WO2024021239A1

WO2024021239A1 - Electric excitation motor driven by means of harmonic magnetic field

Info

Publication number: WO2024021239A1
Application number: PCT/CN2022/117671
Authority: WO
Inventors: 周建民; 许恒帅; 贺海亮; 刘培海
Original assignee: 宁波恒帅股份有限公司
Priority date: 2022-07-27
Filing date: 2022-09-07
Publication date: 2024-02-01
Also published as: CN115483786A

Abstract

An electric excitation motor driven by means of a harmonic magnetic field. In the electric excitation motor: A. a stator is provided with several tooth slots, wherein the number of slots is Z; B. in the 360-degree circumferential mechanical space of the stator, a stator winding is divided into m phases according to a set connection rule; C. with regard to a stator assembly, which is provided with the stator winding, any phase of winding of the stator assembly is supplied with a direct-current constant current, and in the 360-degree circumferential mechanical space of the stator, Pm pairs of phase winding magnetic field poles are formed; D. each phase of stator winding includes k coils, wherein k = n * Pm(n = 1, 2, 3 …), and a single-layer winding is used; E. by means of an excitation winding, rotor pole shoe magnetic poles are sequentially arranged in a circumferential direction according to the sequence of an N pole and an S pole, and in the 360-degree circumferential mechanical space of a rotor, Pr pairs of rotor pole shoe magnetic poles are formed; and F. an electric motor air gap is formed in the 360-degree circumferential mechanical space between the stator and the rotor, wherein the number Pr of rotor pole shoe magnetic pole pairs must satisfy: Pr ＝ Z ± Pm, where the number Z of slots of the stator satisfies: Z = 2 * m * k.

Description

A harmonic magnetic field driven electric excitation motor

Technical field

The invention relates to a motor, in particular to a harmonic magnetic field driven electric excitation motor.

Background technique

As a device that converts electrical energy into rotating mechanical energy, the motor plays an extremely important role in our social production and life. Traditional electric excitation motors are easy to control and easy to assemble. By controlling the excitation current, the magnetic field intensity can be controlled to achieve the purpose of speed regulation. They are highly reliable and are usually used in high-power situations. Their structures are relatively complex, their production processes are rigorous, and they are durable. Advantages of traditional electric excitation motors. Although traditional electric excitation motors have many advantages, they are still inferior to permanent magnet motors in terms of energy-saving effect, production cost and overall size. Therefore, there is an urgent need to design a harmonic magnetic field driven electric excitation motor.

Contents of the invention

The technical problem to be solved by the present invention is to provide a harmonic magnetic field driven electric excitation motor in order to solve the above-mentioned shortcomings of the prior art, so that it can reduce the volume, increase the power density, and achieve the effect of energy saving.

The technical solution adopted by the present invention to solve the above existing problems is: a harmonic magnetic field driven electric excitation motor, which includes: a rotor assembly, a stator assembly, a control module and a wire harness. The wire harness and the control module are connected by welding, and the control module It is fixed to the stator assembly through positioning posts and elastic fixing clips. The wire harness passes through the radial holes provided in the stator assembly and is led out from the axial hole. The bearings provided in the stator assembly support and position the rotor assembly. The harmonic magnetic field drives The energized rotor assembly of the electric excitation motor rotates in the circumferential direction. The main structure is expressed as follows:

A. Several tooth slots are provided on the stator, and the number of slots is Z;

B. In the 360° mechanical space of the stator circumference, the stator winding is divided into m phases according to the set connection rules;

C. Stator assembly with stator winding, any one of its phase windings is supplied with a DC constant current, and the number of pole pairs of the phase winding magnetic field formed in the 360° mechanical space of the stator circumference is Pm;

D. The number of wire packages contained in each phase stator winding is k=n×Pm (n=1, 2, 3...), using single-layer winding;

E. Through the excitation winding, the rotor pole shoe magnetic poles are arranged sequentially in the order of N pole and S pole in the circumferential direction. Along the 360° mechanical space along the rotor circumference, the number of rotor pole shoe magnetic pole pairs formed is Pr;

F. Form an air gap in the motor within the circumferential 360° mechanical space between the stator and rotor;

The number of magnetic pole pairs Pr of the rotor pole shoes must satisfy: Pr=Z±Pm, where the number of stator slots Z: Z=2×m×k.

