Harmonic magnetic field drive motor

Abstract

A harmonic magnetic field driven motor, in which A. some tooth grooves are provided on the stator laminations, and the number of grooves is Z; B. in the 360° mechanical space around the circumference of the stator, the stator winding is divided into m phases according to a set connection rule; C. the stator assembly with the windings is placed independently in free space, a constant DC current is passed through one of the windings of the stator, and the number of pole pairs of the phase winding magnetic field formed in the 360° mechanical space around the circumference of the stator is Pm; and D. the number of coil groups included in the winding of each phase is k=n×Pm, where n=1, 2, 3,… E. the rotor permanent magnets are sequentially arranged in the order of N and S poles in the circumferential direction, and the number of pole pairs of the rotor permanent magnets formed in the 360° mechanical space along the circumference of the rotor is Pr; and F. a motor air gap is formed in a combination space in the 360° mechanical space on the circumference of the stator and rotor, and the number of pole pairs Pr of the rotor permanent magnets of the harmonic magnetic field drive motor must satisfy Pr = Z ± Pm, with the proviso that the number of stator grooves of the harmonic magnetic field drive motor is Z = m × k, and a two-layer winding is used.

Description

[Technical Field]

[0001] The present invention relates to the technical field of motors, and more particularly to harmonic magnetic field driven motors. [Background technology]

[0002] Motors, which convert electrical energy into rotational mechanical energy, have become an essential and irreplaceable core device in people's pursuit of a better life. Permanent magnet motors, with their advantages of small volume and high efficiency, are widely used in various industries. Rare earth permanent magnet materials, in particular, have the remarkable advantage of high magnetic energy product, and are widely used in brushless direct current motors (BLDC) and permanent magnet synchronous motors (PMSM), driving the main development direction and trend of motors. Because rare earth permanent magnet materials are non-renewable resources, how to fully improve material utilization has become an important research topic in countries around the world. Therefore, there is a growing need to design harmonic magnetic field-driven motors that can reduce motor volume under the same output power conditions, which also reduces motor weight synchronously. This can significantly reduce motor material costs, especially the cost of rare earth permanent magnet materials, and greatly enhance product competitive advantages. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE INVENTION The technical problem to be solved by the present invention is to provide a harmonic magnetic field drive motor that can reduce the volume and improve the power density in response to the above-mentioned defects of the prior art. [Means for solving the problem]

[0004] The technical solution used in the present invention to solve the above problems is as follows: a harmonic magnetic field driven motor, comprising a rotor assembly, a stator assembly, a control module and a wire harness, the wire harness is connected to the control module by welding, the control module is fixed to the stator assembly by a positioning post and an elastic locking member, the wire harness passes through a radial hole provided in the stator assembly and is drawn out from an axial hole, and a columnar bearing provided in the stator assembly provides support and positioning for the rotor assembly, when the harmonic magnetic field driven motor is energized, the rotor assembly rotates in the circumferential direction, and the main structure is as follows: A. The stator laminations are provided with some tooth grooves, and the number of grooves is Z. B. In the 360° mechanical space around the circumference of the stator, the stator winding is divided into m phases according to the established connection rules; C. The stator assembly with windings is placed independently in free space (the motor is not assembled), a constant DC current is passed through one of the phase windings, and the number of pole pairs of the phase winding magnetic field formed in the 360° mechanical space around the circumference of the stator is Pm; D. The number of coil groups included in each phase winding is k = n × Pm (n = 1, 2, 3, ...), and E. The rotor permanent magnets are arranged in the circumferential direction in the order of N poles and S poles, and the number of pole pairs of the rotor permanent magnets formed in the 360° mechanical space along the rotor circumference is Pr; F. A motor air gap is formed within the combined space in the 360° mechanical space around the circumference of the stator and rotor.

[0005] An embodiment of the present invention is designed so that the number of stator slots is Z=15, the number of pole pairs of the rotor permanent magnet is Pr=10, the number of pole pairs of the coil group of each phase is Pm=5, and the number of coil groups of each phase is k=5.

