CN2847228Y - Intelligent transducer isolation circuit for two-wire system - Google Patents
Intelligent transducer isolation circuit for two-wire system Download PDFInfo
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- CN2847228Y CN2847228Y CN 200520046248 CN200520046248U CN2847228Y CN 2847228 Y CN2847228 Y CN 2847228Y CN 200520046248 CN200520046248 CN 200520046248 CN 200520046248 U CN200520046248 U CN 200520046248U CN 2847228 Y CN2847228 Y CN 2847228Y
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Abstract
The utility model provides an isolation circuit of an intelligent transducer with a two-wire system. The utility model can effectively avoid interference of strong electromagnetism on an industrial site to a sensor circuit. The isolation circuit comprises a voltage isolation circuit and a signal isolation circuit, wherein the voltage isolation circuit comprises a voltage pick-up circuit, an oscillating circuit, a drive circuit, an isolation transformer and a rectifying voltage stabilizing circuit. The input end of the voltage pick-up circuit is connected to a power supplying circuit; the input end of the oscillating circuit is connected with the output end of the voltage pick-up circuit; a first input end of the drive circuit is connected with the output end of the oscillating circuit, and a second input end of the drive circuit is connected with the output end of the voltage pick-up circuit; a primary coil of the isolation transformer is connected with the output end of the drive circuit; the input end of the rectifying voltage stabilizing circuit is connected with a secondary coil of the transformer. The signal isolation circuit comprises a digital isolator, a connecting sensor circuit and a microprocessor circuit. Simultaneously, the utility model provides an intelligent transducer provided with the isolation circuit with a two-wire system. If applied to an intelligent transducer with a two-wire system, the utility model plays the function of isolating voltage and signal interference.
Description
Technical field
The utility model relates to a kind of buffer circuit, relates in particular to a kind of buffer circuit that is placed in the two-wire system intelligent transducer.
Background technology
In the industrial automation field, especially in industries such as electric power, petrochemical industry, metallurgy, when physical parameters such as needs gaging pressure, flow, temperature, will adopt the two-wire system transformer of 4-20mA industrial standard in a large number.Along with the development of digital technology, adopt the 4-20mA two-wire system intelligent transducer of new generation of microprocessor progressively to replace original 4-20mA two-wire system transformer.
Fig. 1 shows the circuit theory of the 4-20mA two-wire system intelligent transducer of existing employing microprocessor.This transmitter mainly comprises feed circuit 110, microcontroller circuit 120 and sensor circuit 130.In this sensor circuit 130, sensor 131 is connected with A/D change-over circuit 132.When sensor 131 was digital sensor, A/D change-over circuit 132 can omit.In this microcontroller circuit 120, microprocessor 121 and D/A connect with voltage-regulating circuit 122, microprocessor 121 and storer 123 swap datas, and microprocessor 121 sends instructions to D/A and voltage-regulating circuit 122 by telecommunication circuit 124.This adjustment circuit 122 provides stable operating voltage by the field effect transistor 113 of series connection with it.Sensor circuit 130 and microcontroller circuit 130 series connection also can connect electric capacity 141A, 141B and neat sodium diode 142 between two circuit. Electric capacity 141A, 141B are used for reducing the ripple factor of operating voltage, and neat sodium diode 142 is used for overvoltage protection.Microcontroller circuit 120 is serially connected in the feed circuit 110, and these feed circuit 110 also comprise a power supply 111 and a pull-up resistor 112, and this pull-up resistor 112 is used for current signal is transformed into voltage signal.
In the course of work of existing transmitter, sensor circuit 130 is worked under same operating voltage Vc with microcontroller circuit 120, this operating voltage Vc is formed by power supply 111 dividing potential drop in feed circuit 110, so power supply 111 is not isolated with Vc.Under described working condition,, cause the undesired signal of self powered supply 111 to influence sensor circuit 130 by disturbing operating voltage Vc on the one hand because operating voltage Vc is subjected to power supply 111 dominations; On the other hand, the noise that produced of the digital signal processing in the microcontroller circuit 120 part also exerts an influence to sensor circuit 130 easily.Because sensor circuit 130 is not carried out effective isolation with feed circuit 110 with the operating voltage of microcontroller circuit 120 with to digital Signal Processing, thereby has reduced the precision of measuring.