The embodiment of the present invention is designed such that the number of stator slots Z=12, the number of magnetic pole pairs of rotor pole pieces Pr=13, the number of pole pairs per phase line package Pm=1, and the number of line packages per phase k=2.

More specifically, the harmonic magnetic field driven electric excitation motor of the present invention will be further described:

The principle of harmonic magnetic field driving electric excitation motor:

A. Whether used as BLDC control or PMSM control, the necessary condition for the rotation of the motor rotor is that the number of magnetic pole pairs generated by the stator winding in the motor air gap is equal to the number of magnetic pole pairs in the rotor pole shoes;

B. After the stator winding is energized, a fundamental wave magnetomotive force is generated in the air gap of the motor. Under the action of the stator slot magnetic conductance, a series of harmonic magnetic fields are distributed along the air gap space;

C. When the number of pole pairs of the specific air gap harmonic magnetic field is equal to the number of pole pairs Pr of the rotor pole shoes, a stable electromagnetic torque will be output.

In order to meet the principle of harmonic magnetic field driving electric excitation motor, the following conditions must be met:

A. The number of magnetic pole pairs Pr of the rotor pole piece of the harmonic magnetic field driven electric excitation motor must satisfy: Z±Pm=Pr. The specific expression is as follows:

①According to Ampere’s loop law: ∑H×L=W×I=F, where H—magnetic field strength, L—magnetic circuit length, W—number of coil turns, I—coil current, F—magnetomotive force;

② In the closed circuit of the motor magnetic field, it is mainly closed through the ferromagnetic material and the motor air gap, so the motor Ampere's loop law is expressed as: H (δ) × L (δ) + H (ferromagnetic) × L (ferromagnetic) =W×I=F, since in ferromagnetic substances, H (ferromagnetism) is very small and can be approximately equal to zero, so H(δ)×L(δ)=W×I=F;

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

④So F=WI=B(δ)×L(δ)/μ0, where μ0—relative magnetic permeability of air;

⑤The magnetic induction intensity of the motor air gap can be expressed as: B(δ)=F×μ0/L(δ)=F×Λ(δ), where Λ(δ)—the motor air gap magnetic conductance. The smaller the air gap, the smaller the magnetic flux density. The greater the conduction;

⑥The spatial distribution of magnetomotive force F in the air gap of the motor is a rectangular wave, which can be expressed according to the Fourier series 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..., α—represents along the air gap From the mechanical space angle in the circumferential direction, it can be seen that the fundamental wave amplitude of the magnetomotive force is the largest, and the expression of the fundamental wave magnetomotive force is:

F1(α)=(2/π)×F×sin(Pm×α)=(2×WI/π)×sin(Pm×α);

⑦The spatial distribution of the motor air gap tooth magnetic permeance Λδ is approximately a rectangular wave, which can be expressed according to the Fourier series as:

Λδ(α)=Λ0+Λ1×cos(Z×α)+Λ2×cos(2×Z×α)+…+Λn×cos(n×Z×α), where,

n=1, 2, 3..., the fundamental wave magnetic permeance amplitude is the largest, and its expression is: Λδ1(α)=Λ0+Λ1×cos(Z×α);

⑧The expression of the magnetic induction intensity produced by the stator winding fundamental wave magnetomotive force distributed along the space in the motor air gap under the modulation of the stator tooth magnetic conductance:

B(α)＝F×Λ(δ)=(2×WI/π)×sin(Pm×α)×[Λ0+Λ1×cos(Z×α)]

