Harmonic magnetic field driven motor

Abstract

A kind of harmonic magnetic field driven motor, it includes: A. A plurality of tooth slots are arranged on stator lamination, slot number is Z;B. In the 360 ° mechanical space of stator circumference, stator winding is divided into m phases according to the set connection rule;C. The stator assembly with winding is separately placed in free space, arbitrary phase winding is passed with direct current constant current, in the 360 ° mechanical space of stator circumference, the number of pole pairs of phase winding magnetic field formed is Pm;D. The number of wire package included in each phase winding is k=n×Pm (n=1, 2, 3…);E. Permanent magnet rotor magnetic steel is sequentially arranged in the order of N pole and S pole in circumferential direction, along the 360 ° mechanical space of rotor circumference, the number of pole pairs of rotor magnetic steel formed is Pr;F. In the 360 ° mechanical space of stator and rotor circumference, the space formed by combination forms motor air gap;The number of pole pairs of the harmonic magnetic field driven motor rotor Pr must satisfy: Pr=Z±Pm;Wherein the slot number Z of harmonic magnetic field driven motor stator: Z=2×m×k.

Description

Technical Field

[0001] This invention relates to an electric motor, and more particularly to a harmonic magnetic field driven motor. Background Technology

[0002] As a device that converts electrical energy into rotational mechanical energy, the electric motor has become an indispensable and irreplaceable core component in people's pursuit of a better life. Permanent magnet motors, with their advantages of small size and relatively high efficiency, are widely used in various industries. In particular, rare earth permanent magnet materials, with their significant advantage of high magnetic energy product, are widely used in brushless DC motors (BLDC) and permanent magnet synchronous motors (PMSM), becoming a leading development direction and trend in motors. Since rare earth permanent magnet materials are non-renewable resources, how to fully improve the utilization rate of these materials has become a key research topic worldwide. Therefore, there is an urgent need to design a harmonic magnetic field drive motor. Compared with traditional motors, under the same output power conditions, the motor volume can be reduced, meaning the motor weight is also reduced simultaneously, significantly saving on the cost of motor materials, especially rare earth permanent magnet materials, greatly enhancing the product's competitive advantage. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a harmonic magnetic field drive motor that can reduce the size and increase the power density, in order to overcome the shortcomings of the prior art.

[0004] The technical solution adopted by this invention to solve the above-mentioned problems is as follows: a harmonic magnetic field drive motor, comprising: a rotor assembly, a stator assembly, a control module, and a wiring harness. The wiring harness is connected to the control module by welding. The control module is fixed to the stator assembly by positioning posts and elastic fixing clips. The wiring harness passes through radial holes provided in the stator assembly and is led out from axial holes. The cylindrical bearings provided in the stator assembly support and position the rotor assembly. When the harmonic magnetic field drive motor is energized, the rotor assembly rotates in a circumferential direction. The main structure is described as follows:

[0005] A. The stator laminations are provided with a number of slots, Z in total;

[0006] B. In the 360° mechanical space of the stator circumference, the stator windings are divided into m phases according to the set connection rules;

[0007] C. The stator assembly with windings is placed in free space (without motor assembly). A constant DC current is applied to any one phase winding. The number of phase winding magnetic field pole pairs formed in the 360° mechanical space around the stator circumference is Pm.

[0008] D. The number of coils contained in each phase winding is k = n × Pm (n = 1, 2, 3…);

[0009] E. The permanent magnet rotor magnets are arranged in the order of N pole and S pole in the circumferential direction, and the number of rotor magnet pole pairs formed along the 360° mechanical space of the rotor circumference is Pr;

[0010] F. The air gap of the motor is formed in the combined space of the stator and rotor circumference 360° mechanical space.

[0011] In this embodiment of the invention, the stator slot number Z=12, the rotor magnet pole pair number Pr=13, the number of pole pairs per phase coil Pm=1, and the number of coils per phase k=2.

[0012] More specifically, the harmonic magnetic field drive motor of the present invention will be further described as follows:

[0013] The principle of a harmonic magnetic field driven motor: A. Regardless of whether it is controlled by BLDC or PMSM, the necessary condition for the motor rotor to rotate is that the number of pole pairs of the magnetic field generated by the stator winding in the motor air gap is equal to the number of pole pairs of the rotor permanent magnet; B. After the stator winding is energized, a fundamental magnetomotive force is generated in the motor air gap. Under the action of the stator tooth slot magnetic permeability, a series of harmonic magnetic fields are distributed along the air gap space; 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.

