Brushless motor, control method and application method

Abstract

The invention relates to the technical field of brushless motors, in particular to a brushless motor, a control method and an application method. The rotor assembly is arranged in the motor shell; a closed end face is arranged at one end of the cylindrical shell; the magnet units are uniformly distributed on the inner wall of the cylindrical shell; the output shaft is coaxial with the cylindrical shell and penetrates through the closed end face. The stator assembly comprises an iron core which sleeves the output shaft. The iron core is provided with stator teeth, the width of the stator teeth increases from the direction close to the axis to the direction away from the axis, and limiting blocks are arranged at the ends, close to the axis, of the stator teeth. The winding coils are distributed in two layers to form three phases; one end of the bracket is fixedly connected with the iron core; the bearing assembly sleeves the output shaft and is used for supporting the output shaft; the PCB is arranged on the rear shell; the position sensor is used for detecting the magnet unit position; the electronic commutator is used for controlling commutation; the PWM unit is used for adjusting input voltage and current. According to the invention, the smoothness and stability of the brushless motor in the operation process can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of brushless motors, and in particular to a brushless motor, a control method and an application method. Background Art

[0002] Although the development time of brushless motors in my country is short, it has been rapidly developed with the increasing maturity and improvement of technology. Due to its high efficiency, reliability and easy maintenance, brushless motors have been widely used in industrial automation, household appliances and other fields.

[0003] However, the existing brushless motors and their control methods still have some shortcomings. When the motor is running, the heat generated inside is difficult to dissipate; and in the process of starting and stopping the motor, the traditional control method often uses constant speed motion, which is easy to cause mechanical shock and affect the service life of the motor; and when linear acceleration or deceleration is used to control the start and stop of the motor, it is easy to decelerate after receiving the stop command, causing the object to exceed the place where the user wants to stop. In real life applications, people not only require brushless motors to have high efficiency and long life, but also require good smoothness and accuracy during operation, and good stability in the use of electric furniture.

[0004] The present invention aims to solve the problems existing in the traditional brushless motor. Summary of the invention

[0005] The present invention provides a brushless motor, a control method and an application method, which can effectively solve the problems in the background technology.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: The motor housing comprises a front housing and a rear housing, wherein the front housing is fixedly connected to the rear housing; Rotor assembly: installed in the motor housing; including a cylindrical shell; magnet units, evenly distributed on the inner wall of the cylindrical shell along the circumferential direction of the axis; output shaft, the output shaft is coaxial with the cylindrical shell and passes through the front shell; Stator assembly: including an iron core, through which the output shaft passes; the iron core is provided with stator teeth distributed along the circumference of the axis and extending toward the axis center, the width of the stator teeth gradually increases from the direction close to the axis center to the direction away from the axis center, and a limit block is provided at the end of the stator teeth close to the axis center; the winding coil is provided with a double-layer distribution, one layer is wound on the end of the stator teeth close to the axis center, and the other layer is wound on the end of the stator teeth away from the axis center; the winding coil is composed of three phases; a bracket, one end of which is fixedly connected to the iron core and the other end is fixedly connected to the motor housing; Bearing assembly: sleeved on the output shaft, including a first bearing and a second bearing, used to support the output shaft; PCB board: arranged on the rear shell; including a plurality of position sensors, with the inner wall of the cylindrical shell corresponding to the edge of the circular area on the PCB board, and the position sensors are evenly arranged at intervals to detect the position of the magnet unit; including an electronic commutator for controlling the commutation of the brushless motor; including a PWM unit for adjusting the input voltage and current of the motor.

[0007] Furthermore, the motor housing is provided with a heat dissipation port; the outer wall of the cylindrical shell is provided with a wind plate along the circumferential direction of the axis, and the wind plate is at a certain distance from the motor housing.

