Brushless motor control circuit for hair drier and hair drier

Abstract

The utility model discloses a brushless motor control circuit for a hair drier and the hair drier, and relates to the technical field of control circuits. The brushless motor driving circuit comprises a voltage source, a step-down circuit, a heat supply circuit and a brushless motor driving circuit, the output end of the voltage source is connected with the input end of the step-down circuit and the input end of the heat supply circuit, and the output end of the step-down circuit is connected with the input end of the brushless motor driving circuit. The input end of the voltage source is connected with the output end of the brushless motor drive circuit and the output end of the heat supply circuit, and the voltage reduction circuit is used for reducing the voltage output by the voltage source to the working voltage. According to the utility model, high voltage output by the voltage source is effectively reduced to lower voltage suitable for the operation of the brushless motor and the heat supply circuit through the step-down circuit, so that the whole circuit is simplified, the requirement of using a high-voltage-resistant component is reduced, the size and volume of a circuit board are reduced, and the material cost and the production cost are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of control circuits, in particular to a brushless motor control circuit for a hair dryer and the hair dryer. Background Art

[0002] High-speed brushless motors have been widely used in the field of hair dryers due to their high efficiency, long life and low maintenance requirements. High-speed brushless motors generate low noise and vibration during operation, which makes the user experience more comfortable. With the advancement of technology and the increasing demand of consumers for high-performance hair dryers, the application of high-speed brushless motors in this field is increasing, becoming the preferred technology for modern hair dryer design.

[0003] However, existing hair dryers need to convert electricity directly from strong alternating current (AC100-240V). Their circuits must be equipped with components that can withstand high voltage and high current, making the circuit board design complex and bulky. This not only makes the product bulky and difficult to use for a long time, but also significantly increases material and production costs. Utility Model Content

[0004] The purpose of the present utility model is to address the defects and shortcomings of the prior art. On the one hand, it provides a brushless motor control circuit for a hair dryer, comprising a voltage source, a step-down circuit, a heating circuit, and a brushless motor drive circuit, wherein the output end of the voltage source is connected to the input end of the step-down circuit and the input end of the heating circuit, the output end of the step-down circuit is connected to the input end of the brushless motor drive circuit, and the input end of the voltage source is connected to the output end of the brushless motor drive circuit and the output end of the heating circuit, wherein:

[0005] The step-down circuit is used to reduce the voltage output by the voltage source to an operating voltage.

[0006] Furthermore, the step-down circuit includes a first resistor R3 , one end of the first resistor R3 is connected to the output end of the voltage source, and the other end of the first resistor R3 is connected to the input end of the brushless motor drive circuit.

[0007] Furthermore, a rectifier circuit is included, which is used to convert the alternating current output by the voltage source into direct current, wherein:

[0008] The rectifier circuit is provided between the step-down circuit and the brushless motor drive circuit;

[0009] Alternatively, it is provided between the voltage source and the step-down circuit.

[0010] Furthermore, the heating circuit includes a second resistor R1, a third resistor R2 and a fuse FU, one end of the fuse FU is connected to the output end of the voltage source, the other end of the fuse FU is connected to one end of the second resistor R1 and one end of the third resistor R2, and the other end of the second resistor R1 and the other end of the third resistor R2 are connected to the input end of the voltage source.

[0011] Furthermore, the heating circuit also includes a thermostat, a first temperature-controlled switch K1 and a second temperature-controlled switch K2. The thermostat is arranged between the other end of the fuse FU and one end of the second resistor R1, the first temperature-controlled switch K1 is arranged between the thermostat and the second resistor R1, and the second temperature-controlled switch K2 is arranged between the thermostat and the third resistor R2. The thermostat is used to collect the temperature of the heating circuit and control the on / off of the heating circuit.

[0012] Furthermore, the motor drive circuit includes a fourth resistor R11, a fifth resistor R13, a sixth resistor R55, a seventh resistor R56, an eighth resistor R57, a ninth resistor R58, a tenth resistor R17, a first capacitor C23, a second capacitor C35, a third capacitor C29, a fourth capacitor CY1, a first switch tube Q5, a second switch tube Q6, and a controller U6, wherein:

