CN208849740U - A kind of low temperature temperature control pwm circuit - Google Patents
A kind of low temperature temperature control pwm circuit Download PDFInfo
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- CN208849740U CN208849740U CN201821381622.3U CN201821381622U CN208849740U CN 208849740 U CN208849740 U CN 208849740U CN 201821381622 U CN201821381622 U CN 201821381622U CN 208849740 U CN208849740 U CN 208849740U
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Abstract
The utility model discloses a kind of low temperature temperature control pwm circuit, triangular wave generator circuit generates triangular wave Vo1 by self-oscillation；It is sent in error amplification and comparison circuit after temperature signal detection and the amplification of amplifying circuit temperature collection signal；Temperature setting circuit generates the reference voltage with certain adjustable extent, the temperature signal voltage Vo3 as setting；Operational amplifier in error amplification and comparison circuit amplifies the voltage difference of the temperature signal voltage Vo3 of setting and acquisition and the temperature voltage signal Vo2 amplified, and output voltage Vo4 is sent into comparator；By comparator by output voltage Vo4 the generation pulse signal compared with triangular wave Vo1, export final pwm signal after inverted device reverse phase.The utility model circuit structure is simpler, as long as single power supply can work, outside adjustment and interface are convenient, and triangle wave amplitude, the frequency of pwm circuit, sensitivity of pulse width modulation etc. are convenient to adjust.
Description
Technical field
The utility model relates to a kind of modulation of PWM(pulse width) circuit, especially a kind of structure is simple, single supply work
Make, parameter it is easy to adjust be used for the thermostatically controlled pwm circuit of cryogenic refrigeration.
Background technique
In control driving etc. in electronic systems, PWM(pulse width modulation) circuit is usually used in the control such as constant temperature, constant speed.It
Core be by controlled volume real-time control pwm circuit export pulse width, to achieve the purpose that closed loop constant control.
From the aspect of the reliability and cost of system, generally require pwm circuit structure is simple, parameter is easy to adjust, with
The interface compatibility of drive part is good etc..
Pwm circuit for low temperature temperature control most at present or use special chip, parameter adjustment inconvenience, and with survey
Circuit temperature and refrigeration control circuit interface are not easy to realize.Using more devices, need positive-negative power power supply and more complex three
Angle wave producer is used and is adjusted and is all cumbersome so that circuit composition is more complex.
Utility model content
The purpose of this utility model is to provide a kind of structures relatively simply, parameter adjustment and interface are convenient, single supply work
Cryogenic thermostat control pwm circuit.As long as circuit single power supply can work, triangular-wave generator is by single operational amplifier
It constitutes, triangle wave amplitude, the frequency of pwm circuit, sensitivity of pulse width modulation etc. are convenient to adjust.
Realize the technical solution of the utility model aim:
A kind of low temperature temperature control pwm circuit, characterized in that including virtually circuit, triangular wave generator circuit, temperature signal
Detection and amplifying circuit, temperature setting circuit, error amplification and comparison circuit；
Virtually circuit provides for other circuits with reference to no-voltage；
Triangular wave generator circuit generates triangular wave Vo1 by self-oscillation, exports into error amplification and comparison circuit 5
Comparator one of input terminal；
The fortune being sent to after temperature signal detection and the amplification of amplifying circuit temperature collection signal in error amplification and comparison circuit
Calculate one of input terminal of amplifier；
Temperature setting circuit generates the reference voltage with certain adjustable extent, as the temperature signal voltage Vo3 of setting,
It is sent to another input terminal of error amplification and the operational amplifier in comparison circuit；
Operational amplifier in error amplification and comparison circuit by the temperature signal voltage Vo3 of setting and acquires and amplifies
The voltage difference of temperature voltage signal Vo2 amplifies, and output voltage Vo4 is sent into another input terminal of comparator；It will be defeated by comparator
Voltage Vo4 generation pulse signal compared with triangular wave Vo1 out exports final pwm signal after the inverted device reverse phase of pulse signal.
