Motor assembly
By introducing distance sensors and controllers into the motor assembly, the distance between the bearing surface and the sensor is detected, and the safety hazards caused by motor reversal is solved, rapid and economical rotation direction detection is achieved, and the safety of the motor is improved.
Patent Information
- Application Number
- CN202411891253.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-11
AI Technical Summary
During the motor's entire machine maintenance or production test, the wrong connection of the three phase wires of the motor may cause the whole machine to reverse, which will cause the pressure saw blade or frosted flange to loosen or throw out, endangering the safety of the user or producer.
A motor assembly is designed, including a motor, a distance sensor and a controller. The bearing is provided with a detected part that cooperates with the distance sensor. The distance sensor is used to detect the distance between the bearing surface and the sensor, and generates a distance detection signal. The controller determines the rotation direction of the rotor assembly based on the distance detection signal and the preset signal.
By quickly detecting the rotation direction of the motor, ensuring that the motor rotates in the correct direction, effectively reducing the detection cost and improving the safety of the motor use.
Smart Images
Figure CN119813660A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of motor technology, and in particular to a motor component. Background Art
[0002] Motors are widely used in the industrial field and in daily life. For some equipment equipped with motors, such as angle grinders or cutting machines, the motor generally has only one direction of rotation. If the three phases of the motor are connected incorrectly after the whole machine is repaired or during production testing, the whole machine will be reversed, which may cause the flange of the pressure saw blade or grinding disc to loosen or even fall out, thereby injuring the user or producer. Summary of the invention
[0003] In view of this, the present application provides a motor component that can detect motor reversal in a timely manner to improve the safety of the motor.
[0004] The present application provides a first aspect of a motor assembly, comprising a motor, a distance sensor and a controller, wherein the motor comprises a motor shaft, a rotor assembly and a bearing, wherein the bearing rotates together when the rotor assembly rotates, and the bearing is provided with a detected portion cooperating with the distance sensor; the distance sensor is located on a side of the bearing provided with the detected portion, and the distance sensor remains stationary relative to the rotor assembly, and the distance sensor is used to detect the distance between the surface of the side of the bearing provided with the detected portion and the distance sensor when the bearing rotates, and generate a distance detection signal, and the detected portion makes the waveform of the distance detection signal different when the rotor assembly rotates forward and reverse; the controller is used to control the rotation of the rotor assembly, and determine the rotation direction of the rotor assembly according to the distance detection signal and a preset detection signal.
[0005] A further improvement is that a detected portion is provided on one side of the bearing perpendicular to the motor shaft, and the detected portion is at least two grooves.
[0006] A further improvement is that the motor assembly also includes a bearing ring, the bearing ring is arranged on a side of the bearing that is perpendicular to the motor shaft, and the groove is arranged on the surface of the bearing ring.
[0007] A further improvement is that the depth of each groove is different.
[0008] A further improvement is that each groove is located on the same circumference centered on the motor shaft, and the distance sensor is arranged corresponding to the circumference. When three or more grooves are arranged on the bearing, the arc length between every two adjacent grooves on the circumference is different.
[0009] A further improvement is that the motor also includes a bearing bracket, which is used to fix the bearing. One side of the bearing bracket close to the end of the motor shaft extends a distance in a direction parallel to the motor shaft and then extends in a direction close to the motor shaft to form a sensor bracket. The distance sensor is arranged on the sensor bracket.
[0010] A further improvement is that the distance sensor includes a laser sensor or an infrared sensor.
[0011] A further improvement is that the preset detection signal includes a forward rotation detection signal and a reverse rotation detection signal. When the waveform of the distance detection signal matches the forward rotation detection signal, the controller determines that the rotor assembly rotates forward. When the waveform of the distance detection signal matches the reverse rotation detection signal, the controller determines that the rotor assembly rotates reversely.
[0012] A further improvement is that the motor assembly also includes a reminder module electrically connected to the controller, and when the controller determines that the rotor assembly is reversed, the controller also controls the reminder module to output a reminder message.