As mentioned above, two-wire system intelligent transducer of the prior art does not have isolating power, and is not enough to some extent aspect reliability and antijamming capability, particularly the abominable industry spot of strong electromagnetic arranged, the transmitter that has even can't normally use.For this reason, the industry member universal demand provides both has powerful digital signal processing function, possesses the novel two-wire system intelligent transducer of anti-strong electromagnetic again.
Summary of the invention
The purpose of this utility model has been to solve the problem of above-mentioned voltage and signal interference, a kind of two-wire system intelligent transducer that is used for the buffer circuit of two-wire system intelligent transducer and has this buffer circuit is provided, can avoid of the interference of industry spot forceful electric power magnetic effectively, to satisfy the quality requirements of two-wire system intelligent transducer to sensor circuit.
The technical solution of the utility model is that a kind of buffer circuit that is used for the two-wire system intelligent transducer comprises voltage isolation circuit and signal isolation circuit.Wherein voltage isolation circuit comprises the voltage pick-up circuit, and its input end is connected in the feed circuit, is used to receive the voltage of self powered supply; Oscillatory circuit, its input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage, and the output terminal of described oscillatory circuit is used to export the mutually opposite AC signal in two-way position; Driving circuit, be used to strengthen the driving load capacity of described AC signal, the output terminal of its first input end and described oscillatory circuit links to each other, and is used to receive described AC signal, second input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage; Isolating transformer is used to isolate transformation, and the output terminal of its primary coil and described driving circuit links to each other, and is used to receive described ac voltage signal; Regulator rectifier circuit is used for that alternating voltage is transformed into galvanic current and presses, and its input end connects the secondary coil of described isolating transformer, is used to receive the ac voltage signal through after the isolation transformation; Wherein signal isolation circuit comprises: digital isolator and described voltage isolation circuit parallel connection, connect sensor circuit and microcontroller circuit, and be used for isolating the digital signal of transmission course.
In the described buffer circuit, described voltage pick-up circuit can be connected in the described feed circuit, also can be connected between described feed circuit and the microcontroller circuit, is used to pick up the virgin work voltage that forms buffer circuit.Described digital isolator comprises iCoupler digital isolator.The circuit-formed virgin work voltage of described voltage pick-up is 6V.Described oscillatory circuit can comprise multivibrator, also can comprise sine-wave oscillator.Described oscillatory circuit uses cmos device, and oscillation frequency is 1kHz-100kHz.The operating voltage of described regulator rectifier circuit output is 4V, and the load current that is 3.5mA to the maximum is provided.
A kind of two-wire system intelligent transducer with described buffer circuit also is provided, comprise the sensor and the A/D converter that are positioned at the working site, be positioned at power supply, pull-up resistor, D/A and voltage adjuster, telecommunication circuit, storer and the microprocessor of pulpit, also comprise a buffer circuit, described buffer circuit comprises voltage isolation circuit and signal isolation circuit: wherein voltage isolation circuit comprises: the voltage pick-up circuit, its input end is connected in the feed circuit, is used to receive the voltage of self powered supply; Oscillatory circuit, its input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage, and the output terminal of described oscillatory circuit is used to export the mutually opposite AC signal in two-way position; Driving circuit, be used to strengthen the driving load capacity of described AC signal, the output terminal of its first input end and described oscillatory circuit links to each other, and is used to receive described AC signal, second input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage; Isolating transformer is used to isolate transformation, and the output terminal of its primary coil and described driving circuit links to each other, and is used to receive described ac voltage signal; Regulator rectifier circuit is used for that alternating voltage is transformed into galvanic current and presses, and its input end connects the secondary coil of described isolating transformer, is used to receive the ac voltage signal through after the isolation transformation; Wherein signal isolation circuit comprises: digital isolator, be connected with described voltage isolation circuit, and connect sensor circuit and microcontroller circuit, be used for isolating the digital signal of transmission course.
In the described two-wire system intelligent transducer, described voltage pick-up circuit is connected in the described feed circuit, also can be connected between described feed circuit and the microcontroller circuit.In the described two-wire system intelligent transducer, described digital isolator comprises iCoupler digital isolator, the circuit-formed virgin work voltage of described voltage pick-up is 6V, described oscillatory circuit can comprise multivibrator, also can comprise sine-wave oscillator, described oscillatory circuit uses cmos device, and oscillation frequency is 1kHz-100kHz, the operating voltage of described regulator rectifier circuit output is 4V, and the load current that is 3.5mA to the maximum is provided.