[0014] To satisfy the principle of harmonic magnetic field driven motor, the following conditions must be met:

[0015] A. The number of rotor pole pairs Pr of a harmonic magnetic field driven motor must satisfy: Z ± Pm = Pr, as specifically stated below:

[0016] ① According to Ampere's circuital law: ∑H×L=W×I=F, where H—magnetic field strength, L—magnetic circuit length, W—linear magnetic field strength.

[0017] Number of turns; I—coil current; F—magnetic motive force;

[0018] ② In the closed loop of the motor magnetic field, the loop is mainly formed by ferromagnetic material and the air gap of the motor. Therefore, Ampere's circuital law for the motor is expressed as: H(δ)×L(δ)+H(ferromagnetic)×L(ferromagnetic)=W×I=F. Since H(ferromagnetic) is very small in ferromagnetic material and can be approximately equal to zero, H(δ)×L(δ)=W×I=F.

[0019] ③ The relationship between magnetic induction intensity B and magnetic field intensity H is: B = μ × H, where μ is the relative permeability;

[0020] ④ Therefore, F=WI=B(δ)×L(δ) / μ0, where μ0—relative permeability of air;

[0021] ⑤ The air gap magnetic induction intensity of the motor can be expressed as: B(δ)=F×μ0 / L(δ)=F×ʌ(δ), where ʌ(δ) — air gap permeability of the motor, the smaller the air gap, the larger the permeability;

[0022] ⑥ The magnetomotive force F is spatially distributed as a rectangular wave in the air gap of the motor, which can be expressed as a Fourier series:

[0023] F(α)=(2 / π)×F×[sin(Pm×α)+(1 / 3)×sin(3×Pm×α)+ … +(1 / n)×sin(n×Pm×

[0024] α)], where n=1, 2, 3 ..., α—represents the mechanical spatial angle along the circumference of the air gap. It can be seen that the magnetomotive force...

[0025] The fundamental wave has the largest amplitude, and the expression for the fundamental wave magnetomotive force is:

[0026] F1(α)=(2 / π)×F×sin(Pm×α)=(2×WI / π)×sin(Pm×α)

[0027] ⑦ The air gap tooth permeability ʌδ of the motor has an approximate rectangular wave distribution in space, which can be expressed as a Fourier series:

[0028] ʌδ(α)=ʌ0+ʌ1×cos(Z×α)+ʌ2×cos(2×Z×α)+ … +ʌn×cos(n×Z×α), where,

[0029] For n=1, 2, 3 ..., the fundamental magnetic permeability amplitude is the largest, and its expression is: ʌδ1(α)=ʌ0+ʌ1×cos(Z×α);

[0030] ⑧ The fundamental magnetomotive force of the stator winding, modulated by the magnetic permeability of the stator teeth, is spatially distributed in the air gap of the motor.

[0031] The expression for magnetic induction intensity is: B(α) = F × ʌ(δ) = (2 × WI / π) × sin(Pm × α) × [ʌ0 + ʌ1 × cos(Z × α)]

[0032] =Bm0×sin(Ps×α)+Bm1×sin(Pm×α)×cos(Z×α), where Bm0=2×WI×ʌ0 / π, Bm1=2×WI×ʌ1 / π. Using the trigonometric formula theorem: sin(a)×cos(b)=[sin(a+b)+sin(ab)] / 2, we can transform the above formula to obtain:

[0033] B(α)=Bm0×sin(Pm×α)+(Bm1 / 2)×sin[(Z+Pm)×α]+(Bm1 / 2)×sin[(Z-Pm)×α]

[0034] As can be seen from the above equation, the fundamental magnetomotive force generated by the energization of the stator phase windings can produce the following three magnetic fields in the air gap of the motor:

[0035] a. A fundamental magnetomotive force magnetic field with a pole pair number of Pm, the properties of which are equivalent to the magnetic field formed when the stator has no slots;

[0036] b. A tooth harmonic magnetic field with a pole pair number of (Z+Pm), the nature of which is equivalent to the magnetic field formed after the fundamental magnetomotive force is modulated by the stator slots;

[0037] c. A tooth harmonic magnetic field with a pole pair number of (Z-Pm) is a magnetic field whose properties are equivalent to the magnetic field formed after the fundamental magnetomotive force is modulated by the stator slots.

