CN217539080U

CN217539080U - Fan speed regulation circuit based on real-time temperature monitoring

Info

Publication number: CN217539080U
Application number: CN202122469336.0U
Authority: CN
Inventors: 蒋山; 刘鑫; 路燈杰; 陈静; 张家玉; 程昭竣; 陈茂才; 李姗; 闫晓雷; 张超; 黄超; 曹阳
Original assignee: 704th Research Institute of CSIC
Current assignee: 704th Research Institute of CSIC
Priority date: 2021-10-13
Filing date: 2021-10-13
Publication date: 2022-10-04
Anticipated expiration: 2031-10-13

Abstract

The utility model relates to a fan speed regulating circuit based on real-time temperature monitoring, which comprises a power circuit, a temperature sensor, a temperature conditioning circuit, a triangular wave generating circuit, a polarity selecting circuit, a comparison circuit and a signal isolation output circuit; the temperature sensor is attached to a part needing heat dissipation, the temperature sensor outputs a real-time temperature signal to the temperature conditioning circuit, the temperature signal acquired by the sensor is converted into a level signal through the temperature conditioning circuit, the level signal is compared with a triangular wave generated by the triangular wave generating circuit after passing through the polarity selection circuit, a PWM control signal is obtained, and the fan is controlled to operate through the signal isolation output circuit. The fan control system has the advantages that the pure hardware design is adopted, the cost is low, the size is small, the control is accurate, the response speed is high, the rotating speed of the fan can be automatically adjusted according to the loss condition of equipment, the energy is saved, the emission is reduced, and the purposes of vibration reduction and noise reduction can be achieved.

Description

Fan speed regulation circuit based on temperature real-time monitoring

Technical Field

The utility model relates to an electronic circuit technique, in particular to fan speed governing circuit based on temperature real-time supervision.

Background

For power electronic equipment, a common heat dissipation mode is to perform forced air cooling by installing a heat dissipation fan on a heat sink, and for equipment with large loss, a large fan needs to be applied to achieve a heat dissipation effect, but when the equipment runs at low power, the loss is small, the fan with large rotating speed not only causes energy waste, but also reduces the vibration noise level of the equipment, so that the speed regulation control of the fan according to the loss is very important.

The existing fan speed regulation method has poor regulation real-time performance and large system volume, and affects the high integration degree of the whole system.

Disclosure of Invention

Aiming at the problem of fan heat dissipation speed regulation balance, the fan speed regulation circuit for monitoring the temperature in real time is provided, and the problem of high-efficiency heat dissipation of the fan is solved.

The technical scheme of the utility model is that: a fan speed regulation circuit based on real-time temperature monitoring comprises a power supply circuit, a temperature sensor, a temperature conditioning circuit, a triangular wave generating circuit, a polarity selection circuit, a comparison circuit and a signal isolation output circuit; the temperature sensor is attached to a part needing heat dissipation, the temperature sensor outputs a real-time temperature signal to be sent to the temperature conditioning circuit, the temperature signal collected by the temperature conditioning circuit is converted into a level signal, the level signal is compared with a triangular wave generated by the triangular wave generating circuit through the polarity selecting circuit and then sent to the comparing circuit, a PWM control signal is obtained, and the fan is controlled to operate through the signal isolation output circuit.

Preferably, the triangular wave generating circuit comprises a time base chip, wherein a trigger input pin of the time base chip is connected to a threshold input pin, so that the timer is triggered automatically and operates as a multivibrator, the trigger input pin and the threshold input pin are connected to GND (ground) through a charging and discharging capacitor, a triangular wave signal is generated through charging and discharging of the charging and discharging capacitor, the charging and discharging capacitor is connected with VCC through two charging and discharging resistors connected in series, and the charging and discharging capacitor is charged and discharged between a threshold level and a trigger level.

Preferably, the temperature conditioning circuit comprises a two-stage series operational amplifier circuit, the full-speed rotation and the lowest rotation of the fan correspond to set temperatures, and the set temperatures are converted into threshold levels and trigger levels in the corresponding triangular wave signal circuit through the two-stage operational amplifier circuit.

Preferably, the polarity selection circuit is composed of 4 polarity resistors, two inputs are respectively connected with the 1 polarity resistor and one output of the two outputs, and the matching of the resistors changes the level signal waveforms of the homodromous and reverse input ends of the comparator of the input comparison circuit.

Preferably, the comparison circuit comprises a comparator, and the signal waveforms output by the triangular wave generation circuit and the temperature conditioning circuit are respectively input to the comparator after passing through the polarity selection circuit, and output control signals after level comparison.

Preferably, the signal isolation output circuit selects a high-speed optical coupler integrating a high-gain high-speed optical detector and a high-output GaACAs light-emitting diode.