The utility model has following remarkable result: the primary voltage that voltage pick-up circuit self-powered circuit picks up formation is supplied to oscillatory circuit and driving circuit as operating voltage.Oscillatory circuit output AC voltage signal after driving circuit strengthens its load capacity, is isolated through isolating transformer again, after regulator rectifier circuit is transformed into and exports after comparatively galvanic current is pressed, is used for sensor circuit is powered.Adopt the digital signal between digital isolator transmission sensor circuit and the microprocessor simultaneously.Because last form the operating voltage of sensor circuit and the voltage of power supply are isolated fully, this has realized the isolation of transmitter sensor circuit and feed circuit; Owing to adopt the digital isolator transmission of digital signals, this has realized the isolation between transmitter sensor circuit and the microcontroller circuit again.Buffer circuit has been eliminated from above-mentioned two aspects from the influence to sensor circuit of the noise signal of power supply undesired signal and microcontroller circuit, thereby has improved the interference free performance of total system.Because this buffer circuit inner structure is simple, the common and negligible amounts of device so also can satisfy the low-power consumption requirement of 4-20mA industrial standard two-wire system transformer to circuit, also is convenient to produce in enormous quantities simultaneously again.
Description of drawings
Fig. 1 is the circuit theory diagrams of the two-wire system intelligent transducer of prior art.
Fig. 2 is the circuit theory diagrams of a preferred embodiment of the present utility model.
Fig. 3 is the circuit theory diagrams of another preferred embodiment of the present utility model.
Embodiment
Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail:
In preferred embodiment shown in Figure 2, this buffer circuit 250 is to be in series with mu balanced circuit 256 by voltage pick-up circuit 251, oscillatory circuit 252, driving circuit 253, isolating transformer 254, rectification circuit 255.The input end of this series circuit is connected in the feed circuit 210, and output terminal is arranged in sensor circuit 230.A digital isolator 257 is connected on the above-mentioned circuit that is in series simultaneously, and its input end and output terminal lay respectively in sensor circuit 230 and the microcontroller circuit 220.When sensor 231 is digital sensor, in sensor circuit 230, A/D change-over circuit 232 can be set.In the present embodiment, digital isolator 257 is iCoupler digital isolators, the characteristics of this digital isolator are that power consumption is lower than optocoupler, transfer rate is faster than optocoupler, adopting this digital isolator is in order to satisfy the restriction of two-wire channel to power consumption, guarantee certain signal transmission rate simultaneously, but not as to restriction of the present utility model.
The principle of work of this buffer circuit is as follows: at first directly pick up primary voltage by voltage pick-up circuit 251 from the feed circuit 210 of 4-20mA, can directly or indirectly produce the primary voltage of about 6V by mu balanced circuit 258.This mu balanced circuit 258 can be common voltage stabilizer, also can be three sections voltage-stabilizing devices.This voltage is supplied to oscillatory circuit 252 by the output terminal of voltage pick-up circuit 210.
Oscillatory circuit 252 can be that multivibrator also can be a sine-wave oscillator, adopts cmos device, satisfying the low-power consumption requirement of 4-20mA two-wire system, but not as restriction of the present utility model, and its oscillation frequency is 1kHz-100kHz.Oscillatory circuit 252 is exported mutually opposite AC signal A and the B in two-way position under above-mentioned operating voltage of picking up.This AC signal is received by the driving circuit 253 of connecting with oscillatory circuit 252, becomes after treatment to have drive signal C and the D that drives about tens mA load capacity.This drive signal C and D output to the primary coil 254A of isolating transformer 254 then.Because the amplitude of C and D signal is near pick-up voltage 6V, the position is mutually opposite, and the ability that drives load is strong, and therefore as long as use the high isolating transformer 254 of conversion efficiency, the secondary coil 254B of isolating transformer 254 just can produce thereupon and drive strong alternating voltage E and the F of load capacity.Isolate in the transformation process at this, the alternating voltage E of output and F are independent with supply voltage.This alternating voltage E is transferred to the rectification circuit 255 of connecting with it from the secondary coil 254B of isolating transformer 254 with F, becomes DC voltage, again through mu balanced circuit 256, and the voltage Vg that forms stable about 4V and isolate with primary voltage.This voltage can provide the load current of the most about 3.5mA, can satisfy the requirement of most of 4-20mA two-wire system intelligent transducers.
