A fan control circuit

Abstract

The utility model discloses a fan control circuit, including: a main control unit; a current limiting switch circuit, whose power input end is connected to a power supply, and whose current threshold setting end is grounded through a configured resistor; a power supply switch circuit, whose switch path at one end is connected to the power output end of the current limiting switch circuit, whose switch path at the other end is connected to the power supply end of the fan, and whose control end is connected to the power supply control end of the main control unit; a voltage acquisition circuit, whose one end is connected to the power supply end of the fan, and whose other end is connected to the voltage acquisition end of the main control unit. The fan control circuit of the utility model protects the safety of the fan and the fan control circuit by setting a current limiting switch circuit, and realizes current limiting protection; realizes voltage limiting protection by setting a voltage acquisition circuit; and facilitates the main control unit to control the on-off of the connection line between the power output end of the current limiting switch circuit and the power supply end of the fan by setting a power supply switch circuit; and solves the technical problem of poor safety of fans in the prior art.

Description

Technical Field

[0001] The utility model belongs to the technical field of circuits, and in particular relates to a fan control circuit. Background Art

[0002] Among various household appliances, the fan is one of the key components that affect the reliable operation of the whole machine, and is even the core component of the whole machine. Once it fails or is damaged, it will not only cause the fan itself to malfunction, but may also cause damage to the entire circuit.

[0003] The problem of how to drive the fan reliably and smoothly while preventing the fan from operating in abnormal conditions such as stalling, open circuit, short circuit, etc. has long existed.

[0004] The existing control solutions on the market only use transistors to drive the fan, but fail to achieve smooth driving and effective protection of the fan, resulting in poor safety in the current fan operation. Summary of the invention

[0005] The utility model provides a fan control circuit, which solves the technical problem of poor safety of fans in the prior art.

[0006] In order to achieve the above technical objectives, the utility model adopts the following technical solutions:

[0007] A fan control circuit, comprising:

[0008] Main control unit;

[0009] The current limiting switch circuit has a power input terminal connected to the power supply, and a current threshold setting terminal connected to the ground via a configuration resistor;

[0010] A power supply switch circuit, one end of which is connected to the power output end of the current limiting switch circuit, the other end of which is connected to the power supply end of the fan, and the control end of which is connected to the power supply control end of the main control unit;

[0011] A voltage collection circuit has one end connected to the power supply end of the fan and the other end connected to the voltage collection end of the main control unit.

[0012] In some embodiments of the present application, the fan control circuit further includes:

[0013] A speed feedback circuit has one end connected to the feedback end of the fan and the other end connected to the speed acquisition end of the main control unit.

[0014] In some embodiments of the present application, the fan control circuit further includes:

[0015] A current collection circuit collects the current signal at the ground terminal of the fan and sends the collected signal to the current collection terminal of the main control unit.

[0016] In some embodiments of the present application, the current acquisition circuit includes:

[0017] A sampling resistor, one end of which is connected to the GND terminal of the fan, and the other end of which is grounded;

[0018] An operational amplifier, wherein the positive input terminal thereof is connected to one end of the sampling resistor via a first current limiting resistor, the reverse input terminal thereof is connected to the other end of the sampling resistor via a second current limiting resistor, the reverse input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a third current limiting resistor, and the output terminal of the operational amplifier is connected to the current collection terminal of the main control unit via a fourth current limiting resistor.

[0019] In some embodiments of the present application, the power switch circuit includes a first switch tube and a second switch tube;

[0020] The control end of the first switch tube is connected to the power supply control end of the main control unit, one end of the switch path of the first switch tube is grounded, and the other end of the switch path of the first switch tube is connected to the control end of the second switch tube;

[0021] One end of the switch path of the second switch tube is connected to the power output end of the current limiting switch circuit, and the other end of the switch path of the second switch tube is connected to the power end of the fan.

[0022] In some embodiments of the present application, the fan control circuit further includes:

[0023] A charging capacitor, wherein the positive electrode thereof is connected to the other end of the switch path of the second switch tube, and the negative electrode thereof is grounded.

[0024] In some embodiments of the present application, the other end of the switch path of the second switch tube is connected to the positive electrode of the charging capacitor through an inductor.

