CN102820881A - Analog voltage input circuit and method - Google Patents
Analog voltage input circuit and method Download PDFInfo
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- CN102820881A CN102820881A CN2012102763840A CN201210276384A CN102820881A CN 102820881 A CN102820881 A CN 102820881A CN 2012102763840 A CN2012102763840 A CN 2012102763840A CN 201210276384 A CN201210276384 A CN 201210276384A CN 102820881 A CN102820881 A CN 102820881A
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Abstract
The invention provides an analog voltage input circuit, which is used for inputting secondary-side analog voltage into a primary-side digital signal processor. The analog voltage input circuit comprises a voltage to frequency conversion circuit and an optocoupler, wherein analog voltage is input into the input end of the voltage to frequency conversion circuit; the output end of the voltage to frequency conversion circuit is connected to the input end of the optocoupler; the output end of the optocoupler is connected to the input end of the digital signal processor; the input voltage is converted into a corresponding-frequency pulse signal by the voltage to frequency conversion circuit; and the frequency of the pulse signal output by the voltage to frequency conversion circuit is in linear variation along the value of the input voltage. The invention also provides a corresponding method. According to the analog voltage input circuit and the method disclosed by the invention, the input of a weak-current voltage signal to a power supply side can be realized by adopting a common optocoupler via voltage to frequency conversion, the cost is low, and the linearity degree is good.
Description
Technical field
The present invention relates to analog signal input field, more particularly, relate to a kind of aanalogvoltage input circuit and method.
Background technology
When realizing the allomeric function of frequency converter, need carry out the control signal input.Usually digital signal processor places the primary side at power power-supply place, because the power supply and the various signal of primary side are the forceful electric power signals, so the signal of this side does not satisfy the safety requirement.And external terminal is mainly offered the operator use in the frequency converter to carry out the control command input, because this is prone to touch to the external terminal human body, therefore must be satisfied the safety requirement.Analog voltage input is a kind of to external terminal, therefore generally it is arranged on the secondary side of power supply, and this side belongs to the light current district, thereby makes it satisfy the safety requirement.
Therefore, for realizing the analog voltage signal input and satisfying the safety requirement, need analog voltage signal is isolated the digital signal processor that is input to primary side.By isolation scheme analog voltage signal is input to the digital signal processor of primary side, at present mainly by the following two kinds of programs:
(1) utilize linear optical coupling to isolate analog voltage signal being delivered to the digital signal processor side is primary side, and digital signal processor uses the ADC sampling can learn the input analog voltage to external terminal in real time.The aanalogvoltage input signal arrives primary side after the isolation of secondary side through linear optical coupling, both realized the isolation on the safety, and the aanalogvoltage that can satisfy again input is reflected to primary side.
In the such scheme, the linearity of signal and precision can both guarantee that the response time is little, and be higher but the shortcoming of this scheme is the cost of linear optical coupling.
(2) utilize ADC sampling A and optocoupler to form isolation scheme.In this scheme; The ADC chip is located at secondary side; Optocoupler is connected across the primary side and the secondary side of power supply, and plays a part to isolate and transmission of digital signals: analog voltage signal is through directly delivering to the ADC sampling after nursing one's health, digital signal processor is controlled the ADC chip through light-coupled isolation transmission signal and sampled; Sampled data turns back to the digital signal processor from other optocoupler and goes, thereby realizes the collection of analog voltage signal.
The linearity of analog voltage signal and precision are all better in this scheme, but the device of using is many, and (needing 1 ADC sampling A and 2 optocouplers at least), it is big to take volume, is unfavorable for miniaturization.And the ADC chip price that uses in this scheme is high, and the optocoupler that uses is high speed photo coupling, and overall cost is higher.
Summary of the invention
The technical problem that the present invention will solve is, isolates the high problem of input cost to above-mentioned frequency converter analog signal, and a kind of aanalogvoltage input circuit and method are provided.
The technical scheme that the present invention solves the problems of the technologies described above is, a kind of aanalogvoltage input circuit is provided, and is used for the digital signal processor with the aanalogvoltage input primary side of secondary side, comprises voltage-frequency change-over circuit and optocoupler; Wherein: the input of said aanalogvoltage input voltage-frequency change-over circuit and the output of said voltage-frequency change-over circuit are connected to the input of said optocoupler; The output of said optocoupler is connected to the input of digital signal processor; The frequency of pulse signal that said voltage-frequency change-over circuit converts the aanalogvoltage of input into pulse signal and this voltage-frequency change-over circuit output of respective frequencies is linear change with the value of the aanalogvoltage of input.
In aanalogvoltage input circuit of the present invention; Said voltage-frequency change-over circuit is at input voltage output pulse signal during greater than 0V; Said aanalogvoltage is input to the input of voltage-frequency change-over circuit via adder circuit, and said adder circuit is used for input voltage is risen to more than the 0V.