[0013] One end of the fourth resistor R11 and one end of the fifth resistor R13 are connected to the brushless motor, the other end of the fourth resistor R11 is connected to one end of the first capacitor C23 and the second port HIN of the controller U6, the other end of the fifth resistor R13 is connected to the other end of the first capacitor C23 and the third port LIN of the controller U6, one end of the second capacitor C35 is connected to the voltage source and the first port VCC of the controller U6, the other end of the second capacitor C35 is connected to the fourth port COM of the controller U6 and the ground, one end of the third capacitor C29 is connected to the eighth port VB of the controller U6 and the ground, the other end of the third capacitor C29 is connected to one end of the sixth resistor R55, the third port of the first switch tube Q5, and the second switch tube Q6 the first port of the controller U6, the sixth port Vs of the controller U6 and the brushless motor, the other end of the sixth resistor R55 is connected to one end of the seventh resistor R56 and the second port of the first switch tube Q5, the other end of the seventh resistor R56 is connected to the seventh port HO of the controller U6, the first port of the first switch tube Q5 is connected to the brushless motor and the ground end, one end of the eighth resistor R57 is connected to the fifth port LO of the controller U6, the other end of the eighth resistor R57 is connected to one end of the ninth resistor R58 and the second port of the second switch tube Q6, the other end of the ninth resistor R58 is connected to the third port of the second switch tube Q6 and one end of the tenth resistor R17, one end of the fourth capacitor CY1 is grounded, and the other end of the fourth capacitor CY1 is connected to the brushless motor.

[0014] Furthermore, the device further includes a current sampling circuit, which includes a first op amp, a second op amp, a third op amp, an eleventh resistor R31, a twelfth resistor R38, a thirteenth resistor R40, a fourteenth resistor R42, a fifteenth resistor R32, a sixteenth resistor R35, a fifth capacitor C17, a sixth capacitor C26, a seventh capacitor C21, an eighth capacitor C9, a ninth capacitor C16, and a tenth capacitor C22. The other end of the tenth resistor R17 is connected to one end of the twelfth resistor R38, one end of the thirteenth resistor R40, one end of the sixteenth resistor R35, one end of the sixth capacitor C26, one end of the eighth capacitor C9, and one end of the tenth capacitor C22. The other end of the eighth capacitor C9 is connected to one end of the fourteenth resistor R42 and ground. The other end of the fourteenth resistor R42 is connected to one end of the seventh capacitor C21 and the second op amp. The other end of the seventh capacitor C21 is connected to the negative input terminal OPA1N of the third op amp, the other end of the seventh capacitor C21 is connected to the other end of the thirteenth resistor R40 and the positive input terminal OPA1P of the second op amp, one end of the twelfth resistor R38 is connected to one end of the fifth capacitor C17 and the negative input terminal OPA2N of the first op amp, the other end of the fifth capacitor C17 is connected to one end of the eleventh resistor R31 and the positive input terminal OPA2P of the first op amp, the other end of the eleventh resistor R31 is connected to the other end of the sixth capacitor C26, the other end of the sixteenth resistor R35 is connected to the negative input terminal OPA0N of the third op amp and one end of the ninth capacitor C16, the other end of the ninth capacitor C16 is connected to one end of the fifteenth resistor R32 and the positive input terminal OPA0P of the third op amp, and the other end of the fifteenth resistor R32 is connected to the other end of the tenth capacitor C22.

[0015] Furthermore, the first resistor R3, the second resistor R1 and the third resistor R2 are heating resistance wires.

[0016] Furthermore, the controller U6 is a half-bridge driver, model IR2104 or BP6904A.

[0017] On the other hand, the present invention also provides a hair dryer, comprising the brushless motor control circuit for the hair dryer according to the above technical solution.

[0018] The embodiment of the utility model uses a step-down circuit to effectively reduce the high voltage output by the voltage source to a lower voltage suitable for the operation of the brushless motor and the heating circuit, thereby simplifying the overall circuit. This not only reduces the need for using high-voltage components, but also significantly reduces the size and volume of the circuit board, directly reducing material costs and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 It is a structural block diagram of the first embodiment of the utility model;

[0021] Figure 2 It is a structural block diagram of the second embodiment of the utility model;

[0022] Figure 3 It is a circuit diagram of the heating circuit of the utility model;

[0023] Figure 4 This is a circuit diagram of the brushless motor drive circuit of the utility model;

[0024] Figure 5 It is a circuit diagram of the current sampling circuit of the utility model.

[0025] Reference numerals:

[0026] 100, voltage source; 200, step-down circuit; 300, heating circuit; 400, brushless motor drive circuit; 500, rectifier circuit; 600, current sampling circuit. DETAILED DESCRIPTION

[0027] The present invention will be described in further detail below with reference to the accompanying drawings.

