Motor rotor and permanent magnet synchronous motor

Abstract

The present application provides a motor rotor and a permanent magnet synchronous motor. The motor rotor comprises a rotor core (1), the rotor core (1) is alternately provided with rotor teeth (2) and rotor slots (3) along the circumferential direction, a permanent magnet (4) is provided in the rotor slot (3), at least two magnetic flux sorting slots (5) are provided on the outer circumference of the same rotor tooth (2), at least two magnetic flux sorting slots (5) are symmetrical about the center line of the rotor tooth (2) where they are located, and the magnetic flux sorting slots (5) are trapezoidal slots. According to the motor rotor of the present application, the motor harmonic content can be effectively reduced, the fluctuation of the motor output torque can be reduced, and the motor operation stability can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of motors, and in particular to a motor rotor and a permanent magnet synchronous motor. Background Art

[0002] At present, there are a large number of applications in the industrial and household appliance industries that require low-speed and high-torque. For low-speed and high-torque motors, when the permanent magnets are placed radially and magnetized tangentially, the motor can generate higher air gap flux density due to its good magnetic concentration effect on the rotor, and can make full use of the magnetic resistance torque generated by the asymmetry of the cross / direct axis, improve the torque density, and achieve superior performance.

[0003] However, due to the influence of factors such as the slots on the surface of the stator and rotor, this type of motor contains multiple harmonics, and the proportion of harmonics is relatively large, resulting in high torque fluctuations in this type of motor, thereby affecting the motor's vibration and noise performance. In the prior art, the solution to this problem is to make the surface of the rotor core into a wavy structure, so that the air gap becomes a periodically changing uneven air gap, thereby achieving the purpose of reducing harmonics; however, this method has extremely high process requirements. Since the air gap itself is relatively small, a slight processing error will cause the harmonics to increase instead of decrease, making the motor performance worse.

[0004] Therefore, the low-speed, high-torque permanent magnet synchronous motors in the prior art all have the problem of poor improvement effect on harmonic content and insufficient improvement in motor operation stability. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present application is to provide a motor rotor and a permanent magnet synchronous motor that can effectively reduce the harmonic content of the motor, reduce the fluctuation of the motor output torque, and improve the operating stability of the motor.

[0006] In order to solve the above problems, the present application provides a motor rotor, including a rotor core, the rotor core is alternately provided with rotor teeth and rotor slots along the circumferential direction, permanent magnets are arranged in the rotor slots, and at least two magnetic flux sorting grooves are arranged on the outer circumference of the same rotor tooth, at least two magnetic flux sorting grooves are symmetrical about the center line of the rotor tooth where they are located, and the magnetic flux sorting grooves are trapezoidal grooves.

[0007] Preferably, the width of the trapezoidal groove decreases along the radial inward direction.

[0008] Preferably, the cross section of the trapezoidal slot is a right-angled trapezoid, and the right-angled side of the trapezoidal slot is arranged on a side close to the rotor slot.

[0009] Preferably, the distance between the right-angled sides of two magnetic flux sorting grooves on the same rotor tooth at the outer circle of the rotor is L_2ms, the width of the rotor tooth at the outer circle of the rotor is W_Rt, and 0.5≤L_2ms / W_Rt≤0.8.

[0010] Preferably, 0.58≤L_2ms / W_Rt≤0.65.

[0011] Preferably, the right-angled side intersects with the outer circle of the rotor to form an intersection, or an extension line of the right-angled side intersects with the outer circle of the rotor to form an intersection, and the right-angled side is perpendicular to the tangent line of the outer circle of the rotor at the intersection.

[0012] Preferably, the slot width of the trapezoidal slot is W_ms, the slot width of the rotor slot is W_Rs, 0.32≤W_ms / W_Rs≤0.37; and / or, the permanent magnet is tangentially magnetized.

[0013] Preferably, the width of the trapezoidal groove is W_ms, the depth of the trapezoidal groove is T_ms, and W_ms=(1.1-1.2)*T_ms.

[0014] Preferably, the angle between the straight side and the oblique side of the trapezoidal groove is θ0, 20°≤θ0≤35°.

[0015] Preferably, the trapezoidal groove and the outer circumference of the rotor are smoothly transitioned through rounded corners, and the side edge and the bottom edge of the trapezoidal groove are smoothly transitioned through rounded corners.

[0016] Preferably, the radius of the fillet is the same, the radius of the fillet is Ro1, the length of the bottom side of the trapezoidal groove is Lmin, and 0.15≤Ro1 / Lmin≤0.5.

