A DC fan power supply circuit

Abstract

The embodiment of the present invention provides a DC fan power supply circuit, including: a switch unit and a control unit; the input end of the control unit is used to connect to the output end of the vehicle battery, the output end of the control unit is connected to the control end of the switch unit, the first end of the switch unit is used to connect to the first end of the DC fan, the second end of the switch unit is grounded, and the second end of the DC fan is connected to the output end of the vehicle battery; wherein the control unit is used to: obtain the output voltage of the vehicle battery; obtain the duty cycle according to the output voltage; output a control signal to control the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage. The DC fan power supply circuit obtains the duty cycle through the output voltage of the vehicle battery, and controls the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage, and the vehicle battery can be adapted to the DC fans of different parking air conditioners.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of parking air conditioners, and in particular to a DC fan power supply circuit. Background Art

[0002] The evaporation and condensation fans of the parking air conditioner have different voltage specifications. For different vehicles, the battery voltage of the car is often different. In order to solve this problem, it is often necessary to select the evaporation and condensation fans with corresponding voltage specifications according to the vehicle battery voltage. This setting method is more cumbersome. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a DC fan power supply circuit, which can enable a vehicle battery to adapt to the DC fans of different parking air conditioners.

[0004] A technical solution adopted in an embodiment of the present invention is: to provide a DC fan power supply circuit, including: a switch unit and a control unit; the input end of the control unit is used to connect to the output end of a vehicle battery, the output end of the control unit is connected to the control end of the switch unit, the first end of the switch unit is used to connect to the first end of the DC fan, the second end of the switch unit is grounded, and the second end of the DC fan is connected to the output end of the vehicle battery; wherein the control unit is used to: obtain the output voltage of the vehicle battery; obtain a duty cycle according to the output voltage; and output a control signal according to the duty cycle to control the switching state of the switch unit so that the DC fan works at a preset voltage.

[0005] In some embodiments, obtaining the duty cycle according to the output voltage includes: acquiring the preset voltage; and obtaining the duty cycle according to the output voltage and the preset voltage.

[0006] In some embodiments, obtaining the duty cycle according to the output voltage and the preset voltage includes: obtaining the duty cycle according to the following formula: Q=V1 / V2; wherein Q is the duty cycle, V1 is the preset voltage, and V2 is the output voltage.

[0007] In some embodiments, the output voltage includes 12V, 24V or 48V, the preset voltage includes 12V, 24V or 48V, and the control signal is a PWM control signal.

[0008] In some embodiments, the DC fan power supply circuit also includes a voltage acquisition unit; the input end of the voltage acquisition unit is used to connect to the output end of the vehicle battery, the output end of the voltage acquisition unit is connected to the input end of the control unit, and the voltage acquisition unit is used to collect the output voltage of the vehicle battery and send the output voltage to the control unit.

[0009] In some embodiments, the voltage acquisition unit includes a first resistor, a second resistor, a third resistor and a fourth resistor; the first end of the first resistor is used to connect to the output end of the vehicle battery, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the third resistor, the second end of the third resistor is respectively connected to the input end of the control unit and the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

[0010] In some embodiments, the DC fan power supply circuit further includes a freewheeling unit; the freewheeling unit is connected between the first end of the DC fan and the second end of the DC fan.

[0011] In some embodiments, the switching unit includes a driving module and a switching tube; the input end of the driving module is connected to the output end of the control unit, the output end of the driving module is connected to the control end of the switching tube, the first end of the switching tube is connected to the first end of the DC fan, and the second end of the switching tube is grounded.

[0012] In some embodiments, the switch unit further includes a filter module; the filter module is connected between an output end of the control unit and an output end of the driving module.