Physical signalling becomes the electric signal of amplitude with the physical signalling size variation by sensor 231 and modulation circuit (not shown) thereof, becomes digital signal through A/D converter 232; If sensor 231 is digital transducers, then need not A/D converter 232, physical signalling directly becomes frequency signal.This numeral or frequency signal carry out the transmission of digital signal by iCoupler digital isolator and microprocessor 221, thereby have guaranteed the isolation of digital transmission signal.
In another embodiment shown in Figure 3, the input end of voltage pick-up circuit 351 is connected between feed circuit 310 and the microcontroller circuit 320 through mu balanced circuit 358, is changed that by DC/DC the high voltage between feed circuit 310 and the microcontroller circuit 320 is converted to primary voltage about 6V.Other structures and implementation and above-mentioned embodiment shown in Figure 2 are identical, therefore no longer are repeated in this description.
The numerical values recited that above embodiment relates to only is in order to satisfy the requirement of 4-20mA industrial standard two-wire system, if two-wire system adopts other standard, then numerical value will be adjusted accordingly, thereby these numerical value do not limit the utility model.Those of ordinary skills can do various modifications and variation under the prerequisite that does not break away from spirit and scope of the present utility model, but these modifications that are equal to all should drop in the scope of claim of the present utility model with variation.
Claims (10)
1 one kinds of buffer circuits that are used for the two-wire system intelligent transducer is characterized in that, it comprises voltage isolation circuit and signal isolation circuit:
Wherein voltage isolation circuit comprises:
The voltage pick-up circuit, its input end is connected in the feed circuit, is used to receive the voltage of self powered supply;
Oscillatory circuit, its input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage, and the output terminal of described oscillatory circuit is used to export the mutually opposite AC signal in two-way position;
Driving circuit, be used to strengthen the driving load capacity of described AC signal, the output terminal of its first input end and described oscillatory circuit links to each other, and is used to receive described AC signal, second input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage;
Isolating transformer is used to isolate transformation, and the output terminal of its primary coil and described driving circuit links to each other, and is used to receive described ac voltage signal;
Regulator rectifier circuit is used for that alternating voltage is transformed into galvanic current and presses, and its input end connects the secondary coil of described isolating transformer, is used to receive the ac voltage signal through after the isolation transformation;
Wherein signal isolation circuit comprises:
Digital isolator is connected with described voltage isolation circuit, connects sensor circuit and microcontroller circuit, is used for isolating the digital signal of transmission course.
2 buffer circuits according to claim 1 is characterized in that, described voltage pick-up circuit is connected in the described feed circuit, are used to pick up the virgin work voltage that forms buffer circuit.
3 buffer circuits according to claim 1 is characterized in that, described voltage pick-up circuit is connected between described feed circuit and the microcontroller circuit, are used to pick up the virgin work voltage that forms buffer circuit.
4 buffer circuits according to claim 1 is characterized in that, described digital isolator comprises iCoupler digital isolator.
5 buffer circuits according to claim 1 is characterized in that, the circuit-formed virgin work voltage of described voltage pick-up is 6V.
6 buffer circuits according to claim 1 is characterized in that described oscillatory circuit can comprise multivibrator, also can comprise sine-wave oscillator, and described oscillatory circuit uses cmos device, and oscillation frequency is 1kHz-100kHz.
7 buffer circuits according to claim 1 is characterized in that, the operating voltage of described regulator rectifier circuit output is 4V, and the load current that is 3.5mA to the maximum is provided.
8 one kinds of two-wire system intelligent transducers with described buffer circuit, comprise the sensor and the A/D converter that are positioned at the working site, be positioned at power supply, pull-up resistor, field effect transistor, D/A and voltage adjuster, telecommunication circuit, storer and the microprocessor of pulpit, it is characterized in that, also comprise a buffer circuit, described buffer circuit comprises voltage isolation circuit and signal isolation circuit:
Wherein voltage isolation circuit comprises:
The voltage pick-up circuit, its input end is connected in the feed circuit, is used to receive the voltage of self powered supply;
Oscillatory circuit, its input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage, and the output terminal of described oscillatory circuit is used to export the mutually opposite AC signal in two-way position;
Driving circuit, be used to strengthen the driving load capacity of described AC signal, the output terminal of its first input end and described oscillatory circuit links to each other, and is used to receive described AC signal, second input end links to each other with the output terminal of described voltage pick-up circuit, is used to receive operating voltage;
Isolating transformer is used to isolate transformation, and the output terminal of its primary coil and described driving circuit links to each other, and is used to receive described ac voltage signal;
Regulator rectifier circuit is used for that alternating voltage is transformed into galvanic current and presses, and its input end connects the secondary coil of described isolating transformer, is used to receive the ac voltage signal through after the isolation transformation;
Wherein signal isolation circuit comprises:
Digital isolator is connected with described voltage isolation circuit, connects sensor circuit and microcontroller circuit, is used for isolating the digital signal of transmission course.
