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] As a device that converts electrical energy into rotating mechanical energy, a motor has become an essential and irreplaceable core device for people to pursue a better life. Permanent magnet motors have the advantages of small volume and higher efficiency, and are therefore widely used in various industries. In particular, rare earth permanent magnet materials have the remarkable advantage of high magnetic energy product, and are therefore widely used in the fields of brushless direct current motors (hereinafter abbreviated as BLDC) and permanent magnet synchronous motors (hereinafter abbreviated as PMSM), which drives the main development direction and trend of motors. Since rare earth permanent magnet materials belong to non-renewable resources, how to fully improve the utilization rate of materials has become an important issue that countries around the world are researching. Therefore, compared with traditional motors, there is an increasing need to design a harmonic magnetic field drive motor that can reduce the volume of the motor under the same condition of output power, which means that the weight of the motor is also reduced synchronously, which can greatly save the cost of using motor materials, especially the cost of rare earth permanent magnet materials, and greatly improve the competitive advantage of the product. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE PRESENT EMBODIMENT The technical problem to be solved by the present invention is to provide a harmonic magnetic field drive motor capable of reducing the volume and improving the power density in response to the above-mentioned deficiencies 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 includes 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 fixed locking member, the wire harness passes through a radial hole installed in the stator assembly and is drawn out from an axial hole, and a columnar bearing installed in the stator assembly plays a supporting and positioning role for the rotor assembly. When the harmonic magnetic field driven motor is energized, the rotor assembly rotates along the circumferential direction, and the main structure is as follows: A. There are some tooth gaps in the stator laminations, and the number of grooves is Z. B. In the 360° machine 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 (the motor is not assembled), a constant DC current is applied to 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 combination space in the 360° mechanical space around the circumference of the stator and rotor.

[0005] An embodiment of the present invention is designed such 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 described as follows: The principles of a harmonic field driven motor include: A. regardless of whether the motor is BLDC controlled or PMSM controlled, 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 slots; 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 principle of the 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, JPEG2025503301000002.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 JPEG2025503301000003.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 is 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 JPEG2025503301000004.jpg30170JPEG2025503301000005.jpg35170B(α) = Bm0 × sin(Pm × α) + (Bm1 / 2) × sin[(Z + Pm) × α] + (Bm1 / 2) × sin[(Z - Pm) × α] is obtained. 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 nature of which corresponds to a magnetic field formed without drilling a groove in the stator; b. A tooth harmonic magnetic field with a pole pair number of (Z+Pm), the nature of the magnetic field 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. 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, a 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, it is explained to include that 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, and 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 both the left and right sides using upper and lower layers, which means that the number of stator slots is equal to the total number of coil groups. Each phase winding includes k coil groups and the motor is divided into m phases. In this case, the number of stator grooves 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 of each phase of a harmonic magnetic field drive motor and the number Pm of magnetic pole pairs formed by the coil groups of each phase is k = n x Pm, where n = 1, 2, 3, ..., and is specifically explained as follows. As can be seen from the principle of electromagnetic fields, one coil group can form only one counterpole magnetic field, so the number of coil groups k ≧ the number of pole pairs Pm of the coil group magnetic poles. Considering the principle that the magnetic field amplitude of the air gap is symmetric in the 360° machine space on the circumference of the motor air gap, the number of coil groups forming one counterpole may be 1, 2, 3..., the number of coil groups forming two counterpole may be 2, 4, 6..., the number of coil groups forming three counterpole may be 3, 6, 9..., and the number of coil groups forming Pm counterpole 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 combination 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 is shown in the table below. JPEG2025503301000006.jpg38170

[0011] The control methods for harmonic magnetic field drive motors include the BLDC control method and the PMSM control method, with the BLDC being a square wave voltage (current) drive method and the 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 a permanent magnet motor is that, as a rotating machine, it is inevitable that a motor will generate vibration noise. However, the pulsation of the motor's cogging torque is an important root cause of motor 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. In this way, improving the power volume density is what has real meaning. B. The main means for improving the power volume density of a permanent magnet motor include: a. optimizing the magnetic circuit of the motor, which has limited improvement; b. selecting a permanent magnet material with higher magnetic energy product, which causes the manufacturing cost to increase significantly; and c. reducing the air gap value between the stator and rotor of the motor, in which case the magnetic field amplitude of the air gap is basically inversely proportional to the air gap value, so the improvement effect is significant. 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 as follows: 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 cycles of the motor cogging torque fluctuation (the number of cycles in which the cogging torque fluctuates when the rotor rotates once), and the number of cycles of fluctuation should be equal to the least common multiple of the number of stator grooves 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] JPEG2025503301000007.jpg76170

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

[0015] Preferably, an inner arc surface, a left sloping surface of the dovetail groove, and a right sloping surface of the dovetail groove are provided on the rotor laminations to engage with an outer arc surface, a left sloping surface, and a right sloping surface respectively provided on the permanent magnet to position 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 driven motor.

[0016] Preferably, radial and axial holes are provided on the motor shaft of the stator assembly to facilitate passing the wire harness through the radial hole and out of the axial hole, thereby realizing withdrawal 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 its fixing more firm and reliable.