[0008] According to a second aspect of the present invention, there is also provided a brushless motor control method, comprising the following steps: S00: Install the brushless motor into the object, connect the output shaft to the lead screw, and move the slider on the lead screw; set the slider to be at the lowest position when it is closest to the motor on the lead screw, and to be at the highest position when it is farthest from the motor on the lead screw; S10: Initialize the brushless motor and configure the PWM unit; set the slider at several special positions on the screw rod as different gears for application; set the minimum duty cycle Dmin and the maximum duty cycle Dmax; S20: receiving the real-time distance Pc between the position of the slider and the lowest point sent by the object system, receiving the target gear sent by the user, and calculating the target distance Pt between the position of the target gear and the lowest point; calculating the position difference e=Pt-Pc according to the real-time distance Pc and the target distance Pt; and determining the rotation direction of the output shaft at the same time; S30: Determine the position of the magnet unit in the rotor assembly through a position sensor, thereby controlling the power supply of the winding coil to drive the rotation of the rotor assembly; construct a smooth acceleration curve to calculate the duty cycle Dt1 and generate a PWM signal through the duty cycle Dt1; S40: The brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the acceleration period to drive the output shaft to accelerate smoothly; at the same time, during the acceleration period, the motor applies a certain current to the winding coil of the next phase at a manually set phase angle before each phase change; when the duty cycle Dt1 reaches the maximum duty cycle Dmax, the motor exits the acceleration period and generates a PWM signal with the duty cycle Dmax to drive the rotation of the output shaft; S50: When the position difference e is less than a manually set threshold, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and generate a PWM signal through the duty cycle Dt2; the brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters a deceleration period to drive the output shaft to decelerate smoothly; at the same time, during the deceleration period, a certain current is applied to the winding coil of the next phase at a manually set phase angle before each phase change; when the duty cycle Dt2 reaches the minimum duty cycle Dmin, the motor exits the deceleration period, and the brushless motor stops inputting voltage and current, so that the output shaft stops rotating.

[0009] Furthermore, in step S30, a smooth acceleration curve is constructed to calculate the duty cycle Dt1 as follows: Dt1=Dmax·(3t1 2 -2t1 3 ); Wherein, t1 is the timing time of starting, and t1≤1.

[0010] Furthermore, in step S50, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 as follows: Dt2=Dmax-(Dmax-Dmin)·(3t2 2 -2t2 3 ); Wherein, t2 is the timing time starting when the position difference e is less than the artificially set threshold, and t2≤1.

[0011] Further, when the brushless motor moves in an acceleration period or a deceleration period according to the PWM signal, a high-resolution PWM signal is used; and between the acceleration period and the deceleration period of the brushless motor, a low-resolution PWM signal is used.

[0012] Furthermore, when in step S20, the user does not issue a target gear position, making it impossible to calculate the target distance Pt, step S50 is changed to: after receiving a real-time stop command issued by the user, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and a PWM signal is generated through the duty cycle Dt2; the brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters a deceleration period to drive the output shaft to decelerate smoothly, and when the duty cycle Dt2 is the minimum duty cycle Dmin, the motor exits the deceleration period, and the brushless motor stops inputting voltage and current, causing the output shaft to stop rotating.

[0013] Furthermore, when the brushless motor adjusts the motor according to the PWM signal generated by the duty cycle Dt2, it starts to record the number of revolutions a of the rotor assembly around the stator assembly; when the duty cycle Dt2 reaches the minimum duty cycle Dmin, the recording of the number of revolutions a is stopped; the brushless motor inputs voltage and current with the duty cycle Dmin, and uses an electronic commutator to make the rotor assembly rotate in the reverse direction until the number of reverse rotations b=a, at which time the brushless motor stops inputting voltage and current, causing the output shaft to stop rotating.

[0014] Furthermore, after the output shaft stops rotating, the memory distance Pd between the current slider and the lowest point is recorded, and the user can choose to set the memory distance Pd as a memory gear, and the user can select the memory gear as the target gear next time; one memory gear is set, and each time the memory gear is set, the previous memory gear will be overwritten.

[0015] According to a third aspect of the present invention, there is also provided a brushless motor application method, comprising: Install the brushless motor inside the column of the lifting table to drive the lifting table to move up and down; Alternatively, a brushless motor may be installed inside a sofa or recliner seat to drive the movement of the footrest and backrest of the seat to achieve posture changes.