[0025] In some embodiments of the present application, the fan control circuit further includes:

[0026] A clamping protection circuit comprises a first diode and a second diode; the cathode of the first diode is connected to the power supply output end of the current limiting switch circuit, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is grounded; the connection node between the first diode and the second diode is connected to the other end of the switch path of the second switch tube.

[0027] In some embodiments of the present application, the voltage collection circuit includes a voltage collection resistor, one end of the voltage collection resistor is connected to the power supply end of the fan, and the other end of the voltage collection resistor is connected to the voltage collection end of the main control unit.

[0028] In some embodiments of the present application, the speed feedback circuit includes a pull-up resistor, a pull-up power supply, and a speed collection resistor;

[0029] One end of the speed acquisition resistor is connected to the feedback end of the fan, and the other end of the speed acquisition resistor is connected to the speed acquisition end of the main control unit;

[0030] One end of the speed acquisition resistor is connected to the pull-up power supply through the pull-up resistor.

[0031] Compared with the prior art, the advantages and positive effects of the utility model are as follows: the fan control circuit of the utility model, by setting a current limiting switch circuit, disconnects the connection between the power input terminal VIN and the power output terminal SOURCE when the line current exceeds the current threshold, protects the safety of the fan and the fan control circuit, and realizes current limiting protection; by setting a voltage acquisition circuit, the voltage signal at the power terminal VCC of the fan is acquired, and when the voltage signal received by the main control unit exceeds the preset voltage threshold, the power supply switch circuit is controlled to be shut down, so as to avoid excessive voltage from damaging the fan, and realize voltage limiting protection; by setting the power supply switch circuit, it is convenient for the main control unit to control the on-off of the connection line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the power terminal VCC of the fan; therefore, the fan control circuit of the utility model realizes current limiting protection and voltage limiting protection, improves the safety of the fan and the entire fan control circuit, and solves the technical problem of poor safety of the fan in the prior art.

[0032] After reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 It is a principle block diagram of an embodiment of the fan control circuit proposed by the utility model;

[0035] Figure 2 This is a circuit schematic diagram of an embodiment of a fan control circuit proposed by the utility model;

[0036] Figure 3 This is the working flow diagram of the fan. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0038] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0040] Embodiment 1

[0041] The fan control circuit of this embodiment includes a main control unit, a current limiting switch circuit IC1, a power supply switch circuit, a voltage acquisition circuit, etc. Figure 1 , Figure 2 shown.

[0042] The main control unit has a power supply control terminal and a voltage collection terminal.

[0043] The current limiting switch circuit IC1 has a power input terminal VIN connected to a power supply VC1, a power output terminal SOURCE capable of outputting a DC power supply VC2, and a current threshold setting terminal ILIMIT connected to ground via a configuration resistor R13. Different resistance values ​​of the configuration resistors result in different current thresholds of the current limiting switch circuit.

[0044] When the current flowing through the connection line between the power input terminal VIN and the power output terminal SOURCE does not exceed the current threshold, the power output terminal SOURCE can output the DC power VC2.

[0045] When the current flowing through the connection line between the power input terminal VIN and the power output terminal SOURCE exceeds the current threshold, the connection line between the power input terminal VIN and the power output terminal SOURCE is disconnected to protect the safety of the fan and the fan control circuit and achieve current limiting protection.

[0046] The enable terminal EN of the current limiting switch circuit IC1 is connected to the power supply VC1. When the enable terminal EN is at a high level, the current limiting switch circuit starts to work. Alternatively, the enable terminal EN of the current limiting switch circuit IC1 is connected to the main control unit, and the main control unit controls whether the current limiting switch circuit IC1 works or not. The GND terminal of the current limiting switch circuit IC1 is grounded.

[0047] The power supply switch circuit has one end of the switch path connected to the power output terminal SOURCE of the current limiting switch circuit IC1, the other end of the switch path connected to the power supply terminal VCC of the fan, and the control end connected to the power supply control terminal of the main control unit. The main control unit controls the on and off of the power supply switch circuit.

[0048] When the power switch circuit is turned on, the current provided by the power output terminal SOURCE of the current limiting switch circuit IC1 is transmitted to the power terminal VCC of the fan through the switch path of the power switch circuit to supply power to the fan.

[0049] When the power switch circuit is turned off, the power supply line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the fan power terminal VCC is disconnected.