[0013] In some embodiments, the DC fan power supply circuit also includes an overcurrent protection unit; the input end of the overcurrent protection unit is connected to the first end of the switch unit, and the output end of the overcurrent protection unit is connected to the first end of the control unit, the overcurrent protection unit is used to collect the working current of the DC fan and send the working current to the control unit, the control unit is used to determine whether there is an abnormality in the working state of the DC fan according to the working current, and output a shutdown signal to the switch unit when the working state of the DC fan is abnormal; the switch unit is used to disconnect the connection between the first end of the DC fan and the ground according to the shutdown signal.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: Different from the prior art, the embodiment of the present invention provides a DC fan power supply circuit, including: a switch unit and a control unit; the input end of the control unit is used to connect to the output end of the vehicle battery, the output end of the control unit is connected to the control end of the switch unit, the first end of the switch unit is used to connect to the first end of the DC fan, the second end of the switch unit is grounded, and the second end of the DC fan is connected to the output end of the vehicle battery; wherein the control unit is used to: obtain the output voltage of the vehicle battery; obtain the duty cycle according to the output voltage; output a control signal to control the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage. The DC fan power supply circuit obtains the duty cycle through the output voltage of the vehicle battery, and controls the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage, and the vehicle battery can be adapted to the DC fans of different parking air conditioners. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements / modules and steps with the same reference numerals in the drawings are represented as similar elements / modules and steps. Unless otherwise specified, the figures in the drawings do not constitute proportional limitations.

[0016] Figure 1 It is a schematic diagram of a structural block diagram of a DC fan power supply circuit provided by an embodiment of the present invention;

[0017] Figure 2 It is a schematic diagram of a structural block diagram of another DC fan power supply circuit provided by an embodiment of the present invention;

[0018] Figure 3 is a schematic diagram of a circuit structure of a voltage acquisition unit provided in an embodiment of the present invention;

[0019] Figure 4 It is a partial circuit structure schematic diagram of a DC fan power supply circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0021] For ease of understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those generally understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0022] It should be noted that, if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all are within the scope of protection of this application. In addition, although the functional module division is performed in the device schematic, in some cases, the module division can be different from that in the device. In addition, the words "first", "second", etc. used in this article do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0023] The present invention provides a DC fan power supply circuit. Figure 1 The DC fan power supply circuit includes: a switch unit 10 and a control unit 20. The input end of the control unit 20 is used to connect to the output end of the vehicle battery 200, the output end of the control unit 20 is connected to the control end of the switch unit 10, the first end of the switch unit 10 is used to connect to the first end of the DC fan 300, the second end of the switch unit 10 is grounded, and the second end of the DC fan 300 is connected to the output end of the vehicle battery 200; wherein the control unit 20 is used to obtain the output voltage of the vehicle battery 200, obtain the duty cycle according to the output voltage, and output a control signal according to the duty cycle to control the switch state of the switch unit 10, so that the DC fan 300 works at a preset voltage.

[0024] Specifically, the DC fan 300 can be an evaporating fan, a condensing fan or any other suitable DC brush fan of a parking air conditioner. Then, in the DC fan power supply circuit, first, the control unit 20 obtains the output voltage of the vehicle battery 200, then obtains the duty cycle, and outputs a control signal corresponding to the duty cycle to the switch unit 10; then, the switch unit 10 switches on or off the connection between the first end of the DC fan 300 and the ground according to the control signal, so that the equivalent voltage output from the vehicle battery 200 to the DC fan 300 is equal to the preset working voltage of the DC fan 300, which is also the preset voltage described in this article. It can be seen that by controlling the duty cycle of the control signal of the switch unit 10, the actual working voltage at both ends of the DC fan 300 can be controlled, so that the vehicle battery 200 can be adapted to the DC fans 300 of different parking air conditioners, or the DC fans 300 of different parking air conditioners can be adapted to different vehicle batteries 200, thereby improving the adaptability and compatibility of the two.

[0025] In some embodiments, the control unit 20 is further used to obtain a preset voltage after obtaining the output voltage of the vehicle battery 200, and obtain the duty cycle according to the output voltage of the vehicle battery 200 and the preset voltage. Specifically, the control unit 20 can adopt a microcontroller of the STM8, STM16 or STM32 series, or any other suitable microcontroller processor that can be used to receive, process, store and output data.