=Bm0×sin(Ps×α)+Bm1×sin(Pm×α)×cos(Z×α), where,

Bm0=2×WI×Λ0/π, Bm1=2×WI×Λ1/π, using the trigonometric formula theorem: sin(a)× cos(b)=[sin(a+b)+sin(a-b)]/2 , changing the above formula, we get:

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

It can be seen from the above formula that the fundamental wave magnetomotive force generated by the stator phase winding energization can produce the following three magnetic fields in the motor air gap:

a. The fundamental wave magnetomotive force magnetic field with the number of pole pairs Pm, the properties of this magnetic field are equivalent to the magnetic field formed by the stator without slots;

b. The tooth harmonic permeability magnetic field with the pole pair number (Z+Pm), the nature of this magnetic field is equivalent to the magnetic field formed after the fundamental wave magnetomotive force is modulated by the stator slot;

c. The tooth harmonic permeability magnetic field with the pole pair number (Z-Pm), the nature of this magnetic field is equivalent to the magnetic field formed after the fundamental wave magnetomotive force is modulated by the stator slot.

⑨ Selection of the number of pole pairs Pr of the rotor pole shoes of the harmonic magnetic field driven electric excitation motor:

a. According to the basic principles of motor operation, the motor will output stable electromagnetic torque only when the number of magnetic pole pairs formed by the rotor pole shoes and the stator coil are equal;

b. According to the above principle, the number Pr of the rotor pole shoe magnetic pole pairs of the harmonic magnetic field driven electric excitation motor must satisfy: Z+Pm=Pr or Z-Pm=Pr.

B. Selection of stator slot number Z for harmonic magnetic field driven electric excitation motor: Z=2×m×k, the specific expression is as follows:

Each wire package has two component sides, upper and lower. Each stator slot is a single-layer winding, that is, only one component side is placed in one stator slot. Each phase winding contains k wire packages. The motor is divided into m phases, so the number of stator slots in the motor is Z. Need to meet: Z=2×k×m, using single-layer winding.

C. The relationship between the number k of each phase line package of the harmonic magnetic field driven electric excitation motor and the number of magnetic pole pairs Pm formed by each phase line package: k=n×Pm, where n=1, 2, 3..., the specific expression is as follows:

From the principle of electromagnetic field, it can be known that one wire package can only form one pair of magnetic poles, so the number of wire packages k ≥ the number of magnetic pole pairs Pm of the wire package. In the 360° mechanical space around the air gap circumference of the motor, taking into account the principle of symmetry of the air gap magnetic field amplitude: the number of wire packages forming one pair of poles can be 1, 2, 3,...; the number of wire packages forming two pairs of poles It can be 2, 4, 6,...; the number of wire packages forming 3 pairs of poles can be 3, 6, 9,...; the number of wire packages forming Pm poles is: k=n×Pm, where n=1 ,2,3….

According to the principle conditions, when a three-phase (m=3) winding structure is used, the combination of the number of stator slots/number of magnetic pole pairs of rotor pole shoes/number of wire packages per phase of the harmonic magnetic field driven electric excitation motor is as follows:

The control method of harmonic magnetic field driven electric excitation motor: suitable for BLDC control method and PMSM control method, where BLDC is a square wave voltage (current) drive method and PMSM is a sine wave voltage (current) drive method.

The principle of harmonic magnetic field driving electric excitation motor to increase power volume density:

A. Basic evaluation indicators of electric excitation motors: As a rotating mechanical device, the motor will inevitably produce vibration noise, and the cogging torque pulsation of the motor is an important source of vibration and noise in the motor. Therefore, the motor is in pursuit of power volume density (watt/each ) to the extreme, the cogging torque pulsation must also be reduced to ensure that the motor vibration noise is within a reasonable range, so that increasing the power volume density has practical significance;

