Fan driving circuit and device

Abstract

The utility model belongs to the technical field of power electronics, and particularly relates to a fan driving circuit and a fan driving device.The fan driving circuit comprises a power module, a gating module and a switch module; the gating module is connected with the switch module, and the power supply module is connected with a fan through the switch module; the power supply module provides N power supply branches; wherein N is an integer and N is greater than or equal to 2; when receiving a driving signal, the gating module outputs a gating signal to the switch module according to the driving signal; when the switch module receives the gating signal, one power supply branch in the N power supply branches is selected to be connected according to the gating signal so as to supply power to the fan, and therefore the fan is controlled to operate at the two-section speed or the multi-section speed, noise can be reduced, and the service life of the fan is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of power electronics, and in particular to a fan driving circuit and a fan driving device. Background Art

[0002] At present, during the operation of the variable frequency drive, when the inverter bridge in the variable frequency drive reaches a certain temperature, the cooling fan will start to run to dissipate heat from the power device. Usually, the cooling fan will run at full speed with a rated maximum air volume.

[0003] However, the variable frequency drive does not work at full load for a long time, but actually runs intermittently with load. The power devices generate little loss and heat, and natural heat dissipation or a small amount of air is enough to meet the temperature rise of the machine. However, the cooling fan is always running at the maximum speed, which will waste electricity and generate unnecessary noise. Utility Model Content

[0004] The embodiments of the present application provide a fan driving circuit and device, which can drive the fan to operate at two speeds or multiple speeds, thereby saving energy and reducing noise.

[0005] In the first aspect, an embodiment of the present application provides a fan driving circuit, which includes a power supply module, a gating module and a switch module; the gating module is connected to the switch module, and the power supply module is connected to the fan through the switch module; the power supply module provides N power supply branches; wherein N is an integer and N≥2; when the gating module receives a driving signal, the gating module outputs a gating signal to the switch module according to the driving signal; when the switch module receives the gating signal, the switch module selects to connect to one of the N power supply branches according to the gating signal to power the fan.

[0006] In some embodiments, the gating module includes an amplifying unit and a gating unit; the amplifying unit is connected to the gating unit, and the gating unit is also connected to the switching module; when the amplifying unit receives the driving signal, the driving signal is converted into a voltage signal; when the gating unit receives the voltage signal, the gating unit outputs the gating signal according to the voltage signal.

[0007] In some embodiments, the gating unit includes a minimum gating branch, a maximum gating branch and M intermediate gating branches, wherein M=N-2; the minimum gating branch is connected to the power supply branch with the smallest power supply voltage among the N power supply branches through the switch module, the maximum gating branch is connected to the power supply branch with the largest power supply voltage among the N power supply branches through the switch module, and the M intermediate gating branches are correspondingly connected to the remaining M power supply branches through the switch module.

[0008] In some embodiments, the minimum selection branch includes a Zener diode D1, a resistor R6, a resistor R7, a switch tube Q1 and a switch tube Q2; the cathode of the Zener diode D1 is connected to the first end of the resistor R7 and the amplification unit, the anode of the Zener diode D1 is connected to the control end of the switch tube Q1 through the resistor R6, the first end of the switch tube Q1 is connected to the second end of the resistor R7 and the control end of the switch tube Q2, the first end of the switch tube Q2 is connected to the switch module, and the second end of the switch tube Q1 and the second end of the switch tube Q2 are grounded.

[0009] In some embodiments, the maximum selection branch includes a Zener diode D4, a resistor R10 and a switch tube Q5; the cathode of the Zener diode D4 is connected to the amplification unit, the anode of the Zener diode D4 is connected to the control end of the switch tube Q5 through the resistor R10, the first end of the switch tube Q5 is connected to the switch module, and the second end of the switch tube Q5 is grounded.

[0010] In some embodiments, an intermediate selection branch among the M intermediate selection branches includes a Zener diode D2, a Zener diode D3, a resistor R8, a resistor R9, a switch tube Q3, and a switch tube Q4; the cathode of the Zener diode D2 and the cathode of the Zener diode D3 are respectively connected to the amplification unit, the anode of the Zener diode D2 is connected to the control end of the switch tube Q3 through the resistor R8, the anode of the Zener diode D3 is connected to the control end of the switch tube Q4 through the resistor R9, the first end of the switch tube Q4 is connected to the control end of the switch tube Q3, the second end of the switch tube Q4 and the second end of the switch tube Q3 are both grounded, and the first end of the switch tube Q3 is connected to the switch module.