[0013] A further improvement is that the motor also includes a drive circuit and a winding, the drive circuit is electrically connected to the controller and the three-phase coil formed by the winding, and when the controller determines that the rotor assembly is reversed, the controller controls the rotor assembly to switch to forward rotation through the drive circuit.
[0014] Compared with the prior art, this application has the following beneficial effects:
[0015] The motor assembly provided by the present application has a bearing provided with a detection portion that cooperates with the distance sensor, and the distance sensor is located on the side of the bearing provided with the detected portion. The distance sensor is used to detect the distance between the surface of the side of the bearing provided with the detected portion and the distance sensor when the bearing rotates and generate a distance detection signal. The detected portion makes the waveform of the distance detection signal different when the rotor assembly rotates forward and reverse. In this way, after the controller controls the rotation of the rotor assembly, the rotation direction of the rotor assembly can be determined according to the distance detection signal and the preset detection signal. In this way, the motor assembly provided by the present application can quickly determine whether the rotor assembly is reversed based on the above design, while effectively reducing the detection cost and ensuring the safety of the motor assembly. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope of protection of the present application. In each of the drawings, similar components are numbered similarly.
[0017] Figure 1 A module block diagram of a motor component provided in one embodiment of the present application.
[0018] Figure 2 A partial exploded view of a motor provided in one embodiment of the present application.
[0019] Figure 3A schematic diagram of a groove provided on a bearing according to an embodiment of the present application.
[0020] Figure 4A for Figure 3 The waveform diagram of the distance detection signal obtained when the bearing rotates in the first direction is shown.
[0021] Figure 4B for Figure 3 The waveform diagram of the distance detection signal obtained when the bearing rotates in the second direction is shown.
[0022] Figure 5 A schematic diagram of providing a groove on a bearing according to another embodiment of the present application.
[0023] Fig. 6A for Figure 5 The waveform diagram of the distance detection signal obtained when the bearing rotates in the first direction is shown.
[0024] Figure 6B for Figure 5 The waveform diagram of the distance detection signal obtained when the bearing rotates in the second direction is shown.
[0025] Figure 7 A schematic diagram of a bearing ring provided in accordance with an embodiment of the present application.
[0026] Figure 8 for Figure 2 A cross-sectional view of an electric machine is shown.
[0027] Fig. 9 A module block diagram of a motor component provided in accordance with another embodiment of the present application.
[0028] Fig.10 A structural block diagram of an electronic device provided in one embodiment of the present application.
[0029] Main component symbols
[0030] Motor assembly—10 Motor—11 Distance sensor—12 Controller—13
[0031] Motor shaft—111 Bearing—112 Bearing ring—1122 Rotor assembly—113
[0032] Casing—1131 Magnetic seat—1132 Magnetic steel—1133 End cover—11311
[0033] Annular wall—11312 Extension—11313 Stator assembly—114 Stator bracket—1141
[0034] Stator plastic parts—1142 Winding—1143 Bearing bracket—1144 Sensor bracket—1145
[0035] Front bearing—115 Distance value—d Circumference—C First direction—G
[0036] Second direction—H Reminder module—14 Driving circuit—116 Electronic device—100
[0037] Groove—1121, 1121A, 1121B, 1121C, 1121D, 1121E, 1121F
[0038] Arc length—L1, L2, L3 DETAILED DESCRIPTION
[0039] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.
[0040] It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a central component at the same time. When a component is considered to be "located on" another component, it may be directly located on the other component or there may be a central component at the same time. The terms "top", "bottom", "upper", "lower", "left", "right", "front", "back", and similar expressions used herein are for illustrative purposes only.
[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0042] Some embodiments will be described below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.
[0043] Motors are widely used in the industrial field and in daily life. For some equipment equipped with motors, such as angle grinders or cutting machines, the motor generally has only one direction of rotation. If the three phases of the motor are connected incorrectly after the whole machine is repaired or during production testing, the whole machine will be reversed, which may cause the flange of the pressure saw blade or grinding disc to loosen or even fall out, thereby injuring the user or producer.
[0044] In view of this, the present application provides a motor component that can detect motor reversal in a timely manner to improve the safety of the motor.
