Fan brake circuit

Abstract

The present invention provides a fan brake circuit, including a semiconductor switch unit, a motor, a motor drive circuit, an isolation unit, a charge and discharge unit and a control unit. The motor, the semiconductor switch unit and one end of the control unit receive an input power supply, the motor drive circuit is electrically connected to the motor and the other end of the control unit, the isolation unit is electrically connected to the other end of the semiconductor switch unit and the motor drive circuit and the charge and discharge unit. When the fan is powered off, the semiconductor switch unit disconnects itself from the motor, the motor drive circuit receives the operating voltage provided by the charge and discharge unit and transmits the drive signal to the motor, so that the motor forms a short circuit and brakes. Through this design of the present invention, the fan can be effectively stopped quickly when the power is off and the cost can be reduced.

Description

Technical Field

[0001] The present invention relates to a fan brake circuit, and more particularly to a fan brake circuit which can achieve rapid fan braking when power is cut off and reduce costs. Background Art

[0002] See also Figure 1A The existing fan power-off brake circuit 1 is mainly electrically connected to an input power supply Vin through a capacitor 11 (commonly used as an aluminum electrolytic capacitor). The capacitor 11 is used to receive and store the input power supply Vin, and when the fan is powered off, the capacitor 11 releases the stored voltage directly to the upper bridge (upper arm) MOS transistor 121 in the motor 12 to turn on the switch, so that the motor coil 122 forms a short-circuit loop, thereby reflecting the fan motor braking phenomenon. At the same time, during the braking process, a back electromotive force is generated and then charged back to the capacitor 11, thereby generating a braking function by converting kinetic energy into electrical energy until one of the rotational kinetic energy of the fan blades or the stored voltage is consumed first. If the rotational kinetic energy is consumed first, it means that the fan blades are braked first. Otherwise, if the stored voltage is consumed first, the fan blades continue to rotate until the inertial force is eliminated (they will then be consumed by friction).

[0003] The main purpose of the fan power-off brake function is to quickly stop the fan blades completely to avoid safety problems caused by operators accidentally touching the fan blades. However, in the existing original design, the capacitor 11 is consumed first, so it is difficult to effectively achieve the fan power-off fast (or emergency stop) brake demand. Figure 1B, which is an actual measurement waveform diagram of the existing input power supply Vin, capacitor 11 voltage, motor coil 122 voltage and fan current. In the figure, the input power supply Vin waveform symbol is V, and the arrow Vup in the input power supply Vin waveform V represents the input power supply Vin power-on (i.e., fan power-on) and the arrow Vdown represents the input power supply Vin power-down (i.e., fan power-off). The capacitor 11 voltage waveform symbol is C, and the arrow Cv in the capacitor 11 voltage waveform C represents that after the fan is powered off, the capacitor 11 releases the stored voltage which is quickly consumed by the motor coil 122 and is lower than the voltage of the upper arm MOS transistor switch 121. The voltage is turned on, so it is impossible to effectively brake and stop quickly; the motor coil voltage waveform symbol is M, and the dotted frame area Moff in the motor coil voltage waveform M presents an inclined downward line, which means that the fan motor is still running (that is, the fan blades are still rotating) and there is a continuous back electromotive force voltage generated; the fan current waveform symbol is F, so according to the above-mentioned actual measurement waveform results, the existing capacitor 11 can only brake the fan motor 12 briefly and then lose its braking function, so that it is necessary to wait until the fan blades themselves rotate until the inertia force is eliminated before they can completely stop, and the problem of reaction potential will also be generated in the process of the fan blades themselves rotating until the inertia force is eliminated. Therefore, if the industry wants to improve this part, it is generally to enlarge the capacitance specification size of the capacitor 11 to increase the capacitance, but the design space of the fan is often limited, so it is necessary to use a capacitor 11 with a larger size / larger capacitance value or use multiple capacitors 11 in parallel within the limited space specifications, but it is impossible to use a larger size and larger volume capacitor 11 that can quickly stop the fan. Due to the above factors, the overall cost will increase and the fan power-off brake circuit 1 and the fan as a whole cannot be miniaturized, and the improvement effect is not obvious. Summary of the invention

[0004] An object of the present invention is to provide a fan brake circuit which can achieve rapid stopping of the fan when power is cut off and reduce the cost.