The beneficial effects of the utility model reside in that: the utility model discloses temperature real-time supervision's fan speed governing circuit adopts pure hardware design, and is with low costs, small, and control is accurate and response speed is fast, can both can energy saving and emission reduction according to the loss condition automatically regulated fan rotational speed of equipment, can reach the purpose that the damping was fallen and is made an uproar again.

Drawings

FIG. 1 is a block diagram of the fan speed-adjusting circuit for real-time temperature monitoring of the present invention;

FIG. 2 is a circuit diagram of a power supply of the present invention;

FIG. 3 is a circuit diagram of the middle triangular wave generator of the present invention;

FIG. 4 is a circuit diagram of the medium temperature conditioning circuit of the present invention;

fig. 5 is a circuit diagram of the polarity selection circuit of the present invention;

FIG. 6 is a comparison circuit diagram of the present invention;

fig. 7 is a circuit diagram of the middle signal isolation output circuit of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiment of the present invention is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1, the circuit includes a power circuit, a temperature sensor, a temperature conditioning circuit, a triangle wave generating circuit, a polarity selecting circuit, a comparing circuit, a signal isolating output circuit and a fan. The utility model discloses select the fan and be 4 line system speed governing fans, the red black line is positive negative pole direct current input respectively, and rated operating voltage is the VCC, and the third line is the fan control signal line, for the PWM form, accessible duty cycle regulation fan speed, and the fourth line can not use. The temperature sensor is used for detecting the temperature of a part needing heat dissipation, the temperature signal acquired by the sensor is converted into a level form through the temperature conditioning circuit, the level form is compared with a triangular wave generated by the triangular wave generating circuit through the comparison circuit, a PWM control signal is further obtained, the fan is controlled to operate through the isolation output circuit, the polarity selection circuit can change signals of the homodromous and reverse input ends of the comparator according to the actual application condition, and then the positive and negative proportional relation between the PWM duty ratio and the temperature signal is further achieved.

Fig. 2 shows a power conversion circuit, a fan speed regulation circuit external power supply VCC, which is converted to VDD through a level conversion chip 1, wherein VCC and VDD are grounded in common, and GND. The VCC value is fan rated voltage, and the VDD value is fan control signal high level voltage. The level conversion chip 1 needs to be a non-isolated conversion chip.

Fig. 3 shows a triangular wave generating circuit, which uses the time-base chip 2 as a core and cooperates with the peripheral resistors and capacitors to generate triangular wave signals. The 8 pins and the 1 pin of the time base chip 2 are power input ends and are respectively connected with VCC and GND, a filter capacitor 3 is connected between the two pins in parallel, the specific capacitance value can be selected according to the recommended model selection of a chip use manual, and the design capacitance value C1=0.1 muF; the pin 3 is connected to VCC through a load resistor 4, the resistance value of the load resistor 4 is RL, the specific resistance value can be recommended to select according to a chip instruction manual, and RL =1k Ω; pin 4 is directly connected to VCC; one path of the 7 pins is connected to VCC through the charge and discharge resistor 5, the resistance value of the charge and discharge resistor 5 is RA, the other path of the 7 pins is connected to the 2 pins through the charge and discharge resistor 6, and the resistance value of the charge and discharge resistor 6 is RB; connecting a pin 2 (input end) of the trigger to a pin 6 (threshold input), so that the timer is self-triggered and operates as a multivibrator, connecting the pin 2 and the pin 6 to GND through a capacitor 7, generating a triangular wave signal through charging and discharging the capacitor 7, wherein the capacitance value of the capacitor 7 is C2; pin 5 is connected to GND through capacitor 8. The capacitor 7 is charged through the charge and discharge resistor A5, the charge and discharge resistor B6, and then discharged only through the charge and discharge resistor B6, so that the triangular waveform is controlled by the values RA, RB. In this mode of operation, the capacitor 7 is charged and discharged between a threshold level (2/3 VCC) and a trigger level (1/3 VCC). In a monostable circuit, the number of charges and discharges, i.e. the frequency and duty cycle, is independent of the supply voltage. The triangular wave voltage rise process duration is tH, and the fall process duration is tL, where tH =0.693 (RA + RB) C2, tL =0.693 (RB) C2, the single wave period P = tH + tL, the frequency f = 1.44/(RA +2 RB)/C2, and the duty ratio D = tH/P = 1-RB/(RA +2 RB). The output end A is output to the polarity selection circuit A'.