[0045] See also Figure 1The present application provides a motor assembly 10, including a motor 11, a distance sensor 12 and a controller 13. The motor 11 and the distance sensor 12 are both electrically connected to the controller 13. The controller 13 can control the motor 11 to adjust the rotation direction according to the distance detection signal collected by the distance sensor 12.
[0046] This application uses an external rotor motor as an example to illustrate the specific working principle of reverse detection. It is understandable that the technical solution provided by this application can also be applied to other types of motors. For details, please continue to refer to Figure 2 , the motor 11 at least includes a motor shaft 111, a bearing 112 and a rotor assembly 113. Among them, the motor shaft 111 extends in the axial direction, the bearing 112 is sleeved on the rotor assembly 113, and when the rotor assembly 113 rotates, the bearing 112 rotates together. For example, in some embodiments, the inner ring of the bearing 112 is connected to the motor shaft 111, and the outer ring of the bearing 112 is connected to the rotor assembly 113, so that when the rotor assembly 113 rotates, the bearing 112 and the motor shaft 111 can be driven to rotate together. This application does not specifically limit the connection relationship between the motor shaft 111, the bearing 112 and the rotor assembly 113, and it is only necessary that the bearing 112 can rotate together with the rotor assembly 113.
[0047] The rotor assembly 113 further includes a housing 1131, a magnetic steel seat 1132, and a plurality of magnetic steels 1133. The plurality of magnetic steels 1133 are mounted on the magnetic steel seat 1132. The magnetic steel seat 1132 is accommodated in the housing 1131. In some embodiments, the housing 1131 includes an end cover 11311, an annular wall 11312, and an extension portion 11313 bent inwardly from the end cover 11311 (see Figure 8 ). The extension portion 11313 is fixed on the motor shaft 111. The magnet 1133 is uniformly attached to the inner wall of the annular wall 11312 along the circumferential direction, and the magnet 1133 is located radially outside the winding 1143. The magnet 1133 drives the housing 1131 to rotate together. In this embodiment, the magnet 1133 is attached to the inner wall of the annular wall 11312 using a glue.
[0048] The motor 11 further includes a stator assembly 114. The stator assembly 114 is located between the motor shaft 111 and the rotor assembly 113, and the motor shaft 111 rotates relative to the stator assembly 114 along with the rotor assembly 113. The stator assembly 114 includes a stator bracket 1141 sleeved on the outer periphery of the motor shaft 111, a stator overmolding 1142 fixed on the stator bracket 1141, and a winding 1143 wound inside the stator overmolding 1142. The stator assembly 114 further includes a stator core (not shown) overmolded inside the stator overmolding 1142, and the winding 1143 is wound around the outer periphery of the stator core (not shown).
[0049] Please also read Figure 3The bearing 112 is provided with a detected portion, which cooperates with the distance sensor 12. The detected portion is provided on a side of the bearing 112 perpendicular to the motor shaft 111, and the detected portion is at least two grooves 1121. In some embodiments, each groove 1121 is located on the same circumference C centered on the motor shaft 111. In other embodiments, when the opening width of the groove 1121 is large, each groove 1121 can also be staggered, as long as at least part of each groove 1121 is located on the same circumference C centered on the motor shaft 111.
[0050] The distance sensor 12 is located on the side of the bearing 112 where the groove 1121 is provided. The distance sensor 12 remains stationary relative to the rotor assembly 113, and the distance sensor 12 is provided corresponding to the circumference C. The distance sensor 12 is used to detect the distance between the surface of the side of the bearing 112 where the groove 1121 is provided and the distance sensor 12 when the bearing 112 rotates. In other words, the distance sensor 12 is used to detect the distance between the surface where the circumference C is located and the distance sensor 12 and generate a distance detection signal. At least two grooves 1121 make the waveform of the distance detection signal different when the rotor assembly 113 rotates forward and reverse.
[0051] The controller 13 is used to control the rotation of the rotor assembly 113 and determine the rotation direction of the rotor assembly 113 according to the distance detection signal and the preset detection signal. It can be understood that the motor 11 also includes a drive circuit 116 (see Fig. 9 ), and the winding 1143 can form a three-phase coil. In this way, the controller 13 can control the current on the three-phase coil through the driving circuit 116, thereby controlling the rotation of the rotor assembly 113.
