High-torque outer rotor electric motor

Abstract

A high-torque outer rotor electric motor, comprising a stator assembly and a rotor assembly, wherein the stator assembly comprises a stator core, and the stator core is provided with a plurality of stator teeth; and the rotor assembly comprises an annular rotor yoke, a plurality of magnetically conductive protrusions are provided on the inner surface of the rotor yoke, the plurality of magnetically conductive protrusions being uniformly distributed in the circumferential direction of the inner surface of the rotor yoke, a permanent magnet is provided between two adjacent magnetically conductive protrusions, the ratio of the maximum height of the magnetically conductive protrusions to the maximum height of the permanent magnet is 0.5-1.5, and the ratio of the middle width of the magnetically conductive protrusions to the middle width of the stator teeth is 0.3-1.5. The high-torque outer rotor electric motor can significantly increase the total output torque, and has a low production cost.

Description

A high-torque external rotor motor Technical Field

[0001] This invention relates to the field of motor technology, and specifically to a high-torque external rotor motor. Background Technology

[0002] External rotor motors are typically used in low-speed, high-torque applications, such as dough mixers and washing machines. Traditional external rotor motors usually have a yoke made of circular, magnetically conductive low-carbon steel, with surface-mounted permanent magnets. This type of rotor only has permanent magnet torque and no reluctance torque. In current technology, to save on motor costs, low-remanence permanent magnets, such as ferrite, are generally used, resulting in insufficient motor output torque.

[0003] In order to achieve high torque output, traditional external rotor motors use rare earth permanent magnet materials, such as sintered neodymium iron boron, for the permanent magnets. However, rare earth permanent magnet materials are expensive, which increases the cost of the motor. Summary of the Invention

[0004] To address the problems in the prior art, this invention proposes a high-torque external rotor motor that can achieve high torque output while using low-residual-magnetic permanent magnets.

[0005] The present invention proposes a high-torque external rotor motor, comprising:

[0006] A stator assembly, comprising a stator core, wherein the stator core is provided with multiple stator teeth;

[0007] The rotor assembly includes an annular rotor yoke.

[0008] Multiple magnetically conductive protrusions are provided on the inner surface of the rotor yoke. These protrusions are evenly distributed circumferentially along the inner surface of the rotor yoke, and a permanent magnet is placed between two adjacent magnetically conductive protrusions.

[0009] The ratio of the maximum height of the magnetic protrusion to the maximum height of the permanent magnet is 0.5 to 1.5.

[0010] The ratio of the middle width of the magnetic protrusion to the middle width of the stator tooth is 0.3 to 1.5.

[0011] In one implementation, the maximum height of the magnetic protrusion is equal to the maximum height of the permanent magnet.

[0012] In one implementation, the middle width of the magnetic protrusion is equal to the middle width of the stator tooth.

[0013] In one implementation, the magnetic protrusion is fixedly connected to the rotor yoke.

[0014] In one implementation method, the permanent magnet is a ferrite.

[0015] In one implementation, the rotor assembly is disposed outside the stator assembly.

[0016] In one implementation, the stator core is provided with windings.

[0017] The above solution has the following advantages:

[0018] The high-torque external rotor motor of the present invention not only has permanent magnet torque output, but also reluctance torque output, thereby significantly increasing the total output torque of the motor. At the same time, the permanent magnet of the motor can be made of inexpensive ferrite, reducing the production cost of the motor. Attached Figure Description

[0019] The invention will now be further described and explained with reference to the accompanying drawings.

[0020] Figure 1 is a structural schematic diagram of a high-torque external rotor motor according to the preferred embodiment of the present invention.

[0021] Figure 2 is a schematic diagram of the magnetic guide protrusion and permanent magnet of the high-torque external rotor motor in Figure 1.

[0022] Figure 3 is a schematic diagram of the magnetic guide protrusions and stator teeth of the high-torque external rotor motor in Figure 1.

[0023] Figure 4 is a structural schematic diagram of motor B in comparative embodiment one.

[0024] Figure 5 is a schematic diagram of the C motor in Comparative Embodiment 2.

[0025] Figure 6 is a comparison of the total output torque of motors A, B, and C.

[0026] Figure 7 is a schematic diagram of the structure of motor D in comparative embodiment three.

[0027] Figure 8 is a structural schematic diagram of the E motor in Comparative Example 4.

[0028] Figure 9 is a comparison of the total output torque of motors A, D, and E.

[0029] Explanation of reference numerals in the attached drawings: 1. Stator assembly; 101. Stator core; 102. Stator tooth; 2. Rotor assembly; 201. Rotor yoke; 202. Magnetic protrusion; 203. Permanent magnet. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] As shown in Figure 1, a high-torque external rotor motor according to a preferred embodiment of the present invention includes a stator assembly 1 and a rotor assembly 2, with the rotor assembly 2 disposed outside the stator assembly 1. The external rotor structure can reduce the ratio of load inertia to rotor inertia, thereby improving system stability and maintaining stable system operation.

