to claim 6, it is characterized in that: between the inverting input of described the 3rd computing discharger (U3A) and input signal end, be serially connected with the first resistance (R1), input signal is the inverting input to the 3rd computing discharger (U3A) through the first resistance (R1), between input signal end and power supply chip (U1) output, is connected with the 3rd resistance (R3) in parallel and the 5th resistance (R5).
8. the buffer circuit of electric mutual inductor signals collecting according to claim 7, it is characterized in that: the first light-emitting diode (D1) negative terminal of the output termination optical coupler (U5) of described the second operational amplifier (U2A), the positive termination power (IVCC) of the first Light-Emitting Diode (D1); The second photodiode (D2) negative terminal of described optical coupler (U5) connects the reverse input end of the second operational amplifier (U2A), positive ending grounding; The 3rd photodiode (D3) negative terminal of described optical coupler (U5) connects the inverting input of four-operational amplifier (U4A), just terminates to the normal phase input end of four-operational amplifier (U4A).
9. the buffer circuit of electric mutual inductor signals collecting according to claim 8, it is characterized in that: described optical coupler (U5) adopts HCNR201 or HCNR200, the second operational amplifier (U2A) and four-operational amplifier (U4A) adopt AD8607, power supply chip (U1) adopts ADR441, and the 3rd operational amplifier (U3A) adopts AD8607.
10. the buffer circuit of electric mutual inductor signals collecting according to claim 9, it is characterized in that: the reverse input end of described the second operational amplifier (U2A) and output cross-over connection have the second filter capacitor (C2), the reverse input end of four-operational amplifier (U4A) and output cross-over connection have the 5th filter capacitor (C5).
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| CN104135275A (en) * | 2014-07-17 | 2014-11-05 | 沈阳东软医疗系统有限公司 | A signal isolator and a method for debugging the signal isolator |
| CN104660193A (en) * | 2015-01-21 | 2015-05-27 | 上海新研工业设备有限公司 | Linear optocoupler transmitting analog signal circuit |
| US10044447B2 (en) * | 2016-04-04 | 2018-08-07 | Biosense Webster (Israel) Ltd. | Linear isolation amplifier with output DC voltage cancellation |
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| CN86100777A (en) * | 1985-02-03 | 1987-08-19 | 吉林工业大学 | Dual-channel photoelectric isolator for transmission of analogue signal |
| DE3640127A1 (en) * | 1986-11-25 | 1988-06-01 | Standard Elektrik Lorenz Ag | ELECTRONIC FORK GEAR |
| US7279967B2 (en) * | 2005-01-12 | 2007-10-09 | Qsc Audio Products, Inc. | Multi-channel, multi-power class D amplifier with regulated power supply |
| CN101860001B (en) * | 2010-05-06 | 2012-11-28 | 北京鼎汉技术股份有限公司 | Switch power supply current detection circuit |
| CN202189088U (en) * | 2011-08-23 | 2012-04-11 | 浙江德力西电器股份有限公司 | Alternating-current voltage isolating and measuring circuit based on combination of mutual inductor and operational amplifier |
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Effective date of registration: 20170804 Address after: North Road, Gulou District of Nanjing City, Jiangsu province 210000 No. 100 No. 1 Building 8 floor Patentee after: CYG SUNRI MONITORING TECHNOLOGY CO., LTD. Address before: 518057 Nanshan District province high tech Industrial Park, Shenzhen, north of the mountain road, No. 1, No. 3, Patentee before: CYG Sunri Automation Co., Ltd. |