[0038] ⑨ Selection of the number of rotor pole pairs Pr for a harmonic magnetic field driven motor:

[0039] a. According to the basic operating principle of motors, a motor will only output a stable electromagnetic torque when the number of rotor pole pairs is equal to the number of pole pairs formed by the stator coils.

[0040] b. Based on the above principle, the number of rotor pole pairs Pr of a harmonic magnetic field driven motor must satisfy: Z + Pm = Pr or

[0041] Z-Pm=Pr.

[0042] B. Selection of the number of stator slots Z of the harmonic magnetic field drive motor: 2×m×k=Z, specifically as follows:

[0043] Each coil has two element sides, one above the other. Each phase winding contains k coils. The motor is divided into m phases. Then the number of stator slots Z of the motor must satisfy: 2×k×m=Z.

[0044] C. The relationship between the number of coils k per phase and the number of pole pairs Pm formed by each coil in a harmonic magnetic field driven motor: k = n × Pm, where n = 1, 2, 3…, as detailed below:

[0045] According to the principles of electromagnetic fields, one coil can only form one pair of magnetic poles. Therefore, the number of coils, k, is greater than or equal to the number of pole pairs, Pm. Considering the principle of symmetrical amplitude of the air gap magnetic field within the 360° mechanical space of the motor's air gap: the number of coils forming one pair of poles can be 1, 2, 3, ...; the number of coils forming two pairs of poles can be 2, 4, 6, ...; the number of coils forming three pairs of poles can be 3, 6, 9, ...; the number of coils forming Pm pairs of poles is: k = n × Pm, where n = 1, 2, 3, ...

[0046] Based on the principle conditions, when using a three-phase (m=3) winding structure, the combination of stator slot number / rotor magnet pole pairs / number of coils per phase for the harmonic magnetic field driven motor is as follows:

[0047]

[0048] Control methods for harmonic magnetic field driven motors: applicable to BLDC control and PMSM control, where BLDC is a square wave voltage (current) drive method and PMSM is a sine wave voltage (current) drive method.

[0049] The principle of harmonic magnetic field driving motor to increase power volume density:

[0050] A. Basic evaluation indicators of permanent magnet motors: As a rotating mechanical device, motors inevitably generate vibration and noise. The cogging torque pulsation of motors is an important source of motor vibration and noise. Therefore, while pursuing the ultimate power volume density (watts / liter), motors must also reduce cogging torque pulsation to ensure that motor vibration and noise are within a reasonable range. Only in this way can improving power volume density have practical significance.

[0051] B. Main methods to improve the power volume density of permanent magnet motors: a. Optimize the motor magnetic circuit: the improvement effect is limited; b. Select permanent magnet materials with higher magnetic energy product: this leads to a significant increase in manufacturing costs; c. Reduce the air gap value between the motor stator and rotor: basically, the amplitude of the air gap magnetic field is inversely proportional to the air gap value, so the improvement effect is significant.

[0052] C. Reduce the negative impact of motor air gap value on motor cogging torque pulsation: The amplitude of cogging torque is proportional to the square of the amplitude of air gap magnetic field. Therefore, reducing the motor air gap value will significantly increase the motor cogging torque pulsation, which will also significantly increase the motor vibration and noise.

[0053] D. Effective methods to reduce the amplitude of motor cogging torque pulsation:

[0054] a. Under the condition of maintaining a fixed air gap value of the motor, theoretical research shows that an effective way to reduce the cogging torque pulsation of the motor is to increase the number of cogging torque pulsation cycles (the number of cycles of cogging torque pulsation in one revolution of the rotor), where the number of pulsation cycles is equal to the least common multiple of the number of stator slots and the number of rotor poles;

[0055] b. The following table compares the number of oscillation cycles between harmonic magnetic field drive motors and conventional motors under the same stator slot number condition:

[0056]

[0057] The comparison results show that, with the same number of stator slots, the number of cogging torque ripple cycles in the harmonic magnetic field drive motor is significantly increased compared to that in the traditional permanent magnet motor.

[0058] Even better, the inner arc surface, left inclined surface and right inclined surface of the dovetail groove of the rotor lamination are respectively matched with the outer arc surface, left inclined surface and right inclined surface of the magnet to position the magnet in the radial and circumferential directions, thereby improving the positioning accuracy of the magnet and ensuring the smooth operation of the harmonic magnetic field driven motor.