[0026] In some of the embodiments, the control unit includes a processor and a memory, so that the preset voltage of the DC fan can be stored in the memory of the control unit in advance, that is, the preset operating voltage of the DC fan is first stored in the memory of the control unit, and then the control unit can call and obtain the preset voltage of the DC fan from the memory, so that the duty cycle can be obtained according to the output voltage and the preset voltage.

[0027] In some other embodiments, the DC fan power supply circuit further includes an input unit, and the output end of the input unit is connected to the control unit. In this way, the user can input a preset voltage of the DC fan through the input unit. Specifically, the input unit includes an input screen, a button, a microphone, and any other suitable input device, which is not limited here.

[0028] Specifically, in some embodiments, the control unit 20 is used to obtain the duty cycle according to the following formula:

[0029] Q = V1 / V2;

[0030] Wherein, Q is the duty cycle, V1 is the preset voltage, and V2 is the output voltage of the vehicle battery.

[0031] In some of the embodiments, the output voltage includes 12V, 24V or 48V, the preset voltage includes 12V, 24V or 48V, and the control signal is a PWM control signal.

[0032] In some of these examples, see Figure 2 The DC fan power supply circuit also includes a voltage acquisition unit 30. The input end of the voltage acquisition unit 30 is used to connect to the output end of the vehicle battery 200, and the output end of the voltage acquisition unit 30 is connected to the input end of the control unit 20. The voltage acquisition unit 30 is used to collect the output voltage of the vehicle battery 200 and send the output voltage to the control unit 20.

[0033] Specifically, in some of the embodiments, please refer to Figure 3, the voltage acquisition unit 30 includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4. The first end of the first resistor R1 is used to connect to the output terminal BAT+ of the vehicle battery, the second end of the first resistor R1 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the first end of the third resistor R3, the second end of the third resistor R3 is respectively connected to the input end of the control unit 20 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is grounded. The first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are connected in series to form a voltage divider module, and the control unit 20 can calculate the output voltage of the vehicle battery according to the first end voltage of the fourth resistor R4 and the resistance values ​​of each resistor of the voltage divider module. In practical applications, the number and resistance value of the series resistors of the voltage divider module used by the voltage acquisition unit can be set according to actual needs, and there is no need to stick to the limitations in this embodiment.

[0034] In order to avoid clutter interference during voltage acquisition, in some of the embodiments, please continue to refer to Figure 3 The voltage acquisition unit 30 further includes a filter capacitor C6, a first end of the filter capacitor C6 is connected to a first end of the fourth resistor R4, and a second end of the filter capacitor C6 is connected to a second end of the fourth resistor R4. By setting the filter capacitor C6, the voltage signal output from the voltage acquisition unit to the control unit can be filtered. In practical applications, any other suitable filter circuit can also be used to filter the voltage acquisition signal, and it is not necessary to stick to the limitations in this embodiment.

[0035] In some of these examples, see Figure 4 The DC fan power supply circuit also includes a freewheeling unit 40; the freewheeling unit 40 is connected between the first terminal CN1 of the DC fan and the second terminal CN2 of the DC fan. By providing the freewheeling unit 40, a freewheeling loop can be provided for the internal coil of the DC fan when the switch unit 10 disconnects the connection between the first terminal CN1 of the DC fan and the ground.

[0036] Specifically, in some of the embodiments, please continue to refer to Figure 4 The freewheeling unit 40 includes a freewheeling diode, which includes a first diode D1 and a second diode D2, wherein the cathode of the first diode D1 and the cathode of the second diode D2 are both connected to the second end CN2 of the DC fan, and the anode of the first diode D1 and the anode of the second diode D2 are both connected to the first end CN1 of the DC fan. In practical applications, the number of diodes can be set according to actual needs, and the freewheeling unit 40 can also be any other suitable freewheeling module that can provide a freewheeling circuit for the internal coil of the DC fan.