Virtually the power Vcc of input is converted to half by accurate virtually chip using accurate virtually chip by circuit
Power Vcc/2 simultaneously export.
Virtually the output voltage of circuit is input to the non-inverting input terminal of second operational amplifier through first resistor, virtually
The output voltage of circuit is connected to second operational amplifier inverting input terminal through first capacitor simultaneously；Second operational amplifier it is defeated
Outlet is through the positive and negative non-inverting input terminal for being fed to second operational amplifier of second resistance, and the output end of second operational amplifier is through third
Resistive degeneration to operational amplifier inverting input terminal.
It include hygrosensor and third operational amplifier in temperature signal detection and amplifying circuit；Hygrosensor will be visited
The temperature voltage signal for surveying output is input to third operational amplifier and amplifies, and obtains temperature voltage signal Vo2.
Hygrosensor is diode.
It include reference voltage source, the adjustable potentiometer of at least one resistance value or resistor and the 4th fortune in temperature setting circuit
Calculate amplifier；The reference voltage that reference voltage source generates adjusts through potentiometer or resistor and exports adjustable voltage signal, through the
Temperature signal voltage Vo3 after four-operational amplifier amplification as setting.
It further include the 5th resistance and the 8th resistance in error amplification and comparison circuit；Temperature voltage signal Vo2 is through the 5th electricity
Resistance is input to the inverting input terminal of operational amplifier；The output end of operational amplifier is through the 8th resistance feedback to operational amplifier
Inverting input terminal.
The advantages of the utility model are as follows:
Circuit structure is simpler, as long as single power supply can work, outside adjustment and interface are convenient, triangle wave amplitude, PWM
Frequency, sensitivity of pulse width modulation of circuit etc. are convenient to adjust.
Detailed description of the invention
Fig. 1 is the functional block diagram of the utility model pwm circuit.
Fig. 2 is the circuit diagram of the utility model pwm circuit, wherein 1 is virtually circuit, 2 be triangular wave generator circuit,
3 be temperature signal detection and amplifying circuit, 4 be temperature setting circuit, 5 be error amplification and comparison circuit.
Specific embodiment
The utility model is further described with reference to the accompanying drawing.Following embodiment is only used for clearly illustrating this
The technical solution of utility model, and cannot be used as a limitation the limitation protection scope of the utility model.
As shown in a kind of functional block diagram of low temperature temperature control pwm circuit of Fig. 1 the utility model, including virtually circuit, triangle
Wave generation circuit, temperature signal detection and amplifying circuit, temperature setting circuit and error amplification and 5 part of comparison circuit.
As shown in Fig. 2, including virtually circuit 1, triangular-wave generator for a kind of low temperature temperature control pwm circuit of the utility model
Circuit 2, temperature signal detection and amplifying circuit 3, temperature setting circuit 4, error amplification and comparison circuit 5.Vcc is positive electricity in figure
Source, GND are the reference ground of positive supply.
Virtually circuit 1 includes accurate virtually chip N4, and using TLE2426 chip, it converts the power Vcc of input
It for half power Vcc/2 and exports, which has 100mA current throughput ability, using this half power supply as other several partial circuits
The no-voltage (0V) of input and output refers to.Other parts are equivalent in this way works under the dual power supply of ± Vcc/2, guarantees to need double
Each operational amplifier of power work can work normally.
The following description is referred to using Vcc/2 as no-voltage (0V).
Triangular wave generator circuit 2 includes 1 sheet type multi-layer ceramic capacitance C1,3 thick-film resistors R1, R2, R3,1 fortune
Calculate amplifier N1B.Half power Vcc/2 are input to the in-phase end of operational amplifier N1B through resistance R1, and half power Vcc/2 pass through simultaneously
Ceramic condenser C1 is connected to operational amplifier N1B reverse side；The output end of operational amplifier N1B is fed to operation through resistance R2 is positive and negative
The in-phase end of amplifier N1B, the output end of operational amplifier N1B is through resistance R3 negative-feedback to the reverse side of operational amplifier N1B.