[0059] Even better, the stator assembly has radial and axial holes on its motor shaft to facilitate the wire harness passing through the radial holes and through the axial holes, thereby enabling the wire harness to be led out.

[0060] Even better, the stator assembly is provided with elastic fixing clips and positioning posts, which can improve the positioning accuracy of the control module and make it more secure and reliable.

[0061] Alternatively, the magnets of the rotor assembly are designed to be connected to the housing via surface mounting, without using rotor laminations and dovetail groove structures for positioning. The magnet bonding process uses auxiliary tooling for positioning, which can achieve the same positioning effect as the magnets and is also feasible.

[0062] Alternatively, considering the ease of processing, the magnet can be divided into multiple segments without affecting the performance and effect of the harmonic magnetic field drive motor of this patent.

[0063] Alternatively, the harmonic magnetic field drive motor can be designed with an outer stator and inner rotor structure according to different applications, which can achieve the same performance and effect as the outer rotor and inner stator structure in the embodiment of this patent.

[0064] Alternatively, the harmonic magnetic field drive motor is designed with an outer stator and inner rotor structure. The magnets of the rotor assembly can be bonded using either surface mounting or surface embedding methods, which can achieve the same performance and effect.

[0065] Alternatively, the harmonic magnetic field drive motor is designed with an outer stator and inner rotor structure and adopts PMSM control. The magnets of the rotor assembly can be embedded internally, which can achieve the same performance and effect.

[0066] Compared with existing technologies, the advantages of this invention are as follows: The harmonic magnetic field drive motor, through a combination of a set number of stator slots and rotor magnet poles, significantly increases the number of cogging torque fluctuation cycles. This allows for maintaining or reducing the amplitude of cogging torque fluctuations while reducing the air gap value. By using a specific stator winding method, the number of harmonic magnetic field pole pairs generated by the stator equals the number of rotor magnet pole pairs, resulting in a stable electromagnetic torque output. The smaller air gap design significantly increases the air gap magnetic field strength, leading to a proportional increase in the output power and power volume density of the harmonic magnetic field drive motor. Compared to traditional motors, under the same output power conditions, the volume of the harmonic magnetic field drive motor is reduced by more than half, meaning its weight is also reduced by more than half. This significantly reduces the cost of motor materials, especially rare-earth permanent magnet materials, greatly enhancing the product's market competitiveness. This harmonic magnetic field drive motor structure can be matched with traditional BLDC and PMSM motor control modules, offering strong versatility in control. Attached Figure Description

[0067] Figure 1 This is a perspective view of a harmonic magnetic field driven motor according to an embodiment of the present invention.

[0068] Figure 2 This is an exploded schematic diagram of a harmonic magnetic field driven motor according to an embodiment of the present invention.

[0069] Figure 3 This is a schematic diagram of the structure of the harmonic magnetic field driven motor according to an embodiment of the present invention.

[0070] Figure 4 yes Figure 3 A partial view of the AA section.

[0071] Figure 5 yes Figure 4 A magnified view of part F.

[0072] Figure 6 This is an exploded view of the rotor assembly according to an embodiment of the present invention.

[0073] Figure 7 yes Figure 6 A magnified view of the local rotation of W.

[0074] Figure 8 This is a perspective view of the magnet in an embodiment of the present invention.

[0075] Figure 9 This is an exploded view of the stator assembly according to an embodiment of the present invention.

[0076] Figure 10 This is a cross-sectional view of the motor shaft according to an embodiment of the present invention.

[0077] Figure 11 This is a schematic diagram of the rotor of a harmonic magnetic field driven motor in another embodiment of the present invention.

[0078] Figure 12 This is a schematic diagram of the structure including the rotor of a harmonic magnetic field driven motor according to another embodiment of the present invention.

[0079] Figure 13 This is a schematic diagram of the structure of a harmonic magnetic field driven motor rotor, according to another embodiment of the present invention.

[0080] Figure 14 This is a schematic diagram of the structure of a harmonic magnetic field driven motor rotor, according to another embodiment of the present invention. Detailed Implementation

[0081] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0082] like Figure 1 , 2 As shown, a harmonic magnetic field drive motor includes a rotor assembly 1, a stator assembly 2, a control module 3, and a wiring harness 4. When the harmonic magnetic field drive motor is energized, it outputs torque through the rotation of the rotor assembly 1, thereby converting electrical energy into mechanical energy.