[0017] Preferably, the radial length of the permanent magnet is Lmag, the remanence of the permanent magnet is Br, and the width of the rotor teeth at the outer circumference of the rotor is W_Rt, wherein 1.1≤Lmag*Br / W_Rt≤1.98.

[0018] According to another aspect of the present application, a permanent magnet synchronous motor is provided, comprising a motor rotor, which is the motor rotor described above.

[0019] Preferably, the permanent magnet synchronous motor also includes a motor stator, an air gap is formed between the motor stator and the motor rotor, the length of the permanent magnet is Lmag, the width of the permanent magnet is Wmag, the radial width of the air gap is Lair, and the aspect ratio of Lair to the permanent magnet Lmag / Wmag must satisfy: Lmag / Wmag=(1.5~3.5)*Lair.

[0020] Preferably, the rated speed n of the permanent magnet synchronous motor is ≤100 rpm; and / or the number of rotor poles 2*p satisfies 30≤2*p≤80, where p is the number of pole pairs.

[0021] Preferably, the permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core, the axial length of the rotor core is Lef, the outer radius of the stator core is Rso, the aspect ratio of the permanent magnet synchronous motor is x=Lef / Rso, 0.3≤x≤0.45; and / or, the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core is s, and the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, 0.85≤k≤1.2.

[0022] Preferably, the permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core, the inner radius of the stator core is Rsi, the outer radius of the stator core is Rso, the ratio of the inner and outer diameters of the motor stator is m=Rsi / Rso, 0.7≤m≤0.9; and / or the remanence Br of the permanent magnet is ≥1.35T.

[0023] Preferably, the permanent magnet synchronous motor further comprises a motor stator, an air gap is formed between the motor stator and the motor rotor, and the depth T_ms of the trapezoidal slot and the radial width Lair of the air gap satisfy T_ms=(0.85-0.95)*Lair.

[0024] Preferably, the permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core, an air gap is formed between the motor stator and the motor rotor, the opening of the trapezoidal slot faces the air gap, and the two magnetic flux sorting grooves on each rotor tooth act on a section of the air gap, the area of ​​the air gap in the cross section of the rotor core is Sair, the radius of the rotor outer circle of the rotor core is Rro, the radius of the inner circle of the stator core is Rsi, p is the number of pole pairs, Sair = (Rsi^2-Rro^2)*π / (2*p).

[0025] Preferably, the area of ​​a single trapezoidal slot in the cross section of the rotor core is Sms, where Sms=(0.02-0.1)*Sair.

[0026] Preferably, the permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core, the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core is s, the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, the width of the rotor teeth at the outer circle of the rotor is W_Rt, the width of the stator tooth boot of the stator core is W_Stb, and 0.75≤W_Rt / (W_Stb*k)≤1.

[0027] The motor rotor provided by the present application comprises a rotor core, wherein the rotor core is alternately provided with rotor teeth and rotor slots along the circumferential direction, a permanent magnet is provided in the rotor slot, the permanent magnet is tangentially magnetized, and two magnetic flux sorting slots are provided on the outer circumference of the same rotor tooth, the two magnetic flux sorting slots are symmetrical about the center line of the rotor tooth where they are located, and the magnetic flux sorting slots are trapezoidal slots. The motor rotor is provided with magnetic flux sorting slots on the outer circumference of the rotor teeth, and the magnetic flux sorting slots can effectively guide the magnetic lines of force on the rotor teeth and adjust the distribution of the magnetic flux density in the air gap, thereby reducing the harmonic content, reducing the fluctuation of the motor output torque, improving the running stability of the motor, and achieving vibration reduction and noise reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A structural diagram of a motor rotor according to an embodiment of the present application;

[0029] Figure 2 A partial enlarged view of the motor rotor of an embodiment of the present application;

[0030] Figure 3 A diagram showing the relationship between the dimensions of the motor rotor according to an embodiment of the present application;

[0031] Figure 4 A diagram showing the relationship between the dimensions of the motor rotor according to an embodiment of the present application;

[0032] Figure 5 A diagram showing the relationship between the dimensions of the motor rotor according to an embodiment of the present application;

[0033] Figure 6 A schematic diagram of the structure of a permanent magnet synchronous motor according to an embodiment of the present application;

[0034] Figure 7 This is a curve diagram showing the influence of L_2ms / W_Rt on torque fluctuation of the permanent magnet synchronous motor of an embodiment of the present application;

[0035] Figure 8 This is a curve diagram showing the influence of T_ms / Lair on torque fluctuation of the permanent magnet synchronous motor of an embodiment of the present application;

[0036] Fig. 9 A comparison diagram of back-EMF waveforms of the permanent magnet synchronous motor of the embodiment of the present application and the permanent magnet synchronous motor of the related art;

[0037] Fig.10 This is a torque curve comparison diagram of the permanent magnet synchronous motor of the embodiment of the present application and the permanent magnet synchronous motor of the related technology.