[0028] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

[0029] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0031] First embodiment:

[0032] 1 , the present invention provides a brushless motor control circuit for a hair dryer, comprising a voltage source 100, a step-down circuit 200, a heating circuit 300, and a brushless motor drive circuit 400. The output of the voltage source 100 is connected to the input of the step-down circuit 200 and the input of the heating circuit 300, the output of the step-down circuit 200 is connected to the input of the brushless motor drive circuit 400, and the input of the voltage source 100 is connected to the output of the brushless motor drive circuit 400 and the output of the heating circuit 300.

[0033] The step-down circuit 200 is used to reduce the voltage output by the voltage source 100 to an operating voltage.

[0034] The embodiment of the utility model uses a step-down circuit to effectively reduce the high voltage output by the voltage source to a lower voltage suitable for the operation of the brushless motor and the heating circuit, thereby simplifying the overall circuit. This not only reduces the need for using high-voltage components, but also significantly reduces the size and volume of the circuit board, directly reducing material costs and production costs.

[0035] Second embodiment:

[0036] 2-5 , the present invention provides another brushless motor control circuit for a hair dryer. Specifically, the step-down circuit 200 includes a first resistor R3 , one end of the first resistor R3 is connected to the output end of the voltage source 100 , and the other end of the first resistor R3 is connected to the input end of the brushless motor drive circuit 400 .

[0037] In this embodiment, by introducing the first resistor R3 as a voltage-reducing element, the structure of the voltage-reducing circuit is simplified and the complexity of the circuit design is reduced.

[0038] In addition, using resistors to achieve voltage reduction increases the flexibility of circuit design, making it easy to adjust the resistance value according to different design requirements to adapt to different operating voltages and load conditions.

[0039] Optionally, a rectifier circuit 500 is further included, and the rectifier circuit 500 is used to convert the alternating current output by the voltage source 100 into direct current, wherein:

[0040] The rectifier circuit 500 is provided between the step-down circuit 200 and the brushless motor drive circuit 400;

[0041] Alternatively, it is provided between the voltage source 100 and the step-down circuit 200 .

[0042] In this embodiment, by converting the AC power output by the voltage source 100 into DC power, this embodiment is compatible with a DC brushless motor. The use of a DC brushless motor not only improves the overall energy efficiency of the hair dryer, but also optimizes the speed and torque control of the motor, further enhancing the product performance and user experience.

[0043] Optionally, the heating circuit 300 includes a second resistor R1, a third resistor R2 and a fuse FU, one end of the fuse FU is connected to the output end of the voltage source 100, the other end of the fuse FU is connected to one end of the second resistor R1 and one end of the third resistor R2, and the other end of the second resistor R1 and the other end of the third resistor R2 are connected to the input end of the voltage source 100.

[0044] Specifically, the voltage output by the voltage source 100 first passes through the fuse FU. As a safety device, the fuse mainly cuts off the circuit when the current is overloaded to prevent excessive current from causing circuit damage or fire. After the current passes through the fuse, it enters the second resistor R1 and the third resistor R2 respectively. The second resistor R1 and the third resistor R2 serve as heating elements. The heat energy generated when the current passes through the resistors is used to heat the air to realize the drying function of the hair dryer. This not only ensures the heating efficiency of the hair dryer, but also disperses the heat through the second resistor R1 and the third resistor R2, which helps to uniformly heat and improve the blowing effect.

[0045] This embodiment uses the fuse FU to protect the heating circuit from damage due to excessive current, thereby improving the safe service life of the equipment. At the same time, this embodiment uses the second resistor R1 and the third resistor R2 to make the heat distribution more uniform and the heating effect more ideal, so that users can obtain a more stable and comfortable blowing experience when using it.

[0046] Optionally, the heating circuit 300 also includes a thermostat, a first temperature-controlled switch K1 and a second temperature-controlled switch K2. The thermostat is arranged between the other end of the fuse FU and one end of the second resistor R1, the first temperature-controlled switch K1 is arranged between the thermostat and the second resistor R1, and the second temperature-controlled switch K2 is arranged between the thermostat and the third resistor R2. The thermostat is used to collect the temperature of the heating circuit 300 and control the on / off of the heating circuit 300.

[0047] Specifically, the thermostat may be an E5CC series thermostat from Omron or a DT series thermostat from Delta.

[0048] In an embodiment of the present invention, the thermostat is located between the fuse FU and the second resistor R1, and is used to monitor the temperature of the heating circuit in real time, so that the thermostat can adjust the current on and off of the heating circuit based on the current temperature reading, ensuring that the hair dryer operates within a safe and ideal temperature range.