B. The main means to improve the power volume density of electric excitation motors: a. Optimize the motor magnetic circuit: the improvement effect is limited; b. Reduce the air gap value between the motor stator and rotor: Basically, the air gap magnetic field amplitude is inversely proportional to the air gap value , so the improvement effect is obvious;

C. Reducing the negative impact of the motor air gap value on the motor cogging torque pulsation: The cogging torque amplitude is proportional to the square of the air gap magnetic field amplitude, so reducing the motor air gap value will significantly increase the motor cogging torque pulsation, resulting in Motor vibration noise also increases significantly;

D. An effective method to reduce the amplitude of motor cogging torque pulsation:

a. Under the condition of maintaining a fixed motor air gap value, theoretical research shows that an effective method to reduce motor cogging torque pulsation is to increase the number of motor cogging torque fluctuation cycles (the number of cycles of cogging torque fluctuations in one rotation of the rotor), Among them, the number of fluctuation cycles is equal to the least common multiple of the number of stator slots and the number of magnetic poles of the rotor pole shoes;

b. The comparison of the number of fluctuation cycles between harmonic magnetic field driven electric excitation motors and traditional electric excitation motors under the same number of stator slots is as follows:

It can be seen from the comparison results that when the number of stator slots is the same, the number of cogging torque fluctuation cycles of the harmonic magnetic field driven electric excitation motor increases significantly compared with the traditional electric excitation motor.

Preferably, the left side of the yoke, the right side of the yoke, the upper end face of the yoke and the lower end face of the yoke provided on the pole piece are all insulated to play an insulating role with the excitation winding.

Preferably, the left side of the yoke, the right side of the yoke, the upper end face of the yoke and the lower end face of the yoke provided with the pole piece are respectively in contact with the left side of the excitation winding, the right side of the excitation winding and the top end of the excitation winding. Cooperate with the lower side of the excitation winding to position the excitation winding radially and axially.

Preferably, the excitation winding can control the direction of the excitation current by setting the winding method to realize the magnetic distribution of the 26 pole pieces in an alternating arrangement of N poles and S poles.

Preferably, the motor shaft of the stator assembly is provided with a positive conductive ring and a negative conductive ring, the rotor assembly is provided with a positive conductive piece and a negative conductive piece, and the positive and negative poles of the power supply pass through the positive conductive ring, the positive conductive piece and the negative conductive ring respectively. And the negative conductive piece supplies power to the excitation winding.

Preferably, an insulating ring is provided between the positive conductive ring, the negative conductive ring and the motor shaft to provide insulation.

Preferably, a radial hole and an axial hole are provided on the motor shaft of the stator assembly, and the wire harness passes through the radial hole and is led out from the axial hole.

Preferably, elastic fixing clips and positioning posts are provided on the stator assembly to position and fix the control module, which can improve the positioning accuracy of the control module and make its fixing more firm and reliable.

Alternatively, the harmonic magnetic field driven electric excitation motor can be designed with an outer stator and inner rotor structure according to different uses, which can also achieve the same performance and effect as the outer rotor and inner stator structure in the embodiment of this patent.

Compared with the existing technology, the advantage of the present invention is that the harmonic magnetic field driven electric excitation motor greatly increases the number of cogging torque fluctuation cycles through the set combination of the number of stator slots and the number of magnetic poles of the rotor pole shoes, and can reduce harmonics. While the magnetic field drives the air gap value of the electric excitation motor, it maintains or reduces the cogging torque fluctuation amplitude of the harmonic magnetic field-driven electric excitation motor. Through the set stator winding method, the number of pole pairs of the harmonic magnetic field generated by the stator is equal to that of the rotor. The number of magnetic pole pairs of the pole shoes forms a stable electromagnetic torque output, which can use a smaller harmonic magnetic field to drive the air gap of the electric excitation motor, greatly increasing the strength of the air gap magnetic field, so that the output power of the harmonic magnetic field driven electric excitation motor is increased proportionally. The power volume density of the electric excitation motor driven by the wave magnetic field is also increased in proportion. Compared with traditional electric excitation motors, under the same output power conditions, the volume of harmonic magnetic field driven electric excitation motors is more than doubled, which means that the weight of harmonic magnetic field driven electric excitation motors is also more than doubled, which can significantly save motors. The use cost of materials is improved, the power density is improved, and the energy saving effect is achieved, which greatly enhances the product's market competitive advantage. This harmonic magnetic field drives the electric excitation motor structure, which can match the traditional BLDC and PMSM motor control modules, and has strong versatility in control.

