High-sine-wave back-emf micro-wound stator, micro-disc motor and fan

Abstract

The utility model discloses a high sine nature counter electromotive force's miniature winding formula stator, miniature disc motor and fan, including FPC group and stator group, the FPC group contains FPC board and sine wave drive IC, the FPC board has the center through -hole, the stator group includes U coil, V coil and W coil, U coil, V coil and W coil are all crescent coil, U coil, V coil and W coil all include first circular segment, second circular segment and bevel segment, first circular segment is close to the side of center through -hole and set up, and the circular arc end is away from the side of center through -hole, first circular segment is connected with circular segment through bevel segment to form crescent line hole with the surrounding structure, and thus optimization magnetic field distribution, promote the sine nature of counter electromotive force waveform, reduce current harmonic loss, when cooperate sine wave drive IC uses, can effectively offset lateral magnetic pull, reduce motor operation vibration, reduce fan noise.

Description

Technical Field

[0001] This utility model relates to the field of stator technology for miniature axial flux motors, and in particular to a miniature wound stator with high sinusoidal back electromotive force, a miniature disc motor and a fan. Background Technology

[0002] As smart terminal products such as laptops, tablets, and mobile phones become increasingly thinner and lighter, cooling fans are also becoming thinner. The sound quality requirements for micro fans are becoming increasingly stringent, posing a significant challenge to the fan industry. Research shows that the sound quality of micro fans is not only related to the residual imbalance of the rotor but also closely related to the motor. Furthermore, the design and assembly of the motor indirectly affect the optimization of sound quality and the product's market competitiveness. Therefore, while pursuing improved sound quality, cost control is also crucial.

[0003] Most existing micro fans use axial flux disk type coreless motors, which have obvious shortcomings in the stator-rotor slot-pole matching and coil structure: although the multi-coil layout can ensure performance to a certain extent, the large number of solder pads and complicated assembly process result in low production efficiency and high cost. Secondly, traditional coil structures are mostly fan-shaped, rectangular, or arc-shaped, with right angles or acute angles at their corners. When magnetic field lines pass through, they are obstructed, piled up, or broken at the corners, making it impossible to form a continuous magnetic field path. This results in the magnetic field being divided into multiple isolated small areas. Furthermore, because traditional coils do not conform to the straight line of the rotor magnetic pole center and the arc-shaped edge magnetic field trajectory, and there is no smooth transition at the corners, the magnetic reluctance fluctuates. The magnetic field cannot form a continuous and gradual distribution in the stator area, ultimately exhibiting a discontinuous, uneven, and locally strong state, which in turn leads to problems such as back EMF waveform distortion, vibration, and noise.

[0004] Therefore, a new technical solution needs to be researched to address the above problems. Utility Model Content

[0005] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide a miniature wound stator, miniature disc motor and fan with high sinusoidal back EMF. Its U, V and W coils are formed into crescent-shaped wire holes by the first arc segment, the second arc segment and the chamfer segment. This optimizes the magnetic field distribution, improves the sinusoidal nature of the back EMF waveform, and reduces current harmonic losses. When used with a sinusoidal wave drive IC, it can effectively counteract lateral magnetic pull, reduce motor vibration, and thus reduce fan noise.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A miniature wire-wound stator with high sinusoidal back EMF includes an FPC assembly and a stator assembly disposed on the FPC assembly; The FPC assembly includes an FPC board and a sine wave driver IC. The FPC board has a central through hole. The stator assembly includes a U coil, a V coil, and a W coil arranged circumferentially around the central through hole. The U coil, V coil, and W coil are all crescent-shaped coils. The U coil, V coil, and W coil are connected to the sine wave driver IC. The U coil, V coil, and W coil each include a first arc segment, a second arc segment, and a chamfered segment. The first arc segment is located on the side closest to the central through hole, and the arc end is located on the side away from the central through hole. The first arc segment and the arc segments are connected by the chamfered segment to form a crescent-shaped wire hole.

[0007] As a preferred embodiment, the radius of the first arc segment is at least three times the radius of the second arc segment.