9 two-wire system intelligent transducers according to claim 8 is characterized in that described voltage pick-up circuit is connected in the described feed circuit, also can be connected between described feed circuit and the microcontroller circuit.
10 two-wire system intelligent transducers according to claim 8, it is characterized in that, described digital isolator comprises iCoupler digital isolator, the circuit-formed virgin work voltage of described voltage pick-up is 6V, and described oscillatory circuit can comprise multivibrator, also can comprise sine-wave oscillator, described oscillatory circuit uses cmos device, and oscillation frequency is 1kHz-100kHz, and the operating voltage of described regulator rectifier circuit output is 4V, and the load current that is 3.5mA to the maximum is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520046248 CN2847228Y (en) | 2005-11-04 | 2005-11-04 | Intelligent transducer isolation circuit for two-wire system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200520046248 CN2847228Y (en) | 2005-11-04 | 2005-11-04 | Intelligent transducer isolation circuit for two-wire system |
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| Publication Number | Publication Date |
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| CN2847228Y true CN2847228Y (en) | 2006-12-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 200520046248 Expired - Fee Related CN2847228Y (en) | 2005-11-04 | 2005-11-04 | Intelligent transducer isolation circuit for two-wire system |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100490282C (en) * | 2007-04-16 | 2009-05-20 | 中控科技集团有限公司 | Transducer circuit power supply method and transducer |
| CN101877683A (en) * | 2009-03-30 | 2010-11-03 | 硅谷实验室公司 | Capacitive isolation circuitry |
| CN103023340A (en) * | 2012-11-27 | 2013-04-03 | 中环天仪股份有限公司 | Power circuit and method for increasing load capacity of two-wire system instrument |
| CN103226025A (en) * | 2012-12-17 | 2013-07-31 | 天津市北方阀门控制设备有限公司 | Two-wire position transmitter circuit |
| CN104917495A (en) * | 2015-05-23 | 2015-09-16 | 成都众孚理想科技有限公司 | Isolated high-frequency pulse generator |
| CN106384498A (en) * | 2016-11-18 | 2017-02-08 | 广州精秀热工设备有限公司 | Transmitter for converting dichlorodifluoromethane saturation pressure into saturation temperature |
-
2005
- 2005-11-04 CN CN 200520046248 patent/CN2847228Y/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100490282C (en) * | 2007-04-16 | 2009-05-20 | 中控科技集团有限公司 | Transducer circuit power supply method and transducer |
| CN101877683A (en) * | 2009-03-30 | 2010-11-03 | 硅谷实验室公司 | Capacitive isolation circuitry |
| CN101877683B (en) * | 2009-03-30 | 2014-08-13 | 硅谷实验室公司 | Capacitive isolation circuitry |
| CN103023340A (en) * | 2012-11-27 | 2013-04-03 | 中环天仪股份有限公司 | Power circuit and method for increasing load capacity of two-wire system instrument |
| CN103226025A (en) * | 2012-12-17 | 2013-07-31 | 天津市北方阀门控制设备有限公司 | Two-wire position transmitter circuit |
| CN104917495A (en) * | 2015-05-23 | 2015-09-16 | 成都众孚理想科技有限公司 | Isolated high-frequency pulse generator |
| CN104917495B (en) * | 2015-05-23 | 2018-03-06 | 成都众孚理想科技有限公司 | A kind of isolation type high frequency impulse generator |
| CN106384498A (en) * | 2016-11-18 | 2017-02-08 | 广州精秀热工设备有限公司 | Transmitter for converting dichlorodifluoromethane saturation pressure into saturation temperature |
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Legal Events
| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20061213 Termination date: 20101104 |