Description of drawings

Figure 1 is a perspective view of a harmonic magnetic field driven electric excitation motor according to an embodiment of the present invention.

Figure 2 is an exploded schematic diagram of a harmonic magnetic field driven electric excitation motor according to an embodiment of the present invention.

Figure 3 is a schematic structural diagram of a harmonic magnetic field driven electric excitation motor according to an embodiment of the present invention.

FIG. 4 is a partial view of the A-A cross-sectional view in FIG. 3 .

Figure 5 is a partial enlarged view of F in Figure 4.

Figure 6 is an exploded schematic view of the rotor assembly according to the embodiment of the present invention.

Figure 7 is a partially rotated enlarged view of W in Figure 6.

Figure 8 is a perspective view of the field winding according to the embodiment of the present invention.

Figure 9 is an exploded schematic diagram of the stator assembly according to the embodiment of the present invention.

Figure 10 is a cross-sectional view of the motor shaft according to the embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

As shown in Figures 1 and 2, a harmonic magnetic field driven electric excitation motor includes a rotor assembly 1, a stator assembly 2, a control module 3 and a wire harness 4. When the harmonic magnetic field driven electric excitation motor is energized and working, torque is output through the rotation of the rotor assembly 1, thereby converting electrical energy into mechanical energy.

As shown in FIGS. 3 to 10 , the rotor assembly 1 is composed of a casing 11 , a rotor 12 , an excitation winding 13 , a positive conductive sheet 14 and a negative conductive sheet 15 .

The rotor 12 is bonded to the inner circumferential surface of the casing 11 through adhesive.

The rotor 12 is evenly provided with 26 pole pieces 1201 (13 pairs of poles) on the inner circle.

The left side 1202 of the yoke, the right side 1203 of the yoke, the upper end face 1204 and the lower end face 1204 of the yoke provided in the pole piece 1201 are all insulated to play an insulating role with the excitation winding 13 .

The yoke left side 1202, the yoke right side 1203, the yoke upper end face 1204 and the yoke lower end face 1204 provided in the pole piece 1201 are respectively connected with the excitation winding left side 1301 and the excitation winding right side 1302 of the excitation winding 13. , the upper side of the field winding 1303 and the lower side of the field winding 1304 cooperate to position the field winding 13 in the radial and axial directions.

The excitation winding 13 can control the direction of the excitation current by setting the winding method to realize that the magnetic poles of the 26 pole pieces 1201 are alternately arranged and distributed in N poles and S poles.

The motor shaft 211 of the stator assembly is provided with a positive conductive ring 29 and a negative conductive ring 2010. The rotor assembly is provided with a positive conductive sheet 14 and a negative conductive sheet 15. The positive and negative poles of the power supply pass through the positive conductive ring 29 and the positive

conductive sheet

14 and 15 respectively. The negative conductive ring 2010 and the negative conductive sheet 15 provide power to the above-mentioned excitation winding 13 .

An insulating ring 2011 is provided between the positive conductive ring 29 and the negative conductive ring 2010 and the motor shaft 211 to provide insulation.

The stator 21 of the stator assembly 2 is evenly provided with 12 tooth slots on its outer circle, the number of pole pairs of each phase wire package is 1, and the number of each phase wire package is 2.

The outer circle of the stator assembly 2 and the pole piece 1201 of the rotor assembly 1 form a harmonic magnetic field driving electric excitation motor air gap L, which can be reduced due to the adoption of the technical solution of the present invention.