Triangular wave generator circuit 2 generates triangular wave Vo1 by self-oscillation, exports the comparator to error amplification and comparison circuit 5
The non-inverting input terminal of N1A.
The principle for generating triangular wave is: after circuit power-up, due to the positive feedback effect of resistance R2, operational amplifier N1B's
Output is positive rapidly to be saturated, and output saturation voltage Vom, at this moment the voltage of operational amplifier N1B in-phase end is Vom × R1/ (R1+
R2).Thereafter, (1) ceramic condenser C1 is charged by resistance R3, voltage, that is, operational amplifier N1B reverse side of ceramic condenser C1
Voltage charges to Vom × R1/ (R1+R2), the negative saturation of the output of operational amplifier N1B, output saturation voltage-Vom, at this moment operation
The voltage jump of amplifier N1B in-phase end is-Vom × R1/ (R1+R2).(2) ceramic condenser C1 is discharged by R3, from voltage Vom
It is the output of operational amplifier N1B and just saturation after-Vom × R1/ (R1+R2) that × R1/ (R1+R2), which is discharged to voltage, and output is full
With voltage Vom.Then the process of (1) and (2) is repeated.Summarize: the output of operational amplifier N1B positive and negative saturation voltage ±
Vom jumps (oscillation), and the voltage of operational amplifier N1B in-phase end is jumped at ± Vom × R1/ (R1+R2), the electricity of ceramic condenser C1
Pressure is also that the voltage of operational amplifier N1B reverse side passes through resistance R3 repeated charge between ± Vom × R1/ (R1+R2).Many institutes
Known, RC charging/discharging voltage is triangular wave, i.e., the output signal of the voltage of ceramic condenser C1 i.e. circuit is triangular wave Vo1.
According to the formula of RC charge and discharge, ceramic condenser C1 can be obtained from-Vom × R1/ (R1+R2) and charge to Vom × R1/
(R1+R2) time, that is, triangular wave rise time be R3 × C1 × ln (1+2R1/R2), equally can be obtained ceramic condenser C1 from
The time i.e. fall time of triangular wave that Vom × R1/ (R1+R2) is discharged to-Vom × R1/ (R1+R2) is also R3 × C1 × ln (1
+ 2R1/R2), then, the frequency of triangular wave is 1/(2R3 × C1 × ln (1+2R1/R2)).This triangular wave frequency i.e. PWM
Frequency.The frequency of the PWM can change by adjusting resistance R3 or ceramic condenser C1, and triangle wave amplitude can be by adjusting resistance
R1 or resistance R2 changes.
In the present embodiment, the frequency f of triangular wave frequency i.e. PWM are as follows: 1/(2R3 × C1 × ln (1+2R1/R2)), if
When R3=20k, R2=13k, R1=15k, C1=1000P, frequency 20kHz.It is preferable that the usual frequency is located at 10kHz to 20kHz.Such as
The frequency need to be adjusted, pays the utmost attention to adjust the frequency by adjusting resistance R3, capacitor C1.
Triangle wave amplitude are as follows:-Vom × R1/ (R1+R2) to Vom × R1/ (R1+R2).Power Vcc is 12V, operation amplifier
Device selects TL072 class, and Vom is about 5V, then the amplitude of triangular wave is about that -2.7V arrives 2.7V.The amplitude can by adjusting resistance R1,
The value of R2 adjusts, and it is preferable which is located at ± Vcc/3 to ± vcc/2.
