CN118017788A - Permanent magnet synchronous motor structure of electric driving system of electric automobile and optimization method thereof - Google Patents

Abstract

The invention provides a permanent magnet synchronous motor structure of an electric driving system of an electric automobile and an optimization method thereof, the structure comprises a stator, the stator comprises a stator yoke part and a stator winding, the inner ring of the stator yoke part is provided with a plurality of axially arranged stator teeth, and the top of the stator teeth is provided with a first fan-shaped auxiliary groove taking the center line of the stator teeth as the center; the rotor is provided with a rotor surface groove, a permanent magnet and a magnetism isolating bridge, and a second fan-shaped auxiliary groove is formed above the permanent magnet. The invention adopts a double-groove collaborative optimization mode that the tooth tops of the stators and the surfaces of the rotors are provided with fan-shaped auxiliary grooves, thereby achieving the purpose of reducing cogging torque and weakening electromagnetic vibration noise, changing the waveform distribution of air gap magnetic density through collaborative optimization of the first fan-shaped auxiliary grooves and the second fan-shaped auxiliary grooves, weakening the harmonic amplitude of magnetic potential and magnetic conductance, reducing the specific harmonic of the air gap magnetic density, greatly reducing the cogging torque of the permanent magnet synchronous motor and being beneficial to inhibiting the vibration noise of the permanent magnet synchronous motor of the electric driving system of the electric automobile.

Description

Permanent magnet synchronous motor structure and optimization method for electric vehicle electric drive system

Technical Field

The present invention relates to the technical field of electric vehicle motors, and in particular to a permanent magnet synchronous motor structure of an electric drive system of an electric vehicle and an optimization method thereof.

Background technique

The low-noise, high-reliability, integrated electric drive system for electric vehicles has a broad market prospect. However, the three key quality characteristics of vibration, noise, and acoustic roughness generated by the electric drive system under high-speed conditions are the key bottlenecks that limit the NVH technology level and core competitiveness of my country's electric drive system for electric vehicles. The cogging torque of the electric drive system's drive motor is an inherent characteristic of the motor and is also one of the sources of electromagnetic vibration noise.

In the prior art, due to the stator's slot structure and the characteristics of the rotor magnetic field, the rotor magnetic poles will have a balanced position in the circumferential direction. Once the rotor core deviates from this position, a torque will be generated between the stator core and the permanent magnet to reset it. This torque is the cogging torque. The cogging torque will cause the drive motor to vibrate and make noise, causing the speed to fluctuate within a certain range. In addition, the cogging torque will cause torque pulsation, affecting the performance of the electric drive system drive motor and affecting ride comfort.

Summary of the invention

Based on this, the purpose of the present invention is to provide a permanent magnet synchronous motor structure and an optimization method for an electric vehicle electric drive system, so as to at least solve the deficiencies in the above-mentioned prior art.

In a first aspect, the present invention provides a permanent magnet synchronous motor structure of an electric drive system of an electric vehicle, comprising:

A stator, the stator comprising a stator yoke and a stator winding, the inner ring of the stator yoke is provided with a plurality of axially arranged stator teeth, and the top of the stator tooth is provided with a first fan-shaped auxiliary slot centered on its own center line;

A rotor, wherein the rotor is provided with rotor surface grooves, permanent magnets and magnetic isolation bridges, wherein the rotor surface grooves are provided with second sector-shaped auxiliary grooves of corresponding logarithms above the permanent magnets in units of logarithms of the permanent magnets;

The first sector-shaped auxiliary slot and the second sector-shaped auxiliary slot cooperate with each other to reduce the magnetic field asymmetry between the tooth slots and the air gap magnetic resistance, so as to optimize the magnetic field distribution between the rotor and the stator and reduce the tooth slot torque.

Compared with the prior art, the beneficial effects of the present invention are: the double-slot collaborative optimization form of fan-shaped auxiliary slots on the stator tooth top and the rotor surface is adopted to achieve the purpose of reducing the cogging torque and weakening the electromagnetic vibration noise; through the collaborative optimization of the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot, the air gap magnetic flux waveform distribution can be changed, the harmonic amplitude of the magnetic potential and the magnetic permeance can be weakened, and the specific harmonics of the air gap magnetic flux can be reduced, thereby greatly reducing the cogging torque of the permanent magnet synchronous motor, which is beneficial to the stable operation of the permanent magnet synchronous motor in the electric drive system of the electric vehicle.