[0038] The reference numerals are as follows:

[0039] 1. Rotor core; 2. Rotor teeth; 3. Rotor slots; 4. Permanent magnets; 5. Magnetic flux sorting slots; 6. Stator core; 7. Air gap. DETAILED DESCRIPTION

[0040] See also Figures 1 to 10 As shown, according to an embodiment of the present application, the motor rotor includes a rotor core 1, the rotor core 1 is alternately provided with rotor teeth 2 and rotor slots 3 along the circumferential direction, permanent magnets 4 are provided in the rotor slots 3, and at least two magnetic flux sorting grooves 5 are provided on the outer circumference of the same rotor tooth 2, at least two magnetic flux sorting grooves 5 are symmetrical about the center line of the rotor tooth 2 where they are located, and the magnetic flux sorting grooves 5 are trapezoidal grooves.

[0041] The motor rotor is provided with magnetic flux sorting grooves 5 on the outer circumference of the rotor teeth 2. The magnetic flux sorting grooves 5 can effectively guide the magnetic lines of force on the rotor teeth 2 and adjust the distribution of the magnetic flux density in the air gap 7, thereby reducing the harmonic content, reducing the fluctuation of the motor output torque, improving the motor operation stability, and achieving vibration reduction and noise reduction.

[0042] In one embodiment, the permanent magnet 4 is magnetized tangentially.

[0043] In other embodiments, the permanent magnet 4 may also be magnetized radially.

[0044] The structural dimension relationships in the following embodiments all refer to the dimension relationships of the relevant structures on the cross section of the rotor core.

[0045] The motor rotor also includes a rotor yoke, and the rotor teeth 2 and the rotor yoke are the main paths of the main magnetic circuit. The rotor slot 3 is used to place the permanent magnet 4, and the four corners of the rotor slot 3 are embedded to limit the position of the permanent magnet 4 in the slot. Two magnetic flux sorting slots 5 are set on a rotor tooth 2, which can effectively constrain the distribution of the magnetic lines of force of the tooth in the air gap 7, so that the magnetic field distribution in the air gap 7 is more uniform.

[0046] The position of the magnetic flux sorting slot 5 on the rotor tooth 2 directly affects its constraint on the magnetic flux, and thus affects the fluctuation of the output torque. The two magnetic flux sorting slots 5 are symmetrical about the center line of the rotor tooth 2 where they are located, which can further reduce the fluctuation of the output torque and improve the vibration reduction and noise reduction effect.

[0047] The width of the trapezoidal groove decreases along the radial inward direction, so that the magnetic flux sorting groove 5 can be opened on the surface of the rotor tooth 2. The closer to the air gap 7, the larger the area of ​​the magnetic flux sorting groove 5, the stronger the ability to constrain the magnetic lines of force, which is more conducive to the sinusoidalization of the air gap magnetic density, reducing torque fluctuations and improving motor performance.

[0048] The cross section of the trapezoidal slot is a right-angled trapezoid, and the right-angled side of the trapezoidal slot is arranged on a side close to the rotor slot 3 .

[0049] The distance between the right-angled sides of the two magnetic flux sorting grooves 5 on the same rotor tooth 2 at the outer circumference of the rotor is L_2ms, and the width of the rotor tooth 2 at the outer circumference of the rotor is W_Rt, 0.5≤L_2ms / W_Rt≤0.8.

[0050] Preferably, 0.58≤L_2ms / W_Rt≤0.65.

[0051] See also Figure 7 As shown, when the ratio is larger or smaller, the torque fluctuation will increase rapidly. Only within the above range, the torque fluctuation is relatively stable, which is beneficial to improving the motor performance.

[0052] The right-angled side intersects with the outer circle of the rotor to form an intersection, or the extension line of the right-angled side intersects with the outer circle of the rotor to form an intersection, and the right-angled side is perpendicular to the tangent line of the outer circle of the rotor at the intersection.