[0008] As a preferred embodiment, the chamfered segment includes a first chamfered connecting segment and a second chamfered connecting segment. One end of the first arc segment is connected to one end of the second arc segment via the first chamfered connecting segment, and the other end of the first arc segment is connected to the other end of the second arc segment via the second chamfered connecting segment. By splitting the chamfered segment into the first and second chamfered connecting segments, which connect the two ends of the first and second arc segments respectively, the curvature at the corner of the coil better matches the magnetic field trajectory, reduces abrupt changes in magnetic reluctance, makes the magnetic field distribution more uniform, and reduces the sinusoidal nature of the back EMF waveform. At the same time, the double chamfer design enhances the mechanical strength of the coil structure, reduces stress concentration in the conductor during winding, reduces the risk of wire breakage, and improves production yield.

[0009] As a preferred embodiment, the sinusoidal wave driver IC is located on the other end face of the FPC board away from the U coil, V coil, and W coil. The driver circuit and the coil are arranged separately, which can avoid the magnetic field of the coil during operation from interfering with the signal stability of the driver circuit and reduce electromagnetic compatibility issues. At the same time, the separate layout makes full use of the space on the front and back of the FPC board and reduces the overall thickness.

[0010] As a preferred embodiment, the ends of the U coil, V coil, and W coil are welded to the same horizontal plane, with the ends welded to the same plane to ensure that the welding points are at the same height, thus avoiding problems such as uneven conductor stress and incomplete soldering caused by traditional high-low difference welding.

[0011] As a preferred embodiment, the FPC board has at least four pads. When the FPC board has four pads, they are defined as U pad, V pad, W pad, and COM pad, respectively. The U pad includes a U1 line start pad and a U1 line end pad, the V pad includes a V1 line start pad and a V1 line end pad, and the W pad includes a W1 line start pad and a W1 line end pad. The ends of the U coil, V coil and W coil are soldered to their respective end pads, and the ends of the U coil, V coil and W coil are soldered to their respective end pads. The U1 end pad, V1 end pad and W1 end pad are located on the COM pad. When there are six pads on the FPC board, they are defined as U pad, V pad, W pad and three COM pads. The U pad includes a U1 line start pad and a U1 line end pad. The V pad includes a V1 line start pad and a V1 line end pad. The W pad includes a W1 line start pad and a W1 line end pad. The U1 line end pad, V1 line end pad and W1 line end pad are each set on a COM pad.

[0012] As a preferred embodiment, the length-to-width ratio of the crescent-shaped wire hole is 3.0-5.0.

[0013] A miniature disc motor includes a stator winding and a rotor assembly. The stator winding is a miniature wound stator with high sinusoidal back EMF as described in any of the above-mentioned embodiments. The number of poles of the coils of the stator winding and the rotor magnet of the rotor assembly adopts a three-phase three-slot four-pole structure with slot pole matching.

[0014] A fan includes a base, a fan, a backplate, and a motor. The motor is a miniature disc motor as described above. The motor is installed and positioned inside the base. The FPC board is disposed inside the base. The fan blades are rotatably mounted on the rotor assembly of the motor and rotate synchronously with the rotor assembly. The backplate is embedded in the base.

[0015] Compared with the prior art, this utility model has obvious advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly uses the crescent-shaped coil structure design. The U, V, and W three-phase coils are all designed as crescent-shaped, and the first arc segment is close to the central through hole, so that it can adapt to the approximately linear magnetic field trajectory of the rotor magnetic pole center region. Secondly, the second arc segment is designed to be far from the central through hole, which fits the arc-shaped magnetic field trajectory of the magnetic pole edge, so that the angle between the coil conductor and the magnetic field line is always within a reasonable range, avoiding the unevenness of the magnetic field line being perpendicularly cut at the corners and parallelly avoided at the plane in traditional rectangular coils. The chamfered section design eliminates the abrupt change in magnetic field at the conductor bend, allowing the magnetic field to form a continuous and uniform distribution around the coil. When the rotor rotates due to the uniform magnetic field distribution, the speed at which the coil conductor cuts the magnetic field changes continuously, and the rate of change of magnetic flux shows a smooth sine curve trend. The back EMF waveform is closer to the standard sine wave, and the total harmonic distortion rate is greatly reduced. Combined with the sine wave drive, it can effectively counteract the lateral magnetic pull and reduce motor vibration and noise. Furthermore, the FPC board adopts a circumferentially uniform arrangement of three crescent-shaped coils surrounding the central through hole. Compared with the traditional multi-coil solution, this reduces the number of coils and pads, simplifies the assembly process, reduces the risk of assembly errors, improves product yield, and controls production costs.