[0052] In some embodiments, the preset detection signal may include preset waveform information. The controller 13 may sample the sampled distance detection signal according to the preset waveform information to determine whether the waveform of the distance detection signal matches the waveform of the preset detection signal.
[0053] For example, the preset detection signal includes a forward detection signal and a reverse detection signal. When the controller 13 determines that the waveform of the distance detection signal matches the forward detection signal according to the preset waveform of the forward detection signal, the controller 13 determines that the rotor assembly 113 rotates forward, and when the controller 13 determines that the waveform of the distance detection signal matches the reverse detection signal according to the preset waveform of the reverse detection signal, the controller 13 determines that the rotor assembly 113 rotates reversely.
[0054] In summary, the motor assembly 10 provided by the present application has a bearing 112 provided with a detected portion that cooperates with the distance sensor 12, and the distance sensor 12 is located on the side of the bearing 112 provided with the detected portion, and the detected portion is at least two grooves 1121. At least two grooves 1121 are provided on the side of the bearing 112 perpendicular to the motor shaft 111, and at least part of each groove 1121 is located on the same circumference C centered on the motor shaft 111. The distance sensor 12 is located on the side of the bearing 112 provided with the groove 1121, and the distance sensor 12 is provided corresponding to the circumference C. The distance sensor 12 is used to detect the distance between the surface where the circumference C is located and the distance sensor 12 when the bearing 112 rotates and generate a distance detection signal. Among them, at least two grooves 1121 make the waveform of the distance detection signal different when the rotor assembly 113 rotates forward and reverse. In this way, after the controller 13 controls the rotation of the rotor assembly 113, the rotation direction of the rotor assembly 113 can be determined according to the distance detection signal and the preset detection signal. In this way, the motor assembly 10 provided in the present application can quickly determine whether the rotor assembly 113 is reversed based on the above design, thereby effectively reducing the detection cost and ensuring the safety of the motor assembly 10.
[0055] Please refer again Figure 3 In some embodiments, the depth of each groove 1121 is different. In this way, when the distance sensor 12 detects grooves 1121 of different depths, the distance value d corresponding to the distance detection signal at this time is also different. As the rotor assembly 113 rotates periodically, the waveform of the distance detection signal output by the distance sensor 12 corresponding to at least two grooves 1121 is also periodic, and the waveforms of positive rotation and negative rotation are different. For example, please refer to Figure 3 , Figure 4A and Figure 4B , a groove 1121A, a groove 1121B and a groove 1121C are formed on one side of the bearing 112, wherein the depth of the groove 1121A is greater than the depth of the groove 1121B, and the depth of the groove 1121B is greater than the depth of the groove 1121C. Figure 3 When the first direction G is forward, the waveform of the distance detection signal is as follows Figure 4A ; When the bearing 112 moves with the rotor assembly 113 according to Figure 3 When the second direction H is reversed, the waveform of the distance detection signal is as follows Figure 4B Understandably, Figure 4A and Figure 4B The distance k in the figure represents the distance between the ungrooved surface of the circumference C and the distance sensor 12. Figure 4A or Figure 4BThe waveform of the detection signal shown is used to determine whether the distance detection signal matches the waveform of the preset detection signal. It is understandable that in other embodiments, two grooves 1121 or three or more grooves 1121 may be provided on the bearing 112 .
[0056] In some embodiments, when three or more grooves 1121 are provided on the bearing 112, the arc lengths between every two adjacent grooves 1121 on the circumference C are different. In this way, regardless of whether the depths of all the grooves 1121 on the bearing 112 are the same or different, the rotation direction of the bearing 112 can be determined based on the different arc lengths between the adjacent grooves 1121. For example, see Figure 5 In some embodiments, the bearing 112 is provided with a groove 1121D, a groove 1121E and a groove 1121F. The depths of the grooves 1121D, 1121E and 1121F are equal. The arc length L1 between the grooves 1121D and 1121E is smaller than the arc length L2 between the grooves 1121E and 1121F. The arc length L2 between the grooves 1121E and 1121F is smaller than the arc length L3 between the grooves 1121F and 1121D. In this way, when the bearing 112 is rotated along with the rotor assembly 113, Figure 5 When the first direction G is forward, the waveform of the distance detection signal is as follows Fig. 6A ; When the bearing 112 moves with the rotor assembly 113 according to Figure 5 When the second direction H is reversed, the waveform of the distance detection signal is as follows Figure 6B In this way, the controller 13 can Fig. 6A or Figure 6B The waveform of the detection signal shown is used to determine whether the distance detection signal matches the waveform of the preset detection signal.