[0005] Another object of the present invention is to provide a device that can achieve the effect of miniaturization of the fan brake circuit.

[0006] To achieve the above-mentioned purpose, the present invention provides a fan brake circuit, including a semiconductor switch unit, a motor, a motor drive circuit, an isolation unit, a charge and discharge unit and a control unit, wherein the semiconductor switch unit has a first end and a second end, the first end is used to receive an input power supply, the motor is electrically connected to the input power supply and the first end, the motor drive circuit is electrically connected to the motor, the motor drive circuit is used to output a drive signal to the motor, the isolation unit is electrically connected between the semiconductor switch unit and the motor drive circuit, the isolation unit has a plurality of resistors, and the plurality of resistors are respectively electrically connected to the motor drive circuit and the second end. The first end is connected to the motor drive circuit and the motor, and the second end is connected to the motor drive circuit. The first end is connected to the motor drive circuit and the motor, and the second end is connected to the motor drive circuit. The second ... motor, when connected to the motor drive circuit, the motor, and the motor, when connected to the motor drive circuit, the motor

[0007] Among them, the multiple resistors include a first resistor, a second resistor, a third resistor and a fourth resistor, one end of the first, second, third and fourth resistors are electrically connected to the corresponding motor drive circuit, the other ends of the first and third resistors are electrically connected to the second end of the semiconductor switch unit, and the other ends of the second and fourth resistors are electrically connected to each other.

[0008] The charge-discharge unit includes a capacitor and a charge-discharge resistor, the charge-discharge resistor is electrically connected to the other end of the second resistor and one end of the capacitor respectively, and the other end of the capacitor is electrically connected to a ground terminal.

[0009] The semiconductor switch unit is a diode, an anode terminal of the semiconductor switch unit is the first terminal, and a cathode terminal of the semiconductor switch unit is the second terminal.

[0010] Wherein, the semiconductor switch unit has a third end, a first semiconductor switch and a second semiconductor switch, the first and second semiconductor switches each have a first extreme end, a second extreme end and a third extreme end, the third end of the semiconductor switch unit is the first extreme end of the first semiconductor switch electrically connected to the control unit and the input power supply, the third extreme end of the first semiconductor switch is electrically connected to the first extreme end of the second semiconductor switch, the second extreme ends of the first and second semiconductor switches are electrically connected to the ground end and the input power supply respectively, and the second extreme end of the second semiconductor switch is the first end of the semiconductor switch unit, and the second end of the semiconductor switch unit is the third extreme end of the second semiconductor switch electrically connected to the other end of the first and third resistors.

[0011] The first and second semiconductor switches are respectively an N-type metal oxide semiconductor transistor and a P-type metal oxide semiconductor transistor, and the first terminals of the first and second semiconductor switches are both gate terminals, the second terminals of the first and second semiconductor switches are both source terminals, and the third terminals of the first and second semiconductor switches are both drain terminals.

[0012] The first and second semiconductor switches are semiconductor transistors, and the semiconductor transistors are field effect transistors or IGBT transistors.

[0013] In which, the control unit has multiple pins, and the motor drive circuit includes a first motor drive unit and a second motor drive unit, one end of the first and second motor drive units are respectively electrically connected to a second pin and a third pin among the multiple pins, the other end of the first motor drive unit is respectively electrically connected to one end of the first and second resistors and the motor, the other end of the second motor drive unit is respectively electrically connected to one end of the third and fourth resistors and the motor, and a first pin and a fourth pin among the multiple pins are respectively electrically connected to the motor.

[0014] The motor has a plurality of upper arm switches, a plurality of lower arm switches and a motor coil, wherein the plurality of upper arm switches are correspondingly connected to the plurality of lower arm switches, the connection points between the plurality of upper arm switches and the plurality of lower arm switches are connected to the motor coil, the other end of the first motor drive unit is electrically connected to one of the plurality of lower arm switches, and the other end of the second motor drive unit is electrically connected to another of the plurality of lower arm switches.

[0015] Wherein, the control unit is a central processing unit, a microcontroller or a digital signal processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1A The figure is a block diagram of an existing fan power-off brake circuit.

[0017] Figure 1B The actual measured waveforms of the existing input power, capacitor voltage, motor coil voltage and fan current are shown in Figure 2.

[0018] Figure 2A FIG. 4 is a block diagram of a fan brake circuit according to an embodiment of the present invention.