[0016] The technical solution of the present invention can achieve the following technical effects: The present invention designs a brushless motor, a control method and an application method; a stator tooth width gradient is designed to optimize the magnetic field distribution and reduce the cogging effect, so as to achieve the purpose of improving the running stability of the motor; the wind plate is driven to dissipate heat by the rotation of the rotor assembly during operation; the vibration of the motor to the object is reduced by constructing a smooth curve when starting and stopping the motor, so as to improve the smoothness and stability during operation; the targeted operation in both cases can also stop the object accurately at the position desired by the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of a brushless motor in an embodiment of the present invention; Figure 2 Schematic diagram of the structure of the iron core and stator teeth in the brushless motor in an embodiment of the present invention; Figure 3 A step diagram of a brushless motor control method according to an embodiment of the present invention; Figure 4 It is a smooth acceleration curve function diagram in the brushless motor control method in an embodiment of the present invention; Figure 5 It is a smooth deceleration curve function diagram in the brushless motor control method in an embodiment of the present invention; Figure numerals: 11, front shell; 12, rear shell; 13, heat dissipation port; 21, cylindrical shell; 21a, wind plate; 22, magnet unit; 23, output shaft; 3, stator assembly; 31, iron core; 32, stator teeth; 32a, limit block; 33, bracket; 41, first bearing; 42, second bearing; 5, PCB board. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by “center”, “up”, “down”, “left”, “right”, “vertical”, “horizontal”, “inside” and “outside”, etc., are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] A brushless motor, such as Figure 1~2 As shown, including: Motor housing: includes a front housing 11 and a rear housing 12, the front housing 11 and the rear housing 12 are fixedly connected; The rotor assembly is installed in the motor housing; it includes a cylindrical shell 21; a magnet unit 22, which is evenly distributed on the inner wall of the cylindrical shell 21 along the circumferential direction of the axis; and an output shaft 23, which is coaxial with the cylindrical shell 21 and passes through the front shell 11; Stator assembly 3: includes an iron core 31, and the output shaft 23 passes through the iron core 31; the iron core 31 is provided with stator teeth 32 distributed along the circumferential direction of the axis and extending toward the axis center, and the tooth width of the stator teeth 32 gradually increases from the direction close to the axis center to the direction away from the axis center. The end with a larger tooth width enhances the heat dissipation of the area, and can better optimize the magnetic field distribution, reduce the tooth slot effect, and improve the stability and stability of the brushless motor during operation; a limit block 32a is provided at the end of the stator tooth 32 close to the axis center; the winding coil, the winding coil is arranged in a double-layer distribution, one layer is wound on the end of the stator tooth 32 close to the axis center, and the other layer is wound on the end of the stator tooth 32 away from the axis center; the double-layer winding can accommodate more wires, thereby improving the electromagnetic force and output power of the motor, and can better disperse the current and reduce eddy current loss; the winding coil consists of three phases; a bracket 33, one end of which is fixedly connected to the iron core 31, and the other end is fixedly connected to the motor housing; Bearing assembly: sleeved on the output shaft 23, including a first bearing 41 and a second bearing 42, used to support the output shaft 23; PCB board 5: arranged on the rear shell 12, so that there is no need to set additional wiring inside the motor to connect with external objects; including a plurality of position sensors, which can be Hall sensors or encoders; the position sensors are evenly spaced at the edge of the circular area corresponding to the inner wall of the cylindrical shell 21 on the PCB board 5, for accurately detecting the position of the magnet unit 22; including an electronic commutator for controlling the commutation of the brushless motor; including a PWM unit for adjusting the input voltage and current of the motor.

[0023] The operating principle of the brushless motor is to detect the position of the rotor assembly through a position sensor, and then commutate the current of the winding coil on the stator assembly 3 in a certain order (that is, detect the position of the magnetic pole of the magnet unit 22 on the rotor assembly relative to the winding coil of the stator assembly, and generate a position sensing signal at a determined position, which is processed by the signal conversion circuit to control the power switch circuit and switch the winding current according to a certain logical relationship), so that the rotor assembly rotates around the stator assembly 3, driving the output shaft 23 to rotate.