[0011] In some embodiments, the amplifying unit includes a filtering branch and an amplifying branch; the filtering branch includes a resistor R1 and a capacitor C1, the first end of the resistor R1 is connected to the controller, the second end of the resistor R1 is connected to the first end of the capacitor C1 and the amplifying branch, and the second end of the capacitor C1 is grounded; the amplifying branch includes an amplifier U1, a resistor R3 and a resistor R5, the in-phase input end of the amplifier U1 is connected to the filtering branch, the inverting input end of the amplifier U1 is connected to the output end of the amplifier U1 through the resistor R5, and the output end of the amplifier U1 is connected to the selection unit through the resistor R3.

[0012] In some embodiments, the switch module includes N switch branches; the control end of each of the N switch branches is connected to the selection module, the first end of each of the N switch branches is correspondingly connected to one of the N power supply branches, and the second end of each of the N switch branches is connected to the fan.

[0013] In some embodiments, the fan driving circuit further includes a fan current detection module, and the fan current detection module is connected to the fan.

[0014] In a second aspect, an embodiment of the present application provides a fan driving device, which includes the fan driving circuit as described above.

[0015] The beneficial effects of the present application are as follows: the embodiments of the present application provide a fan driving circuit and a fan driving device, wherein the fan driving circuit comprises a power supply module, a gating module and a switch module; the gating module is connected to the switch module, and the power supply module is connected to the fan through the switch module; the power supply module provides N power supply branches; wherein N is an integer and N≥2; when the gating module receives a driving signal, the gating module outputs a gating signal to the switch module according to the driving signal; when the switch module receives the gating signal, the switch module selects to connect to one of the N power supply branches according to the gating signal to power the fan, and can control the fan to operate at two or more speeds, thereby saving energy consumption, reducing noise, and increasing the service life of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0017] Figure 1 is a structural block diagram of a fan driving circuit provided by an embodiment of the present application;

[0018] Figure 2 is a detailed structural block diagram of a fan driving circuit provided in an embodiment of the present application;

[0019] Figure 3 is a circuit structure diagram of a fan driving circuit provided in an embodiment of the present application;

[0020] Figure 4 is a circuit structure diagram of a fan driving circuit provided in another embodiment of the present application;

[0021] Figure 5 is a schematic diagram of the circuit structure of a power module provided in one embodiment of the present application;

[0022] Figure 6 Schematic diagram of the circuit structure of a fan current detection module provided in one embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0025] When an element is referred to as being “connected to” another element, it can be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0026] The terms "first", "second", etc. in the specification and claims of this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0027] In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the previously and subsequently associated objects are in an "or" relationship.

[0028] See also Figure 1 , Figure 1 1 is a structural block diagram of a fan driving circuit 100 provided in an embodiment of the present application.

[0029] The embodiment of the present application provides a fan driving circuit 100 , which includes a power module 10 , a gating module 20 and a switch module 30 .

[0030] Specifically, the selection module 20 is connected to the switch module 30 , and the power module 10 is connected to the fan 200 through the switch module 30 .

[0031] The power module 10 provides N power branches, where N is an integer and N≥2. When receiving the driving signal, the gating module 20 outputs a gating signal to the switch module 30 according to the driving signal. When receiving the gating signal, the switch module 30 selects to access one of the N power branches according to the gating signal to supply power to the fan 200.

[0032] The gating module 20 is also connected to the controller 300, and the controller 300 sends a driving signal to the gating module 20. In some embodiments, the controller 300 is a single chip microcomputer, and the driving signal is a PWM (Pulse Width Modulation) signal. The controller 300 can control the voltage and current by adjusting the pulse width and pulse period of the PWM signal.

[0033] The strobe signal includes a high level signal and / or a low level signal.

[0034] See also Figure 2 , Figure 2 Detailed structural block diagram of a fan driving circuit 100 provided in one embodiment of the present application.

[0035] In some embodiments, the gating module 20 includes an amplifying unit 21 and a gating unit 22. Specifically, the amplifying unit 21 is connected to the gating unit 22, and the gating unit 22 is also connected to the switch module 30.