Furthermore, the groove depth of the first fan-shaped auxiliary groove is 0.2 mm.

Furthermore, the arc length of the first fan-shaped auxiliary slot is based on the center line of the stator tooth, a stator slot is made on the center line of the stator tooth with the top of the stator tooth as the starting point, the stator slot is used as the first line segment, and the first line segment is swept 1.2 degrees to both sides along the center line of the stator tooth to form a first swept surface, the first swept surface is fan-shaped, and the arc length of the first swept surface is the arc length of the first fan-shaped auxiliary slot.

Furthermore, the depth of the stator slot is 0.2 mm, and the depth of the second fan-shaped auxiliary slot is 0.4 mm.

Furthermore, the arc length of the second fan-shaped auxiliary groove is based on the center line of each pair of permanent magnets, and a second line segment is made on the center line of the permanent magnet through the outermost end of the rotor as a starting point. The second line segment is swept 1.4 degrees along both sides of the center line of the permanent magnet to form a second swept surface. The second swept surface is fan-shaped, and the arc length of the second swept surface is the arc length of the second fan-shaped auxiliary groove.

Furthermore, the length of the second line segment is 0.4 mm.

Furthermore, the position angle of the second fan-shaped auxiliary groove is 17.5 degrees on both sides of the second sweeping surface rotating around the center line of the permanent magnet.

Furthermore, the magnetic isolation bridge is arranged at one end of the permanent magnet close to the first fan-shaped auxiliary slot, and the rotor surface slot is arranged at one end of the magnetic isolation bridge close to the first fan-shaped auxiliary slot.

Furthermore, a plurality of the stator windings are arranged in the stator yoke in a circular array.

In a second aspect, the present invention further provides a method for optimizing the structure of a permanent magnet synchronous motor of an electric drive system of an electric vehicle, which is applied to the permanent magnet synchronous motor structure of the electric drive system of an electric vehicle, and the method comprises:

A first fan-shaped auxiliary slot is provided at the top of a stator tooth in a permanent magnet synchronous motor with the center of the stator tooth, wherein a plurality of stator teeth are provided, and the plurality of stator teeth are axially arranged on the inner ring of a stator yoke;

A second fan-shaped auxiliary slot is provided on the rotor in the permanent magnet synchronous motor, wherein the rotor is provided with rotor surface slots, permanent magnets and magnetic isolation bridges, and the number of the second fan-shaped auxiliary slots is the corresponding logarithm of the rotor surface slots in units of the logarithm of the permanent magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the overall structure of a permanent magnet synchronous motor structure of an electric drive system of an electric vehicle in an embodiment of the present invention;

FIG2 is an enlarged structural schematic diagram of stator teeth and a rotor in an embodiment of the present invention;

FIG3 is a comparison diagram of the permanent magnet synchronous motor structure of the electric drive system of an electric vehicle in an embodiment of the present invention and the optimal solution of the original motor torque;

FIG. 4 is a comparison diagram of the air gap flux density of the permanent magnet synchronous motor structure of the electric drive system of the electric vehicle in the embodiment of the present invention and the original motor.

Description of main component symbols:

10. stator; 11. stator yoke; 12. stator winding; 13. stator teeth; 14. first sector-shaped auxiliary slot

20. Rotor; 21. Rotor surface groove; 22. Permanent magnet; 23. Magnetic isolation bridge; 24. Second fan-shaped auxiliary groove.

The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and/or" used herein includes any and all combinations of one or more of the related listed items.

Please refer to FIG. 1 and FIG. 2 , which show the structure of a permanent magnet synchronous motor of an electric drive system of an electric vehicle in an embodiment of the present invention, including a stator 10 and a rotor 20 .

The stator 10 includes a stator yoke 11 and a stator winding 12. The inner ring of the stator yoke 11 is provided with a plurality of axially arranged stator teeth 13. The top of the stator tooth 13 is provided with a first fan-shaped auxiliary slot 14 centered on its own center line. The rotor 20 is provided with a rotor surface slot 21, a permanent magnet 22 and a magnetic isolation bridge 23. The rotor surface slot 21 is provided with a corresponding number of second fan-shaped auxiliary slots 24 above the permanent magnet 22 in units of the logarithm of the permanent magnet 22. The first fan-shaped auxiliary slot 14 and the second fan-shaped auxiliary slot 24 cooperate with each other to reduce the magnetic field asymmetry and air gap magnetic resistance between the tooth slots, so as to optimize the magnetic field distribution between the rotor 20 and the stator 10 and reduce the torque of the tooth slots.