[0019] Figure 2B For the present invention Figure 2A Circuit diagram of the fan brake circuit.

[0020] Figure 2C FIG. 4 is a circuit diagram of a fan brake circuit according to a feasible embodiment of the present invention.

[0021] Figure 3A FIG. 1 is a block diagram of a fan brake circuit according to an alternative embodiment of the present invention.

[0022] Figure 3B For the present invention Figure 3A Circuit diagram of the fan brake circuit.

[0023] Figure 4 The figure is a diagram of actual measured waveforms of input power, capacitor voltage of a charge-discharge unit, motor coil voltage and fan current according to an embodiment of the present invention.

[0024] List of reference numerals: 2-fan brake circuit; 21-semiconductor switch unit; 211, 212, 213-first, second, and third terminals; 21a, 21b-first and second semiconductor switches; 211a, 211b-first terminal; 212a, 212b-second terminal; 213a, 213b-third terminal; 22-motor; 221-upper arm switch; 222-lower arm switch; 223-motor coil; 23-motor drive circuit; 231-first motor drive unit; 232-second motor drive Unit; 24-isolation unit; 241, 242, 243, 244-first, second, third, fourth resistors; 25-charge and discharge unit; 251, 28-capacitor; 252-charge and discharge resistors; 26-control unit; 261-first pin; 262-second pin; 263-third pin; 264-fourth pin; 265-fifth pin; 27-protection unit; 271-circuit breaker; 272, 273-first and second diodes; Gnd-ground terminal; Vin-input power supply; Vc-operating voltage. DETAILED DESCRIPTION

[0025] The above-mentioned objects and the structural and functional characteristics of the present invention will be described based on the preferred embodiments shown in the accompanying drawings.

[0026] The present invention provides a fan brake circuit, please refer to Figure 2A A block diagram of a fan brake circuit according to an embodiment of the present invention; Figure 2BFor the present invention Figure 2A Circuit diagram of the fan brake circuit; Figure 2C A circuit diagram of a fan brake circuit in a feasible embodiment of the present invention; Figure 3A is a block diagram of a fan brake circuit according to an alternative embodiment of the present invention; Figure 3B For the present invention Figure 3A Circuit diagram of the fan brake circuit; Figure 4 1 is an actual measured waveform diagram of the input power supply, the capacitor voltage of the charge and discharge unit, the motor coil voltage and the fan current according to an embodiment of the present invention. Figure 2A , 2B As shown, the fan brake circuit 2 includes a semiconductor switch unit 21, a motor 22, a motor drive circuit 23, an isolation unit 24, a charge and discharge unit 25 and a control unit 26. Figure 2B In the embodiment, the semiconductor switch unit 21 can be a diode for illustration. The semiconductor switch unit 21 has a first end 211 and a second end 212. An anode end of the semiconductor switch unit 21 is the first end 211 receiving an input power Vin (e.g., the input power Vin output by the power supply is 10 volts), and a cathode end of the semiconductor switch unit 21 is the second end 212. A protection unit 27 is electrically connected between the semiconductor switch unit 21 and the input power Vin. The protection unit 27 is provided with a circuit breaker 271 and a first diode 272. The circuit breaker 271 is a fuse. One end of the circuit breaker 271 is electrically connected to the input power Vin. The circuit breaker 271 is used to allow the input power Vin to pass when the fan is normal. If the fan is abnormal (such as overload or line failure), the circuit is cut off for protection. An anode end and a cathode end of the first diode 272 are electrically connected to the other end of the circuit breaker 271 and the anode end (i.e., the first end 211) of the semiconductor switch unit 21, respectively.

[0027] The motor 22 is electrically connected to the input power source Vin and the first end 211 of the semiconductor switch unit 21. The motor 22 may be a three-phase motor or a single-phase motor. In the present embodiment, the motor 22 is a single-phase motor. The motor 22 includes a plurality of upper arm switches 221, a plurality of lower arm switches 222 and a motor coil 223. The plurality of upper and lower arm switches 221 and 222 are respectively represented as two upper arm switches 221 as PMOS transistors and two lower arm switches 222 as NMOS transistors in the present embodiment, but are not limited thereto. The multiple upper arm switches 221 are correspondingly connected to the multiple lower arm switches 222, that is, the drain terminals of the two upper arm switches 221 are electrically connected to the input power supply Vin and the anode terminal (i.e., the first terminal 211) of the semiconductor switch unit 21, and the drain terminals of the two upper arm switches 221 are the motor power supply terminals, the source terminals of the two upper arm switches 221 are electrically connected to the drain terminals of the corresponding two lower arm switches 222, and the connection points between the two upper arm switches 221 and the two lower arm switches 222 are connected to the motor coil 223, and the source terminals of the two lower arm switches 222 are electrically connected to a ground terminal Gnd.