[0016] To more clearly illustrate the structural features and effects of this utility model, the following detailed description of this utility model is provided in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 This is a perspective view of a miniature wound stator according to an embodiment of this utility model; Figure 2 This is a structural diagram of a miniature wound stator according to an embodiment of this utility model; Figure 3 This is another perspective view of a miniature wound stator according to an embodiment of this utility model; Figure 4 This is a structural diagram of a fan according to an embodiment of the present invention; Figure 5 This is a cross-sectional view of a fan according to an embodiment of this utility model; Figure 6 This is an exploded view of a fan according to an embodiment of this utility model; Figure 7 This is a simulation diagram of the unbalanced lateral magnetic pull of a sector coil in existing technology; Figure 8 This is a simulation diagram of the unbalanced lateral magnetic pull of a crescent-shaped coil according to an embodiment of this utility model.

[0018] Explanation of reference numerals in the attached diagram: 10. FPC board; 11. Center through hole 12. U coil 13. V coil 14. W coil 15. First arc segment 16. Second arc segment 17. Chamfer segment 18. Crescent-shaped thread hole 171. First chamfered connecting segment 172. Second chamfered connecting segment 20. Sine wave driver IC 30. Stator winding; 40. Rotor assembly. 41. Magnet 50, base 60, fan blades. Detailed Implementation

[0019] Please refer to Figures 1 to 8 As shown, it illustrates the specific structure of an embodiment of the present invention.

[0020] In the description of this utility model, it should be noted that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0021] A miniature wound stator with high sinusoidal back EMF, comprising an FPC assembly and a stator assembly.

[0022] The stator assembly is mounted on the FPC assembly; the FPC assembly includes an FPC board 10 and a sine wave drive IC 20. The FPC board 10 has a central through hole 11 and U coils 12, V coils 13, and W coils 14 arranged circumferentially around the central through hole 11; the U coils 12, V coils 13, and W coils 14 are all crescent-shaped coils; the U coils 12, V coils 13, and W coils 14 are connected to the sine wave drive IC 20. The U coil 12, V coil 13 and W coil 14 each include a first arc segment 15, a second arc segment 16 and a chamfered segment 17. The first arc segment 15 is located on the side close to the central through hole 11, and the arc end is located on the side away from the central through hole 11. The first arc segment 15 and the second arc segment 16 are connected by the chamfered segment 17 to form a crescent-shaped wire hole 18.

[0023] The radius of the first arc segment is at least three times the radius of the second arc segment, or the radius of the first arc segment can be infinitely large, to the point that it degenerates into a straight line.

[0024] Preferably, the chamfered segment 17 includes a first chamfered connecting segment 171 and a second chamfered connecting segment 172. One end of the first arc segment 15 is connected to one end of the second arc segment 16 through the first chamfered connecting segment 171, and the other end of the first arc segment 15 is connected to the other end of the second arc segment 16 through the second chamfered connecting segment 172. By splitting the chamfered segment 17 into the first and second chamfered connecting segments 172, which connect the two ends of the first arc segment 15 and the second arc segment 16 respectively, the curvature at the corner of the coil is made to better fit the magnetic field trajectory, reducing magnetic reluctance abrupt changes, making the magnetic field distribution more uniform, and reducing the sinusoidal nature of the back EMF waveform. At the same time, the double chamfer design enhances the mechanical strength of the coil structure, reduces stress concentration in the wires during winding, reduces the risk of wire breakage, and improves production yield.