[0053] The slot width of the trapezoidal slot is W_ms, the slot width of the rotor slot 3 is W_Rs, 0.32≤

[0054] W_ms / W_Rs≤0.37, which can ensure that there is a sufficient magnetic flux path on the rotor core 1, thereby ensuring that the output torque is maintained at the required level.

[0055] In one embodiment, the slot width of the trapezoidal slot is W_ms, the depth of the trapezoidal slot is T_ms, and W_ms=(1.1-1.2)*T_ms, so that better torque performance can be obtained.

[0056] In one embodiment, the angle between the straight side and the oblique side of the trapezoidal slot is θ0, 20°≤θ0≤35°. The size of θ0 affects the magnetic flux distribution of the rotor tooth portion close to the air gap side. When the angle satisfies 20°≤θ0≤35°, the magnetic flux sorting slot 5 achieves the best regulation effect on the air gap magnetic flux distribution.

[0057] The trapezoidal slot and the outer circle of the rotor are smoothly transitioned by chamfering, and the side and bottom of the trapezoidal slot are smoothly transitioned by chamfering. The radius of the fillet is the same, the radius of the fillet is Ro1, the length of the bottom of the trapezoidal slot is Lmin, 0.15≤Ro1 / Lmin≤0.5. Since the magnetic field at each vertex of the trapezoidal slot is prone to saturation, the four vertex corners of the magnetic flux sorting slot are all transitioned with fillets. The radius of all transition fillets is the same, and when the radius of the fillet Ro1 and the length of the bottom of the trapezoidal slot Lmin satisfy 0.15≤Ro1 / Lmin≤0.5, the magnetic lines of force can be well transitioned and saturation is not likely to occur.

[0058] In one embodiment, the radial length of the permanent magnet 4 is Lmag, the residual magnetism of the permanent magnet 4 is Br, and the width of the rotor tooth 2 at the outer circle of the rotor is W_Rt, wherein 1.1≤Lmag*Br / W_Rt≤1.98. Within this range, it can be ensured that most of the magnetic field provided by the permanent magnet 4 enters the air gap 7 through the rotor teeth, thereby increasing the magnetic density of the air gap 7 and improving the output torque.

[0059] See also Figures 1 to 9 As shown, according to an embodiment of the present application, the permanent magnet synchronous motor includes a motor rotor, which is the motor rotor mentioned above.

[0060] In one embodiment, the permanent magnet synchronous motor also includes a motor stator, an air gap 7 is formed between the motor stator and the motor rotor, the length of the permanent magnet 4 is Lmag, the width of the permanent magnet 4 is Wmag, the radial width of the air gap 7 is Lair, and the aspect ratio Lmag / Wmag of Lair and the permanent magnet 4 must satisfy: Lmag / Wmag=(1.5~3.5)*Lair, which can ensure that the utilization rate of the permanent magnet is within an advantageous range.

[0061] In one embodiment, the rated speed n of the permanent magnet synchronous motor is ≤100 rpm; and / or the number of rotor poles 2*p satisfies 30≤2*p≤80, where p is the number of pole pairs.

[0062] The permanent magnet synchronous motor also includes a motor stator, which includes a stator core 6. The axial length of the rotor core 1 is Lef, the outer radius of the stator core 6 is Rso, and the aspect ratio of the permanent magnet synchronous motor is x=Lef / Rso, 0.3≤x≤0.45; and / or, the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core 6 is s, and the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, 0.85≤k≤1.2.

[0063] The permanent magnet synchronous motor also includes a motor stator, which includes a stator core 6, the inner radius of the stator core 6 is Rsi, the outer radius of the stator core 6 is Rso, the ratio of the inner and outer diameters of the motor stator is m=Rsi / Rso, 0.7≤m≤0.9; and / or the remanence Br of the permanent magnet 4 is Br≥1.35T.

[0064] Through the above-mentioned restrictions, the structural parameters of the motor can be accurately defined, so that the motor using the motor rotor of the above-mentioned embodiment of the present application can have greater advantages when applied to the above-defined motor. It can reduce the amount of permanent magnets used and reduce the cost of permanent magnets while meeting the torque requirements.

[0065] In this embodiment, the working principle of the permanent magnet synchronous motor is that a three-phase symmetrical current is passed through the winding on the motor stator, which will generate a circular rotating magnetic field. The number of pole pairs of this magnetic field is equal to the number of pole pairs of the magnetic field generated by the permanent magnet 4 on the motor rotor. The two magnetic fields rotate at the same speed, and energy conversion is carried out through the air gap to stably transmit torque.