The wire harness 4 and the control module 3 are connected by welding.

The stator assembly 2 is provided with elastic fixing clips 212 and positioning posts 213 to position and fix the control module 3, making the fixation of the control module 3 more firm and reliable.

A radial hole 2111 and an axial hole 2112 are provided on the motor shaft 211 of the stator assembly 2 to facilitate the wire harness 4 to pass through the radial hole 2111 and the axial hole 2112 to realize the extraction of the wire harness 4.

The

bearings

23 and 28 provided in the stator assembly 2 are fixed in the casing 11 of the rotor assembly 1 and play a role in supporting and positioning the rotor assembly 1. When the harmonic magnetic field drives the electric excitation motor, the rotor assembly can rotate in a circular motion. direction of rotation.

The stator assembly 2 is provided with stop rings 25 and 26 to fix the

bearings

23 and 28 respectively to achieve axial limitation of the rotor assembly 1, and the wear-resistant gaskets 24 and 27 are provided to reduce friction. .

Claims

A harmonic magnetic field driven electric excitation motor, which is characterized by: including:

A. Several tooth slots are provided on the stator, and the number of slots is Z;

B. In the 360° mechanical space of the stator circumference, the stator winding is divided into m phases according to the set connection rules;

C. Stator assembly with stator winding, any one of its phase windings is supplied with a constant DC current, and the number of pole pairs of the phase winding magnetic field formed in the 360° mechanical space of the stator circumference is Pm;

D. The number of wire packages contained in each phase stator winding is k=n×Pm (n=1, 2, 3...), using single-layer winding;

E. Through the excitation winding, the rotor pole shoe magnetic poles are arranged sequentially in the order of N pole and S pole in the circumferential direction. Along the 360° mechanical space along the rotor circumference, the number of rotor pole shoe magnetic pole pairs formed is Pr;

F. Form an air gap in the motor within the circumferential 360° mechanical space between the stator and rotor;

The number of magnetic pole pairs Pr of the rotor pole shoes must satisfy: Pr=Z±Pm, where the number of stator slots Z: Z=2×m×k.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that: the number of stator slots Z=12, the number of magnetic pole pairs of rotor pole shoes Pr=13, the number of pole pairs of each phase line Pm=1, and each The number of phase wire packages k=2.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that: the left side of the yoke, the right side of the yoke, the upper end face of the yoke and the lower end face of the yoke provided with the pole pieces of the electric excitation rotor are evenly spaced. Insulation treatment is performed to provide insulation from the excitation winding.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that: the electric excitation rotor pole piece is provided with the left side of the yoke, the right side of the yoke, the upper end face of the yoke and the lower end face of the yoke. Cooperate with the left side of the field winding, the right side of the field winding, the upper side of the field winding and the lower side of the field winding respectively to position the field winding in the radial and axial directions.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that: the excitation winding controls the direction of the excitation current by setting the winding method to realize that the magnetic poles of the 26 pole pieces alternate between N poles and S poles. Arrangement and distribution.
The harmonic magnetic field driven electric excitation motor according to claim 5, characterized in that: the motor shaft of the stator assembly is provided with a positive conductive ring and a negative conductive ring, the rotor assembly is provided with a positive conductive piece and a negative conductive piece, and the positive pole of the power supply is and negative pole respectively supply power to the excitation winding through the positive conductive ring and the positive conductive sheet and the negative conductive ring and the negative conductive sheet.
The harmonic magnetic field driven electric excitation motor according to claim 6, wherein an insulating ring is provided between the positive conductive ring, the negative conductive ring and the motor shaft.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that: a radial hole and an axial hole are provided on the motor shaft of the stator assembly, and the wire harness passes through the radial hole and is led out from the axial hole.
The harmonic magnetic field driven electric excitation motor according to claim 1, characterized in that elastic fixing clips and positioning posts are provided on the stator assembly to position and fix the control module.