Specifically, in the present embodiment, the groove depth of the first fan-shaped auxiliary groove is 0.2 mm, the arc length of the first fan-shaped auxiliary groove is based on the center line of the stator tooth, and a stator groove is made on the center line of the stator tooth with the top of the stator tooth as the starting point, and the stator groove is used as a first line segment, and the first line segment is swept 1.2 degrees to both sides along the center line of the stator tooth to form a first swept surface, the first swept surface is fan-shaped, and the arc length of the first swept surface is the arc length of the first fan-shaped auxiliary groove. In the present embodiment, the depth of the stator slot is 0.2 mm, the depth of the second fan-shaped auxiliary slot is 0.4 mm, and the second fan-shaped auxiliary slot is 0.6 mm. The arc length is based on the center line of each pair of permanent magnets. A second line segment is made on the center line of the permanent magnet through the outermost end of the rotor as the starting point. The second line segment is swept 1.4 degrees along both sides of the center line of the permanent magnet to form a second swept surface. The second swept surface is fan-shaped, and the arc length of the second swept surface is the arc length of the second fan-shaped auxiliary groove. It is worth noting that the arc length of the second swept surface is the arc length of the second fan-shaped auxiliary groove, wherein the length of the second line segment is 0.4 mm, and the second line segment is longitudinally arranged, and the position angle of the second fan-shaped auxiliary groove is that the second swept surface is rotated 17.5 degrees on both sides around the center line of the permanent magnet.

Furthermore, a plurality of the stator windings are arranged in a circular array in the stator yoke, the magnetic isolation bridge is arranged at one end of the permanent magnet close to the first fan-shaped auxiliary slot, and the rotor surface slot is arranged at one end of the magnetic isolation bridge close to the first fan-shaped auxiliary slot.

It can be understood that for the permanent magnet synchronous drive motor of the electric drive system, the motor magnetic field energy W stored in the magnetic field is:

;

Where: Indicates winding self-inductance; /> Indicates the stator winding phase current; /> Indicates the number of stator winding turns; /> represents the air gap reluctance; /> Represents the stator reluctance of the closed magnetic circuit; /> represents the permanent magnet flux;

Assuming current is a constant, and the torque generated by the motor magnetic field energy is calculated as follows:

;

Further we can get:

;

In the formula, represents the torque caused by the change of winding self-inductance with position,/> Indicates the cogging torque ,/> It indicates that the effective torque of the motor is generated by the interaction between the rotor permanent magnet and the stator magnetomotive force;

Assuming that the magnetic permeability of the armature core is infinite, when the armature winding is not connected to current, the motor magnetic field energy is approximately the sum of the permanent magnet magnetic field energy and the air gap magnetic field energy, as shown in the following formula:

;

Where: Represents the magnetic field energy of the permanent magnet; /> Represents the air gap magnetic field energy; /> Represents the distribution function of air gap magnetic flux density; /> represents magnetic permeability; /> Indicates the change angle of air gap flux density along the motor rotation direction; /> It represents the angle between the armature centerline and the permanent magnet pole centerline;

The distribution function of the air gap flux along the armature surface is:

;

Where: Represents the pole remanent magnetic density;/> Indicates the distribution of air gap flux relative permeability along the armature surface; /> It represents the function of the angle of change of the length of the permanent magnet in the magnetizing direction along the motor rotation direction;/> Represents the effective air gap length;

Then the expression of cogging torque is:

;

Using Fourier series and/> Expand it and get:

;

Where: Indicates the number of stator slots; /> Indicates the number of magnetic pole pairs; /> Indicates the axial length of the stator core; /> In order to make An integer that is an integer; /> Indicates the inner radius of the motor stator yoke; /> Indicates the outer radius of the motor stator; /> Fourier decomposition coefficient representing relative permeability relative to the square of air gap permeance; /> Fourier decomposition function representing the square of the air gap flux density generated by the permanent magnet poles;

Furthermore, the relationship between the stator tooth top auxiliary slot and the cogging torque of the permanent magnet synchronous motor structure of the electric drive system of electric vehicles is analyzed. When different pole slots are matched, the harmonic order of the cogging torque is different. The harmonic order of the cogging torque is ;