[0006] More specifically, the harmonic magnetic field drive motor according to the present invention will be further described as follows: The principles of a harmonic field driven motor include: A. regardless of whether it is BLDC control or PMSM control, a necessary condition for the motor rotor to rotate is that the number of pole pairs of the magnetic field generated in the motor air gap of the stator winding is equal to the number of pole pairs of the rotor permanent magnet; B. when current is applied to the stator winding, a fundamental magnetomotive force is generated in the motor air gap, and a series of harmonic magnetic fields are distributed along the air gap space due to the magnetic action of the stator tooth gaps; and C. when the number of pole pairs of a specific air gap harmonic magnetic field is equal to the number of pole pairs Pr of the permanent magnet rotor, a stable electromagnetic torque will be output.

[0007] In order to satisfy the principles of a harmonic magnetic field drive motor, the following conditions A to C must be met. A. The number of pole pairs Pr of the rotor of a harmonic magnetic field drive motor must satisfy Z±Pm=Pr, specifically, JPEG0007771420000001.jpg141702) In the closed circuit of the motor magnetic field, the closed circuit is mainly formed by the ferromagnetic material and the motor air gap, so the motor Ampere's circuit law is shown as H(δ)×L(δ)+H(ferromagnetic)×L(ferromagnetic)=W×I=F, and since H(ferromagnetic) in the ferromagnetic material can be small and approximately equal to zero, H(δ)×L(δ)=W×I=F; 3) The relationship between magnetic induction strength B and magnetic field strength H is B = μ × H, where μ is the relative magnetic permeability. 4) Therefore, F = WI = B(δ) × L(δ) / μ0, where μ0 is the relative permeability of air, and JPEG0007771420000002.jpg151706) The spatial distribution of the magnetomotive force F in the motor air gap is a square wave, and based on the Fourier series, F(α) may be expressed as F(α)=(2 / π)×F×[sin(Pm×α)+(1 / 3)×sin(3×Pm×α)+...+(1 / n)×sin(n×Pm×α)], where n=1, 2, 3... and α indicates the mechanical space angle along the circumferential direction of the air gap. As can be seen from the above, the fundamental wave amplitude of the magnetomotive force is the largest, and the expression for the fundamental wave magnetomotive force is: F1(α)=(2 / π)×F×sin(Pm×α)=(2×WI / π)×sin(Pm×α), and JPEG0007771420000003.jpg30170JPEG0007771420000004.jpg35170Get B(α)=Bm0×sin(Pm×α)+(Bm1 / 2)×sin[(Z+Pm)×α]+(Bm1 / 2)×sin[(Z-Pm)×α] As can be seen from the above formula, the fundamental wave magnetomotive force generated by energizing the stator phase winding is a. A fundamental wave magnetomotive force magnetic field with a pole pair number of Pm, the properties of which correspond to a magnetic field formed without opening a groove in the stator; b. A tooth harmonic magnetic field with a pole pair number of (Z+Pm), the nature of which corresponds to the magnetic field formed after the fundamental wave magnetomotive force is modulated by the stator tooth gap; c. A tooth harmonic magnetic field with a pole pair number of (Z-Pm), the nature of which corresponds to the magnetic field formed after the fundamental wave magnetomotive force is modulated by the stator tooth gap, and 9) Regarding the selection of the number of pole pairs Pr of the rotor of a harmonic magnetic field drive motor, a. Based on the basic principle of motor operation, the motor will output a stable electromagnetic torque only when the number of pole pairs of the rotor is equal to the number of pole pairs formed by the stator coils; b. Based on the above principle, the number of magnetic pole pairs Pr of the rotor of the harmonic magnetic field drive motor must satisfy Z+Pm=Pr or Z-Pm=Pr.

[0008] B. The number of stator grooves Z of the harmonic magnetic field drive motor is selected as Z=m×k, specifically, It is explained that each coil group has two element edges, and each stator slot has two layers of winding, with two element edges on either the top and bottom layers or on both the left and right sides, which means that the number of stator slots is equal to the total number of coil groups. Each phase winding contains k coil groups, and the motor is divided into m phases. In this case, the number of stator slots Z of the motor must satisfy Z=m×k, and a two-layer winding is used.

[0009] C. The relationship between the number k of coil groups in each phase of a harmonic magnetic field drive motor and the number Pm of magnetic pole pairs formed by the coil groups in each phase is k = n × Pm, where n = 1, 2, 3, ..., and is specifically explained as follows. As can be seen from the principles of electromagnetic fields, one coil group can form only one opposing magnetic field, so the number of coil groups k ≥ the number of pole pairs Pm of coil group magnetic poles. Considering the principle that the magnetic field amplitude of the air gap is symmetrical in the 360° machine space around the circumference of the motor air gap, the number of coil groups forming one opposing pole may be 1, 2, 3..., the number of coil groups forming two opposing poles may be 2, 4, 6..., the number of coil groups forming three opposing poles may be 3, 6, 9..., and the number of coil groups forming Pm opposing poles is k = n × Pm, where n = 1, 2, 3...