Temperature signal detection and amplifying circuit 3 include hygrosensor VTD, 1 sheet type multi-layer ceramic capacitance C2,7 thickness
Film resistance R4, R6, R7, R9, R10, R11 and R12,2 operational amplifiers N2A and N2B.Hygrosensor VTD is substantially one
The temperature voltage signal of semiconductor diode, detection output is exactly its forward voltage drop VT.First order operational amplifier N2A is complete
It is acquired at the constant biasing and VTD forward voltage drop of hygrosensor VTD, second level operational amplifier N2B realization degree detector VTD
The amplification of forward voltage drop VT.The anode of hygrosensor VTD connects the output in operational amplifier N2A, and cathode connects in operation amplifier
The reverse side of device N2A and one end of resistance R9, resistance R9 is another to terminate at virtual ground terminal Vcc/2.Capacitor C2 and hygrosensor
VTD is in parallel, and effect is filtering noise reduction.The output end of operational amplifier N2A meets virtual ground terminal Vcc/2 through resistance R4, R12, and
The in-phase end of operational amplifier N2B is connected to after resistance R4, R12 partial pressure.
Electric current of the electric current of hygrosensor VTD equal to resistance R9 subtracts operational amplifier plus the electric current of resistance R6 again
N2A reverse side electric current.The biased electrical that the in-phase end of operational amplifier N2A is provided by 2.5V reference voltage source and resistance R10, R11
Pressure is 2.5V × R10/(R10+R11)=1V, the voltage of operational amplifier N2A reverse side is also that the voltage of resistance R9 is also simultaneously
1V.The electric current of resistance R9 is 1V/R9=100uA, and the electric current very little of resistance R6 and operational amplifier N2A reverse side is less than 0.7uA
And variable quantity is smaller can ignore completely.That is the electric current of hygrosensor VTD is constant about 100uA.Operation amplifier
Voltage of the voltage equal to resistance R9 of device N2A output adds the forward voltage of hygrosensor VTD to be 1V+VT.Operational amplifier N2A
Output voltage through resistance R4 and R12 2/3rds divide send the second level operational amplifier N2B in-phase end.Resistance R6 connects
Between the reverse side of operational amplifier N2B and the negative terminal of hygrosensor VTD, feedback resistance R7 is connect in the defeated of operational amplifier N2B
Between outlet and reverse side.The output voltage Vo2 of operational amplifier N2B=(1+R7/R6) (1V+VT) R12/ (R4+R12) -1V ×
R7/R6=2VT。
Temperature signal detection and the main function of amplifying circuit 3 are temperature collection voltage signal and amplified temperature signal
Vo2 is sent to the inverting input terminal of the operational amplifier N2D of error amplification and comparison circuit 5, and usual amplification factor is 2 times, i.e. Vo2
=2VT。
Temperature setting circuit 4 includes 1 reference voltage source N3,2 resistance R13 and R14,1 potentiometer RW, 1 operation
Amplifier N2C.2.5V voltage-reference N3, the ground terminal GND of reference voltage source N3 is used to be connected to virtually in the present embodiment
Vcc/2 generates the 2.5V reference voltage relative to virtually Vcc/2, and reference voltage REF is through resistance R13, R14 and potentiometer RW
After partial pressure, adjustable voltage signal is exported, the temperature after the voltage follower amplification constituted via operational amplifier N2C as setting
Spend signal voltage Vo3.The function of temperature setting circuit 4 is to generate the reference voltage with certain adjustable extent, as setting
Temperature signal voltage Vo3 is sent to the non-inverting input terminal of the operational amplifier N2D of error amplification and comparison circuit 5.The voltage can
Tune range is Vo3=2.5V × R13/(R13+RW+R14)~2.5V × (R13+RW)/(R13+RW+R14).In the present embodiment,
The amplitude range of Vo3 should cover the amplitude of 2VT: the temperature of this example temperature control is about low temperature 75K, and VT is about 1.05V, 2VT 2.1V.