[0036] When the amplifying unit 21 receives the driving signal, it converts the driving signal into a voltage signal. The amplifying unit 21 generates an analog voltage, i.e., a voltage signal, after amplifying the driving signal. Depending on the driving signal, the voltage of the obtained voltage signal is also different, usually 1V, 1.5V, 2V, etc.

[0037] Next, when receiving the voltage signal, the gating unit 22 outputs a gating signal according to the voltage signal, wherein the combination of the high level signal and the low level signal output by the gating signal is different according to the voltage of the voltage signal.

[0038] In some embodiments, the gating unit 22 includes a minimum gating branch 221, a maximum gating branch 222, and M intermediate gating branches 223. Wherein, M=N-2, and M is an integer greater than or equal to zero. Figure 2 Take N=3, M=1 as an example.

[0039] Specifically, the minimum selection branch 221 is connected to the power supply branch with the smallest power supply voltage among the N power supply branches through the switch module 30, the maximum selection branch 222 is connected to the power supply branch with the largest power supply voltage among the N power supply branches through the switch module 30, and the M intermediate selection branches 223 are correspondingly connected to the remaining M power supply branches through the switch module 30.

[0040] In some embodiments, the switch module 30 includes N switch branches, Figure 2 Taking N = 2 as an example. Specifically, the control end of each switch branch among the N switch branches is connected to the gating module 20, the first end of each switch branch among the N switch branches is correspondingly connected to one of the N power branches, and the second end of each switch branch among the N switch branches is connected to the fan.

[0041] In some embodiments, the amplifying unit 21 includes a filtering branch 211 and an amplifying branch 212. The filtering branch 211 is connected to the controller 300, and the amplifying branch 212 is connected to the filtering branch 211 and the gating unit 22. The filtering branch 211 filters the driving signal, and the amplifying branch 212 amplifies the filtered driving signal to obtain a voltage signal.

[0042] For example, when N = 2 and M = 0, the fan driving circuit 100 has a total of 2 power branches, namely the power branch A1 with a power supply voltage of V1 and the power branch A2 with a power supply voltage of V2, and V1 is less than V2. The gating unit 22 includes 1 minimum gating branch B1 and 1 maximum gating branch B2. The switch module 30 includes 2 switch branches, namely the switch branch C1 and the switch branch C2. Then the minimum gating branch B1 is connected to the power branch A1 through the switch branch C1; the maximum gating branch B2 is connected to the power branch A2 through the switch branch C2.

[0043] When N = 3 and M = 1, the fan driving circuit 100 has a total of 3 power branches, namely the power branch A1 with a power supply voltage of V1, the power branch A2 with a power supply voltage of V2, and the power branch A3 with a power supply voltage of V3, and V1 < V2 < V3. The gating unit 22 includes 1 minimum gating branch B1, 1 intermediate gating branch B2, and 1 maximum gating branch B3. The switch module 30 includes 3 switch branches, namely the switch branch C1, the switch branch C2, and the switch branch C3. Then the minimum gating branch B1 is connected to the power branch A1 through the switch branch C1; the intermediate gating branch B2 is connected to the power branch A2 through the switch branch C2; the maximum gating branch B3 is connected to the power branch A3 through the switch branch C3.

[0044] When N = 4 and M = 2, the fan driving circuit 100 has a total of 4 power branches, namely power branch A1 with a power supply voltage of V1, power branch A2 with a power supply voltage of V2, power branch A3 with a power supply voltage of V3, and power branch A4 with a power supply voltage of V4, and V1 < V2 < V3 < V4. The selection unit 22 includes 1 minimum selection branch B1, 1 intermediate selection branch B2, 1 intermediate selection branch B3, and 1 maximum selection branch B4. The switch module 30 includes 4 switch branches, namely switch branch C1, switch branch C2, switch branch C3, and switch branch C4. Then the minimum selection branch B1 is connected to the power branch A1 through the switch branch C1; the intermediate selection branch B2 is connected to the power branch A2 through the switch branch C2; the intermediate selection branch B3 is connected to the power branch A3 through the switch branch C3; the maximum selection branch B4 is connected to the power branch A4 through the switch branch C4.