[0050] The voltage acquisition circuit has one end connected to the power supply terminal VCC of the fan, and the other end connected to the voltage acquisition terminal of the main control unit. The voltage acquisition circuit collects the voltage signal at the power supply terminal VCC of the fan and feeds it back to the main control unit. When the detected voltage signal exceeds the preset voltage threshold, the main control unit can control the power supply switch circuit to shut down to avoid excessive voltage damaging the fan and achieve voltage limiting protection.

[0051] The fan control circuit of the present embodiment, by setting a current limiting switch circuit, disconnects the connection between the power input terminal VIN and the power output terminal SOURCE when the line current exceeds the current threshold, thereby protecting the safety of the fan and the fan control circuit and realizing current limiting protection; by setting a voltage acquisition circuit, the voltage signal at the power terminal VCC of the fan is acquired, and when the voltage signal received by the main control unit exceeds the preset voltage threshold, the power supply switch circuit is controlled to shut down to avoid damage to the fan due to excessive voltage, thereby realizing voltage limiting protection; by setting the power supply switch circuit, it is convenient for the main control unit to control the connection and disconnection of the connection line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the power terminal VCC of the fan; therefore, the fan control circuit of the present embodiment realizes current limiting protection and voltage limiting protection, improves the safety of the fan and the entire fan control circuit, and solves the technical problem of poor safety of the fan in the prior art.

[0052] The current limiting switch circuit of this embodiment is a current limiting switch chip, which is used to realize the current limiting protection function.

[0053] The current limiting switch chip IC1 has functions such as fast response of short-circuit protection and automatic recovery of overcurrent protection, and meets the requirements of safety certification. The current threshold is realized by resistor R13. When the ILIMIT terminal is floating, the current threshold is a fixed value of 2.5A. When the fan is blocked, short-circuited or in abnormal conditions, the fan current will increase instantly. When the current flowing through the current limiting switch chip IC1 exceeds the current threshold, the current limiting switch chip IC1 will respond quickly and disconnect the connection between the power input terminal VIN and the power output terminal SOURCE, thereby achieving effective protection for the fan and the fan control circuit. By setting up a current limiting switch circuit, the occurrence of fire accidents due to fan short circuit is effectively avoided, the safety of the fan is improved, and the safety of the user is improved to avoid user injury.

[0054] In some embodiments of the present application, the fan control circuit also includes a speed feedback circuit to facilitate the main control unit to obtain the speed of the fan.

[0055] The speed feedback circuit has one end connected to the feedback terminal FB of the fan and the other end connected to the speed acquisition terminal of the main control unit. The speed feedback circuit collects the speed signal sent by the feedback terminal FB of the fan and feeds it back to the main control unit. The real-time speed of the fan is fed back to the main control unit through the speed feedback circuit. After the main control unit obtains the real-time speed signal of the fan, it can adjust the speed of the fan.

[0056] In some embodiments of the present application, the speed feedback circuit includes a pull-up resistor R1, a pull-up power supply VC3, a speed acquisition resistor R2, etc., one end of the speed acquisition resistor R2 is connected to the feedback end FB of the fan, and the other end of the speed acquisition resistor R2 is connected to the speed acquisition end of the main control unit; one end of the speed acquisition resistor R2 is connected to the pull-up power supply VC3 through the pull-up resistor R1.

[0057] By designing the speed feedback circuit of the above structure, it is convenient for the main control unit to obtain the speed signal of the fan, and the circuit structure is simple, easy to build and low in cost.

[0058] In some embodiments of the present application, the voltage collection circuit includes a voltage collection resistor R8, one end of the voltage collection resistor R8 is connected to the power supply terminal VCC of the fan, and the other end of the voltage collection resistor R8 is connected to the voltage collection terminal of the main control unit.

[0059] The voltage signal at the power supply terminal VCC of the fan is collected by the voltage collection resistor R8, and fed back to the main control unit, so that the main control unit can know the input voltage of the fan. Moreover, the circuit structure is simple, easy to build and low cost.

[0060] The voltage acquisition circuit acquires the voltage signal at the fan power supply terminal VCC, which is used by the main control unit to determine whether the voltage value supplied to the fan is normal and whether the power supply switch circuit is open.