Fig. 4 is a temperature sensor and temperature conditioning circuit. The temperature sensor 9 is selected from an NTC negative temperature coefficient thermistor type, the resistance end is attached to the surface of a component needing temperature detection, the lead wire end is connected to a temperature conditioning circuit wiring terminal 10, and the temperature sensor 9 has a variable resistance RT. The wiring terminal 10 is in a 2pin form, a pin 1 is connected with a power supply VDD, a pin 2 is divided into two paths, one path is connected to GND through a divider resistor 11, two ends of the divider resistor 11 are connected in parallel to a filter capacitor 12, the capacitance value of the filter capacitor 12 is C41, and the value of the divider resistor 11 is R41; the other path is connected to the equidirectional input end 5 of the operational amplifier 14 through a current-limiting resistor 13, and the resistance value of the current-limiting resistor is R42. The voltage dividing resistor 11 interacts with the temperature sensor 9 to divide the VDD voltage, so that the temperature level signal UT input to the operational amplifier changes with the temperature change, where UT = VDD × R41/(R41 + RT), that is, the change in UT value can be used to represent the collected temperature. R42 is related to the operating current I1 and the level UT of the operational amplifier chip 14, where R42< UT/I1, and R42=0.5UT/I1 may be selected. C41 empirically selects a 1 μ F patch capacitance.

Pins

8 and 4 of the operational amplifier 14 are power input pins, which are respectively connected to VCC and GND, the input pins are 5 and 6, and the output pin is 7. The inverting input terminal 6 is connected with the output terminal 7 through the amplifying resistor 15, the inverting input terminal 6 is connected with GND through the amplifying resistor 16, the resistance value of the amplifying resistor 15 is R43, and the resistance value of the amplifying resistor 16 is R44. The output level of the operational amplifier 147 pin is U41.

According to the design, the temperature of the fan required to rotate at full speed is T1, the corresponding RT resistance value is RT1, the maximum temperature corresponding to the lowest-speed operation of the fan of the temperature level signal UT1 is T0, the corresponding RT resistance value is RT0, and the temperature level signal UT0 is calculated, UT1= VDD × R41/(R41 + RT 1), UT0= VDD × R41/(R41 + RT 0), and assuming that the amplification factor of the amplification circuit composed of the operational amplifier 14 and the peripheral circuit is a, since the peak level of the triangular wave signal is 2VCC/3 and the valley level is VCC/3, the corresponding level value U41 of the amplified TIT0 temperature level signal is 2VCC/3 and VCC/3, there are: a, UT1=2VCC/3, a, ut0= VCC/3, then: r41= RT0-2RT1, and amplification factor a = (2 VCC/3 VDD) (RT 0-RT 1)/(RT 0-2RT 1), i.e., R43+ R44/R44= (2 VCC/3 VDD) (RT 0-RT 1)/(RT 0-2RT 1), and R43 and R44 can be taken from a proportional relationship.

The output end 7 is connected with the same-direction input end, namely a pin 3, of the operational amplifier 18 through a current limiting resistor 17, the resistance value of the current limiting resistor 17 is R45, the resistance value is related to the working current I2 of the operational amplifier chip 18 and the output level U41 of the operational amplifier 14, R45 is less than U41/I2, and R45=0.5U41/I2 can be selected. The operational amplifier 18 and the operational amplifier 14 can select two operational amplifier modules integrated in the same chip, so that the size is saved. The inverting input end 2 is connected with the output end 1 through the amplifying resistor 19, the inverting input end 2 is connected with GND through the amplifying resistor 20, the resistance value of the amplifying resistor 19 is R46, and the resistance value of the amplifying resistor 20 is R47. The operational amplifier and the peripheral circuit thereof play the role of a voltage follower, wherein the value of R46 is 0 omega, and the value of R47 is infinity. The output end B is output to the polarity selection circuit B'.

Fig. 5 shows a polarity selection circuit, which is implemented by four

polarity selection resistors

21, 22, 23, 24. When the device is used, a user can carry out resistance value matching according to actual conditions. When the

resistors

21 and 23 are 0 Ω and the

resistors

22 and 24 are infinity, the signal a 'is transmitted to the next stage circuit through the output terminal C, and the signal B' is transmitted to the next stage circuit through the output terminal D; when the

resistors

21 and 23 are infinite and the

resistors

22 and 24 are 0 Ω, the signal a 'is transmitted to the next stage circuit through the output terminal D, and the signal B' is transmitted to the next stage circuit through the output terminal C. Through the matching of the resistors, the level signal waveforms of the homodromous input end and the reverse input end of the input comparator are changed, and the purpose of outputting PWM level polarity is changed, so that the condition that the detection temperature and the PWM duty ratio are in direct proportion or inverse proportion is controlled. The output ends C and D are output to the comparison circuits C 'and D'.

