Intelligent fan rotating speed adjusting circuit

Abstract

The utility model relates to the technical field of fan rotating speed regulation and control, in particular to an intelligent fan rotating speed regulating circuit. The circuit comprises a thermistor, an operational amplifier integrated circuit, a pulse width modulation integrated circuit and a fan driving circuit. Temperature is collected through a thermal inductance resistor and converted into a voltage signal, and then the voltage signal is input into the operational amplifier integrated circuit to be amplified. The operational amplifier integrated circuit comprises four operational amplifiers; the amplified voltage signal passes through a pulse width modulation integrated circuit to output a PWM (Pulse Width Modulation) signal; and the fan driving circuit controls the rotating speed of the fan according to the PWM signal. The temperature of a hot spot area is monitored in real time through the circuit, the rotating speed of the fan is automatically adjusted according to dynamic changes of the temperature, and the temperature in the cold pool is kept uniform and stable.

Description

Technical Field

[0001] This utility model relates to the field of fan speed control technology, specifically to an intelligent fan speed adjustment circuit. Background Technology

[0002] Currently, data centers generally adopt an airflow organization method of underfloor air supply and ceiling return. Server racks are arranged in rows "back-to-back, face-to-face". Ventilation floor is installed between the front of the two rows of server racks facing the aisle to arrange cold air outlets, forming a cold air zone called a "cold aisle". To save energy and reduce consumption and improve the efficiency of cooling, the cold aisle is usually closed to form a cold pool. The cold air in the cold pool only flows through the IT equipment, and the resulting hot air is discharged into the "hot aisle" at the back of the two rows of server racks. The hot air returns to the air conditioning system through the hot aisle and the ceiling. In this way, the cold and hot air are completely isolated, preventing short circuits and repeated cooling, so that the airflow in the entire data center is smooth, improving the utilization rate and cooling efficiency of the data center's precision air conditioning, and achieving energy-saving effects.

[0003] However, some cold storage areas are far from air conditioning units, have poor airflow under the floor, low air volume, and many internal devices with high power consumption. These conditions cause temperature differences between the upper and lower parts of the cabinets inside the cold storage area, creating localized hot spots that affect the normal operation of IT equipment in that area. Therefore, a device circuit is needed to achieve automatic airflow cooling and regulate the temperature inside the cold storage area through intelligent control. Utility Model Content

[0004] To address the problems existing in the prior art, this utility model provides an intelligent fan speed regulation circuit. The circuit includes a thermistor, an operational amplifier integrated circuit, a pulse width modulation integrated circuit, and a fan drive circuit. The thermistor collects temperature data, converts it into a voltage signal, and then inputs it to the operational amplifier integrated circuit for amplification. The operational amplifier integrated circuit includes four operational amplifiers. The amplified voltage signal is then output as a PWM (Pulse Width Modulation) signal by the PWM integrated circuit. The fan drive circuit controls the fan speed according to the PWM signal. This application uses this circuit to monitor the temperature of hot spots in real time and automatically adjust the fan speed according to dynamic temperature changes, maintaining a uniform and stable temperature within the cold pool.

[0005] The present invention adopts the following technical solution: an intelligent fan speed regulation circuit, comprising: a thermistor, an operational amplifier integrated circuit, a pulse width modulation integrated circuit, and a fan drive circuit;

[0006] The thermistor collects the temperature and converts it into a voltage signal, which is then amplified by the operational amplifier integrated circuit. The operational amplifier integrated circuit includes four operational amplifiers. The amplified voltage signal is then output as a PWM (Pulse Width Modulation) signal by the pulse width modulation integrated circuit. The fan drive circuit controls the fan speed according to the PWM signal.

[0007] Furthermore, the operational amplifier integrated circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and a fourth operational amplifier; the first operational amplifier and the third operational amplifier form a differential amplifier circuit; the first operational amplifier and the fourth operational amplifier respectively form a non-inverting proportional operational amplifier circuit.

[0008] Furthermore, the pulse width modulation integrated circuit uses the KA7500B control chip.

[0009] Furthermore, the fan drive circuit includes: a push-pull circuit composed of transistors Q1 and Q2, a Schottky diode D, resistors R11 and R12, and a field-effect transistor Q3. The drain of the field-effect transistor Q3 is connected to the DC fan, the source is grounded, and the gate is connected to the PWM pulse width modulation signal output by the push-pull circuit.

[0010] Furthermore, the fan speed adjustment circuit also includes a potentiometer VR for adjusting the reference voltage of the operational amplifier integrated circuit.