[0061] In some embodiments of the present application, the fan control circuit also includes a current acquisition circuit to facilitate the main control unit to obtain the operating current of the fan.

[0062] The current collection circuit collects the current signal at the ground terminal GND of the fan and sends the collected signal to the current collection terminal of the main control unit.

[0063] In some embodiments of the present application, the current acquisition circuit includes a sampling resistor R6 and an operational amplifier.

[0064] The sampling resistor R6 has one end connected to the GND terminal of the fan and the other end connected to the ground.

[0065] An operational amplifier, wherein the positive input terminal thereof is connected to one end of the sampling resistor R6 via a first current limiting resistor R7, the reverse input terminal thereof is connected to the other end of the sampling resistor R6 via a second current limiting resistor R4, the reverse input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a third current limiting resistor R3, and the output terminal of the operational amplifier is connected to the current collection terminal of the main control unit via a fourth current limiting resistor R5.

[0066] The GND terminal of the fan is grounded through the sampling resistor R6, and the voltage across the sampling resistor R6 is amplified by the operational amplifier and then output to the current collection terminal of the main control unit.

[0067] By designing the current acquisition circuit of the above structure, it is convenient for the main control unit to obtain the operating current of the fan, and the circuit structure is simple, easy to build and low in cost.

[0068] In some embodiments of the present application, the power supply switch circuit includes a first switch tube N1, a second switch tube TR1, etc.; the control end of the first switch tube N1 is connected to the power supply control end of the main control unit, one end of the switch path of the first switch tube N1 is grounded, and the other end of the switch path of the first switch tube N1 is connected to the control end of the second switch tube TR1; one end of the switch path of the second switch tube TR1 is connected to the power output end SOURCE of the current limiting switch circuit IC1, and the other end of the switch path of the second switch tube TR1 is connected to the power supply end VCC of the fan.

[0069] When the first switch tube N1 is turned off, the second switch tube TR1 is turned off, and the power supply line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the fan power supply terminal VCC is disconnected.

[0070] When the first switch tube N1 is turned on, the second switch tube TR1 is turned on, and the power supply line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the fan power supply terminal VCC is turned on.

[0071] By designing the first switch tube N1 and the second switch tube TR1 in the power supply switch circuit, it is convenient to control the on and off of the power supply line between the power output terminal SOURCE of the current limiting switch circuit IC1 and the fan power terminal VCC, so as to control whether the fan is powered or not. Moreover, the circuit structure is simple and easy to implement.

[0072] In some embodiments of the present application, in order to ensure the stability of the power supply to the fan, the fan control circuit also includes a charging capacitor E1.

[0073] The positive electrode of the charging capacitor E1 is connected to the other end of the switch path of the second switch tube TR1. At the same time, the positive electrode of the charging capacitor E1 is connected to the power supply terminal VCC of the fan, and the negative electrode of the charging capacitor E1 is grounded.

[0074] When the power supply switch circuit is turned on, the power output terminal SOURCE of the current limiting switch circuit IC1 charges the charging capacitor E1 and supplies power to the power supply terminal VCC of the fan at the same time.

[0075] When the power supply switch circuit is disconnected, the current provided by the charging capacitor E1 is transmitted to the power supply terminal VCC of the fan to supply power to the fan.

[0076] In some embodiments of the present application, the other end of the switch path of the second switch tube TR1 is connected to the positive electrode of the charging capacitor E1 through the inductor L2. The DC power supply provided by the power output terminal SOURCE of the current limiting switch circuit IC1 may have ripple current, and the inductor L2 is used to stabilize the current to avoid affecting the power supply of the fan and ensure the stability of the power supply.

[0077] To reduce costs, inductor L2 can be replaced by a jumper wire.

[0078] In some embodiments of the present application, in order to further improve the safety of the circuit, the fan control circuit also includes a clamping protection circuit.

[0079] The clamping protection circuit includes a first diode D1 and a second diode D2; the cathode of the first diode D1 is connected to the power output terminal SOURCE of the current limiting switch circuit, the anode of the first diode D1 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is grounded; the connection node between the first diode D1 and the second diode D2 is connected to the other end of the switch path of the second switch tube TR1.

[0080] By designing a clamping protection circuit, it can prevent the damage of the subsequent circuit caused by large impact energy at the moment of fan startup and shutdown.