FIG. 6 shows waveforms of signals outputted from the comparison circuit, the triangular wave generation circuit and the temperature adjustment circuit, which are inputted to the comparison circuit from C 'and D' respectively after passing through the polarity selection circuit. C 'is input to the comparator 27 through the current limiting resistor 25 and the inverting input terminal 3, d' is input to the inverting input terminal 2 of the comparator 27 through the current limiting resistor 26, the resistance of the current limiting resistor 25 is R61, the resistance of the current limiting resistor 26 is R62, the resistance is related to the input current I2 of the comparator, and R61= R62>2/3VCC/I2. The power supply voltage of the comparator 27 includes VCC, and is supplied by VCC, and

pins

8 and 4 are connected to VCC and GND, respectively. The comparator 27 input-output voltage capability is greater than VCC. The output end 1 is output to the next stage circuit, meanwhile, the output end 1 is connected with VCC through a pull-up resistor 28, and the resistance R63 of the pull-up resistor 28 is selected to be 10k omega according to empirical values. The output end E outputs to the isolation signal output circuit E'.

Fig. 7 is an isolated signal output circuit. An input signal E' is input into a pin 2 at the input end of the high-speed optocoupler 29, a pin 1 at the input end of the high-speed optocoupler 29 is connected with VCC through a current limiting resistor 30, the high-speed optocoupler 29 recommends selecting products integrating a high-gain high-speed photodetector and a high-output GaACAs light emitting diode, and the maximum transmission rate is not less than the frequency of PWM controlled by a fan. The resistance value of the current limiting resistor 30 is R71, and the value of the current limiting resistor is related to the maximum working current I3 and the threshold input current I4 of the input pin of the high-speed optocoupler 29, wherein VCC/I4 is less than R71 and less than VCC/I3. A pin 6 of the high-speed optical coupler 29 is connected with VDD, a pin 4 of the high-speed optical coupler is connected with GND, a pin 5 of the high-speed optical coupler is used as a signal output end, a fan control signal is output to the fan, meanwhile, the signal output end 5 is connected with VDD through a pull-up resistor R31, and the resistance value R72 of the pull-up resistor 31 is selected to be 10k omega according to empirical values.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A fan speed regulation circuit based on real-time temperature monitoring is characterized by comprising a power supply circuit, a temperature sensor, a temperature conditioning circuit, a triangular wave generating circuit, a polarity selection circuit, a comparison circuit and a signal isolation output circuit; the temperature sensor is attached to a part needing heat dissipation, the temperature sensor outputs a real-time temperature signal to be sent to the temperature conditioning circuit, the temperature signal collected by the sensor is converted into a level signal through the temperature conditioning circuit, the level signal is compared with a triangular wave generated by the triangular wave generating circuit through the polarity selecting circuit and then sent to the comparing circuit, a PWM control signal is obtained, and the fan is controlled to operate through the signal isolation output circuit.

2. The real-time temperature monitoring based fan speed regulation circuit of claim 1, wherein the triangular wave generation circuit comprises a time base chip, a trigger input pin of the time base chip is connected to the threshold input pin, the timer is enabled to self-trigger and operate as a multivibrator, the trigger input pin and the threshold input pin are connected to GND through a charge-discharge capacitor, a triangular wave signal is generated through charge and discharge of the charge-discharge capacitor, the charge-discharge capacitor is connected with VCC through two charge-discharge resistors connected in series, and the charge-discharge capacitor is charged and discharged between a threshold level and a trigger level.

3. The real-time temperature monitoring-based fan speed regulation circuit of claim 2, wherein the temperature conditioning circuit comprises a two-stage series operational amplifier circuit, the full-speed rotation and the lowest rotation of the fan correspond to set temperatures, and the set temperatures are converted into threshold levels and trigger levels in the corresponding triangular wave signal circuit through the two-stage operational amplifier circuit.

4. The fan speed regulating circuit based on real-time temperature monitoring of claim 3, wherein the polarity selection circuit is composed of 4 polarity resistors, two inputs of the polarity selection circuit are respectively connected with the 1 polarity resistor and one output of the two outputs, and the matching of the resistors changes the level signal waveforms of the same-direction and reverse-direction input ends of the comparator of the input comparison circuit.

5. The fan speed regulation circuit based on real-time temperature monitoring according to any one of claims 1 to 4, wherein the comparison circuit comprises a comparator, and the signal waveforms output by the triangular wave generation circuit and the temperature conditioning circuit are respectively input to the comparator after passing through the polarity selection circuit, and are subjected to level comparison, and then control signals are output.

6. The fan speed regulation circuit based on real-time temperature monitoring of claim 5, wherein the signal isolation output circuit selects a high-speed optical coupler integrating a high-gain high-speed optical detector and a high-output GaACAs light emitting diode.