[0018] Alternatively, the permanent magnets and casing of the rotor assembly can be designed to be connected in a surface mount manner, and instead of using the rotor lamination and dovetail structure for positioning, an auxiliary tool can be used for positioning during the bonding process of the permanent magnets, which can achieve the same positioning effect on the permanent magnets, and this is also feasible.

[0019] As an option, the permanent magnet is divided into a multi-stage structure for the convenience of the processing process, without affecting the performance and effect of the harmonic magnetic field driving motor in this patent.

[0020] Alternatively, the harmonic magnetic field driving motor may be designed with an external stator / internal rotor structure according to different applications, which can also achieve the same performance and effect as the external 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 attachment method of the rotor assembly may use a surface mount method or a surface embedded method, which can achieve the same performance and effect.

[0022] Alternatively, the harmonic 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 effectiveness. Effect of the Invention

[0023] Compared with the prior art, the advantages of the present invention are that the harmonic magnetic field driven motor greatly increases the number of cogging torque fluctuation cycles through the combination of the set number of stator grooves and the number of rotor permanent magnet poles, the air gap value of the harmonic magnetic field driven motor is reduced, and the fluctuation amplitude of the cogging torque of the harmonic magnetic field driven motor is maintained or reduced; 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 to form a stable electromagnetic torque output; and by using a relatively small air gap design of the harmonic magnetic field driven motor, the magnetic field strength of the air gap is greatly improved, the output power of the harmonic magnetic field driven motor is directly proportionally improved, and the power volume density of the harmonic magnetic field driven motor is also directly proportionally improved synchronously. Compared with conventional motors, under the same output power conditions, the volume of the harmonic magnetic field driven motor is reduced by more than one time, which means that the weight of the harmonic magnetic field driven motor is also reduced by more than one time, which can greatly reduce the cost of motor materials, especially the cost of rare earth permanent magnet materials, and greatly improve the competitive advantage of the product in the market. The structure of the harmonic magnetic field driven motor can be adapted to the control module of conventional BLDC and PMSM motors, and has higher versatility in terms of control. [Brief description of the drawings]

[0024] [Figure 1]FIG. 1 is a perspective view of a harmonic magnetic field driving motor according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded schematic diagram of a harmonic magnetic field driving motor according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing the structure of a harmonic magnetic field driving 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 partially enlarged view of F in FIG. 4a. [Figure 5b] FIG. 5b is an enlarged view of a portion 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 schematic diagram of the structure of a rotor of a harmonic magnetic field driving motor according to another embodiment of the present invention, as viewed from the outside. [Figure 12] FIG. 12 is a schematic diagram of the structure seen from inside the rotor of a harmonic magnetic field driving motor according to still another embodiment of the present invention. [Figure 13] FIG. 13 is a schematic diagram of the structure seen from inside of a rotor of a harmonic magnetic field driving motor according to a further embodiment of the present invention. [Figure 14] FIG. 14 is a schematic diagram of the structure seen from inside of a rotor of a harmonic magnetic field driving motor according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0026] 1 and 2, the harmonic magnetic field driving motor includes a rotor assembly 1, a stator assembly 2, a control module 3, and a wire harness 4. The harmonic magnetic field driving motor outputs torque by rotating the rotor assembly 1 when current is applied, 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 laminations 12 have 20 permanent magnets (10 opposing poles) evenly spaced on the inner circle.

[0030] By providing an inner arc surface 1201, a left slope 1202 of the dovetail groove and a right slope 1203 of the dovetail groove on the rotor laminations 12, these engage with outer arc surfaces 1301, left slope 1302 and right slope 1303 provided on the permanent magnet 13, respectively, thereby positioning the permanent magnet 13 in the radial and circumferential directions, and are then adhesively bonded into the dovetail grooves of the rotor laminations 12 so that the N poles and S poles are arranged alternately, thereby improving the operational stability of the harmonic magnetic field driven motor.

[0031] The laminations of the stator assembly 2 have 15 teeth evenly arranged on the outer circle, 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 both the left and right sides using upper and lower layers, 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 secure.

[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 wire harness 4 to pass 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 serve to support and position the rotor assembly 1, so that the harmonic magnetic field driven motor allows the rotor assembly to rotate in the circumferential direction when current is applied.

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

[0039] As shown in FIG. 11, the permanent magnets N, S and 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 driven motor is designed with an outer stator / inner rotor structure, and the adhesive method of the permanent magnets N and S of the rotor assembly is connected to the rotor laminations 222 by a surface mounting method or a surface embedding method, which can achieve the same performance and effect.

[0041] As shown in FIG. 14, the harmonic magnetic field driving 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 may be internally embedded, which can achieve the same performance and effect.

Claims

1. A harmonic magnetic field drive motor, A, the stator lamination is provided with some tooth spaces, 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 the windings is placed independently in free space, a constant DC current is applied to any one of the 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 x Pm, where n = 1, 2, 3, ...; 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 in a combination 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, and a two-layer winding is used.

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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