[0045] It should be noted that N is greater than or equal to 2 and N is an integer, and M = N - 2. The above examples of the cases of N = 2, N = 3, and N = 4 are for reference, and the rest of the cases can be deduced by analogy and will not be elaborated here.

[0046] Please refer to Figure 3 , Figure 3 which is a schematic circuit diagram of the fan driving circuit 100 provided by an embodiment of the present application.

[0047] Figure 3 Taking N = 3 as an example, the power supply module 30 includes a switch branch with a power supply voltage of VDC1, a switch branch with a power supply voltage of VDC2, and a switch branch with a power supply voltage of VDC3, and VDC1 < VDC2 < VDC3.

[0048] In some embodiments, the amplification unit 21 includes a filtering branch 211 and an amplification branch 212. Specifically, the filtering branch 211 includes a resistor R1 and a capacitor C1. The first end of the resistor R1 is connected to the controller 300, the second end of the resistor R1 is connected to the first end of the capacitor C1 and the amplification branch 212, and the second end of the capacitor C1 is grounded. Specifically through Figure 3The FAN_CON terminal in receives the control signal input by the controller 300. Among them, the resistor R1 and the capacitor C1 form a low-pass filter, which filters the control signal to obtain a DC level. The amplification branch 212 includes an amplifier U1, a resistor R3 and a resistor R5. The in-phase input terminal of the amplifier U1 is connected to the filter branch 211, the inverting input terminal of the amplifier U1 is connected to the output terminal of the amplifier U1 through the resistor R5, and the output terminal of the amplifier U1 is connected to the gating unit 22 through the resistor R3. In some embodiments, the amplification branch 212 also includes a resistor R2 and a resistor R4. Among them, the amplifier U1, the resistor R2, the resistor R3, the resistor R4 and the resistor R5 form an active amplifier circuit, and the filtered control signal is amplified to obtain a suitable voltage signal.

[0049] In some embodiments, the minimum selection branch 221 includes a voltage regulator diode D1, a resistor R6, a resistor R7, a switch tube Q1 and a switch tube Q2. Specifically, the cathode of the voltage regulator diode D1 is connected to the first end of the resistor R7 and the amplification unit 21, the anode of the voltage regulator diode D1 is connected to the control end of the switch tube Q1 through the resistor R6, the first end of the switch tube Q1 is connected to the second end of the resistor R7 and the control end of the switch tube Q2, the first end of the switch tube Q2 is connected to the switch module 30, and the second end of the switch tube Q1 and the second end of the switch tube Q2 are grounded. In some embodiments, the switch tube Q1 and the switch tube Q2 are both NPN transistors. The base of the switch tube Q1 is the control end of the switch tube Q1, the collector of the switch tube Q1 is the first end of the switch tube Q1, and the emitter of the switch tube Q1 is the second end of the switch tube Q1; the base of the switch tube Q2 is the control end of the switch tube Q2, the collector of the switch tube Q2 is the first end of the switch tube Q2, and the emitter of the switch tube Q2 is the second end of the switch tube Q2. In some embodiments, the minimum selection branch 221 also includes a resistor R14 at the base of the switch tube Q1, a resistor R15 at the base of the switch tube Q2, and a resistor R16 at the collector of the switch tube Q2, so that the current when the switch tubes Q1 and Q2 are turned on is within a suitable range. In some embodiments, the switch branch connected to the power supply branch with a power supply voltage of VDC1 includes a resistor R11 and a switch tube Q6. The control end of the switch tube Q6 is connected to the second end of the resistor R11 and the first end of the resistor R16, the first end of the resistor R11 and the first end of the switch tube Q6 are both connected to the power supply branch, and the second end of the switch tube Q6 is connected to the fan FAN_P. Among them, the switch tube Q6 is a PMOS tube, the gate of the switch tube Q6 is the control end of the switch tube Q6, the source of the switch tube Q6 is the first end of the switch tube Q6, and the drain of the switch tube Q6 is the second end of the switch tube Q6. The resistor R11 is the gate resistor of the switch tube Q6, and a discharge circuit can be provided when the power is off.