[0037] In some of these examples, see Figure 4, the switch unit 10 includes a driving module U1 and a switch tube Q1; the input end of the driving module U1 is connected to the output end of the control unit 20, the output end of the driving module U1 is connected to the control end of the switch tube Q1, the first end of the switch tube Q1 is connected to the first end CN1 of the DC fan, and the second end of the switch tube Q1 is grounded. Specifically, the driving module U1 may include a driving chip, such as UCC27524 or any other chip that can output a signal with the same duty cycle to the control end of the switch tube Q1 according to the control signal of the control unit 20.

[0038] In some embodiments, the switch tube Q1 includes an NMOS tube, the gate of the NMOS tube is connected to the output end of the driving module U1, the source of the NMOS tube is grounded, and the drain of the NMOS tube is connected to the first end CN1 of the DC fan. In practical applications, the switch tube Q1 can also be a PMOS tube, a triode, or any other suitable switch device.

[0039] In order to limit the signal size input from the control unit 20 to the driving module U1, in some embodiments, please continue to refer to Figure 4 The switch unit 10 further includes a fifth resistor R5 and a sixth resistor R6, wherein a first end of the fifth resistor R5 is connected to an output end of the control unit 20, a second end of the fifth resistor R5 is respectively connected to an input end of the driving module U1 and a first end of the sixth resistor R6, and a second end of the sixth resistor R6 is grounded. By setting the fifth resistor R5 and the sixth resistor R6, the signal size input from the control unit 20 to the driving module U1 can be limited, thereby protecting the driving module U1.

[0040] In order to prevent clutter from interfering with the signal input from the control unit 20 to the driving module U1, in some embodiments, the switch unit 10 further includes a filter module; the filter module is connected between the output end of the control unit 20 and the input end of the driving module U1. Specifically, the filter module includes a first capacitor C1, a first end of the first capacitor C1 is connected to the second end of the fifth resistor R5, and a second end of the first capacitor C1 is grounded. By setting the first capacitor C1 and the sixth resistor R6, the control signal input to the driving module U1 can be filtered.

[0041] In some embodiments, the switch unit 10 further includes a fast charge and discharge module, which is connected between the output end of the driving module U1 and the control end of the switch tube Q1. Specifically, the fast charge and discharge module includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a second capacitor C2, a third capacitor C3 and a third diode D3, wherein the first end of the seventh resistor R7 is respectively connected to the output end of the driving module U1, the first end of the eighth resistor R8 and the first end of the second capacitor C2, the second end of the seventh resistor R7 is respectively connected to the control end of the switch tube Q1, the second end of the second capacitor C2, the anode of the third diode D3, the first end of the third capacitor C3 and the first end of the ninth resistor R9, the cathode of the third diode D3 is connected to the second end of the eighth resistor R8, and the second end of the third capacitor C3 and the second end of the ninth resistor R9 are both connected to the second end of the switch tube Q1. By setting the fast charge and discharge module, a fast charge and discharge circuit can be provided for the switch tube Q1, and mis-conduction can be prevented.

[0042] In some of these embodiments, please continue to see Figure 4 The DC fan power supply circuit also includes an absorption unit 50, the first end of the absorption unit 50 is connected to the first end of the freewheeling unit 40, the first end of the absorption unit 50 is connected to the second end of the freewheeling unit 40, and the third end of the absorption unit 50 is connected to the second end of the switch tube Q1. Specifically, the absorption unit 50 includes a tenth resistor R10, a fourth capacitor C4 and a fifth capacitor C5, the first end of the tenth resistor R10 is respectively connected to the cathode of the freewheeling diode and the first end of the fifth capacitor C5, the second end of the tenth resistor R10 is connected to the first end of the fourth capacitor C4, the second end of the fourth capacitor C4 is connected to the anode of the freewheeling diode, and the second end of the fifth capacitor C5 is connected to the second end of the switch tube Q1. By setting the absorption capacitor, the peak voltage generated by the high-speed switching of the on or off state at both ends of the freewheeling diode can be reduced, thereby protecting the freewheeling unit 40.