;

In the formula, is the number of stator slots and poles/> The lowest common multiple of , when m auxiliary slots are opened on the stator, then the number of slots/> becomes/> ,/> The harmonic order of the basic cogging torque/> , after the stator teeth are slotted with auxiliary slots, the harmonic order of the basic cogging torque will change as the number of slots increases. When a single auxiliary slot is opened on each stator tooth, the harmonic order of the basic cogging torque / > Since increasing the harmonic order of the cogging torque can reduce the harmonic amplitude of the magnetic potential and the magnetic permeance, thereby weakening the cogging torque of the permanent magnet synchronous motor, the more auxiliary slots are opened on each stator tooth, the better the weakening effect of the cogging torque of the permanent magnet synchronous motor. However, too many auxiliary slots will weaken the amplitude of the air gap magnetic flux density, and the number of auxiliary slots will also be limited by the motor structure and manufacturing process. Therefore, in this embodiment, only one fan-shaped auxiliary slot is opened on the top of each stator tooth.

In addition, it needs to be explained that the effect of opening a second fan-shaped auxiliary slot on the rotor on the cogging torque is equivalent to changing the pole slot matching. Selecting a suitable second fan-shaped auxiliary slot can significantly weaken the cogging torque. From the above analytical analysis of the cogging torque, it can be seen that opening slots at specific positions on the surface of the motor rotor will increase the effective length of the air gap, affect the width and angle of the unsaturated area of the air gap magnetic flux, change the waveform distribution of the air gap magnetic flux, reduce the specific harmonics of the air gap magnetic flux, and achieve the purpose of weakening the cogging torque.

When there is no second fan-shaped auxiliary slot on the rotor, The Fourier decomposition coefficient expression is:

;

When there is a second fan-shaped auxiliary slot and k is an even number, The Fourier decomposition coefficient expression is:

=

;

When selecting the second sector-shaped auxiliary groove on the rotor surface, its depth and size have a great influence on the result: if it is too shallow or too small, the optimization effect is not obvious; if it is too deep or too large, it affects the rotor magnetic circuit. Therefore, in this embodiment, the depth of the second sector-shaped auxiliary groove on the rotor surface is 0.4 mm from the outermost end of the rotor tooth top, and the arc length of the second sector-shaped auxiliary groove above each permanent magnet on the rotor surface is based on the center of each pair of permanent magnets. A second line segment with a groove depth of 0.4 mm is made on the center line through the outermost end of the rotor as the starting point, and it is scanned 1.4 degrees on both sides of the center line. Finally, each pair of sector-shaped auxiliary grooves that have been scanned are rotated 17.5 degrees around both sides of the center line of each pair of permanent magnets.

It is worth noting that the depth of the stator inner slot in the first sector-shaped auxiliary slot is ; Take the center line of the stator tooth as the reference, and take the stator tooth top as the starting point on the center line to make the stator slot depth as/> Segment, sweep it along both sides of the center line/> degrees, which is the angle from the outermost edge of the fan-shaped auxiliary slot to the center line of the stator tooth; the obtained fan-shaped slot is the determined stator auxiliary slot; the slot depth of the fan-shaped slot in the rotor surface auxiliary slot 5 is / > Taking the center line of each pair of permanent magnets as the reference, and starting from the outermost end of the rotor surface on the center line, make a groove with a depth of / > Segment, sweep it along both sides of the center line/> degrees, to obtain two second sector-shaped auxiliary grooves above the permanent magnets, and to rotate the two second sector-shaped auxiliary grooves on each pair of permanent magnets around the center line of each pair of permanent magnets by one degree. The specific position and size of the tooth slot torque optimization structure of the permanent magnet synchronous motor with the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot are finally obtained. By calculating the specific motor structural parameters, and then according to the parametric design of the motor, the finite element analysis software is used for parametric scanning to find the optimal solution for the tooth slot torque optimization structure size of the permanent magnet synchronous motor with the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot. The slot depth of the first fan-shaped auxiliary slot at the stator tooth top of the motor is 0.2mm. The arc length of the first fan-shaped auxiliary slot at the top of each stator tooth is based on the center line of the stator tooth. On the center line, a line segment with a stator slot depth of 0.2mm is made, and it is swept 1.2deg on both sides of the center line. The depth of the second fan-shaped auxiliary groove on the rotor surface of the motor is 0.4mm. The arc length of the second fan-shaped auxiliary groove above each permanent magnet on the rotor surface is based on the center of each pair of permanent magnets. A line segment with a groove depth of 0.4mm is made on the center line through the outermost end of the rotor as the starting point, and it is scanned 1.4 degrees along both sides of the center line. Finally, each pair of second fan-shaped auxiliary grooves that have been scanned are rotated 17.5 degrees on both sides of the center line of each pair of permanent magnets. The final specific new double-slot permanent magnet synchronous motor cogging torque optimization structure size is obtained.