[0057] Please continue reading Figure 7 In some embodiments, the motor assembly 10 further includes a bearing ring 1122. The bearing ring 1122 is disposed on a side of the bearing 112 perpendicular to the motor shaft 111, and the groove 1121 is disposed on the surface of the bearing ring 1122. In this way, it is possible to avoid directly opening the groove 1121 on the surface of the bearing 112, thereby increasing the life of the bearing 112. The bearing ring 1122 can be made of a material that is easy to assemble and mold, such as plastic or metal, and the present application does not limit the material of the bearing ring 1122.
[0058] Please also read Figure 2 and Figure 8In some embodiments, the stator assembly 114 further includes a bearing bracket 1144 disposed at one end of the overmolded part 1142 close to the bearing 112. The bearing bracket 1144 is used to hold the bearing 112. The side of the bearing bracket 1144 close to the end of the motor shaft 111 extends a distance in a direction parallel to the motor shaft 111 and then extends in a direction close to the motor shaft 111 to form a sensor bracket 1145. In other words, the bearing bracket 1144 also extends a distance to the side close to the end cover 11311 and then extends to the side close to the motor shaft 111 to form the sensor bracket 1145 (that is, the bearing bracket 1144 first extends downward for a distance and then extends inward for a distance to form the sensor bracket 1145). The distance sensor 12 is disposed on the sensor bracket 1145. Since the stator assembly 114 remains stationary relative to the rotor assembly 113, the distance sensor 12 disposed on the sensor bracket 1145 can also remain stationary relative to the rotor assembly 113. In other embodiments, the distance sensor 12 may also be disposed at any other position in the motor 11 . The specific location may be determined according to the specific structure of the motor 11 . The present application does not limit the location of the distance sensor 12 .
[0059] It is understandable that the distance sensor 12 of the present application may be, for example, an infrared sensor or a laser sensor, etc. The present application does not limit the specific type of the distance sensor 12, as long as the distance sensor 12 can achieve the distance measurement function.
[0060] See also Fig. 9 In some embodiments, the motor assembly 10 further includes a reminder module 14 electrically connected to the controller 13. The reminder module 14 may include, for example, an electronic device with a reminder function, such as a speaker and / or an LED light. When the controller 13 determines that the rotor assembly 113 is reversed, the controller 13 further controls the reminder module 14 to output a reminder message. In some embodiments, when the reminder module 14 includes a speaker, the reminder message may be a sound reminder message; when the reminder module 14 includes an LED light, the reminder message may be an LED light of a corresponding color that is turned on.
[0061] In some embodiments, the motor 11 further includes a drive circuit 116. The drive circuit 116 is electrically connected to the controller 13 and the three-phase coil formed by the winding 1143. The drive circuit 116 may include six switch tubes. The six switch tubes form three bridge arms, and the three bridge arms are respectively connected to the three-phase coils. The controller 13 outputs a drive signal by controlling the six switch tubes to turn on / off, thereby controlling the corresponding coils to generate a magnetic field and drive the rotor assembly 113 to rotate. The controller 13 may be implemented by a chip with a control function such as a microprocessor or FPGA. In this way, when the controller 13 determines that the rotor assembly 113 is reversed, the controller 13 controls the rotor assembly 113 to switch to forward rotation through the drive circuit 116. Specifically, a position sensor is also provided in the motor 11 for detecting the position of the rotor assembly 113. The controller 13 obtains the position of the rotating assembly 113 through the position sensor, and then adjusts the coil current of the corresponding phase in sequence according to the current position and rotation direction of the rotating assembly 113, thereby controlling the rotor assembly 113 to switch to forward rotation.