In aanalogvoltage input circuit of the present invention, the RC filter circuit that said voltage-frequency change-over circuit comprises aanalogvoltage/frequency inverted chip NJM4151 and is located at the input of this aanalogvoltage/frequency inverted chip NJM4151.
In aanalogvoltage input circuit of the present invention, the 6th pin of said aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection, the frequency of the 3rd pin output pulse of said aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of said aanalogvoltage/frequency inverted chip NJM4151.
In aanalogvoltage input circuit of the present invention, said capacitor C
BCapacitance be 0.01uf, said resistance R
OResistance satisfy: 6.8k Ω＜R
O＜680k Ω, said capacitor C
OThe appearance value satisfy: 0.001uf＜C
O＜1.0uf.
The present invention also provides a kind of aanalogvoltage input method, is used for the digital signal processor with the aanalogvoltage input primary side of secondary side, may further comprise the steps:
(a) convert aanalogvoltage into pulse signal, the frequency of said pulse signal is linear change with the value of aanalogvoltage;
(b) with the former limit of said output pulse input optocoupler, the secondary of said optocoupler is connected to the input of digital signal processor.
In aanalogvoltage input method of the present invention, said step (a) comprising: with the value of said aanalogvoltage rise to more than the 0V and will promote after aanalogvoltage convert pulse signal into.
In aanalogvoltage input method of the present invention, pass through the conversion that the voltage-frequency change-over circuit is realized aanalogvoltage and pulse signal in the said step (a), and realize the lifting of aanalogvoltage through adder circuit.
In aanalogvoltage input method of the present invention; Said voltage-frequency change-over circuit comprises aanalogvoltage/frequency inverted chip NJM4151, and said analog voltage input is connected to the input of said aanalogvoltage/frequency inverted chip NJM4151 via the RC filter circuit.
In aanalogvoltage input method of the present invention, the 6th pin of said aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection; The frequency of the 3rd pin output pulse of said aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of said aanalogvoltage/frequency inverted chip NJM4151.
Aanalogvoltage input circuit of the present invention and method through the voltage-frequency conversion, make and adopt common optocoupler can realize the input of light current voltage signal to mains side that not only cost is lower, and the linearity is good.The present invention adopts the combination of aanalogvoltage/frequency inverted chip NJM4151 and common optocoupler, has overcome the difficult problem of slow, overshoot of existing scheme response time, and has made whole cost significantly reduce.Through test, the present invention is applicable to the voltage range of input ± 10V, and linear precision satisfies 1% requirement.
Description of drawings
Fig. 1 is the structured flowchart of aanalogvoltage input circuit first embodiment of the present invention.
Fig. 2 is the structured flowchart of aanalogvoltage input circuit second embodiment of the present invention.
Fig. 3 is the sketch map of voltage-frequency change-over circuit among Fig. 2.
Fig. 4 is the schematic flow sheet of aanalogvoltage input method embodiment of the present invention.
Embodiment
In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
The present invention converts aanalogvoltage to the pulse signal of respective frequencies; Deliver to digital signal processor through after the light-coupled isolation; Become pulse signal to deliver to the digital signal processor port with regard to the analog signal conversion of accomplishing secondary side like this; Digital signal processor calculates the frequency of pulse signal, just can collect the size of aanalogvoltage in real time, thereby carry out control corresponding.
As shown in Figure 1, be the structured flowchart of aanalogvoltage input circuit first embodiment of the present invention, this aanalogvoltage input circuit is used for the aanalogvoltage of secondary side is input to the digital signal processor of primary side.In the present embodiment, this aanalogvoltage input circuit comprises voltage-frequency change-over circuit 11 and optocoupler 12, and wherein the output of the input of the input of voltage-frequency change-over circuit 11 reception aanalogvoltage and this voltage-frequency change-over circuit 11 is connected to the input of optocoupler 12.The output of optocoupler 12 is connected to the input of digital signal processor 13.Above-mentioned voltage-frequency change-over circuit 11 converts input voltage the pulse signal of respective frequencies into, and the frequency of the pulse signal of these voltage-frequency change-over circuit 11 outputs is linear change with the value of input voltage.
Utilize the voltage-frequency change-over circuit 11 of secondary side in the foregoing circuit; Aanalogvoltage is converted into the pulse signal of different frequency by the different voltages with different value; And pass through optocoupler 12 and transmit above-mentioned pulse signal to primary side, the digital signal processor 13 of primary side restores the size of aanalogvoltage according to the frequency that samples pulse signal.
Such scheme utilizes numeral to isolate the isolation that realizes the aanalogvoltage input, can significantly reduce cost with the analog signal isolation scheme than direct.And compare with the existing scheme of ADC chip and optocoupler combination that adopts, can reduce the fabric swatch area greatly, help the miniaturization of veneer.