[0028] The motor driving circuit 23 is electrically connected to the motor 22 and the control unit 26. The motor driving circuit 23 is used to output a driving signal to the motor 22, and the motor driving circuit 23 includes a first motor driving unit 231 and a second motor driving unit 232. In the present embodiment, the first and second motor driving units 231 and 232 each include a plurality of resistors and at least one transistor (such as an NMOS transistor), and the other ends of the first and second motor driving units 231 and 232 are respectively electrically connected to the gate ends of the plurality of lower arm switches 222 of the motor 22, and the first and second motor driving units 231 and 232 each transmit a driving signal to the plurality of lower arm switches 222 of the motor 22. In the actual implementation of the present invention, the number of the motor drive unit and the plurality of upper and lower arm switches 221, 222 is adjusted and changed in accordance with the number of phases of the motor 22. For example, if the motor 22 is a three-phase motor, the number of the motor drive units is adjusted to three motor drive units in accordance with the three upper arm switches 221 and the three lower arm switches 222, and so on.

[0029] The isolation unit 24 is electrically connected between the semiconductor switch unit 21 and the motor drive circuit 23. The isolation unit 24 has a plurality of resistors, and the plurality of resistors are electrically connected to the motor drive circuit 23 and the second end 212, respectively. In this embodiment, the plurality of resistors represent four resistors, that is, the plurality of resistors have a first resistor 241, a second resistor 242, a third resistor 243 and a fourth resistor 244. One end of the first and second resistors 241 and 242 is electrically connected to the other end corresponding to the first motor drive unit 231 and the gate end of the first lower arm switch 222 of the motor 22. The third resistor 243 is electrically connected to the gate end of the first lower arm switch 222 of the motor 22. One end of the first and fourth resistors 243 and 244 is electrically connected to the other end of the second motor drive unit 232 and the gate end of the second lower arm switch 222 of the motor 22. The other ends of the first and third resistors 241 and 243 are electrically connected to the second end 212 of the semiconductor switch unit 21 and an operating voltage Vc (such as 5 volts). The other ends of the second and fourth resistors 242 and 244 are electrically connected to each other, so the plurality of resistors (i.e., the first, second, third, and fourth resistors 241, 242, 243, and 244) are used as a driving signal for separating the normal driving of the fan motor 22 (single-phase motor or three-phase motor). In the actual implementation of the present invention, the number of the plurality of resistors is matched with the number of the motor drive units, for example, 3 motor drive units are matched with 3 groups of resistors, and each group of resistors is composed of 2 resistors or more than 2 resistors.

[0030] The charge-discharge unit 25 is electrically connected to the multiple resistors of the isolation unit 24 to receive and store the operating voltage Vc. The charge-discharge unit 25 includes a capacitor 251 and a charge-discharge resistor 252. One end of the charge-discharge resistor 252 is electrically connected to the other end of the second resistor 242 and the other end of the fourth resistor 244, respectively. The other end of the charge-discharge resistor 252 is electrically connected to one end of the capacitor 251. The other end of the capacitor 251 is electrically connected to the ground terminal Gnd. The first and second motor drive units 231 and 232 receive the high-voltage operating voltage Vc released by the charge-discharge unit 25 to transmit respective drive signals to the multiple lower arm switches 222 for conduction. Therefore, by adjusting the capacitance value of the capacitor 251 in the charge-discharge unit 25 and the resistance value of the charge-discharge resistor 252, the time length of the potential charge-discharge adjustment can be controlled, and then the conduction time length of the multiple lower arm switches 222 and the fan brake stop time can be controlled, so as to effectively achieve good adjustment flexibility.