[0025] The U, V, and W three-phase coils use a crescent-shaped wire hole 18 formed by the first arc segment 15, the second arc segment 16, and the chamfered segment 17. By adapting the conductor spatial arrangement to the rotor magnetic field trajectory, the uniformity and continuity of the magnetic field distribution are achieved. Since the rotor magnetic poles of the micro disc motor are distributed in a ring, the trajectory of the magnetic field lines from the N pole to the S pole is a composite curve with an approximately straight line in the central region and an arc shape in the edge region. The first arc segment 15 of the crescent-shaped wire hole 18 is close to the central through hole 11 of the FPC board 10, which corresponds exactly to the straight magnetic field trajectory at the center of the rotor magnetic pole. The second arc segment 16 fits the arc-shaped magnetic field trajectory at the edge of the magnetic pole, so that the angle between the coil conductor and the magnetic field line is always within a reasonable range, avoiding the unevenness problem of the magnetic field lines being perpendicularly cut at the corners and parallelly avoided at the plane in traditional rectangular coils.

[0026] Secondly, since the corners of traditional coils are mostly right angles or acute angles, magnetic field lines will accumulate or break at the corners when passing through, resulting in a sudden change in magnetic reluctance. The chamfered section 17 of the crescent-shaped wire hole 18 adopts a smooth transition design, optimizing the transition between the first arc section 15 and the second arc section 16 into an arc transition, so that the magnetic field lines can flow continuously along the surface of the coil conductor, and the rate of change of magnetic reluctance is reduced to a minimum, thereby forming a uniform magnetic field distribution that is continuously and gradually changes from the center to the edge, avoiding the fragmentation of the magnetic field distribution and local strong or weak areas.

[0027] Furthermore, the U, V, and W three-phase coils are evenly arranged around the central through hole 11, and the crescent-shaped wire holes 18 of each coil face the same direction and have an electrical phase difference of 120°. This arrangement allows the magnetic fields generated by the three-phase coils to be superimposed and complementary in space, forming a stable composite magnetic field, which further weakens the local fluctuations of the magnetic field of a single coil and ensures the uniformity of the magnetic field distribution in the entire stator area.

[0028] Since the waveform characteristics of back EMF are determined by the rate of change of magnetic flux, and the crescent-shaped wire hole 18 improves the continuity of magnetic flux change from the root by optimizing the magnetic field distribution, the essence of back EMF is the induced electromotive force generated when the conductor cuts the magnetic field. Its magnitude is proportional to the rate of change of magnetic flux (Faraday's law of electromagnetic induction). Due to the uneven distribution of the magnetic field in traditional coils, the magnetic flux changes in a stepwise manner with the rotation of the rotor. In the abrupt magnetic field change regions at the center and edge of the magnetic pole, the rate of change of magnetic flux rises and falls sharply, resulting in distortions such as spikes and dips in the back EMF waveform and poor sinusoidal characteristics. However, in the uniform magnetic field corresponding to the crescent-shaped coil, when the rotor rotates, the speed at which the coil conductor cuts the magnetic field changes continuously with the magnetic pole trajectory. The rate of change of magnetic flux presents a smooth oscillation in the form of a sine curve, and the back EMF waveform naturally conforms to the standard sine wave. Because abrupt changes in the magnetic field of a traditional coil can trigger high-order harmonics in the change of magnetic flux, these harmonics will be superimposed on the fundamental wave of the back EMF, resulting in waveform distortion. The crescent-shaped wire hole 18 eliminates abrupt changes in the magnetic field and optimizes the change of magnetic reluctance, so that the change of magnetic flux is dominated by the fundamental wave and the high-order harmonic components are greatly attenuated. The total harmonic distortion rate of the back EMF waveform of the crescent-shaped coil is lower than that of the traditional rectangular coil, and the sinusoidal nature is significantly improved. Preferably, the sinusoidal wave driver IC20 is disposed on the other end face of the FPC board away from the U coil 12, V coil 13, and W coil 14, and the sinusoidal wave driver IC20 is integrated on the FPC board 10. The split arrangement of the drive circuit and the coil can avoid the magnetic field interference of the coil during operation on the signal stability of the drive circuit and reduce electromagnetic compatibility issues. At the same time, the split layout makes full use of the space on both sides of the FPC board 10, reducing the overall thickness. The sinusoidal current output by the sinusoidal wave driver IC20 needs to be in phase synchronization with the back EMF of the motor to do work efficiently. The traditional distorted back EMF will produce a phase deviation with the sinusoidal wave drive current, forcing the current to generate additional harmonic components to compensate for the phase difference. These harmonic currents (such as the 3rd and 5th harmonics) cannot be converted into mechanical power and instead become a source of loss. However, the high sinusoidal back EMF of the crescent-shaped coil can achieve precise matching with the sinusoidal wave drive current in the same frequency and phase, greatly reducing the current harmonic components and increasing the proportion of the fundamental current. like Figure 7 The diagram shown is a simulation test schematic of the unbalanced lateral magnetic pull (UMP) of a prior art sector coil, with a peak UMP of 0.00214 N. like Figure 8 This diagram illustrates a simulation test of the unbalanced lateral magnetic pull (UMP) of the crescent-shaped coil in this embodiment. The peak value of the UMP is 0.00173 N, a decrease of 19%. The combination of unbalanced lateral magnetic pull and centrifugal force caused by residual imbalance will generate additional vibration and noise. Therefore, the sine wave drive of the crescent-shaped coil can effectively counteract the lateral magnetic pull and reduce motor vibration and noise.