[0081] In some embodiments of the present application, the first switch tube N1 is a high on-state voltage drop switch tube, such as an NPN transistor, and the second switch tube TR1 is a low on-state voltage drop switch tube, such as a PMOS transistor.

[0082] The base of the NPN transistor is connected to the power supply control terminal of the main control unit, the emitter of the NPN transistor is grounded, and the collector of the NPN transistor is connected to the gate of the PMOS tube through the resistor R12.

[0083] The source of the PMOS tube is connected to the power output terminal SOURCE of the current limiting switch circuit IC1;

[0084] The drain of the PMOS tube is connected to the positive electrode of the charging capacitor E1 through the inductor L2, and the positive electrode of the charging capacitor E1 is connected to the power supply terminal VCC of the fan.

[0085] When the power supply control terminal of the main control unit outputs a low level, the NPN transistor is turned off and the PMOS tube is turned off;

[0086] When the power supply control terminal of the main control unit outputs a high level, the NPN transistor is turned on and the PMOS tube is turned on.

[0087] By selecting NPN transistors and PMOS tubes, the control is simple, the on and off control is convenient, the performance is stable and the cost is low.

[0088] The main control unit has a speed control terminal for connecting to the speed control terminal of the fan. The speed control terminal of the main control unit sends a PWM signal to the speed control terminal of the fan to adjust the speed of the fan.

[0089] The speed control terminal of the main control unit is connected to the speed control terminal of the fan through the resistor R14. The speed control terminal of the main control unit outputs a speed control signal (PWM signal), which is transmitted to the speed control terminal of the fan through the resistor R14 to control the speed of the fan.

[0090] The four-wire fan has a power supply terminal VCC, a ground terminal GND, a feedback terminal FB, and a speed regulation terminal PWM.

[0091] The three-wire fan has a power supply terminal VCC, a ground terminal GND, and a feedback terminal FB.

[0092] The main control unit has a speed acquisition terminal, a current acquisition terminal, a voltage acquisition terminal, a power supply control terminal, and a speed regulation control terminal.

[0093] When the fan control circuit is connected to a four-wire fan, the speed control terminal of the main control unit outputs a PWM signal, which is transmitted to the speed control terminal of the fan through resistor R14 to adjust the fan speed. The power supply control terminal of the main control unit is only used as a control switch, outputting a switch signal to the power supply switch circuit.

[0094] When the fan control circuit is connected to a three-wire fan, the speed control terminal of the main control unit does not work, and the line where the resistor R14 is located does not work. The power supply control terminal of the main control unit outputs a PWM signal to the control terminal of the power supply switch circuit, and the purpose of fan speed regulation is achieved by controlling the on and off of the power supply switch circuit.

[0095] Therefore, the fan control circuit of this embodiment is compatible with both three-wire fans and four-wire fans.

[0096] Taking the three-wire fan as an example, briefly introduce the working process of the fan, see Figure 3 shown.

[0097] The main control unit (MCU) outputs a PWM signal through the power supply control terminal to adjust the power supply voltage of the fan, thereby realizing fan speed regulation. Different fan speeds result in different fan operating currents. The main control unit adjusts the fan speed through the collected speed signal, and then performs more detailed speed regulation through the collected fan current. This dual-channel feedback cross-coordination control method makes the fan drive stable and reliable. In order to ensure the smooth and reliable operation of the fan, the circuit has also added many protection measures. The current limiting switch chip IC1 will play a current limiting protection role when the fan is blocked or short-circuited, avoiding fires caused by excessive current, avoiding damage to the fan and fan circuit, and ensuring the safety of the user.

[0098] The fan control circuit of this embodiment adds fan current feedback on the basis of fan speed feedback regulation, and makes the fan run smoothly and reliably through the control method of double-path feedback cross-coordination. On the basis of ensuring the smooth and reliable operation of the fan, current limiting protection and voltage detection protection are added to ensure that the fan and the fan control circuit are effectively protected, and can play a protective role in the event of abnormal conditions such as fan stalling, open circuit, short circuit, etc. Therefore, the fan control circuit of this embodiment, while ensuring the smooth, safe, reliable and good performance of the fan drive, also adds a variety of protection measures to ensure the reliable and safe operation of the fan; and also realizes the compatibility of three-wire and four-wire fans, increasing the scope of circuit application.