In the voltage-frequency change-over circuit,, need this moment the voltage of input voltage-frequency conversion chip is promoted if the voltage-frequency conversion chip (VFC) that adopts only can be realized the above voltage transitions of 0V (promptly only satisfying the positive voltage input).As shown in Figure 2, be the structured flowchart of aanalogvoltage input circuit second embodiment of the present invention.In the present embodiment, except comprising voltage-frequency change-over circuit 22 and optocoupler 23, also comprise being used for input voltage is risen to the adder circuit 21 more than the 0V.Aanalogvoltage carries out being input to voltage-frequency change-over circuit 22 after voltage promotes through adder circuit 21.The pulse signal of voltage-frequency change-over circuit 22 outputs is input in the digital signal processor 24 via optocoupler 23.
Through above-mentioned adder circuit 21, make the input that the voltage-frequency conversion chip only can realize the positive voltage input can compatible negative voltage.
Especially, as shown in Figure 3, be the structural representation of voltage-frequency change-over circuit 24 among Fig. 2.This voltage-frequency change-over circuit 24 comprises aanalogvoltage/frequency inverted chip NJM4151, and the input of aanalogvoltage/frequency inverted chip NJM4151 is provided with the RC filter circuit.Through above-mentioned RC filter circuit, can in aanalogvoltage/frequency inverted chip NJM4151, add the RC filtering time, thereby solve over control.
The 6th pin of above-mentioned aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection, the frequency of the 3rd pin output pulse of said aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of aanalogvoltage/frequency inverted chip NJM4151.The pulsewidth T=1.1R of the output pulse of aanalogvoltage/frequency inverted chip NJM4151
OC
O
In order to give full play to the linearity advantage of aanalogvoltage/frequency inverted chip NJM4151; The running parameter of configurable aanalogvoltage/frequency inverted chip NJM4151; With according to the relation between aanalogvoltage/frequency inverted chip NJM4151 supply power voltage and the output frequency, guarantee that the minor variations of operating voltage is little to the output frequency influence.For example the supply power voltage of aanalogvoltage/frequency inverted chip NJM4151 is set to+14.25V, and this moment, the flat region of relation curve was dropped in aanalogvoltage/frequency inverted chip NJM4151 working point.
In above-mentioned voltage-frequency change-over circuit, the frequency that the output pulse of aanalogvoltage/frequency inverted chip NJM4151 possibly occur can not be followed phenomenons such as input voltage variation fast.In order to solve the problem of above-mentioned response time, overshoot, need the running parameter of configuration aanalogvoltage/frequency inverted chip NJM4151.C wherein
BParameter influence is very crucial, particularly to the influence in reaction time of input and output, finds through test, at C
BThe phenomenon (responding untimely performance) that can occur the dead band frequency during=0.1uf, but and C
BThe frequency that occurs dead band during=1.0uf is different, and it only occurred when moment, saltus step was bigger at input voltage, and promptly the jump frequency of input voltage is when higher, like 50Hz.Work as C
B=0.01uf, when higher, jump frequency can reach 1kHz in the jump frequency of input voltage; This moment, the phenomenon of dead band frequency can not appear in output yet; And the linearity of output is also very good, and this moment, output frequency can be followed the tracks of the variation of input voltage fast, was about 1ms time of delay.
Especially, the frequency range of the design of above-mentioned aanalogvoltage/frequency inverted chip NJM4151 output is 2.0kHz ~ 20kHz, and when selecting parameter, the restriction relation that parameter can be set is following: 6.8k Ω＜R
O＜680k Ω, 0.001uf＜C
O＜1.0uf, C
B=0.01uf.
As shown in Figure 4, be the schematic flow sheet of aanalogvoltage input method embodiment of the present invention, this method is used for the digital signal processor with the aanalogvoltage input primary side of secondary side.This method may further comprise the steps:
Step S41: convert aanalogvoltage into pulse signal, wherein the frequency of pulse signal is linear change with the value of aanalogvoltage.
In this step, can be through realize the conversion of aanalogvoltage and pulse signal such as voltage-frequency change-over circuit etc.In addition; The voltage-frequency conversion chip that only can import positive voltage for this method is applicable to; Can promote through the aanalogvoltage of adder circuit, import the voltage-frequency change-over circuit again after just rising to the value of aanalogvoltage more than the 0V to convert pulse signal into input.
Step S42: with the former limit of above-mentioned output pulse input optocoupler, the secondary of this optocoupler is connected to the input of digital signal processor.
Above-mentioned voltage-frequency change-over circuit can adopt aanalogvoltage/frequency inverted chip NJM4151.Especially, the input of this aanalogvoltage/frequency inverted chip NJM4151 is provided with the RC filter circuit, thereby solves over control.