[0066] In one embodiment, the permanent magnet synchronous motor further includes a motor stator, an air gap 7 is formed between the motor stator and the motor rotor, and the depth T_ms of the trapezoidal slot and the radial width Lair of the air gap 7 satisfy T_ms=(0.85-0.95)*Lair. Since the air permeability is different from the core permeability, if T_ms is too small, it cannot play the role of guiding the magnetic lines of force. If T_ms is too large, it will affect the number of magnetic lines of force entering the air gap, thereby increasing the torque fluctuation and sharply reducing the output torque. Figure 8 As shown, when the ratio is limited to the above value, it can ensure that the fluctuation of the motor output torque is small and maintained within a lower torque fluctuation range.

[0067] In one embodiment, the permanent magnet synchronous motor also includes a motor stator, which includes a stator core 6. An air gap 7 is formed between the motor stator and the motor rotor. The opening of the trapezoidal slot faces the air gap 7. The two magnetic flux sorting slots 5 on each rotor tooth 2 act on a section of the air gap 7. The area of ​​the section of the air gap 7 on the cross section of the rotor core 1 is Sair, the radius of the rotor outer circle of the rotor core 1 is Rro, the inner circle radius of the stator core 6 is Rsi, p is the number of pole pairs, and Sair = (Rsi^2-Rro^2)*π / (2*p).

[0068] In one embodiment, the area of ​​a single trapezoidal slot on the cross section of the rotor core 1 is Sms, Sms=(0.02-0.1)*Sair, which can make the influence of the magnetic flux sorting slot 5 on the air gap flux density within a preferred range.

[0069] In one embodiment, the permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core 6, the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core 6 is s, the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, the width of the rotor tooth 2 at the outer circle of the rotor is W_Rt, the width of the stator tooth shoe of the stator core 6 is W_Stb, 0.75≤W_Rt / (W_Stb*k)≤1, preferably, 0.75≤W_Rt / (W_Stb*k)≤0.85, at this time, the magnetic resistance of the main magnetic circuit between the stator and rotor under each pole and each slot is the smallest, which is conducive to the passage of magnetic lines of force.

[0070] See also Fig. 9 As shown, the low-speed, high-torque permanent magnet synchronous motor of the embodiment of the present application has a significantly improved sinusoidal degree of the back-EMF waveform compared to the permanent magnet synchronous motor of the related art.

[0071] See also Fig.10 As shown, the low-speed, high-torque permanent magnet synchronous motor of the embodiment of the present application has a significantly reduced torque fluctuation at the same output torque level compared to the permanent magnet synchronous motor of the related art.

[0072] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0073] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A motor rotor, characterized in that: The invention comprises a rotor core (1), wherein the rotor core (1) is alternately provided with rotor teeth (2) and rotor slots (3) along the circumferential direction, wherein permanent magnets (4) are provided in the rotor slots (3), and the permanent magnets (4) are magnetized tangentially or radially; at least two magnetic flux sorting grooves (5) are provided on the outer circumference of the same rotor tooth (2), wherein the at least two magnetic flux sorting grooves (5) are symmetrical about the center line of the rotor tooth (2) where they are located, and the magnetic flux sorting grooves (5) are trapezoidal grooves; The width of the trapezoidal groove decreases along the radial inward direction, the cross-section of the trapezoidal groove is a right-angled trapezoid, and the right-angled side of the trapezoidal groove is arranged on a side close to the rotor slot (3); the angle between the straight side and the oblique side of the trapezoidal groove is θ0, 20°≤θ0≤35°.

2. The motor rotor according to claim 1, characterized in that: The distance between the right-angled sides of the two magnetic flux sorting grooves (5) on the same rotor tooth (2) at the outer circle of the rotor is L_2ms, and the width of the rotor tooth (2) at the outer circle of the rotor is W_Rt, 0.5≤L_2ms / W_Rt≤0.

8.

3. The motor rotor according to claim 2, characterized in that: 0.58≤L_2ms / W_Rt≤0.

65.

4. The motor rotor according to claim 1, characterized in that: The right-angled side intersects with the outer circle of the rotor to form an intersection, or an extension line of the right-angled side intersects with the outer circle of the rotor to form an intersection, and the right-angled side is perpendicular to the tangent line of the outer circle of the rotor at the intersection.