[0011] The beneficial effects of this utility model are: This utility model can monitor the temperature of hot spots in real time and automatically adjust the fan speed according to the dynamic changes in temperature. The higher the temperature, the faster the fan speed, thereby realizing intelligent adjustment of the cold air supply volume of the cold pool and maintaining a uniform and stable temperature in the cold pool. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of an intelligent fan speed regulation circuit according to an embodiment of the present invention. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] This application first installs a DC fan at the bottom of the ventilated floor in the hot spot area of ​​the cold pool, and installs an NTC thermistor as a temperature sensor in the hot spot area to be detected. Specifically, in the circuit of this application, the thermistor used for temperature detection is a 10K negative temperature coefficient (NTC) temperature probe commonly used in air conditioners. This probe is installed in the hot spot area to be detected in the cold pool. The operational amplifier integrated circuit is composed of an LM324 quad operational amplifier integrated circuit, and the pulse width modulation integrated circuit is composed of a KA7500B pulse width modulation integrated circuit (PWM). By acquiring, amplifying, and comparing the temperature data through the operational amplifier, the pulse width modulation (PWM) output signal is controlled to adjust the fan speed. The temperature control range set in this application is 22℃~27℃, and the higher the temperature, the faster the fan speed.

[0016] A schematic diagram of an intelligent fan speed regulation circuit according to an embodiment of this utility model is shown below. Figure 1 As shown, it includes: a thermistor, an operational amplifier integrated circuit, a pulse width modulation integrated circuit, and a fan drive circuit, wherein:

[0017] Thermistor RT collects temperature and converts it into a voltage signal. The voltage signal is input to the positive input terminal of the second operational amplifier A2 in the operational amplifier integrated circuit through resistor R5. Resistor R4 is connected to the negative input terminal of the second operational amplifier, and the other end of resistor R4 is grounded. After amplifying the voltage signal, the second operational amplifier A2 outputs a voltage signal. The signal is then input to the positive input terminal of the third operational amplifier A3 via resistor R8. A resistor is also connected between the negative input terminal and the output terminal of the second operational amplifier A2. .

[0018] according to Figure 1 The circuit principle in the diagram can be used to obtain:

[0019] =

[0020] in, This refers to the thermistor value;

[0021] When the temperature is 22℃ =11.5kΩ, =0.98(V);

[0022] When the temperature is 27℃ =9.1kΩ, =0.81(V);

[0023] The temperature sensor detects the pressure difference Δ when the temperature is between 22°C and 27°C. =0.17(V).

[0024] Based on the virtual short and virtual open of the operational amplifier:

[0025] = (1+ )

[0026] According to parameters in this application embodiment =68kΩ and =15kΩ, therefore: =5.53 ;

[0027] At 22℃, =0.98(V), then =5.42 (V);

[0028] At 27℃, =0.81(V), then =4.48 (V);

[0029] The pressure difference detected by the temperature sensing probe at 22℃ to 27℃, magnified 5.53 times: .

[0030] Operational amplifiers A1 and A3 form a differential amplifier circuit. The negative input of operational amplifier A1 is connected to resistor R1, with the other end of R1 grounded. The positive input uses a 5V voltage source, which outputs a reference voltage source Vi1 via potentiometer VR. One end of Vi1 is connected to the positive input of operational amplifier A1 via resistor R2, and the other end is grounded via resistor R3. The output of operational amplifier A1 outputs a voltage signal. The resistor R7 is connected to the negative input terminal of the third operational amplifier A3. A resistor Rf1 is also connected between the negative input terminal and the output terminal of the first operational amplifier A1.

[0031] In this embodiment, potentiometer VR is used to fine-tune the reference voltage of the operational amplifier, which can change... and The voltage value is adjusted via the duty cycle of the output through pin 4 of the KA7500B to control the fan speed.

[0032] The negative input terminal of the third operational amplifier A3 receives the voltage signal from the first operational amplifier A1. The positive input terminal receives the voltage signal from the second operational amplifier A2. The output terminal outputs a differentially amplified voltage signal. The resistor R9 serves as the input voltage source for the positive input terminal of the fourth operational amplifier A4. Furthermore, there is a resistor Rf3 directly between the negative input and output terminals of the third operational amplifier A3.

[0033] In this embodiment, the first operational amplifier A1 and the third operational amplifier A3 form a differential amplifier circuit, based on virtual short and virtual open:

[0034] = +(1+ )

[0035] =(1+ )

[0036] =- (1+ ) +(1+ ) =- ( + )+(1+ )

[0037] Pick , = ,but:

[0038] =(1+ ) ( - )

[0039] Substitute parameters =100kΩ =15kΩ:

[0040] =7.67 ( - )

[0041] As the reference voltage for comparison and amplification in the control circuit, it is supplied by a 5V power supply. and Voltage value is obtained by voltage division:

[0042] =

[0043] Based on the circuit parameters, it can be calculated that... The voltage adjustment range is 4.4V to 5V.

[0044] When adjusting the voltage of potentiometer VR hour, The voltage range can be obtained as follows:

[0045] .

[0046] Theoretically, when the temperature changes between 22℃ and 27℃, The voltage should vary between 0V and 7.2V. Since the operational amplifier operates in single-supply mode, there is a transistor saturation voltage drop at the output, preventing an actual output of 0V. To match the voltage adjustment range of 0.12V to 2.4V at pin 4 of the KA7500B's PWM duty cycle adjustment terminal, in this embodiment, resistors R9 and R10 are used to... By performing voltage division, the input voltage of A4 is obtained. : = .