[0050] In this embodiment, when the voltage signal is divided by the resistor R7, the base voltage input to the switch tube Q2 is greater than the conduction voltage of the switch tube Q2, and the switch tube Q1 is not turned on, the switch tube Q2 is turned on, and then the gate voltage of the switch tube Q6 is pulled down, and the switch tube Q6 is turned on, and the power supply voltage is VDC1, and the power supply is used to supply power to the fan. When the voltage signal is divided by the voltage-stabilizing diode D1 and the resistor R6, the base voltage input to the switch tube Q1 is greater than the conduction voltage of the switch tube Q1, the switch tube Q1 is turned on, and then the base voltage of the switch tube Q2 is pulled down to turn off the switch tube Q2, and at the same time, the gate voltage of the switch tube Q6 is high, and the switch tube Q6 is turned off. It should be noted that a suitable voltage-stabilizing diode D1, resistor R6, and resistor R7 can be set to control the on and off of the switch tubes Q1 and Q2, so as to control the on and off of the switch tube Q6 accordingly.

[0051] In some embodiments, the maximum selection branch 222 includes a voltage regulator diode D4, a resistor R10 and a switch tube Q5. Specifically, the cathode of the voltage regulator diode D4 is connected to the amplification unit 21, the anode of the voltage regulator diode D4 is connected to the control end of the switch tube Q5 through the resistor R10, the first end of the switch tube Q5 is connected to the switch module 30, and the second end of the switch tube Q5 is grounded. In some embodiments, the switch tubes Q5 and are NPN type triodes. The base of the switch tube Q5 is the control end of the switch tube Q5, the collector of the switch tube Q5 is the first end of the switch tube Q5, and the emitter of the switch tube Q5 is the second end of the switch tube Q5. In some embodiments, the maximum selection branch 222 also includes a resistor R20 of the base of the switch tube Q5, a resistor R21 of the collector of the switch tube Q5, and a resistor R22, so that the current when the switch tube Q5 is turned on is within a suitable range. In some embodiments, the switch branch connected to the power supply branch with a power supply voltage of VDC3 includes a resistor R13 and a switch tube Q8. The control end of the switch tube Q8 is connected to the second end of the resistor R13 and the first end of the resistor R21, the first end of the resistor R13 and the first end of the switch tube Q8 are both connected to the power branch, and the second end of the switch tube Q8 is connected to the fan FAN_P. Among them, the switch tube Q8 is a PMOS tube, the gate of the switch tube Q8 is the control end of the switch tube Q8, the source of the switch tube Q8 is the first end of the switch tube Q8, and the drain of the switch tube Q8 is the second end of the switch tube Q8. The resistor R13 is the gate resistor of the switch tube Q8, which can provide a discharge circuit when the power is off.

[0052] In this embodiment, when the voltage signal is divided by the resistor R22, the voltage-stabilizing diode D4, and the resistor R10, and the base voltage input to the switch tube Q5 is greater than the conduction voltage of the switch tube Q5, the switch tube Q5 is turned on, and then the gate voltage of the switch tube Q8 is pulled down, then the switch tube Q8 is turned on, and the power supply voltage is VDC3, and the power supply supplies power to the fan. On the contrary, when the base voltage input to the switch tube Q5 is less than the conduction voltage of the switch tube Q5, the switch tube Q5 is turned off, and then the gate voltage of the switch tube Q8 is high, then the switch tube Q8 is turned off, and the power supply voltage is VDC3, and the power supply does not supply power to the fan. It should be noted that a suitable voltage-stabilizing diode D4 and a resistor R10 can be set to control the on-off of the switch tube Q5, so as to control the on-off of the switch tube Q8 accordingly.