[0043] In some of these examples, see Figure 4 The DC fan power supply circuit also includes an overcurrent protection unit 60; the input end of the overcurrent protection unit 60 is connected to the first end of the switch unit 10, and the output end of the overcurrent protection unit 60 is connected to the first end of the control unit 20. The overcurrent protection unit 60 is used to collect the working current of the DC fan and send the working current to the control unit 20. The control unit 20 is used to determine whether the working state of the DC fan is abnormal according to the working current, and output a shutdown signal to the switch unit 10 when the working state of the DC fan is abnormal; the switch unit 10 is used to disconnect the connection between the first end CN1 of the DC fan and the ground according to the shutdown signal. In the DC fan power supply circuit, the control unit 20 can disconnect the switch unit 10 when the working current of the DC fan is abnormal, for example, when the working current of the DC fan is too large, so as to open the circuit of the DC fan, thereby protecting the DC fan.

[0044] Specifically, in some of the embodiments, please continue to refer to Figure 4 , the overcurrent protection unit 60 includes a sampling resistor RS1 and an operational amplifier module 61, the first end of the sampling resistor RS1 is connected to the first end of the switch unit 10, the second end of the sampling resistor RS1 is grounded, the first end and the second end of the sampling resistor RS1 are both connected to the operational amplifier module 61, and the output end of the operational amplifier module 61 is connected to the first end of the control unit 20. The voltage signal of the working current of the DC fan flowing through the sampling resistor RS1 is collected by the sampling resistor RS1, the operational amplifier module 61 performs operational amplifier amplification on the voltage signal, and then outputs it to the control unit 20, and the control unit 20 can process the amplified voltage signal to obtain the working current of the DC fan. It should be noted that the resistance value of the sampling resistor should be as small as possible when selecting to avoid interfering with the normal operation of the DC fan power supply circuit. In practical applications, the operational amplifier module can adopt the operational amplifier circuit in the prior art, which is not limited here.

[0045] Combine the following Figure 3 and Figure 4 The illustrated embodiment describes in detail the specific working process of the DC fan power supply circuit provided by the embodiment of the present invention.

[0046] Assume that the voltage of the output terminal BAT+ of the vehicle battery is 48V, and the preset voltage of the DC fan is 24V. Then, the control unit 20 collects the output voltage of the vehicle battery through the voltage divider module composed of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4, and obtains that the output voltage of the vehicle battery is 48V; then, the preset voltage of the DC fan is 24V; then, the duty cycle is calculated to be 24V / 48V=50%, then, the control unit outputs a PWM control signal with a duty cycle of 50%.

[0047] Then, the PWM control signal enters the PIN4 input pin of the driver chip U1, and then sends the same PWM wave with a duty cycle of 50% through the PIN5 signal output pin of U4 to control the on and off of the switch tube Q1. When the switch tube Q1 is turned off, the voltage between the source and drain of the switch tube Q1 is 48V, and when the switch tube Q1 is turned on, the voltage between the source and drain of the switch tube Q1 is 0V. Since the switch tube Q1 is turned on and off under the PWM signal with a duty cycle of 50%, the effective value of the voltage difference between the source and drain of the switch tube Q1 is 48V*0.5=24V, and the voltage across the DC fan is 48V-24V=24V, so that the DC fan can work at the preset voltage. It should be noted that all voltage values ​​are based on GND as the reference ground.

[0048] It can be seen that the DC fan power supply circuit achieves the purpose of controlling the voltage across the fan by controlling the duty cycle value of the control signal, so that different vehicle batteries can be matched with different DC fans.