The 6th pin of above-mentioned aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection; The frequency of the 3rd pin output pulse of aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of aanalogvoltage/frequency inverted chip NJM4151.
The above; Be merely the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, any technical staff who is familiar with the present technique field is in the technical scope that the present invention discloses; The variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Claims (10)
1. an aanalogvoltage input circuit is used for the digital signal processor with the aanalogvoltage input primary side of secondary side, it is characterized in that: comprise voltage-frequency change-over circuit and optocoupler; Wherein: the input of said aanalogvoltage input voltage-frequency change-over circuit and the output of said voltage-frequency change-over circuit are connected to the input of said optocoupler; The output of said optocoupler is connected to the input of digital signal processor; The frequency of pulse signal that said voltage-frequency change-over circuit converts the aanalogvoltage of input into pulse signal and this voltage-frequency change-over circuit output of respective frequencies is linear change with the value of the aanalogvoltage of input.
2. aanalogvoltage input circuit according to claim 1; It is characterized in that: said voltage-frequency change-over circuit is at input voltage output pulse signal during greater than 0V; Said aanalogvoltage is input to the input of voltage-frequency change-over circuit via adder circuit, and said adder circuit is used for input voltage is risen to more than the 0V.
3. aanalogvoltage input circuit according to claim 2 is characterized in that: the RC filter circuit that said voltage-frequency change-over circuit comprises aanalogvoltage/frequency inverted chip NJM4151 and is located at the input of this aanalogvoltage/frequency inverted chip NJM4151.
4. aanalogvoltage input circuit according to claim 3 is characterized in that: the 6th pin of said aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection, the frequency of the 3rd pin output pulse of said aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of said aanalogvoltage/frequency inverted chip NJM4151.
5. aanalogvoltage input circuit according to claim 4 is characterized in that: said capacitor C
BCapacitance be 0.01uf, said resistance R
OResistance satisfy: 6.8k Ω＜R
O＜680k Ω, said capacitor C
OThe appearance value satisfy: 0.001uf＜C
O＜1.0uf.
6. an aanalogvoltage input method is used for the digital signal processor with the aanalogvoltage input primary side of secondary side, it is characterized in that: may further comprise the steps:
(a) convert aanalogvoltage into pulse signal, the frequency of said pulse signal is linear change with the value of aanalogvoltage;
(b) with the former limit of said output pulse input optocoupler, the secondary of said optocoupler is connected to the input of digital signal processor.
7. aanalogvoltage input method according to claim 6 is characterized in that: said step (a) comprising: with the value of said aanalogvoltage rise to more than the 0V and will promote after aanalogvoltage convert pulse signal into.
8. aanalogvoltage input method according to claim 7 is characterized in that: pass through the conversion that the voltage-frequency change-over circuit is realized aanalogvoltage and pulse signal in the said step (a), and realize the lifting of aanalogvoltage through adder circuit.
9. aanalogvoltage input method according to claim 8; It is characterized in that: said voltage-frequency change-over circuit comprises aanalogvoltage/frequency inverted chip NJM4151, and said analog voltage input is connected to the input of said aanalogvoltage/frequency inverted chip NJM4151 via the RC filter circuit.
10. aanalogvoltage input method according to claim 9 is characterized in that: the 6th pin of said aanalogvoltage/frequency inverted chip NJM4151 is respectively via capacitor C
BAnd resistance R
BGround connection, the 5th pin are via capacitor C
OGround connection and via resistance R
OBe connected to supply power voltage, the 2nd pin via resistance R
SGround connection; The frequency of the 3rd pin output pulse of said aanalogvoltage/frequency inverted chip NJM4151 is: f
O=KV
1, K=0.486*R wherein
S/ (R
BR
OC
O), V
1Value for the input voltage of the 7th pin of said aanalogvoltage/frequency inverted chip NJM4151.
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| CN2012102763840A CN102820881A (en) | 2012-08-06 | 2012-08-06 | Analog voltage input circuit and method |
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|---|---|---|---|
| CN2012102763840A CN102820881A (en) | 2012-08-06 | 2012-08-06 | Analog voltage input circuit and method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104977281A (en) * | 2015-06-26 | 2015-10-14 | 桂林电子科技大学 | High-precision online fluorescence detector and detection method thereof |
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| WO2008060670A2 (en) * | 2006-04-20 | 2008-05-22 | Multi-Dimensional Imaging, Inc. | Low noise voltage-to-frequency conversion apparatus and method for quantum measurements |
| CN201331553Y (en) * | 2008-12-22 | 2009-10-21 | 义乌市华晨机电有限公司 | DC (direct current) voltage measuring circuit with isolation |
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Application publication date: 20121212 |