[0053] In some embodiments, the intermediate selection branch 223 includes a voltage regulator diode D2, a voltage regulator diode D3, a resistor R8, a resistor R9, a switch tube Q3, and a switch tube Q4. Specifically, the cathode of the voltage regulator diode D2 and the cathode of the voltage regulator diode D3 are respectively connected to the amplification unit 21, the anode of the voltage regulator diode D2 is connected to the control end of the switch tube Q3 through the resistor R8, the anode of the voltage regulator diode D3 is connected to the control end of the switch tube Q4 through the resistor R9, the first end of the switch tube Q4 is connected to the control end of the switch tube Q3, the second end of the switch tube Q4 and the second end of the switch tube Q3 are both grounded, and the first end of the switch tube Q3 is connected to the switch module 30. In some embodiments, the switch tube Q3 and the switch tube Q4 are both NPN transistors. The base of the switch tube Q3 is the control end of the switch tube Q3, the collector of the switch tube Q3 is the first end of the switch tube Q3, and the emitter of the switch tube Q3 is the second end of the switch tube Q3; the base of the switch tube Q4 is the control end of the switch tube Q4, the collector of the switch tube Q4 is the first end of the switch tube Q4, and the emitter of the switch tube Q4 is the second end of the switch tube Q4. In some embodiments, the intermediate selection branch 223 also includes a resistor R18 at the base of the switch tube Q3, a resistor R17 at the base of the switch tube Q4, and a resistor R19 at the collector of the switch tube Q3, so that the current when the switch tubes Q3 and Q4 are turned on is within a suitable range. In some embodiments, the switch branch connected to the power supply branch with a power supply voltage of VDC2 includes a resistor R12 and a switch tube Q7. The control end of the switch tube Q7 is connected to the second end of the resistor R12 and the first end of the resistor R19, the first end of the resistor R12 and the first end of the switch tube Q7 are both connected to the power supply branch, and the second end of the switch tube Q7 is connected to the fan FAN_P. The switch tube Q7 is a PMOS tube, the gate of the switch tube Q7 is the control end of the switch tube Q7, the source of the switch tube Q7 is the first end of the switch tube Q7, and the drain of the switch tube Q7 is the second end of the switch tube Q7. The resistor R12 is the gate resistor of the switch tube Q7, which can provide a discharge circuit when the power is off.

[0054] In this embodiment, when the voltage signal is divided by the voltage-stabilizing diode D2 and the resistor R8, the base voltage input to the switch tube Q3 is greater than the conduction voltage of the switch tube Q2, and the switch tube Q4 is not turned on, the switch tube Q3 is turned on, and then the gate voltage of the switch tube Q7 is pulled down, and the switch tube Q7 is turned on, and the power supply voltage is VDC2, and the power supply is used to supply power to the fan. When the voltage signal is divided by the voltage-stabilizing diode D3 and the resistor R9, the base voltage input to the switch tube Q4 is greater than the conduction voltage of the switch tube Q4, the switch tube Q4 is turned on, and then the base voltage of the switch tube Q3 is pulled down to turn off the switch tube Q3, and at the same time, the gate voltage of the switch tube Q7 is high, and the switch tube Q7 is turned off. It should be noted that appropriate voltage-stabilizing diodes D2, voltage-stabilizing diodes D3, resistors R8, and resistors R9 can be set to control the on and off of the switch tubes Q3 and Q4, so as to control the on and off of the switch tube Q7 accordingly.

[0055] In some embodiments, when N=3, the breakdown voltage of the Zener diode D1 is equal to the breakdown voltage of the Zener diode D2, and the breakdown voltage of the Zener diode D3 is equal to the breakdown voltage of the Zener diode D4, so as to avoid the situation where two or more power branches are connected at the same time.

[0056] For example, the breakdown voltage of the Zener diode D1 can be set to 2.4V, the breakdown voltage of the Zener diode D2 can be set to 2.4V, the breakdown voltage of the Zener diode D3 can be set to 3.0V, and the breakdown voltage of the Zener diode D4 can be set to 3.0V. When a power supply with a gate voltage of VDC1 is required, the controller 300 sends a control signal, which is filtered and amplified to generate a voltage signal of 1.5V (only needs to be greater than the conduction voltage of the switch tube Q5 and less than 2.4V), and then flows through the resistor R7 to turn on the switch tube Q2. After the switch tube Q2 is turned on, the gate of the switch tube Q6 is pulled down, so that the switch tube Q6 turns on the power supply with a gate voltage of VDC1.

[0057] For example, when it is necessary to select a power supply with a voltage of VDC2, the controller 300 sends a control signal, which is filtered and amplified to generate a voltage signal of 2.5V (only needs to be greater than 2.4V and less than 3.0V), and then flows through the voltage stabilizing diode D2 and the resistor R8 to turn on the switch tube Q3. After the switch tube Q3 is turned on, the gate of the switch tube Q7 is pulled down, so that the switch tube Q7 is turned on to select the power supply with a voltage of VDC2. In addition, at this time, the switch tube Q1 is also turned on, which lowers the base voltage of the switch tube Q2, and the switch tube Q2 is turned off, and then the switch tube Q6 is turned off, so that the power supply with a voltage of VDC1 will not be connected.