[0083] like Figures 3 to 10 As shown, the rotor assembly 1 consists of a housing 11, rotor laminations 12, and magnets 13.

[0084] The rotor laminations 12 are bonded to the inner circular surface of the housing 11 with an adhesive.

[0085] The rotor lamination 12 has 26 magnets (13 pairs of poles) evenly arranged on its inner circle.

[0086] The rotor laminations 12 are provided with an inner arc surface 1201, a left inclined surface 1202 and a right inclined surface 1203 of the dovetail groove, which cooperate with the outer arc surface 1301, the left inclined surface 1302 and the right inclined surface 1303 of the magnet 13 to position the magnet 13 in the radial and circumferential directions. They are then bonded to the dovetail grooves of the rotor laminations 12 with an adhesive in an alternating N and S pole arrangement to improve the smoothness of the operation of the harmonic magnetic field driven motor.

[0087] The stator assembly 2 has 12 teeth evenly arranged on its outer circle, with 1 pole pair per phase coil and 2 coils per phase.

[0088] The outer circle of the laminations of the stator assembly 2 and the magnet 13 of the rotor assembly 1 form a harmonic magnetic field to drive the air gap L of the motor.

[0089] The wiring harness 4 is connected to the control module 3 by welding.

[0090] The stator assembly 2 is equipped with an elastic fixing clip 212 and a positioning post 213 to position and fix the control module 3, making the fixation of the control module 3 more secure and reliable.

[0091] The stator assembly 2 has a radial hole 2111 and an axial hole 2112 on its motor shaft 211 to facilitate the wire harness 4 to pass through the radial hole 2111 and through the axial hole 2112, thereby enabling the wire harness 4 to be led out.

[0092] The cylindrical bearings 23 and 28 of the stator assembly 2 are fixed inside the housing 11 of the rotor assembly 1 and provide support and positioning for the rotor assembly 1. When the harmonic magnetic field drive motor is powered on, the rotor assembly can rotate in a circumferential direction.

[0093] The stator assembly 2 is provided with stop rings 25 and 26 to fix the cylindrical bearings 23 and 28 respectively, so as to achieve axial positioning of the rotor assembly 1. The wear-resistant shims 24 and 27 are provided to reduce friction.

[0094] like Figure 11 As shown, the magnets N and S of the rotor assembly are connected to the housing 111 by surface mounting, without using the dovetail slot positioning of the rotor laminations, which can achieve the same positioning effect as the magnets.

[0095] like Figure 12 and Figure 13 As shown, the harmonic magnetic field drive motor is designed with an outer stator and inner rotor structure. The magnets N and S of the rotor assembly are bonded to the rotor laminations 222 by surface mounting or surface embedding, which can achieve the same performance and effect.

[0096] like Figure 14 As shown, the harmonic magnetic field drive motor is designed with an outer stator and inner rotor structure and adopts PMSM control. The magnets N and S of the rotor assembly can be embedded to achieve the same performance and effect.

Claims

1. A harmonic magnetic field driven motor, comprising: A. The stator laminations on the stator assembly are provided with a number of slots, and the number of slots is Z; B. In the 360° mechanical space around the stator assembly, the stator windings are divided into m phases according to a set connection rule; C. A stator assembly with stator windings is placed in free space. A constant DC current is applied to any one phase winding. The number of phase winding magnetic field pole pairs formed in the 360° mechanical space around the stator assembly is Pm. D. The number of coils in each phase winding is k = n × Pm, where n = 1, 2, 3…; E. The permanent magnets of the rotor assembly are arranged in the order of N pole and S pole in the circumferential direction. The number of permanent magnet magnetic field pole pairs formed along the 360° mechanical space of the rotor circumference is Pr. F. An air gap for the motor is formed within the combined space of the stator assembly and rotor assembly in a 360° mechanical space around their circumference. Its characteristic is that Pr must satisfy: Pr = Z ± Pm; where Z = 2 × m × k; The control module of the harmonic magnetic field drive motor is fixed to the stator assembly by positioning posts and elastic fixing clips set on the stator assembly.

2. The harmonic magnetic field drive motor as described in claim 1, characterized in that: The values ​​are Z=12, Pr=13, Pm=1, and k=2.

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