[0062] Please refer again Figure 2 The motor 11 further includes a front bearing 115, and accordingly, the bearing 112 can be used as a rear bearing of the motor 11. In other embodiments, the above-mentioned solution can also be applied to the front bearing 115.
[0063] Please continue reading Fig.10 An embodiment of the present application further provides an electronic device 100, comprising the motor assembly 10 as described in any of the above embodiments.
[0064] In some embodiments, a corresponding switch button (not shown) is also provided on the electronic device 100. When the controller 13 confirms that the rotor assembly 113 is reversed and outputs a prompt message, the controller 13 can also control the rotor assembly 113 to switch from reverse rotation to forward rotation after the user presses or touches the switch button.
[0065] It is understandable that the electronic device 100 includes but is not limited to an angle grinder, a cutting machine, a lawn mower, etc. The present application does not limit the specific device type of the electronic device 100.
[0066] In addition, the above drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to be limiting.
[0067] The present application is not limited to the above specific implementations. A person skilled in the art can easily understand that there are many alternatives to the test fixture of the present application without departing from the principle and scope of the present application. The scope of protection of the present application shall be subject to the content of the claims.
Claims
1. A motor assembly, characterized in that: It includes a motor, a distance sensor and a controller, wherein the motor includes a motor shaft, a rotor assembly and a bearing, wherein: The bearing rotates together with the rotor assembly when the rotor assembly rotates, and the bearing is provided with a detected portion that cooperates with the distance sensor; The distance sensor is located at a side of the bearing where the detected part is provided, and the distance sensor remains stationary relative to the rotor assembly. The distance sensor is used to detect the distance between the surface of the bearing where the detected part is provided and the distance sensor when the bearing rotates, and generate a distance detection signal. The detected part makes the waveform of the distance detection signal different when the rotor assembly rotates forward and reversely. The controller is used to control the rotation of the rotor assembly and determine the rotation direction of the rotor assembly according to the distance detection signal and the preset detection signal.
2. The motor assembly according to claim 1, characterized in that: The detected portion is provided on one side of the bearing perpendicular to the motor shaft, and the detected portion is at least two grooves.
3. The motor assembly according to claim 2, characterized in that: The motor assembly further comprises a bearing ring, which is arranged on a side of the bearing perpendicular to the motor shaft, and the groove is arranged on a surface of the bearing ring.
4. The motor assembly according to claim 2, characterized in that: The depth of each of the grooves is different.
5. The motor assembly according to any one of claims 2 to 4, characterized in that: Each of the grooves is located on the same circumference centered on the motor shaft, and the distance sensor is arranged corresponding to the circumference. When three or more grooves are arranged on the bearing, the arc lengths between every two adjacent grooves on the circumference are different.
6. The motor assembly according to claim 2, characterized in that: The motor also includes a bearing bracket, which is used to hold the bearing. One side of the bearing bracket close to the end of the motor shaft extends a distance in a direction parallel to the motor shaft and then extends in a direction close to the motor shaft to form a sensor bracket. The distance sensor is arranged on the sensor bracket.
7. The motor assembly according to claim 2, characterized in that: The distance sensor includes a laser sensor or an infrared sensor.
8. The motor assembly according to claim 2, characterized in that: The preset detection signal includes a forward rotation detection signal and a reverse rotation detection signal. When the waveform of the distance detection signal matches the forward rotation detection signal, the controller determines that the rotor assembly rotates forward. When the waveform of the distance detection signal matches the reverse rotation detection signal, the controller determines that the rotor assembly rotates reversely.
9. The motor assembly according to claim 2, characterized in that: The motor assembly further includes a reminder module electrically connected to the controller. When the controller determines that the rotor assembly is reversed, the controller further controls the reminder module to output reminder information.
10. The motor assembly according to claim 2, characterized in that The motor also includes a drive circuit and a winding, wherein the drive circuit is electrically connected to the controller and a three-phase coil formed by the winding. When the controller determines that the rotor assembly is reversed, the controller controls the rotor assembly to switch to forward rotation through the drive circuit.