[0031] In addition, the semiconductor switch unit 21 of the present invention can prevent the voltage (potential) of the capacitor 251 of the charge-discharge unit 25 from being discharged from the connection path between the first end 211 and the motor power supply end after the fan is powered off, so as to keep the voltage of the capacitor 251 of the charge-discharge unit 25 to be continuously provided to the first and second motor drive units 231 and 232 for a long time, so that the first and second motor drive units 231 and 232 each transmit the drive signal to drive the corresponding multiple lower arm switches 222 to conduct to form a short circuit with the two ends of the motor coil 223, so that the fan motor 22 can achieve the effect of rapid braking and complete stop. Figure 4 1 is a diagram showing an actual measurement waveform of the input power supply Vin, the voltage of the capacitor 251 of the charge and discharge unit 25, the voltage of the motor coil 223 and the fan current in one embodiment of the present invention. In the figure, the waveform symbol of the input power supply Vin is V, and the arrow Vup in the waveform V of the input power supply Vin represents the power-on of the input power supply Vin (i.e., the fan is powered on) and the arrow Vdown represents the power-down of the input power supply Vin (i.e., the fan is powered off). The voltage waveform symbol of the capacitor 251 is C, and the arrow Cv in the voltage waveform C of the capacitor 251 represents the power-off of the fan. , the operating voltage Vc stored in the capacitor 251 can be maintained above the conduction voltage of the multiple lower arm switches 222 and the conduction time of the lower arm switches 222 is relatively long; the voltage waveform symbol of the motor coil 223 is M, and the horizontal smooth line in the dashed box area Moff in the voltage waveform M of the motor coil 223 represents that the fan motor has been quickly braked and stopped (that is, the fan blades have stopped suddenly and are completely still) and there is no back electromotive force voltage; the fan current waveform symbol is F, so according to the above actual measurement waveform results, the present invention can indeed achieve the effect of quickly braking the fan. In one embodiment, the charge and discharge unit 25 includes multiple capacitors 251 and multiple charge and discharge resistors 252.

[0032] The control unit 26 is a central processing unit (CPU) or a microcontroller (MCU) or a digital signal processor (DSP). The control unit 26 is connected to the input power supply Vin and the motor 22 to output multiple control signals (such as PWM signals) to control the motor drive circuit 23 and the motor 22 respectively. In this embodiment, a second diode 273 is provided between the control unit 26 and the input power supply Vin, and the anode end of the second diode 273 is electrically connected to the input power supply Vin, and the cathode end of the second diode 273 is electrically connected to the control unit 26. The control unit 26 has a plurality of pins, wherein a first and a fourth pin 261, 264 are electrically connected to the gate terminals of the plurality of upper arm switches 221 of the motor 22, a second and a third pin 262, 263 are electrically connected to one end of the first and the second motor driving units 231, 232, and a fifth pin 265 is electrically connected to the cathode terminal of the second diode 273. The four pins (i.e., the first, second, third, and fourth pins 261, 262, 263, and 264) of the control unit 26 each output a control signal (Pulse Width Modulation; PWM signal) to control the switching actions of the plurality of upper arm switches 221 (such as whether the switches are turned on or off) and to control the first and the second motor driving units 231, 232 to respectively drive the switching actions of the corresponding plurality of lower arm switches 222 (such as whether the switches are turned on or off) to allow the fan motor 22 to operate.

[0033] Therefore, when the fan is powered off, the semiconductor switch unit 21 will disconnect the first end 211 from the motor 22 (i.e., disconnect the first end 211 from the motor power supply end). At the same time, the semiconductor switch unit 21 will prevent the voltage (potential) of the capacitor 251 of the rear end charge and discharge unit 25 from being consumed in reverse. At this time, the charge and discharge unit 25 will release the stored operating voltage Vc to the first and second motor drive units 231 and 232, so that the first and second motor drive units 231 and 232 drive the corresponding first and second lower arm switches 222 to remain conductive to form the short-circuit loop with the two ends of the motor coil 223, so that the motor 22 can achieve a rapid braking effect.

[0034] In one possible embodiment, see Figure 2CA capacitor 28 is provided between the first diode 272 and the semiconductor switch unit 21, one end of the capacitor 28 is electrically connected to the cathode end of the first diode 272, the anode end of the semiconductor switch unit 21 and the power supply end of the motor 22, the capacitor 28 receives and stores the input power Vin, and provides the input power Vin to the multiple upper arm switches 221 to conduct when the fan is powered off, so that the multiple upper arm switches 221 and the motor coil 223 are short-circuited to brake, because the motor coil 223 will quickly consume the input power Vin provided by the capacitor 28, so that the multiple upper arm switches 221 are not conducting, and at the same time, the charge and discharge unit 25 will provide the operating voltage Vc to the first and second motor drive units 231, 232 to drive the multiple lower arm switches 222 to maintain conduction (open), so as to continuously short-circuit the motor coil 223 to achieve the effect of rapid fan braking and double braking.