[0024] Preferably, the motor housing is provided with a heat dissipation port 13; the outer wall of the cylindrical housing 21 is provided with a wind plate 21a along the circumferential direction of the axis, and the wind plate 21a is a certain distance away from the motor housing; when the motor is running, the rotor assembly rotates around the stator assembly 3, thereby driving the wind plate 21a on the cylindrical housing 21 to rotate around the stator assembly 3, and the air inside the motor moves faster, and then exchanges through the heat dissipation port 13 opened in the middle section of the motor housing, so as to dissipate the heat generated during the operation of the motor in time, so that the inside of the motor will not overheat and cause damage to the components, and the influence of heat on the operation of the motor is avoided; a circulation hole can also be opened on the rear shell 12 of the motor housing to make the air exchange inside the motor smoother.

[0025] According to a second aspect of the present invention, a brushless motor control method is also provided. Figure 3 As shown in , the following steps are included: S00: Install the brushless motor into the object, connect the output shaft 23 to the screw rod, and the slider moves on the screw rod, so that the slider can drive the shape change of the object system (such as the lifting and lowering of the lifting table, the movement of the footrest and backrest of the sofa recliner); set the slider to be at the lowest position when it is closest to the motor on the screw rod, and to be at the highest position when the slider is farthest from the motor on the screw rod.

[0026] S10: Initialize the brushless motor and configure the PWM unit; set the slider at several special positions on the screw rod as different gears for the application, and different gears correspond to different forms of the object system (such as the gears at various high and low positions of the lifting table); set the minimum duty cycle Dmin and the maximum duty cycle Dmax.

[0027] S20: Receive the real-time distance Pc between the position of the slider and the lowest point sent by the object system, receive the target gear sent by the user, and calculate the target distance Pt between the position of the target gear and the lowest point; calculate the position difference e=Pt-Pc according to the real-time distance Pc and the target distance Pt; at the same time, the rotation direction of the output shaft 23 can be determined by the positive and negative of the position difference e calculation structure. For example, if the motor is set to rotate forward, the slider will move from the lowest point to the highest point. Then when e>0, it means that the target position is farther away from the motor, and the motor needs to rotate forward to drive the slider to the target position.

[0028] S30: Determine the position of the magnet unit 22 in the rotor assembly through the position sensor, thereby controlling the power supply of the winding coil to drive the rotation of the rotor assembly to achieve forward and reverse rotation of the motor; construct a smooth acceleration curve to calculate the duty cycle Dt1 and generate a PWM signal through the duty cycle Dt1; By smoothing the acceleration curve, the motor will not reach the maximum speed or maximum torque immediately at startup, but will increase gradually, which can significantly reduce the impact on the mechanical parts of the object at the moment of startup; and smooth acceleration reduces the instantaneous acceleration at startup, thereby reducing the vibration and noise caused by rapid acceleration; such a startup effectively reduces the vibration caused by the motor to the object at the beginning of startup, making the user feel more stable and comfortable when using the object.

[0029] S40: The brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the acceleration period to drive the output shaft 23 to accelerate smoothly; at the same time, during the acceleration period, the motor applies a certain current to the winding coil of the next phase at a manually set phase angle before each phase change, and the current value is usually a manually set constant value; when the duty cycle Dt1 reaches the maximum duty cycle Dmax, the motor exits the acceleration period, and generates a PWM signal with the duty cycle Dmax to drive the rotation of the output shaft 23, so that the object moves to the target gear faster; The traditional commutation process is that the motor runs on the first phase winding. When the motor reaches the commutation point, the current of the first phase will be cut off and the current of the second phase will be connected. After the commutation, the current of the second phase starts to rise from zero, while the current of the first phase quickly drops from the original value to zero; the rapid change of current will cause the torque generated by the motor to change rapidly, thereby causing torque fluctuations; torque fluctuations will cause the motor to vibrate and make noise during commutation, affecting the smooth operation of the motor; and by applying a certain current to the next phase winding in advance at a phase angle before each commutation, the current of the next phase does not rise from zero, making the current change smoother, reducing the torque fluctuation caused by the current jump, and making the motor run more smoothly.