5. The motor rotor according to claim 1, characterized in that: The slot width of the trapezoidal slot is W_ms, the slot width of the rotor slot (3) is W_Rs, 0.32≤W_ms / W_Rs≤ 0.37; and / or, the permanent magnet (4) is tangentially magnetized.

6. The motor rotor according to claim 1, characterized in that: The width of the trapezoidal groove is W_ms, the depth of the trapezoidal groove is T_ms, and W_ms=(1.1-1.2)*T_ms.

7. The motor rotor according to claim 1, characterized in that: The trapezoidal groove and the outer circle of the rotor are smoothly transitioned through rounded corners, and the side edge and the bottom edge of the trapezoidal groove are smoothly transitioned through rounded corners.

8. The motor rotor according to claim 7, characterized in that: The radius of the fillet is the same, the radius of the fillet is Ro1, the length of the bottom side of the trapezoidal groove is Lmin, and 0.15≤Ro1 / Lmin≤0.

5.

9. The motor rotor according to claim 1, characterized in that: The radial length of the permanent magnet (4) is Lmag, the residual magnetism of the permanent magnet (4) is Br, and the width of the rotor tooth (2) at the outer circumference of the rotor is W_Rt, wherein 1.1≤Lmag*Br / W_Rt≤1.

98.

10. A permanent magnet synchronous motor, comprising a motor rotor, characterized in that: The motor rotor is the motor rotor according to any one of claims 1 to 9.

11. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor also includes a motor stator, an air gap (7) is formed between the motor stator and the motor rotor, the length of the permanent magnet (4) is Lmag, the width of the permanent magnet (4) is Wmag, the radial width of the air gap (7) is Lair, and the aspect ratio Lmag / Wmag of Lair and the permanent magnet (4) must satisfy the following: Lmag / Wmag=(1.5-3.5)*Lair.

12. The permanent magnet synchronous motor according to claim 10, characterized in that: The rated speed n of the permanent magnet synchronous motor is ≤100 rpm; and / or the number of rotor poles 2*p satisfies 30≤2*p≤80, where p is the number of pole pairs.

13. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor further comprises a motor stator, the motor stator comprises a stator core (6), the axial length of the rotor core (1) is Lef, the outer radius of the stator core (6) is Rso, the aspect ratio of the permanent magnet synchronous motor is x=Lef / Rso, 0.3≤x≤0.45; and / or the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core (6) is s, the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, 0.85≤k≤1.

2.

14. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor further comprises a motor stator, the motor stator comprises a stator core (6), the inner radius of the stator core (6) is Rsi, the outer radius of the stator core (6) is Rso, the ratio of the inner and outer diameters of the motor stator is m=Rsi / Rso, 0.7≤m≤0.9; and / or the remanence Br of the permanent magnet (4) is ≥ 1.35T。 15. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor also includes a motor stator, an air gap (7) is formed between the motor stator and the motor rotor, and the depth T_ms of the trapezoidal groove and the radial width Lair of the air gap (7) satisfy T_ms=(0.85-0.95)*Lair.

16. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor also includes a motor stator, which includes a stator core (6). An air gap (7) is formed between the motor stator and the motor rotor. The opening of the trapezoidal slot faces the air gap (7). The two magnetic flux sorting slots (5) on each rotor tooth (2) act on a section of the air gap (7). The area of ​​the section of the air gap (7) on the cross section of the rotor core (1) is Sair. The radius of the rotor outer circle of the rotor core (1) is Rro. The radius of the inner circle of the stator core (6) is Rsi. p is the number of pole pairs. Sair = (Rsi^2-Rro^2)*π / (2*p).

17. The permanent magnet synchronous motor according to claim 16, characterized in that: The area of ​​a single trapezoidal slot in the cross section of the rotor core (1) is Sms, where Sms=(0.02-0.1)*Sair.

18. The permanent magnet synchronous motor according to claim 10, characterized in that: The permanent magnet synchronous motor also includes a motor stator, the motor stator includes a stator core (6), the number of rotor poles of the permanent magnet synchronous motor is 2*p, p is the number of pole pairs, the number of slots of the stator core (6) is s, the pole-slot ratio of the permanent magnet synchronous motor is k=2*p / s, the width of the rotor teeth (2) at the outer circle of the rotor is W_Rt, the width of the stator tooth shoe of the stator core (6) is W_Stb, and 0.75≤W_Rt / (W_Stb*k)≤1.

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