[0058] For example, when it is necessary to select a power supply with a voltage of VDC3, the controller 300 sends a control signal, which generates a voltage signal of 4V (only needs to be greater than 3.0V) after filtering and amplification, and then flows through the resistor R22, the voltage stabilizing diode D4 and the resistor R8 to turn on the switch tube Q5. After the switch tube Q5 is turned on, the gate of the switch tube Q8 is pulled down, so that the switch tube Q8 is turned on to select the power supply with a voltage of VDC3. In addition, at this time, the switch tube Q1 is also turned on, which lowers the base voltage of the switch tube Q2, and the switch tube Q2 is turned off, and then the switch tube Q6 is turned off, so the power supply with a voltage of VDC1 will not be connected. At this time, the switch tube Q4 is also turned on, which lowers the base voltage of the switch tube Q3, and the switch tube Q3 is turned off, and then the switch tube Q7 is turned off, so the power supply with a voltage of VDC2 will not be connected.

[0059] See also Figure 4 , Figure 4 FIG. 1 is a circuit structure diagram of a fan driving circuit 100 provided in another embodiment of the present application. Figure 4 Taking N=2 as an example, the power module 30 includes a power branch with a power supply voltage of VDC1, a power branch with a power supply voltage of VDC3, and VDC1 <VDC3。 Figure 4 The principle of the fan driving circuit 100 may refer to the principle of the related circuits with the power supply voltage being VDC1 and the power supply voltage being VDC3, and will not be described in detail here.

[0060] See also Figure 5 , Figure 5 Schematic diagram of the circuit structure of a power module 10 provided in one embodiment of the present application.

[0061] in, Figure 5 Take N=3, and the power module 10 includes 3 power branches as an example. In some embodiments, the power module 10 includes a transformer T3, a first power branch, a second power branch, and a third power branch. The first power branch of the power module 10 includes a diode D12 and a capacitor C6, and the output power voltage is VDC1. The second power branch of the power module 10 includes a diode D10 and a capacitor C4, and the output power voltage is VDC2. The third power branch of the power module 10 includes a diode D11 and a capacitor C5, and the output power voltage is VDC3. In some embodiments, VDC1 is 8V, VDC2 is 16V, and VDC3 is 24V.

[0062] It should be noted that the power module 10 includes N power branches, where N≥2 and N is an integer. The number of power branches of the power module 10 can be set according to actual applications.

[0063] See also Figure 6 , Figure 6 Schematic diagram of the circuit structure of a fan current detection module provided in one embodiment of the present application.

[0064] In some embodiments, the fan driving circuit 100 further includes a fan current detection module, and the fan current detection module is connected to the fan.

[0065] Specifically, the fan current detection module includes a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a capacitor C2 and a clamping diode U2. The resistor R23, the resistor R24, the resistor R25, the resistor R26, the resistor R27 and the resistor R28 are arranged in parallel. The resistor R29 and the capacitor C2 form a filter circuit, which plays a filtering role. The clamping diode U2 plays a role of clamping protection. The fan current signal is received from the FAN_N terminal, and the fan current detection signal is output from the FAN_FAIL terminal to the external device through the fan current detection module, so that the external device can detect the current when the fan is running.

[0066] An embodiment of the present application provides a fan driving circuit, which includes a power module, a gating module and a switch module; the gating module is connected to the switch module, and the power module is connected to the fan through the switch module; the power module provides N power branches; when the gating module receives a driving signal, the gating module outputs a gating signal to the switch module according to the driving signal; when the switch module receives the gating signal, it selects to connect to one of the N power branches according to the gating signal to power the fan, and the fan can be controlled to operate at two speeds or multiple speeds, which can save energy consumption, reduce noise, and increase the service life of the fan.

[0067] The embodiment of the present application provides a fan driving device, which includes the above-mentioned fan driving circuit 100. The fan driving device is a two-speed or multi-speed fan driving device.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the idea of ​​the present application, the technical features in the above embodiments or different embodiments may also be combined, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. 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 application.

Claims

1. A fan driving circuit, characterized in that: The fan driving circuit includes a power module, a gating module and a switch module; The gating module is connected to the switch module, and the power supply module is connected to the fan through the switch module; The power supply module provides N power supply branches; wherein N is an integer and N≥2; When receiving the driving signal, the gating module outputs a gating signal to the switch module according to the driving signal; When receiving the selection signal, the switch module selects to access one of the N power supply branches according to the selection signal to supply power to the fan.