[0035] In an alternative embodiment, referring to FIGS. 3A and 3B, the semiconductor switch unit 21 is a semiconductor transistor, which is a field effect transistor (such as a MOS transistor) or an IGBT transistor. In this embodiment, the semiconductor switch unit 21 is a MOS transistor with a switch function, which is used to disconnect the connection between the first end 211 of the semiconductor switch unit 21 and the motor power supply end when the fan is powered off, but is not limited thereto. Any semiconductor transistor that can disconnect the connection between the first end and the motor power supply end when the fan is powered off is the semiconductor switch unit 21 referred to in the present invention. The semiconductor switch unit 21 has at least one semiconductor switch. In this alternative embodiment, the semiconductor switch unit 21 is represented as two semiconductor switches for illustration, that is, the semiconductor switch unit 21 has a first semiconductor switch 21a and a second semiconductor switch 21b. The first and second semiconductor switches 21a and 21b are respectively represented as an N-type metal oxide semiconductor (MOS) transistor and a P-type metal oxide semiconductor (MOS) transistor in this embodiment, and the first and second semiconductor switches 21a and 21b each have a first semiconductor switch 21a and a second semiconductor switch 21b. The first semiconductor switch 21a has a first terminal 211a, 211b, a second terminal 212a, 212b and a third terminal 213a, 213b. The first terminal 211a of the first semiconductor switch 21a (i.e., the third terminal 213 of the semiconductor switch unit 21) is a gate terminal electrically connected to the control unit 26 and the input power supply Vin. The third terminal 213a of the first semiconductor switch 21a is a drain terminal electrically connected to the first terminal 211b of the second semiconductor switch 21b as a gate terminal. The second terminal 212a of the first semiconductor switch 21a is a source terminal. The first terminal 212a (the gate terminal) of the first semiconductor switch 21a is electrically connected to the ground terminal Gnd, the second terminal 212b (the first terminal 211 of the semiconductor switch unit 21) of the second semiconductor switch 21b is the source terminal electrically connected to the input power supply Vin and the motor power terminal, and the third terminal 213b (the second terminal 212 of the semiconductor switch unit 21) of the second semiconductor switch 21b is the drain terminal electrically connected to the other end of the first and third resistors 241 and 243. When the fan is powered off, the voltage of the first terminal (gate terminal) of the first semiconductor switch 21a is less than the voltage of the second terminal 212a (the source terminal) of the first semiconductor switch 21a. The voltage at the first terminal 211b (gate terminal) of the second semiconductor switch 21b is open circuit (non-conducting), the voltage at the first terminal 211b (gate terminal) of the second semiconductor switch 21b is greater than the voltage at the second terminal 212b (source terminal), and the resistance from the second terminal 212b to the third terminal 213b is very large, so that the second semiconductor switch 21b is open circuit (non-conducting). Therefore, the first and second semiconductor switches 21a and 21b of the present invention can prevent the voltage (potential) of the capacitor 251 of the charge and discharge unit 25 from being discharged from the path between the first terminal 211 and the motor power supply terminal after the fan is powered off.

[0036] Therefore, through the design of the fan brake circuit 2 of the present invention, the fan can be effectively stopped quickly when the power is cut off and the cost can be reduced. In addition, the capacitance value in the charge-discharge unit 25 does not need to be a large capacitance value with a large capacitor size and there is no need to increase the capacitance all the time. Therefore, the capacitor element 251 of the charge-discharge unit 25 of the present invention can be a small capacitor (for example, a small ceramic chip capacitor of 0402, 0603, 0805 size, but not limited to this), so as to facilitate installation on the fan circuit board (PCB) without space restrictions, or to leave more space on the circuit board under the limited space for other electronic components (such as IC chips, heat dissipation components or transistors) to be set up and used, so as to effectively achieve the miniaturization of the fan brake circuit 2, and the fan as a whole in the present case can also achieve the miniaturization effect with the design of small capacitor size and small volume.