The range of this example Vo3 be 2.5V × (R13)/(R13+RW+R14)~2.5V × (R13+RW)/(R13+RW+R14)=2V~
2.2V。
Error amplification and comparison circuit 5 include 2 resistance R5 and R8,1 capacitor C3, comparator N1A, operational amplifier
N2D, 1 phase inverter D1.It is defeated through resistance R5 that temperature signal detection and amplifying circuit 3 acquire amplified temperature voltage signal Vo2
Enter to the inverting input terminal of operational amplifier N2D.The temperature signal voltage Vo3 for the setting that temperature setting circuit 4 generates is input to
The non-inverting input terminal of operational amplifier N2D.The output end of operational amplifier N2D is connected to the inverting input terminal of comparator N1A, and three
The triangular wave Vo1 that angle wave generation circuit 2 generates is input to the non-inverting input terminal of comparator N1A, and the output end of comparator N1A connects
It is connected to the input terminal of phase inverter D1, the output end of phase inverter D1 exports final pwm signal.The output end of operational amplifier N2D
Its inverting input terminal also is fed back to through resistance R8, the effect of the both ends shunt capacitance C3 of resistance R8, capacitor C3 are filtering noise reduction.
The multiple of error amplification is R8/R5.The function of the circuit is first that the temperature signal voltage Vo3 of setting and acquisition is amplified
The voltage difference of temperature voltage signal Vo2 amplifies, output voltage Vo4, then by voltage Vo4 compared with triangular wave Vo1 generation arteries and veins
Rush signal.Phase inverter D1 effect is will to export final pwm signal after signal inversion that operational amplifier N1A is exported.Output electricity
Press Vo4=(Vo3-2VT) R8/R5+Vo3.The pulse width of final PWM depends on the amplitude of output voltage Vo4, output voltage Vo4
Amplitude when changing to positive peak Vom × R1/ (R1+R2) from negative peak-Vom × R1/ (R1+R2) of triangular wave, the pulse of PWM
Width changes to 100% from 0.Actual meaning is that the pulse width of PWM when the temperature to be controlled is higher than set temperature will increase, instead
Then reduce.Lead to the pulse width variation of PWM by adjusting error amplification factor R8/R5, adjustable temperature difference Vo3-2VT
Sensitivity.
The pulse width of PWM depends on the amplitude of output voltage Vo4, output voltage Vo4=(Vo3-2VT) R8/R5 in this example
+ Vo3=317(Vo3-2VT)+Vo3, the amplitude of output voltage Vo4 changes to positive peak 2.7V from the negative peak -2.7V of triangular wave
When, the pulse width of PWM changes to 100% from 0, then the variation of VT offer 8.5mV of forward voltage drop, the pulse width of PWM is from 0
100% is changed to, forward voltage drop VT variation 1mV(is equivalent to and is approximately equivalent to temperature change 0.4K), pwm pulse change width about 12%,
This variable quantity is related to the sensitivity of temperature control.By adjusting error amplification factor R8/R5, adjustable accidentally temperature difference Vo3-
2VT leads to the sensitivity of the pulse width variation of PWM, the i.e. sensitivity of temperature control.When the temperature of control is equal to set temperature
Vo3=2VT, at this moment Vo4=Vo3, the pulse width of PWM keep a scheduled width, which is actually that refrigeration system is rigid
The good width that can maintain setting cryogenic temperature, the width is related to system, and different systems may need to adjust setting
Range, triangle wave amplitude of temperature signal voltage Vo3 etc., but this is not problem to be solved in the utility model.
The above is only the preferred embodiment of the utility model, it is noted that for the common skill of the art
For art personnel, without deviating from the technical principle of the utility model, several improvement and deformations can also be made, these change
It also should be regarded as the protection scope of the utility model into deformation.
Claims (7)
1. a kind of low temperature temperature control pwm circuit, characterized in that including virtually circuit, triangular wave generator circuit, temperature signal inspection
Survey and amplifying circuit, temperature setting circuit, error amplification and comparison circuit；
Virtually circuit provides for above-mentioned other circuits with reference to no-voltage；
Triangular wave generator circuit generates triangular wave Vo1 by self-oscillation, exports the ratio into error amplification and comparison circuit 5
Compared with one of input terminal of device；
The operation being sent in error amplification and comparison circuit after temperature signal detection and the amplification of amplifying circuit temperature collection signal is put
One of input terminal of big device；
Temperature setting circuit generates, and there is the reference voltage of certain adjustable extent to be sent to as the temperature signal voltage Vo3 of setting
Another input terminal of error amplification and the operational amplifier in comparison circuit；
Operational amplifier in error amplification and comparison circuit is by the temperature signal voltage Vo3 of setting and acquires and the temperature amplified
The voltage difference of voltage signal Vo2 amplifies, and output voltage Vo4 is sent into another input terminal of comparator；Electricity will be exported by comparator
Vo4 generation pulse signal compared with triangular wave Vo1 is pressed, exports final pwm signal after the inverted device reverse phase of pulse signal.