[0029] Preferably, the ends of the U coil 12, V coil 13 and W coil 14 are welded to the same horizontal plane, and the ends are welded to the same plane to ensure that the height of the welding point is consistent, thus avoiding problems such as uneven force on the conductor and poor soldering caused by traditional high-low difference welding.

[0030] Preferably, the FPC board 10 has at least four pads. When the FPC board 10 has four pads, they are defined as U pad, V pad, W pad, and COM pad, respectively. The U pad includes a U1 line start pad and a U1 line end pad, the V pad includes a V1 line start pad and a V1 line end pad, and the W pad includes a W1 line start pad and a W1 line end pad. The ends of the U coil 12, V coil 13 and W coil 14 are soldered to their respective end pads, and the ends of the U coil 12, V coil 13 and W coil 14 are soldered to their respective end pads. The U1 end pad, V1 end pad and W1 end pad are located on the COM pad. When the FPC board 10 has six pads, they are defined as U pad, V pad, W pad and three COM pads respectively. The U pad includes a U1 line start pad and a U1 line end pad. The V pad includes a V1 line start pad and a V1 line end pad. The W pad includes a W1 line start pad and a W1 line end pad. The U1 line end pad, V1 line end pad and W1 line end pad are each set on a COM pad.

[0031] Preferably, the length-to-width ratio of the crescent-shaped wire hole 18 is 3.0-5.0.

[0032] A miniature disc motor includes a stator winding 30 and a rotor assembly 40. The stator winding 30 is a miniature wound stator with high sinusoidal back electromotive force. The coils of the stator winding 30 and the rotor magnets 41 of the rotor assembly 40 adopt a slot-pole matching structure with a three-phase three-slot four-pole configuration.

[0033] A fan includes a base 50, a fan, a back iron, and a motor, wherein the motor is the aforementioned miniature disc motor, and the miniature disc motor is a disc-type coreless motor. The motor is installed and positioned within the base 50, and the FPC board 10 is disposed within the base 50. The fan blade 60 is rotatably mounted on the rotor assembly 40 of the motor and rotates synchronously with the rotor assembly 40. The back plate is embedded within the base 50.