[0010] Based on the principles and conditions, when using a three-phase (m=3) winding structure, the combinations of the number of stator grooves / number of pole pairs of the rotor permanent magnet / number of coil groups for each phase of a harmonic magnetic field drive motor are shown in the table below. JPEG0007771420000005.jpg38170

[0011] The control methods for harmonic magnetic field drive motors are BLDC control and PMSM control, with BLDC being a square wave voltage (current) drive method and PMSM being a sinusoidal wave voltage (current) drive method.

[0012] The principle of improving the power volume density of a harmonic magnetic field drive motor is as follows: A. The basic evaluation index for permanent magnet motors is that, as a rotating machine, a motor inevitably generates vibration noise, and the pulsation of the motor's cogging torque is the main root cause of the motor's vibration noise. Therefore, the motor must pursue the maximum power volume density (watts / liter) while reducing the cogging torque pulsation to ensure that the motor's vibration noise is within a reasonable range, and thus improving the power volume density is what actually has meaning. B. The main means for improving the power volume density of permanent magnet motors include: a. optimizing the magnetic circuit of the motor, which has limited improvement effect; b. selecting permanent magnet materials with higher magnetic energy product, which will significantly increase the manufacturing cost; and c. reducing the air gap value between the stator and rotor of the motor, which will basically increase the magnetic field amplitude of the air gap inversely proportional to the air gap value, thus achieving a significant improvement effect. C. Reduce the adverse effect of the motor air gap value on the pulsation of the motor cogging torque. That is, since the amplitude of the cogging torque is directly proportional to the square of the magnetic field amplitude of the air gap, if the motor air gap value is reduced, the pulsation of the motor cogging torque will increase significantly, and the motor vibration noise will also increase significantly. D. Effective methods for reducing the pulsation amplitude of motor cogging torque are: a. Under the condition of maintaining a constant motor air gap value, theoretical research reveals that an effective way to reduce the pulsation of the motor cogging torque is to increase the number of fluctuation cycles of the motor cogging torque (the number of cycles in which the cogging torque fluctuates when the rotor rotates once), and the number of fluctuation cycles should be equal to the least common multiple of the number of stator slots and the number of rotor poles. b. A comparison of the number of cycles of fluctuation between a harmonic magnetic field drive motor and a conventional motor under the condition of the same number of stator slots is shown in the table below.

[0013] JPEG0007771420000006.jpg76170

[0014] As can be seen from the comparison results in the table above, when the number of stator slots is the same, there is a clear tendency for the number of cogging torque fluctuation cycles to increase in the harmonic magnetic field drive motor compared to the conventional permanent magnet motor.

[0015] Preferably, an inner arc surface, a left slant surface of the dovetail groove, and a right slant surface of the dovetail groove are provided on the rotor laminations to engage with the outer arc surface, the left slant surface, and the right slant surface provided on the permanent magnet, respectively, thereby positioning the permanent magnet in the radial and circumferential directions, thereby improving the positioning accuracy of the permanent magnet and ensuring the operational stability of the harmonic magnetic field drive motor.

[0016] Preferably, radial holes and axial holes are provided on the motor shaft of the stator assembly, facilitating the passage of the wire harness through the radial holes and from the axial holes, thereby realizing the extraction of the wire harness.

[0017] Preferably, the stator assembly is provided with an elastic fixing locking member and a positioning post, which can improve the positioning precision of the control module and make the fixing more firm and reliable.

[0018] Alternatively, the permanent magnets and casing of the rotor assembly may be designed to be connected in a surface-mounted manner, and the same positioning effect can be achieved by using an auxiliary tool during the permanent magnet bonding process, rather than using the rotor lamination and dovetail structure for positioning. This is also feasible.

[0019] Alternatively, the permanent magnet may be divided into a multi-stage structure for the convenience of the processing process, without affecting the performance and effect of the harmonic magnetic field drive motor of this patent.

[0020] Alternatively, the harmonic magnetic field drive motor may be designed with an outer stator / internal rotor structure according to different applications, which can also achieve the same performance and effect as the outer rotor / internal stator structure in the embodiments of the present invention.