[0030] S50: When the position difference e is less than the manually set threshold, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and generate a PWM signal through the duty cycle Dt2; the brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the deceleration period to drive the output shaft 23 to decelerate smoothly, and the remaining position difference e is reset to zero during the deceleration period to reach the position of the target gear, and the position of the target gear will not be exceeded because the deceleration period is entered only when the target gear is reached; at the same time, during the deceleration period, a certain current is applied to the winding coil of the next phase at a manually set phase angle before each phase change; when the duty cycle Dt2 is the minimum duty cycle Dmin, the motor exits the deceleration period. At this time, because the movement amplitude of the object driven by the motor is already very small, the brushless motor stops inputting voltage and current, causing the output shaft 23 to stop rotating, and does not bring an abrupt vibration feeling to the user.

[0031] like Figure 4 As shown, in step S30, a smooth acceleration curve is constructed to calculate the duty cycle Dt1 as follows: Dt1=Dmax·(3t1 2 -2t1 3 ); Wherein, t1 is the timing time of starting, and t1≤1; The constructed smooth acceleration curve will not produce strong vibration similar to that caused by linear acceleration when starting and reaching the maximum duty cycle Dmax, so as to ensure that there is no sudden change in the duty cycle Dt1 during the entire acceleration period; as t1 changes from 0 to 1, through the smooth acceleration curve, the duty cycle Dt1 can increase smoothly from 0 to Dmax within 1 second to reach the maximum duty cycle.

[0032] like Figure 5 As shown, in step S50, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 as follows: Dt2=Dmax-(Dmax-Dmin)·(3t2 2 -2t2 3 ); Wherein, t2 is the timing time starting when the position difference e is less than the artificially set threshold, and t2≤1; Similarly, the constructed smooth deceleration curve also ensures that the duty cycle Dt2 does not change suddenly during the entire deceleration period; and the duty cycle Dt2 during the deceleration period is reduced to the minimum duty cycle Dmin through the method of (Dmax-Dmin), which also avoids the vibration caused by the motor directly decaying to 0 after high-speed operation; and by decaying to the minimum duty cycle Dmin, it can also solve the impact caused by the user not issuing the target gear at the beginning.

[0033] Preferably, when the brushless motor moves in the acceleration period or the deceleration period according to the PWM signal, a high-resolution PWM signal is used; between the acceleration period and the deceleration period of the brushless motor, a low-resolution PWM signal is used; during the acceleration period or the deceleration period, the motor speed is low, and very fine speed control is required at this time; the use of high-resolution PWM signals can achieve more detailed current adjustment, thereby improving the control accuracy and smooth operation of the motor speed; in the high-speed range, the motor speed is high, and the accuracy requirements for speed control are relatively low at this time; the use of lower-resolution PWM signals can simplify the control algorithm and reduce the computational burden, while still being able to maintain sufficient control accuracy.

[0034] In some embodiments, when the user does not issue a target gear in step S20, so that the target distance Pt cannot be calculated, step S50 is changed to: after receiving a real-time stop command issued by the user, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and a PWM signal is generated through the duty cycle Dt2; the brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the deceleration period to drive the output shaft 23 to decelerate smoothly, and when the duty cycle Dt2 is the minimum duty cycle Dmin, the motor exits the deceleration period, and the brushless motor stops inputting voltage and current, so that the output shaft 23 stops rotating; in life, when using an object, the user does not know what position is more suitable for his or her own use requirements, so he or she will not choose a gear, but control the movement by himself or herself, and will not issue a stop command until the movement reaches a position that the user thinks is suitable, for example, when the lifting table is lifting, the user will first choose to let the table rise, and issue a stop command when it rises to a suitable position; at this time, we need to change the premise of constructing a smooth deceleration curve to calculate the duty cycle Dt2, so that the motor can enter the deceleration period.