Claims

1. A fan brake circuit, characterized in that: include: A semiconductor switch unit having a first end and a second end, wherein the first end is used to receive an input power source; a motor electrically connected to the input power source and the first end; a motor driving circuit, electrically connected to the motor, for outputting a driving signal to the motor; an isolation unit electrically connected between the semiconductor switch unit and the motor drive circuit, the isolation unit having a plurality of resistors, the plurality of resistors being electrically connected to the motor drive circuit and the second end respectively; a charge-discharge unit, electrically connected to the plurality of resistors, for receiving and storing an operating voltage; a control unit electrically connected to the input power source, the motor drive circuit and the motor, and configured to output a plurality of control signals to control the motor drive circuit and the motor respectively; and When the fan is powered off, the semiconductor switch unit disconnects the first end from the motor, and the motor drive circuit receives the operating voltage provided by the charge and discharge unit and transmits the drive signal to the motor, so that the motor forms a short circuit and brakes.

2. The fan brake circuit according to claim 1, characterized in that: The multiple resistors include a first resistor, a second resistor, a third resistor and a fourth resistor. One end of the first, second, third and fourth resistors is electrically connected to the corresponding motor drive circuit, the other ends of the first and third resistors are electrically connected to the second end of the semiconductor switch unit, and the other ends of the second and fourth resistors are electrically connected to each other.

3. The fan brake circuit according to claim 2, characterized in that: The charge-discharge unit includes a capacitor and a charge-discharge resistor. The charge-discharge resistor is electrically connected to the other end of the second resistor and one end of the capacitor respectively. The other end of the capacitor is electrically connected to a ground terminal.

4. The fan brake circuit according to claim 3, characterized in that: The semiconductor switch unit is a diode, an anode terminal of the semiconductor switch unit is the first terminal, and a cathode terminal of the semiconductor switch unit is the second terminal.

5. The fan brake circuit according to claim 3, characterized in that: The semiconductor switch unit has a third end, a first semiconductor switch and a second semiconductor switch. The first semiconductor switch and the second semiconductor switch each have a first end, a second end and a third end. The third end of the semiconductor switch unit is the first end of the first semiconductor switch electrically connected to the control unit and the input power supply. The third end of the first semiconductor switch is electrically connected to the first end of the second semiconductor switch. The second end of the first semiconductor switch and the second end of the second semiconductor switch are electrically connected to the ground end and the input power supply respectively. The second end of the second semiconductor switch is the first end of the semiconductor switch unit. The second end of the semiconductor switch unit is the third end of the second semiconductor switch electrically connected to the other end of the first and three resistors.

6. The fan brake circuit according to claim 5, characterized in that: The first and second semiconductor switches are respectively an N-type metal oxide semiconductor transistor and a P-type metal oxide semiconductor transistor, and the first terminals of the first and second semiconductor switches are both gate terminals, the second terminals of the first and second semiconductor switches are both source terminals, and the third terminals of the first and second semiconductor switches are both drain terminals.

7. The fan brake circuit according to claim 5, characterized in that: The first and second semiconductor switches are semiconductor transistors, and the semiconductor transistors are field effect transistors or IGBT transistors.

8. The fan brake circuit according to claim 2, characterized in that: The control unit has a plurality of pins, and the motor drive circuit includes a first motor drive unit and a second motor drive unit, one end of the first motor drive unit and the second motor drive unit are respectively electrically connected to a second pin and a third pin among the plurality of pins, the other end of the first motor drive unit is respectively electrically connected to one end of the first resistor and the second resistor and the motor, the other end of the second motor drive unit is respectively electrically connected to one end of the third resistor and the fourth resistor and the motor, and a first pin and a fourth pin among the plurality of pins are respectively electrically connected to the motor.

9. The fan brake circuit according to claim 8, characterized in that: The motor has multiple upper arm switches, multiple lower arm switches and a motor coil, the multiple upper arm switches are correspondingly connected to the multiple lower arm switches, the connection points between the multiple upper arm switches and the multiple lower arm switches are connected to the motor coil, the other end of the first motor drive unit is electrically connected to one of the multiple lower arm switches, and the other end of the second motor drive unit is electrically connected to another lower arm switch among the multiple lower arm switches.

10. The fan brake circuit according to claim 1, characterized in that: The control unit is a central processing unit, a microcontroller or a digital signal processor.

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