The cogging torque of the permanent magnet synchronous motor structure of the electric drive system of the electric vehicle in this embodiment needs to be completed under no-load state, so the current excitation of the motor is set to no-load and then simulated, and the optimal solution of the cogging torque of the permanent magnet synchronous motor with the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot is compared with the optimal solution of the cogging torque when the motor is not slotted, the optimal solution of the cogging torque when the single stator is slotted and the optimal solution when the single rotor is slotted. As shown in Figure 3, the cogging torque of the new double-slotted built-in V-type permanent magnet synchronous motor using the present invention is 23.9mN·m, the cogging torque of the traditional unslotted built-in V-type permanent magnet synchronous motor is 577.0mN·m, the optimal solution of the cogging torque when the single stator is slotted is 356.9mN·m, and the optimal solution of the cogging torque when the single rotor is slotted is 110.2mN·m. It can be seen that the cogging torque of the permanent magnet synchronous motor is optimized by about 38.1% when a single stator is slotted, and the cogging torque of the permanent magnet synchronous motor is optimized by about 80.9% when a single rotor is slotted. The cogging torque of the double-slot permanent magnet synchronous motor adopted in the present invention is optimized by about 95.9%, and the optimization effect is extremely good.

In addition, the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot are respectively opened on the stator and the rotor to cooperate and increase the effective length of the air gap of the motor, increase the magnetic resistance, and reduce the magnetic lines of force passing through the auxiliary slot area. The first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot change the direction of the magnetic lines of force and the magnetic flux density in the two areas, affecting the radial magnetic flux distribution of the air gap. The radial magnetic flux distribution curve of the air gap before and after the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot and the Fourier decomposition harmonics of the radial magnetic flux of the air gap are shown in Figure 4 respectively. After the double auxiliary slots are opened, the air gap magnetic flux waveform is locally distorted, which changes the width and height of the unsaturated area of the radial air gap magnetic flux of the motor, and the fundamental wave of the air gap magnetic flux decreases significantly, which reduces the electromagnetic force on the stator teeth and the rotor, which is conducive to the weakening of electromagnetic vibration noise.

The present invention also provides a method for optimizing the structure of a permanent magnet synchronous motor of an electric drive system of an electric vehicle, which is applied to the permanent magnet synchronous motor structure of the electric drive system of an electric vehicle. The method includes S1 to S2:

S1, a first fan-shaped auxiliary slot is opened at the top of a stator tooth in a permanent magnet synchronous motor with the center of the stator tooth, wherein a plurality of stator teeth are provided, and the plurality of stator teeth are axially arranged on the inner ring of the stator yoke;

S2, a second fan-shaped auxiliary slot is opened on the rotor in the permanent magnet synchronous motor, wherein the rotor is provided with rotor surface slots, permanent magnets and magnetic isolation bridges, and the number of the second fan-shaped auxiliary slots is the corresponding logarithm of the rotor surface slots with the logarithm of the permanent magnets as a unit.

In summary, the electric vehicle electric drive system permanent magnet synchronous motor structure and optimization method of the above-mentioned embodiment of the present invention, the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot can reduce the magnetic field asymmetry and air gap magnetic resistance between the tooth slots, and optimize the magnetic field distribution between the rotor and the stator, thereby reducing the tooth slot torque and improving the stability and efficiency of the motor. The distribution of the rotor magnetic field can also be changed to make it more uniform, thereby reducing torque fluctuations. At the same time, the path and distribution of the magnetic field can be changed so that the magnetic field propagates more smoothly between the tooth slots, reducing the magnetic field asymmetry, reducing the amplitude of the harmonic order that plays a major role, and weakening the radial magnetic flux density in the air gap. In addition, the presence of the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot can also reduce the magnetic resistance loss, so that the magnetic field can more fully penetrate the space between the stator and the rotor. It is worth noting that the geometric shape and position of the first fan-shaped auxiliary slot and the second fan-shaped auxiliary slot can be adjusted and processed in proportion according to the arc size of the motor, so that its processing accuracy is higher than that of other geometric shapes.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims (10)