[0049] In an embodiment of the present invention, the first temperature-controlled switch K1 and the second temperature-controlled switch K2 are respectively arranged between the thermostat and the second resistor R1 and the third resistor R2. The first temperature-controlled switch K1 and the second temperature-controlled switch K2 are respectively used to control the heating resistors, allowing the thermostat to independently adjust the heating output of each resistor as needed.

[0050] Optionally, the motor drive circuit includes a fourth resistor R11, a fifth resistor R13, a sixth resistor R55, a seventh resistor R56, an eighth resistor R57, a ninth resistor R58, a tenth resistor R17, a first capacitor C23, a second capacitor C35, a third capacitor C29, a fourth capacitor CY1, a first switch tube Q5, a second switch tube Q6, and a controller U6, wherein:

[0051] One end of the fourth resistor R11 and one end of the fifth resistor R13 are connected to the brushless motor, the other end of the fourth resistor R11 is connected to one end of the first capacitor C23 and the second port HIN of the controller U6, the other end of the fifth resistor R13 is connected to the other end of the first capacitor C23 and the third port LIN of the controller U6, one end of the second capacitor C35 is connected to the voltage source 100 and the first port VCC of the controller U6, the other end of the second capacitor C35 is connected to the fourth port COM of the controller U6 and the ground, one end of the third capacitor C29 is connected to the eighth port VB of the controller U6 and the ground, the other end of the third capacitor C29 is connected to one end of the sixth resistor R55, the third port of the first switch tube Q5, and the second switch tube Q 6, the sixth port Vs of the controller U6 and the brushless motor, the other end of the sixth resistor R55 is connected to one end of the seventh resistor R56 and the second port of the first switch tube Q5, the other end of the seventh resistor R56 is connected to the seventh port HO of the controller U6, the first port of the first switch tube Q5 is connected to the brushless motor and the ground end, one end of the eighth resistor R57 is connected to the fifth port LO of the controller U6, the other end of the eighth resistor R57 is connected to one end of the ninth resistor R58 and the second port of the second switch tube Q6, the other end of the ninth resistor R58 is connected to the third port of the second switch tube Q6 and one end of the tenth resistor R17, one end of the fourth capacitor CY1 is grounded, and the other end of the fourth capacitor CY1 is connected to the brushless motor.

[0052] Specifically, the port functions of controller U6 are as follows:

[0053] HIN: high-side input;

[0054] LIN: low side input;

[0055] COM: Commons;

[0056] LO: low side output;

[0057] Vs: high-side floating power supply loop;

[0058] HO: high-side output;

[0059] VB: high-side floating power supply;

[0060] VCC: logic power supply.

[0061] Specifically, the first switch tube Q5 and the second switch tube Q6 are N-MOSFETs, the first ports of the first switch tube Q5 and the second switch tube Q6 are drains, the second ports of the first switch tube Q5 and the second switch tube Q6 are gates, and the third ports of the first switch tube Q5 and the second switch tube Q6 are sources.

[0062] In this embodiment, resistors R11 and R13 are located on the high-side and low-side input lines of the controller U6 and are connected to the first capacitor C23 to stabilize the input signal and prevent noise from interfering with the performance of the controller. Resistors R55, R56, R57 and R58 are used for current sampling and ensuring the correct driving of the switching tube. Capacitors C35, C29 and CY1 are used for power supply filtering and decoupling to ensure stable operation of the circuit and improve response speed.

[0063] In this embodiment, when the controller U6 receives signals from an external control system (such as a microcontroller or sensor), it adjusts the states of the HIN and LIN ports according to these signals, thereby controlling the opening and closing of Q5 and Q6. For example, when the HIN port is activated, Q5 is turned on, allowing current to flow from the power supply through Q5 to the motor, driving the motor to rotate. Correspondingly, when the LIN port is activated, Q6 is turned on, allowing current to flow back to the ground through Q6, completing the current cycle.

[0064] In the above manner, the motor drive circuit in this embodiment can not only accurately control the start, stop and speed regulation of the brushless motor, but also control the torque output by adjusting the magnitude and direction of the current, thereby adapting to different loads and operating conditions.