2. a kind of low temperature temperature control pwm circuit according to claim 1, characterized in that virtually circuit is using accurate virtual
The power Vcc of input is converted to half power Vcc/2 and is exported by ground chip by accurate virtually chip.
3. a kind of low temperature temperature control pwm circuit according to claim 1, characterized in that the virtually output voltage warp of circuit
First resistor is input to the non-inverting input terminal of second operational amplifier, and virtually the output voltage of circuit connects through first capacitor simultaneously
It is connected to second operational amplifier inverting input terminal；The output end of second operational amplifier is fed to the second operation through second resistance is positive and negative
The output end of the non-inverting input terminal of amplifier, second operational amplifier is defeated through the reverse phase of 3rd resistor negative-feedback to operational amplifier
Enter end.
4. a kind of low temperature temperature control pwm circuit according to claim 1, characterized in that temperature signal detection and amplifying circuit
In include hygrosensor and third operational amplifier；The temperature voltage signal of detection output is input to third by hygrosensor
Operational amplifier amplifies, and obtains temperature voltage signal Vo2.
5. a kind of low temperature temperature control pwm circuit according to claim 4, characterized in that hygrosensor is diode.
6. a kind of low temperature temperature control pwm circuit according to claim 1, characterized in that include benchmark in temperature setting circuit
Voltage source, the adjustable potentiometer of at least one resistance value or resistor and four-operational amplifier；The reference that reference voltage source generates
Voltage adjusts through potentiometer or resistor and exports adjustable voltage signal, the temperature after four-operational amplifier amplification as setting
Spend signal voltage Vo3.
7. a kind of low temperature temperature control pwm circuit according to claim 1, characterized in that in error amplification and comparison circuit also
Including the 5th resistance and the 8th resistance；Temperature voltage signal Vo2 is input to the inverting input terminal of operational amplifier through the 5th resistance；
Inverting input terminal of the output end of operational amplifier through the 8th resistance feedback to operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821381622.3U CN208849740U (en) | 2018-08-24 | 2018-08-24 | A kind of low temperature temperature control pwm circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821381622.3U CN208849740U (en) | 2018-08-24 | 2018-08-24 | A kind of low temperature temperature control pwm circuit |
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| Publication Number | Publication Date |
|---|---|
| CN208849740U true CN208849740U (en) | 2019-05-10 |
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ID=66356429
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CN201821381622.3U Active CN208849740U (en) | 2018-08-24 | 2018-08-24 | A kind of low temperature temperature control pwm circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109004917A (en) * | 2018-08-24 | 2018-12-14 | 北方电子研究院安徽有限公司 | A kind of low temperature temperature control pwm circuit |
-
2018
- 2018-08-24 CN CN201821381622.3U patent/CN208849740U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109004917A (en) * | 2018-08-24 | 2018-12-14 | 北方电子研究院安徽有限公司 | A kind of low temperature temperature control pwm circuit |
| CN109004917B (en) * | 2018-08-24 | 2024-01-30 | 北方电子研究院安徽有限公司 | Low-temperature control PWM circuit |
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Address after: 233040 No.10 Caiyuan Road, Bengbu City, Anhui Province Patentee after: Anhui North Microelectronics Research Institute Group Co.,Ltd. Address before: 233040 No.10 Caiyuan Road, Bengbu City, Anhui Province Patentee before: NORTH ELECTRON RESEARCH INSTITUTE ANHUI Co.,Ltd. |
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