2. The fan driving circuit according to claim 1, characterized in that: The gating module comprises an amplifying unit and a gating unit; The amplification unit is connected to the gating unit, and the gating unit is also connected to the switch module; When receiving the driving signal, the amplifying unit converts the driving signal into a voltage signal; When receiving the voltage signal, the gating unit outputs the gating signal according to the voltage signal.

3. The fan driving circuit according to claim 2, characterized in that: The gating unit includes a minimum gating branch, a maximum gating branch and M intermediate gating branches, wherein M=N-2; The minimum selection branch is connected to the power supply branch with the smallest power supply voltage among the N power supply branches through the switch module, the maximum selection branch is connected to the power supply branch with the largest power supply voltage among the N power supply branches through the switch module, and the M intermediate selection branches are correspondingly connected to the remaining M power supply branches through the switch module.

4. The fan driving circuit according to claim 3, characterized in that: The minimum gate branch includes a voltage stabilizing diode D1, a resistor R6, a resistor R7, a switch tube Q1 and a switch tube Q2; The cathode of the voltage-stabilizing diode D1 is connected to the first end of the resistor R7 and the amplifying unit, the anode of the voltage-stabilizing diode D1 is connected to the control end of the switch tube Q1 through the resistor R6, the first end of the switch tube Q1 is connected to the second end of the resistor R7 and the control end of the switch tube Q2, the first end of the switch tube Q2 is connected to the switch module, and the second end of the switch tube Q1 and the second end of the switch tube Q2 are grounded.

5. The fan driving circuit according to claim 3, characterized in that: The maximum gate branch includes a voltage stabilizing diode D4, a resistor R10 and a switch tube Q5; The cathode of the voltage-stabilizing diode D4 is connected to the amplifying unit, the anode of the voltage-stabilizing diode D4 is connected to the control end of the switch tube Q5 through the resistor R10, the first end of the switch tube Q5 is connected to the switch module, and the second end of the switch tube Q5 is grounded.

6. The fan driving circuit according to claim 3, characterized in that: One of the M intermediate gating branches includes a voltage stabilizing diode D2, a voltage stabilizing diode D3, a resistor R8, a resistor R9, a switch tube Q3, and a switch tube Q4; The cathode of the voltage-stabilizing diode D2 and the cathode of the voltage-stabilizing diode D3 are respectively connected to the amplifying unit, the anode of the voltage-stabilizing diode D2 is connected to the control end of the switch tube Q3 through the resistor R8, the anode of the voltage-stabilizing diode D3 is connected to the control end of the switch tube Q4 through the resistor R9, the first end of the switch tube Q4 is connected to the control end of the switch tube Q3, the second end of the switch tube Q4 and the second end of the switch tube Q3 are both grounded, and the first end of the switch tube Q3 is connected to the switch module.

7. The fan driving circuit according to claim 2, characterized in that: The amplification unit comprises a filtering branch and an amplification branch; The filtering branch includes a resistor R1 and a capacitor C1, a first end of the resistor R1 is connected to the controller, a second end of the resistor R1 is connected to the first end of the capacitor C1 and the amplifying branch, and a second end of the capacitor C1 is grounded; The amplifying branch includes an amplifier U1, a resistor R3 and a resistor R5. The in-phase input terminal of the amplifier U1 is connected to the filtering branch, the inverting input terminal of the amplifier U1 is connected to the output terminal of the amplifier U1 through the resistor R5, and the output terminal of the amplifier U1 is connected to the gating unit through the resistor R3.

8. The fan driving circuit according to claim 1, characterized in that: The switch module includes N switch branches; The control end of each of the N switch branches is connected to the selection module, the first end of each of the N switch branches is correspondingly connected to a power supply branch of the N power supply branches, and the second end of each of the N switch branches is connected to the fan.

9. The fan driving circuit according to any one of claims 1 to 8, characterized in that: The fan driving circuit further includes a fan current detection module, and the fan current detection module is connected to the fan.

10. A fan driving device, characterized in that: The fan driving device comprises a fan driving circuit as described in any one of claims 1-9.

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