[0035] When the brushless motor adjusts the motor according to the PWM signal generated by the duty cycle Dt2, it starts to record the number of revolutions a of the rotor assembly around the stator assembly 3; when the duty cycle Dt2 is the minimum duty cycle Dmin, the recording of the number of revolutions a is stopped; the brushless motor inputs voltage and current at the duty cycle Dmin, and uses the electronic commutator to make the rotor assembly rotate in the opposite direction, until the reverse rotation number b=a, the brushless motor stops inputting voltage and current, so that the output shaft 23 stops rotating. In the case where the user does not issue the target gear and the user issues a stop command, the motor enters the deceleration period. At this moment, the continued movement of the slider on the lead screw during the deceleration period has caused the movement of the object to exceed the position where the user wants the object to stop; therefore, the number of revolutions a of the rotor assembly around the stator assembly 3 during the deceleration period is recorded, and then the slow callback position of the minimum duty cycle Dmin is used to finally stop at the position where the user issues the stop command, thereby avoiding the vibration caused by the emergency stop and improving the stability and accuracy during the operation.

[0036] Preferably, after the output shaft 23 stops rotating, the memory distance Pd between the current slider and the lowest point is recorded, and the user can choose to set the memory distance Pd as a memory gear, and the user can select the memory gear as the target gear next time; one memory gear is set, and each memory gear setting will overwrite the previous memory gear. In the above case, the user makes the object stop at a position that he feels suitable and wants to stop. The user can choose to set the memory distance Pd from the lowest point of the slider on the screw rod at this time as a memory gear, so that the next time the object is used, it can reach this position faster and more conveniently, which improves the flexibility of use.

[0037] According to a third aspect of the present invention, there is also provided a brushless motor application method, comprising: The brushless motor is installed inside the column of the lifting table to drive the extension and retraction of the column of the lifting table, thereby driving the lifting table to move up and down; Alternatively, a brushless motor can be installed inside a sofa, recliner or other seat and connected to a screw slider structure to drive the movement of the footrest and backrest of the seat, thereby switching between sitting, TV and lying positions to meet user needs.

[0038] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A brushless motor, characterized in that: include: Motor housing: comprising a front housing and a rear housing, wherein the front housing is fixedly connected to the rear housing; Rotor assembly: installed in the motor housing; including a cylindrical housing; The magnet units are evenly distributed on the inner wall of the cylindrical shell along the axis circumference; the output shaft is coaxial with the cylindrical shell and passes through the front shell; Stator assembly: comprising an iron core, the output shaft passes through the iron core; the iron core is provided with stator teeth distributed along the axis circumferentially and extending toward the axis center, the stator tooth width gradually increases from the direction close to the axis center to the direction away from the axis center, and a limit block is provided at the end of the stator tooth close to the axis center; the winding coil, the winding coil is arranged in a double-layer distribution, one layer is wound around the end of the stator tooth close to the axis center, and the other layer is wound around the end of the stator tooth away from the axis center; the winding coil forms three phases; a bracket, one end of which is fixedly connected to the iron core, and the other end is fixedly connected to the motor housing; Bearing assembly: sleeved on the output shaft, including a first bearing and a second bearing, used to support the output shaft; PCB board: arranged on the rear shell; including a plurality of position sensors, with the inner wall of the cylindrical shell on the edge of the circular area corresponding to the PCB board, and the position sensors are evenly arranged at intervals to detect the position of the magnet unit; including an electronic commutator for controlling the commutation of the brushless motor; including a PWM unit for adjusting the input voltage and current of the motor.

2. The brushless motor according to claim 1, characterized in that: The motor housing is provided with a heat dissipation port; the outer wall of the cylindrical shell is provided with a wind plate along the circumferential direction of the axis, and the wind plate is at a certain distance from the motor housing.