1. The utility model provides an electric automobile electric drive system PMSM structure which characterized in that includes:

The stator comprises a stator yoke part and a stator winding, a plurality of axially arranged stator teeth are arranged on the inner ring of the stator yoke part, and a first fan-shaped auxiliary groove is formed in the top of each stator tooth by taking the center line of the stator tooth as the center;

The rotor is provided with a rotor surface groove, permanent magnets and a magnetism isolating bridge, and the rotor surface groove is provided with a second fan-shaped auxiliary groove with corresponding logarithm above the permanent magnets by taking the logarithm of the permanent magnets as a unit;

The first fan-shaped auxiliary grooves and the second fan-shaped auxiliary grooves are mutually matched to reduce magnetic field asymmetry and air gap magnetic resistance between tooth grooves, so that magnetic field distribution between the rotor and the stator is optimized, and torque of the tooth grooves is reduced.

2. The electric drive system permanent magnet synchronous motor structure of claim 1, wherein the first fan-shaped auxiliary groove has a groove depth of 0.2mm.

3. The electric drive system permanent magnet synchronous motor structure of claim 1, wherein the arc length of the first fan-shaped auxiliary groove is based on the center line of the stator tooth, the top of the stator tooth is used as a starting point on the center line of the stator tooth to serve as a stator groove, the stator groove is used as a first line segment, the first line segment is swept to two sides along the center line of the stator tooth by 1.2 degrees to form a first sweeping surface, the first sweeping surface is fan-shaped, and the arc length of the first sweeping surface is the arc length of the first fan-shaped auxiliary groove.

4. A permanent magnet synchronous motor structure of an electric drive system of an electric vehicle according to claim 3, wherein the depth of the stator slot is 0.2mm and the depth of the second fan-shaped auxiliary slot is 0.4mm.

5. The electric drive system permanent magnet synchronous motor structure of claim 1, wherein the arc length of the second fan-shaped auxiliary groove is based on the center line of each pair of permanent magnets, a second line segment is formed on the center line of the permanent magnets by taking the outermost end of the rotor as a starting point, the second line segment is swept along two sides of the center line of the permanent magnets for 1.4 degrees to form a second sweeping surface, the second sweeping surface is fan-shaped, and the arc length of the second sweeping surface is the arc length of the second fan-shaped auxiliary groove.

6. The electric drive system permanent magnet synchronous motor structure of claim 5, wherein the length of the second line segment is 0.4mm.

7. The electric drive system permanent magnet synchronous motor structure of claim 5, wherein the second fan-shaped auxiliary groove is located at an angle of 17.5 degrees to each side of the second sweeping surface around the center line of the permanent magnet.

8. The electric drive system permanent magnet synchronous motor structure of claim 1, wherein the magnetism isolating bridge is disposed at an end of the permanent magnet close to the first fan-shaped auxiliary groove, and the rotor surface groove is disposed at an end of the magnetism isolating bridge close to the first fan-shaped auxiliary groove.

9. The electric drive system permanent magnet synchronous motor structure of claim 1, wherein a plurality of the stator windings are disposed in an annular array within the stator yoke.

10. A method for optimizing a permanent magnet synchronous motor structure of an electric driving system of an electric vehicle, which is applied to the permanent magnet synchronous motor structure of the electric driving system of the electric vehicle according to any one of claims 1 to 9, and is characterized in that the method comprises the following steps:

a first fan-shaped auxiliary groove is formed in the top of a stator tooth in the permanent magnet synchronous motor at the center of the stator tooth, wherein a plurality of stator teeth are arranged, and the stator teeth are axially arranged on the inner ring of a stator yoke part;

The rotor in the permanent magnet synchronous motor is provided with a second fan-shaped auxiliary groove, wherein rotor surface grooves, permanent magnets and magnetism isolating bridges are arranged on the rotor, and the number of the second fan-shaped auxiliary grooves is corresponding to the number of the rotor surface grooves taking the number of the permanent magnets as a unit.