[0049] The embodiment of the present invention provides a DC fan power supply circuit, including: a switch unit and a control unit; the input end of the control unit is used to connect to the output end of the vehicle battery, the output end of the control unit is connected to the control end of the switch unit, the first end of the switch unit is used to connect to the first end of the DC fan, the second end of the switch unit is grounded, and the second end of the DC fan is connected to the output end of the vehicle battery; wherein the control unit is used to: obtain the output voltage of the vehicle battery; obtain the duty cycle according to the output voltage; output a control signal to control the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage. The DC fan power supply circuit obtains the duty cycle through the output voltage of the vehicle battery, and controls the switch state of the switch unit according to the duty cycle, so that the DC fan works at a preset voltage, and the vehicle battery can be adapted to the DC fans of different parking air conditioners.

[0050] It should be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may 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 scope of the technical solutions of the embodiments of the present invention.

Claims

1. A DC fan power supply circuit, characterized in that: include: Switching unit and control unit; The input end of the control unit is used to connect to the output end of the vehicle battery, the output end of the control unit is connected to the control end of the switch unit, the first end of the switch unit is used to connect to the first end of the DC fan, the second end of the switch unit is grounded, and the second end of the DC fan is connected to the output end of the vehicle battery; Wherein, the control unit is used for: Obtaining the output voltage of the vehicle battery; Get the preset voltage; The duty cycle is obtained according to the following formula: Q = V1 / V2; Wherein, Q is the duty cycle, V1 is the preset voltage, and V2 is the output voltage; According to the duty cycle, a control signal is output to control the switching state of the switch unit so that the DC fan operates at a preset voltage.

2. The DC fan power supply circuit according to claim 1, characterized in that: The output voltage includes 12V, 24V or 48V, the preset voltage includes 12V, 24V or 48V, and the control signal is a PWM control signal.

3. The DC fan power supply circuit according to any one of claims 1 to 2, characterized in that: The DC fan power supply circuit also includes a voltage acquisition unit; The input end of the voltage acquisition unit is used to connect to the output end of the vehicle battery, the output end of the voltage acquisition unit is connected to the input end of the control unit, and the voltage acquisition unit is used to acquire the output voltage of the vehicle battery and send the output voltage to the control unit.

4. The DC fan power supply circuit according to claim 3, characterized in that: The voltage acquisition unit includes a first resistor, a second resistor, a third resistor and a fourth resistor; The first end of the first resistor is used to connect to the output end of the vehicle battery, the second end of the first resistor is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the third resistor, the second end of the third resistor is respectively connected to the input end of the control unit and the first end of the fourth resistor, and the second end of the fourth resistor is grounded.

5. The DC fan power supply circuit according to claim 4, characterized in that: The DC fan power supply circuit also includes a freewheeling unit; The freewheeling unit is connected between the first end of the DC fan and the second end of the DC fan.

6. The DC fan power supply circuit according to claim 5, characterized in that: The switch unit includes a driving module and a switch tube; The input end of the driving module is connected to the output end of the control unit, the output end of the driving module is connected to the control end of the switch tube, the first end of the switch tube is connected to the first end of the DC fan, and the second end of the switch tube is grounded.

7. The DC fan power supply circuit according to claim 6, characterized in that: The switch unit also includes a filter module; The filter module is connected between the output end of the control unit and the input end of the driving module.

8. The DC fan power supply circuit according to claim 7, characterized in that: The DC fan power supply circuit also includes an overcurrent protection unit; The input end of the overcurrent protection unit is connected to the first end of the switch unit, and the output end of the overcurrent protection unit is connected to the first end of the control unit. The overcurrent protection unit is used to collect the working current of the DC fan and send the working current to the control unit. The control unit is used to determine whether the working state of the DC fan is abnormal according to the working current, and output a shutdown signal to the switch unit when the working state of the DC fan is abnormal; the switch unit is used to disconnect the connection between the first end of the DC fan and the ground according to the shutdown signal.

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