[0034] The key design feature of this utility model is that it mainly uses the crescent-shaped coil structure design. The U, V and W three-phase coils are all designed as crescent-shaped. The first arc segment is close to the central through hole, so that it can adapt to the approximately linear magnetic field trajectory of the rotor magnetic pole center region. Secondly, the second arc segment is designed to be far from the central through hole, which fits the arc-shaped magnetic field trajectory of the magnetic pole edge, so that the angle between the coil conductor and the magnetic field line is always within a reasonable range, avoiding the unevenness of the magnetic field line being perpendicularly cut at the corners and parallelly avoided at the plane in traditional rectangular coils. The chamfered section design eliminates the abrupt change in magnetic field at the conductor bend, allowing the magnetic field to form a continuous and uniform distribution around the coil. When the rotor rotates due to the uniform magnetic field distribution, the speed at which the coil conductor cuts the magnetic field changes continuously, and the rate of change of magnetic flux shows a smooth sine curve trend. The back EMF waveform is closer to the standard sine wave, and the total harmonic distortion rate is greatly reduced. Combined with the sine wave drive, it can effectively counteract the lateral magnetic pull and reduce motor vibration and noise. Furthermore, the FPC board adopts a circumferentially uniform arrangement of three crescent-shaped coils surrounding the central through hole. Compared with the traditional multi-coil solution, this reduces the number of coils and pads, simplifies the assembly process, reduces the risk of assembly errors, improves product yield, and controls production costs.

[0035] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A miniature wound stator with high sinusoidal back electromotive force, characterized in that: This includes FPC assembly and stator assembly mounted on the FPC assembly; The FPC assembly includes an FPC board and a sine wave driver IC. The FPC board has a central through hole. The stator assembly includes a U coil, a V coil, and a W coil arranged circumferentially around the central through hole. The U coil, V coil, and W coil are all crescent-shaped coils. The U coil, V coil, and W coil are connected to the sine wave driver IC. The U coil, V coil, and W coil each include a first arc segment, a second arc segment, and a chamfer segment. The first arc segment is located on the side closer to the central through hole, and the second arc segment is located on the side away from the central through hole. The first arc segment and the second arc segment are connected by the chamfer segment to form a crescent-shaped wire hole.

2. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The radius of the first arc segment is at least three times the radius of the second arc segment.

3. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The chamfered segment includes a first chamfered connecting segment and a second chamfered connecting segment. One end of the first arc segment is connected to one end of the second arc segment through the first chamfered connecting segment, and the other end of the first arc segment is connected to the other end of the second arc segment through the second chamfered connecting segment.

4. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The sinusoidal drive IC is located on the other end face of the FPC board, away from the U coil, V coil, and W coil.

5. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The ends of the U-coil, V-coil, and W-coil are welded to the same horizontal plane.

6. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The FPC board has at least four pads, which are defined as U pad, V pad, W pad, and COM pad, respectively. The U pad includes a U1 line start pad and a U1 line end pad; the V pad includes a V1 line start pad and a V1 line end pad; and the W pad includes a W1 line start pad and a W1 line end pad. The ends of the U coil, V coil and W coil are soldered to their respective end pads, and the ends of the U coil, V coil and W coil are soldered to their respective end pads. The U1 end pad, V1 end pad and W1 end pad are located on the COM pad. When there are six pads on the FPC board, they are defined as U pad, V pad, W pad and three COM pads. The U pad includes a U1 line start pad and a U1 line end pad. The V pad includes a V1 line start pad and a V1 line end pad. The W pad includes a W1 line start pad and a W1 line end pad. The U1 line end pad, V1 line end pad and W1 line end pad are each set on a COM pad.

7. The miniature wound stator with high sinusoidal back electromotive force according to claim 1, characterized in that: The length-to-width ratio of the crescent-shaped wire hole is 3.0-5.

0.

8. A miniature disc motor, characterized in that: It includes a stator winding and a rotor assembly, wherein the stator winding is a miniature wound stator with high sinusoidal back EMF as described in any one of claims 1 to 7, and the number of poles of the rotor magnet of the stator winding and the rotor assembly adopts a slot pole matching structure of three-phase three-slot four-pole.

9. A fan, characterized in that: It includes a base, a fan, a back iron, and a motor. The motor is a miniature disc motor as described in claim 8. The motor is installed and positioned inside the base. The FPC board is disposed inside the base. The fan is rotatably mounted on the rotor assembly of the motor and rotates synchronously with the rotor assembly. The back iron is embedded in the base.

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