[0021] Alternatively, the harmonic magnetic field drive motor may be designed with an outer stator / inner rotor structure, and the permanent magnet bonding method of the rotor assembly may be surface mounted or surface embedded, which can achieve the same performance and effect.

[0022] Alternatively, the harmonic magnetic field drive motor may be designed with an external stator / internal rotor structure, use a PMSM control method, and have the permanent magnets of the rotor assembly embedded inside, which can also achieve the same performance and effect. [Effects of the Invention]

[0023] Compared with the prior art, the advantages of the present invention are that the harmonic magnetic field drive motor significantly increases the number of cogging torque fluctuation cycles by combining the set number of stator slots and the number of rotor permanent magnet poles, thereby reducing the air gap value of the harmonic magnetic field drive motor and maintaining or reducing the cogging torque fluctuation amplitude of the harmonic magnetic field drive motor; the set stator wire winding method makes the number of pole pairs of the harmonic magnetic field generated in the stator equal to the number of pole pairs of the rotor permanent magnet, thereby forming a stable electromagnetic torque output; the use of a relatively small air gap design of the harmonic magnetic field drive motor significantly improves the air gap magnetic field strength, which proportionally improves the output power of the harmonic magnetic field drive motor and also proportionally improves the power volume density of the harmonic magnetic field drive motor. Compared with conventional motors, under the same output power conditions, the volume of a harmonic magnetic field drive motor is reduced by more than one-fold, which means that the weight of the harmonic magnetic field drive motor is also reduced by more than one-fold, which greatly reduces the cost of motor materials, especially the cost of rare earth permanent magnet materials, and greatly improves the product's competitive advantage in the market.The structure of this harmonic magnetic field drive motor can be adapted to the control modules of conventional BLDC and PMSM motors, giving it greater versatility in terms of control. [Brief explanation of the drawings]

[0024] [Figure 1]FIG. 1 is a perspective view of a harmonic magnetic field drive motor according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded schematic view of a harmonic magnetic field drive motor according to an embodiment of the present invention. [Figure 3] FIG. 3 is a structural schematic diagram of a harmonic magnetic field drive motor according to an embodiment of the present invention. [Figure 4a] FIG. 4a is a partial view of the cross section taken along line AA in FIG. [Figure 4b] FIG. 4b is a partial view of the cross section taken along line BB in FIG. [Figure 5a] FIG. 5a is a partial enlarged view of F in FIG. 4a. [Figure 5b] FIG. 5b is a partial enlarged view of P in FIG. 4b. [Figure 6] FIG. 6 is an exploded schematic view of a rotor assembly according to an embodiment of the present invention. [Figure 7] FIG. 7 is a partially rotated and enlarged view of W in FIG. [Figure 8] FIG. 8 is a perspective view of a permanent magnet according to an embodiment of the present invention. [Figure 9] FIG. 9 is an exploded schematic view of a stator assembly according to an embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view of a motor shaft according to an embodiment of the present invention. [Figure 11] FIG. 11 is a structural schematic diagram of a rotor of a harmonic magnetic field drive motor according to another embodiment of the present invention, viewed from the outside. [Figure 12] FIG. 12 is a structural schematic diagram seen from the inside of the rotor of a harmonic magnetic field drive motor according to yet another embodiment of the present invention. [Figure 13] FIG. 13 is a structural schematic diagram seen from the inside of the rotor of a harmonic magnetic field drive motor according to a further embodiment of the present invention. [Figure 14] FIG. 14 is a structural schematic diagram seen from the inside of the rotor of a harmonic magnetic field drive motor according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be further described by way of examples with reference to the drawings.

[0026] As shown in Figures 1 and 2, this harmonic magnetic field drive motor comprises a rotor assembly 1, a stator assembly 2, a control module 3, and a wiring harness 4. When energized, the harmonic magnetic field drive motor outputs torque by rotating the rotor assembly 1, thereby achieving conversion from electrical energy to mechanical energy.

[0027] As shown in FIGS. 3 to 10, the rotor assembly 1 comprises a casing 11, rotor laminations 12 and permanent magnets 13.

[0028] The rotor laminations 12 are adhered to the inner circular surface of the casing 11 with an adhesive.

[0029] The rotor lamination 12 has 20 permanent magnets (10 opposing poles) evenly arranged on the inner circle.