[0047] The positive input terminal of the fourth operational amplifier A4 receives the input voltage source Vi4, and the negative input terminal is connected to pin 4 of the KA7500B control chip in the pulse width modulation integrated circuit. After amplifying the voltage source, the fourth operational amplifier A4 outputs a voltage signal to the pulse width modulation integrated circuit. It is connected to pin 4 of the KA7500B control chip; a resistor Rf4 is connected between the negative input and output of the fourth operational amplifier A4.

[0048] In this embodiment, the non-inverting input terminal of op-amp A4 The voltage input range becomes 0.12V to 2.4V. Since the non-inverting operational amplifier circuit, composed of the fourth operational amplifier, uses a voltage follower circuit structure, the output... It is also 0.12V to 2.4V.

[0049] The pulse width modulation integrated circuit uses the KA7500B control chip. Pins 1 and 2 of the control chip are connected to pin 7, pin 3 is grounded, pin 4 receives the voltage signal output from the operational amplifier integrated circuit, pin 5 is connected to the oscillation capacitor Ct, pin 6 is connected to the oscillation resistor Rt, pins 8 and 11 are connected, and pins 9 and 10 are connected to form a parallel output that is connected to the fan drive circuit. Pin 12 is connected to a 12V voltage source, one end of pin 13 is connected to pins 15 and 16, and the other end is grounded, and pin 14 is connected to a 5V reference voltage source.

[0050] The circuit in this application uses the KA7500B integrated circuit as a pulse width modulation (PWM) generation and output chip. The KA7500B is mainly used in switching power supply control circuits and can generate PWM signals. When the output control pin 13 is set to low level, the two outputs of the KA7500B chip are synchronized and can be connected in parallel (pins 8 and 11 connected, pins 9 and 10 connected) to drive the single-ended circuit at the back end. By adjusting the voltage input at pin 4, the duty cycle of the PWM outputs at pins 9 and 10 can be changed. The adjustment range of pin 4 is 0.12V to 2.4V, and the maximum duty cycle can reach 96%. The oscillation frequency of the KA7500B is determined by the charging and discharging time Rt and Ct, and the calculation formula is as follows:

[0051] Oscillation frequency f=

[0052] in, The oscillation resistance (unit: ohms) is the resistance of the oscillation. The oscillating capacitance (unit: farad) is used in the embodiments of this application. Figure 1 middle, =3kΩ =0.022μF, the pulse oscillation frequency of the circuit in this application is f=16.7 (kHz).

[0053] The fan drive circuit consists of a push-pull circuit composed of transistors Q1 and Q2, a Schottky diode D, resistors R11 and R12, and a field-effect transistor Q3. The bases of transistors Q1 and Q2 are connected to the output of the pulse width modulation integrated circuit to receive the modulated PWM signal. The drain of the field-effect transistor Q3 is connected to the DC fan, the source is grounded, and the gate is connected to the pulse width modulation signal output by the push-pull circuit. The circuit dynamically adjusts the conduction and cutoff of the field-effect transistor according to the signal changes to control the fan speed.

[0054] In another embodiment of this application, the circuit operates on a 12V power supply, thus enabling it to drive a 12V DC fan. If a 24V power supply is used, a 12V voltage regulator module (such as a 7812) can be added when using a 24V DC fan. Figure 1 As shown by the dashed line.

[0055] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A smart fan speed regulation circuit, characterized in that, include: Thermistors, operational amplifier integrated circuits, pulse width modulation integrated circuits, and fan drive circuits; The thermistor collects the temperature and converts it into a voltage signal, which is then amplified by the operational amplifier integrated circuit. The operational amplifier integrated circuit includes four operational amplifiers. The amplified voltage signal is then output as a PWM (Pulse Width Modulation) signal by the pulse width modulation integrated circuit. The fan drive circuit controls the fan speed according to the PWM signal.

2. The intelligent fan speed regulation circuit according to claim 1, characterized in that: The operational amplifier integrated circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, and a fourth operational amplifier; the first operational amplifier and the third operational amplifier form a differential amplifier circuit; the first operational amplifier and the fourth operational amplifier respectively form a non-inverting proportional operational amplifier circuit.

3. The intelligent fan speed regulation circuit according to claim 1, characterized in that: The pulse width modulation integrated circuit uses the KA7500B control chip.

4. The intelligent fan speed regulation circuit according to claim 1, characterized in that: The fan drive circuit includes: a push-pull circuit composed of transistors Q1 and Q2, a Schottky diode D, resistors R11 and R12, and a field-effect transistor Q3. The drain of the field-effect transistor Q3 is connected to the DC fan, the source is grounded, and the gate is connected to the PWM pulse width modulation signal output by the push-pull circuit.

5. The intelligent fan speed regulation circuit according to claim 1, characterized in that: The fan speed adjustment circuit also includes a potentiometer VR, used to adjust the reference voltage of the operational amplifier integrated circuit.

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