[0065] Optionally, a current sampling circuit 600 is further included, wherein the current sampling circuit 600 includes a first op amp, a second op amp, a third op amp, an eleventh resistor R31, a twelfth resistor R38, a thirteenth resistor R40, a fourteenth resistor R42, a fifteenth resistor R32, a sixteenth resistor R35, a fifth capacitor C17, a sixth capacitor C26, a seventh capacitor C21, an eighth capacitor C9, a ninth capacitor C16, and a tenth capacitor C22, wherein the other end of the tenth resistor R17 is connected to one end of the twelfth resistor R38, one end of the thirteenth resistor R40, one end of the sixteenth resistor R35, one end of the sixth capacitor C26, one end of the eighth capacitor C9, and one end of the tenth capacitor C22, the other end of the eighth capacitor C9 is connected to one end of the fourteenth resistor R42 and ground, and the other end of the fourteenth resistor R42 is connected to one end of the seventh capacitor C21 and the The negative input terminal OPA1N of the second op amp, the other end of the seventh capacitor C21 is connected to the other end of the thirteenth resistor R40 and the positive input terminal OPA1P of the second op amp, one end of the twelfth resistor R38 is connected to one end of the fifth capacitor C17 and the negative input terminal OPA2N of the first op amp, the other end of the fifth capacitor C17 is connected to one end of the eleventh resistor R31 and the positive input terminal OPA2P of the first op amp, the other end of the eleventh resistor R31 is connected to the other end of the sixth capacitor C26, the other end of the sixteenth resistor R35 is connected to the negative input terminal OPA0N of the third op amp and one end of the ninth capacitor C16, the other end of the ninth capacitor C16 is connected to one end of the fifteenth resistor R32 and the positive input terminal OPA0P of the third op amp, and the other end of the fifteenth resistor R32 is connected to the other end of the tenth capacitor C22.

[0066] Specifically, in the present invention, the current sampling circuit 600 is designed to accurately measure and monitor the current flow in each circuit part of the hair dryer, thereby providing the necessary data to support the circuit's optimized control and protection mechanism; the first op amp, the second op amp, and the third op amp amplify the current signal in the circuit to a level suitable for processing; the eleventh resistor R31, the twelfth resistor R38, the thirteenth resistor R40, the fourteenth resistor R42, the fifteenth resistor R32, and the sixteenth resistor R35 serve as sensitive elements for current detection. They provide the necessary signals for current measurement through the voltage drop when current passes through. The above-mentioned resistors are connected to the input terminals of each operational amplifier to generate a voltage signal proportional to the current.

[0067] Specifically, the fifth capacitor C17, the sixth capacitor C26, the seventh capacitor C21, the eighth capacitor C9, the ninth capacitor C16, and the tenth capacitor C22 are used to filter and stabilize the signal to prevent high-frequency noise from interfering with the measurement results. The above capacitors play a role in decoupling and response speed adjustment at the input and output ends of the operational amplifier, ensuring that the operational amplifier can stably and accurately amplify the current signal.

[0068] In this embodiment, the main function of the current sampling circuit is to monitor the magnitude and changes of the current in real time to ensure that the hair dryer operates in an optimal state of safety and efficiency. By accurately measuring the current of each part, the circuit can promptly detect any abnormal conditions such as overload or short circuit, and respond quickly through the control system to prevent possible circuit damage or failure.

[0069] Optionally, the first resistor R3, the second resistor R1 and the third resistor R2 are heating resistance wires.

[0070] In this embodiment, the first resistor R3 divides the voltage so that the voltage input to the brushless motor driving circuit 400 is reduced to between 2.5V and 50V.

[0071] Optionally, the controller U6 is a half-bridge driver, model IR2104 or BP6904A.

[0072] In this embodiment, the controller U6 uses a half-bridge driver of model IR2104 or BP6904A, which can efficiently control the power output of the motor, optimize performance, and reduce system complexity and cost.

[0073] The above is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A brushless motor control circuit for a hair dryer, characterized in that: The invention comprises a voltage source (100), a step-down circuit (200), a heating circuit (300), and a brushless motor drive circuit (400), wherein the output end of the voltage source (100) is connected to the input end of the step-down circuit (200) and the input end of the heating circuit (300), the output end of the step-down circuit (200) is connected to the input end of the brushless motor drive circuit (400), and the input end of the voltage source (100) is connected to the output end of the brushless motor drive circuit (400) and the output end of the heating circuit (300), wherein: The step-down circuit (200) is used to reduce the voltage output by the voltage source (100) to an operating voltage.

2. A brushless motor control circuit for a hair dryer according to claim 1, characterized in that: The step-down circuit (200) comprises a first resistor, one end of the first resistor being connected to the output end of the voltage source (100), and the other end of the first resistor being connected to the input end of the brushless motor drive circuit (400).