[0030] The rotor laminations 12 are provided with an inner arc surface 1201, a left slope 1202 of the dovetail groove, and a right slope 1203 of the dovetail groove, which respectively engage with the outer arc surface 1301, the left slope 1302, and the right slope 1303 of the permanent magnet 13, thereby positioning the permanent magnet 13 radially and circumferentially. They are then glued into the dovetail grooves of the rotor laminations 12 with an adhesive so that the north and south poles are arranged alternately, thereby improving the operational stability of the harmonic magnetic field drive motor.

[0031] The laminations of the stator assembly 2 have 15 tooth grooves evenly arranged on the outer circle, and the number of pole pairs in each phase coil group is 5, and the number of coil groups in each phase is 5.

[0032] Each coil group has two element edges, and each stator slot is designed to use two layers of winding, with two element edges on the top and bottom layers or on both the left and right sides, and the number of stator slots is equal to the total number of coil groups.

[0033] The outer circle of the laminations of the stator assembly 2 and the permanent magnets 13 of the rotor assembly 1 form an air gap L of the harmonic magnetic field drive motor.

[0034] The wire harness 4 is connected to the control module 3 by welding.

[0035] The control module 3 is positioned and fixed by providing the elastic fixing locking member 212 and the positioning post 213 on the stator assembly 2, thereby making the fixing of the control module 3 more firm and reliable.

[0036] A radial hole 2111 and an axial hole 2112 are provided on the motor shaft 211 of the stator assembly 2, which facilitates the passage of the wire harness 4 through the radial hole 2111 and from the axial hole 2112, thereby enabling the wire harness 4 to be pulled out.

[0037] The columnar bearings 23, 28 installed on the stator assembly 2 are fixed inside the casing 11 of the rotor assembly 1 and perform supporting and positioning functions for the rotor assembly 1, so that the rotor assembly of the harmonic magnetic field driven motor can rotate in the circumferential direction when current is applied.

[0038] Stop rings 25 and 26 are installed on the stator assembly 2 to fix the columnar bearings 23 and 28, respectively, thereby realizing axial restriction for the rotor assembly 1, and wear-resistant gaskets 24 and 27 are installed to reduce frictional force.

[0039] As shown in FIG. 11, the permanent magnets N, S and the casing 111 of the rotor assembly are designed to be connected in a surface mount manner, which can achieve the same positioning effect for the permanent magnets without using the dovetail grooves of the rotor laminations for positioning.

[0040] As shown in Figures 12 and 13, the harmonic magnetic field drive motor is designed with an outer stator / inner rotor structure, and the permanent magnets N and S of the rotor assembly are attached to the rotor laminations 222 using a surface mounting method or a surface embedding method, which can achieve the same performance and effect.

[0041] As shown in Figure 14, the harmonic magnetic field drive motor is designed with an external stator / internal rotor structure and uses a PMSM control method, and the permanent magnets N and S of the rotor assembly can be internally embedded, which can also achieve the same performance and effect.

Claims

1. A harmonic magnetic field drive motor, A, some tooth spaces are provided on the stator lamination, and the number of spaces is Z; B. In the 360° mechanical space around the circumference of the stator, the stator winding is divided into m phases according to a set connection rule; C. The stator assembly with windings is placed independently in free space, a constant DC current is passed through any one of the phase windings, and the number of pole pairs of the phase winding magnetic field formed in the machine space 360° around the circumference of the stator is Pm; D. The number of coil groups included in each phase winding is k = n × Pm, where n = 1, 2, 3, ...; E. The rotor permanent magnets are arranged in the circumferential direction in the order of north poles and south poles, and the number of pole pairs of the rotor permanent magnets formed in the 360° mechanical space along the rotor circumference is Pr; F. A motor air gap is formed in a combined space in a 360° mechanical space around the circumference of the stator and rotor; The number of pole pairs Pr of the rotor permanent magnet of the harmonic magnetic field drive motor must satisfy Pr = Z ± Pm, provided that the number of stator grooves Z of the harmonic magnetic field drive motor is Z = m × k, a two-layer two-phase winding is used, A harmonic magnetic field drive motor, wherein the two-layer winding in each of the Z tooth spaces is a different phase winding.

2. 2. The harmonic magnetic field drive motor according to claim 1, wherein the number of grooves in the stator laminations is Z=15, the number of pole pairs in the rotor permanent magnet is Pr=10, the number of pole pairs in the coil group of each phase is Pm=5, and the number of coil groups in each phase is k=5.

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