[0099] The fan control circuit of this embodiment controls the operation of the fan by designing speed feedback and current feedback, and the dual-path feedback cross-coordinates to control the operation of the fan, so that the fan drive is stable and reliable; by designing a current limiting switch circuit, it plays a role in current limiting protection under abnormal conditions such as fan stalling and short circuit; by designing a voltage acquisition circuit, it can perform voltage detection under conditions such as fan disconnection and operation to play a role in voltage limiting protection; it can also perform clamping protection when the impact energy of the fan is large at the moment of startup and shutdown; and it is also compatible with three-wire and four-wire fans.

[0100] Embodiment 2

[0101] Based on the design of the fan control circuit in the first embodiment, the second embodiment further proposes an electronic product, including the fan control circuit in the first embodiment.

[0102] By designing fan control circuits in electronic products, the operating reliability and safety of electronic products are improved, and the competitiveness of electronic products is enhanced.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the utility model.

Claims

1. A fan control circuit, characterized in that: include: Main control unit; The current limiting switch circuit has a power input terminal connected to the power supply, and a current threshold setting terminal connected to the ground via a configuration resistor; A power supply switch circuit, one end of which is connected to the power output end of the current limiting switch circuit, the other end of which is connected to the power supply end of the fan, and the control end of which is connected to the power supply control end of the main control unit; A voltage collection circuit has one end connected to the power supply end of the fan and the other end connected to the voltage collection end of the main control unit.

2. The fan control circuit according to claim 1, characterized in that: The fan control circuit also includes: A speed feedback circuit has one end connected to the feedback end of the fan and the other end connected to the speed acquisition end of the main control unit.

3. The fan control circuit according to claim 1, characterized in that: The fan control circuit also includes: A current collection circuit collects the current signal at the ground terminal of the fan and sends the collected signal to the current collection terminal of the main control unit.

4. The fan control circuit according to claim 3, characterized in that: The current collection circuit comprises: A sampling resistor, one end of which is connected to the GND terminal of the fan, and the other end of which is grounded; An operational amplifier, wherein the positive input terminal thereof is connected to one end of the sampling resistor via a first current limiting resistor, the reverse input terminal thereof is connected to the other end of the sampling resistor via a second current limiting resistor, the reverse input terminal of the operational amplifier is connected to the output terminal of the operational amplifier via a third current limiting resistor, and the output terminal of the operational amplifier is connected to the current collection terminal of the main control unit via a fourth current limiting resistor.

5. The fan control circuit according to claim 1, characterized in that: The power supply switch circuit includes a first switch tube and a second switch tube; The control end of the first switch tube is connected to the power supply control end of the main control unit, one end of the switch path of the first switch tube is grounded, and the other end of the switch path of the first switch tube is connected to the control end of the second switch tube; One end of the switch path of the second switch tube is connected to the power output end of the current limiting switch circuit, and the other end of the switch path of the second switch tube is connected to the power end of the fan.

6. The fan control circuit according to claim 5, characterized in that: The fan control circuit also includes: A charging capacitor, wherein the positive electrode thereof is connected to the other end of the switch path of the second switch tube, and the negative electrode thereof is grounded.

7. The fan control circuit according to claim 6, characterized in that: The other end of the switch path of the second switch tube is connected to the positive electrode of the charging capacitor through an inductor.

8. The fan control circuit according to claim 5, characterized in that: The fan control circuit also includes: A clamping protection circuit comprises a first diode and a second diode; the cathode of the first diode is connected to the power supply output end of the current limiting switch circuit, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is grounded; the connection node between the first diode and the second diode is connected to the other end of the switch path of the second switch tube.

9. The fan control circuit according to claim 1, characterized in that: The voltage collection circuit comprises a voltage collection resistor, one end of which is connected to the power supply end of the fan, and the other end of which is connected to the voltage collection end of the main control unit.

10. The fan control circuit according to claim 2, characterized in that: The speed feedback circuit includes a pull-up resistor, a pull-up power supply, and a speed collection resistor; One end of the speed acquisition resistor is connected to the feedback end of the fan, and the other end of the speed acquisition resistor is connected to the speed acquisition end of the main control unit; One end of the speed acquisition resistor is connected to the pull-up power supply through the pull-up resistor.

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