3. A brushless motor control method, using the brushless motor as claimed in claim 1, characterized in that: The steps include: S00: Install the brushless motor into the object, connect the output shaft to the lead screw, and move the slider on the lead screw; set the slider to be at the lowest position when it is closest to the motor on the lead screw, and to be at the highest position when it is farthest from the motor on the lead screw; S10: Initialize the brushless motor and configure the PWM unit; Set the slider at several special positions on the screw rod as different gears for application; Set the minimum duty cycle Dmin and the maximum duty cycle Dmax; S20: receiving the real-time distance Pc between the position of the slider and the lowest point sent by the object system, receiving the target gear sent by the user, and calculating the target distance Pt between the position of the target gear and the lowest point; calculating the position difference e=Pt-Pc according to the real-time distance Pc and the target distance Pt; and determining the rotation direction of the output shaft at the same time; S30: Determine the position of the magnet unit in the rotor assembly through a position sensor, thereby controlling the power supply of the winding coil to drive the rotation of the rotor assembly; construct a smooth acceleration curve to calculate the duty cycle Dt1 and generate a PWM signal through the duty cycle Dt1; S40: The brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the acceleration period to drive the output shaft to accelerate smoothly; at the same time, during the acceleration period, a certain current is applied to the winding coil of the next phase at a manually set phase angle before the phase change each time the motor is in the acceleration period; When the duty cycle Dt1 reaches the maximum duty cycle Dmax, the motor exits the acceleration period and generates a PWM signal with the duty cycle Dmax to drive the rotation of the output shaft; S50: when the position difference e is less than a manually set threshold, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and a PWM signal is generated by the duty cycle Dt2; The brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the deceleration period to drive the output shaft to decelerate smoothly; at the same time, during the deceleration period, the motor applies a certain current to the winding coil of the next phase at a manually set phase angle before each phase change. When the duty cycle Dt2 reaches the minimum duty cycle Dmin, the motor exits the deceleration period, and the brushless motor stops inputting voltage and current, causing the output shaft to stop rotating.

4. The brushless motor control method according to claim 3, characterized in that: In step S30, a smooth acceleration curve is constructed to calculate the duty cycle Dt1 as follows: Dt1=Dmax·(3t1 2 -2t1 3 ); Wherein, t1 is the timing time of starting, and t1≤1.

5. The brushless motor control method according to claim 3, characterized in that: In step S50, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 as follows: Dt2=Dmax-(Dmax-Dmin)·(3t2 2 -2t2 3 ); Wherein, t2 is the timing time starting when the position difference e is less than the artificially set threshold, and t2≤1.

6. The brushless motor control method according to claim 3, characterized in that: When the brushless motor moves in an acceleration period or a deceleration period according to the PWM signal, a high-resolution PWM signal is used; between the acceleration period and the deceleration period of the brushless motor, a low-resolution PWM signal is used.

7. The brushless motor control method according to claim 3, characterized in that: When the user does not issue a target gear in step S20, so that the target distance Pt cannot be calculated, step S50 is changed to: after receiving a real-time stop command issued by the user, a smooth deceleration curve is constructed to calculate the duty cycle Dt2 and a PWM signal is generated by the duty cycle Dt2; The brushless motor adjusts the input voltage and current of the motor according to the PWM signal, so that the motor enters the deceleration period to drive the output shaft to decelerate smoothly. When the duty cycle Dt2 reaches the minimum duty cycle Dmin, the motor exits the deceleration period, and the brushless motor stops inputting voltage and current, causing the output shaft to stop rotating.

8. The brushless motor control method according to claim 7, characterized in that: When the brushless motor adjusts the motor according to the PWM signal generated by the duty cycle Dt2, it starts to record the number of revolutions a of the rotor assembly around the stator assembly; when the duty cycle Dt2 reaches the minimum duty cycle Dmin, the recording of the number of revolutions a is stopped; the brushless motor inputs voltage and current at the duty cycle Dmin, and uses an electronic commutator to make the rotor assembly rotate in the reverse direction until the number of reverse rotations b=a, at which time the brushless motor stops inputting voltage and current, causing the output shaft to stop rotating.

9. The brushless motor control method according to claim 8, characterized in that: After the output shaft stops rotating, the memory distance Pd between the current slider and the lowest point is recorded. The user can choose to set the memory distance Pd as a memory gear, and the user can select the memory gear as the target gear next time; one memory gear is set, and each time the memory gear is set, it will overwrite the previous memory gear.

10. A brushless motor application method, characterized in that: Using the brushless motor as claimed in claim 1, comprising: installing the brushless motor inside the column of the lifting table to drive the lifting table to move up and down; Alternatively, a brushless motor can be installed inside a sofa or recliner seat to drive the movement of the seat's footrest and backrest to achieve posture changes.

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