3. A brushless motor control circuit for a hair dryer according to claim 2, characterized in that: It also includes a rectifier circuit (500), which is used to convert the alternating current output by the voltage source (100) into direct current, wherein: The rectifier circuit (500) is provided between the step-down circuit (200) and the brushless motor drive circuit (400); Alternatively, it is provided between the voltage source (100) and the step-down circuit (200).

4. A brushless motor control circuit for a hair dryer according to claim 3, characterized in that: The heating circuit (300) comprises a second resistor, a third resistor and a fuse, one end of the fuse is connected to the output end of the voltage source (100), the other end of the fuse is connected to one end of the second resistor and one end of the third resistor, and the other end of the second resistor and the other end of the third resistor are connected to the input end of the voltage source (100).

5. The brushless motor control circuit for a hair dryer according to claim 4, characterized in that: The heating circuit (300) further comprises a thermostat, a first temperature-controlled switch, and a second temperature-controlled switch; the thermostat is arranged between the other end of the fuse and one end of the second resistor; the first temperature-controlled switch is arranged between the thermostat and the second resistor; the second temperature-controlled switch is arranged between the thermostat and the third resistor; the thermostat is used to collect the temperature of the heating circuit (300) and control the on / off state of the heating circuit (300).

6. The brushless motor control circuit for a hair dryer according to claim 3, characterized in that: The motor drive circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first switch tube, a second switch tube and a controller, wherein: One end of the fourth resistor and one end of the fifth resistor are connected to the brushless motor, the other end of the fourth resistor is connected to one end of the first capacitor and the second port of the controller, the other end of the fifth resistor is connected to the other end of the first capacitor and the third port of the controller, one end of the second capacitor is connected to the voltage source (100) and the first port of the controller, the other end of the second capacitor is connected to the fourth port of the controller and the ground, one end of the third capacitor is connected to the eighth port of the controller and the ground, the other end of the third capacitor is connected to one end of the sixth resistor, the third port of the first switch tube, the first port of the second switch tube, the sixth port of the controller and the brushless motor, the other end of the sixth resistor is connected to one end of the seventh resistor and the second port of the first switch tube, the other end of the seventh resistor is connected to the seventh port of the controller, the first port of the first switch tube is connected to the brushless motor and the ground, one end of the eighth resistor is connected to the fifth port of the controller, the other end of the eighth resistor is connected to one end of the ninth resistor and the second port of the second switch tube, the other end of the ninth resistor is connected to the third port of the second switch tube and one end of the tenth resistor, one end of the fourth capacitor is grounded, and the other end of the fourth capacitor is connected to the brushless motor.

7. A brushless motor control circuit for a hair dryer according to claim 6, characterized in that: The current sampling circuit (600) is further comprised of a first operational amplifier, a second operational amplifier, a third operational amplifier, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, and a tenth capacitor, wherein the other end of the tenth resistor is connected to one end of the twelfth resistor, one end of the thirteenth resistor, one end of the sixteenth resistor, one end of the sixth capacitor, one end of the eighth capacitor, and one end of the tenth capacitor, the other end of the eighth capacitor is connected to one end of the fourteenth resistor and ground, and the other end of the fourteenth resistor is connected to one end of the seventh capacitor. and the negative input terminal of the second operational amplifier, the other end of the seventh capacitor is connected to the other end of the thirteenth resistor and the positive input terminal of the second operational amplifier, one end of the twelfth resistor is connected to one end of the fifth capacitor and the negative input terminal of the first operational amplifier, the other end of the fifth capacitor is connected to one end of the eleventh resistor and the positive input terminal of the first operational amplifier, the other end of the eleventh resistor is connected to the other end of the sixth capacitor, the other end of the sixteenth resistor is connected to the negative input terminal of the third operational amplifier and one end of the ninth capacitor, the other end of the ninth capacitor is connected to one end of the fifteenth resistor and the positive input terminal of the third operational amplifier, and the other end of the fifteenth resistor is connected to the other end of the tenth capacitor.

8. The brushless motor control circuit for a hair dryer according to claim 4, characterized in that: The first resistor, the second resistor and the third resistor are heating resistance wires.

9. The brushless motor control circuit for a hair dryer according to claim 6, characterized in that: The controller is a half-bridge driver, model IR2104 or BP6904A.

10. A hair dryer, characterized in that: The invention comprises a brushless motor control circuit for a hair dryer as described in any one of claims 1 to 9.

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