[0032] The stator assembly 1 includes a stator core 101, which is provided with a plurality of stator teeth 102. The stator teeth 102 are evenly distributed along the circumference of the stator core 101. The stator teeth 102 are provided with windings (not shown) to generate a rotating magnetic field, thereby driving the motor to run.

[0033] The rotor assembly 2 includes an annular rotor yoke 201. Multiple magnetically conductive protrusions 202 are provided on the inner surface of the rotor yoke 201. The multiple magnetically conductive protrusions 202 are evenly distributed along the circumference of the inner surface of the rotor yoke 201. The magnetically conductive protrusions 202 have the function of conducting magnetic fields.

[0034] The magnetic protrusion 202 is fixedly connected to the rotor yoke 201. As an alternative implementation, the magnetic protrusion 202 and the rotor yoke 201 can be an integral structure or a separate structure, connected to each other by a suitable connection method.

[0035] A permanent magnet 203 is disposed between two adjacent magnetically conductive protrusions 202. Preferably, the permanent magnet 203 is made of ferrite, which has a simple manufacturing process and is inexpensive, thus reducing the production cost of the motor.

[0036] In the existing technology, the rotor yoke of an external rotor motor is usually made of circular magnetic low carbon steel, and the permanent magnet is usually surface-mounted, attached to the inner surface of the rotor yoke, and continuously pasted to form a ring of permanent magnets. Therefore, the rotor of this type of motor only has permanent magnet torque and no reluctance torque, resulting in a smaller total output torque of the motor.

[0037] In this invention, multiple magnetic protrusions are provided on the inner surface of the rotor yoke, which enables the external rotor motor to have not only permanent magnet torque output but also reluctance torque output, thereby significantly increasing the total output torque of the motor. At the same time, it also reduces the amount of permanent magnets used, thereby further reducing the cost of the motor.

[0038] As shown in Figure 2, the magnetic protrusion 202 has a maximum height H1, and the permanent magnet 203 has a maximum height H2. The ratio of H1 to H2 is 0.5 to 1.5. Preferably, the ratio of H1 to H2 is 1, that is, the maximum height H1 of the magnetic protrusion 202 is equal to the maximum height H2 of the permanent magnet 203. Here, "maximum height H1" and "maximum height H2" refer to the maximum dimensions of the magnetic protrusion 202 and the permanent magnet 203 in the radial direction of the motor, respectively.

[0039] In this invention, the ratio of the maximum height H1 of the magnetic protrusion 202 to the maximum height H2 of the permanent magnet 203 is set to 0.5–1.5, which effectively improves the permanent magnet torque and reluctance torque of the motor. When the ratio of H1 to H2 is less than 0.5, the height of the magnetic protrusion 202 is too low, resulting in an excessively large air gap between the magnetic protrusion 202 and the outer end face of the stator tooth 102, thus the proportion of reluctance torque in the total output torque will be too small. When the ratio of H1 to H2 is greater than 1.5, the height of the permanent magnet 203 is too low, resulting in an excessively large air gap between the permanent magnet 203 and the outer end face of the stator tooth 102, again resulting in an excessively small proportion of permanent magnet torque in the total output torque. Neither of these two situations can achieve the maximum output coordination of permanent magnet torque and reluctance torque, i.e., the maximum total output torque cannot be achieved.

[0040] As shown in Figure 3, the magnetic protrusion 202 has a middle width W1, and the stator tooth 102 of the stator core 101 has a middle width W2. The ratio of W1 to W2 is 0.3 to 1.5. Preferably, the ratio of W1 to W2 is 1, that is, the middle width W1 of the magnetic protrusion 202 is equal to the middle width W2 of the stator tooth 102. Here, "middle width W1" and "middle width W2" refer to the widths of the magnetic protrusion 202 and the stator tooth 102 at the midpoint of their radial dimensions, respectively.

[0041] In this invention, the ratio of the middle width W1 of the magnetic protrusion 202 to the middle width W2 of the stator tooth 102 is set to 0.3 to 1.5, which can effectively improve the permanent magnet torque, magnetic permeability, and reluctance torque of the motor, and also improve the saliency ratio of the motor. When the saliency ratio increases, the reluctance torque of the motor increases, thereby enabling the motor to have a larger torque output. For an external rotor motor, the magnetic protrusion and the stator tooth need to pass through the same magnetic flux to ensure the maximum output of reluctance torque. When the ratio of W1 to W2 is less than 0.3, the magnetic protrusion 202 is prone to magnetic saturation and cannot achieve the maximum output of reluctance torque. Conversely, when the ratio of W1 to W2 is greater than 1.5, the stator 102 is prone to magnetic saturation and cannot achieve the maximum output of reluctance torque.

[0042] As shown in Figures 1, 4, 5, and 6, the motor is an external rotor motor with uniformly distributed magnetic protrusions 202 on the rotor yoke 201. The motor adopts a 10-pole, 12-slot structure, with an outer diameter of 115 mm, a stack thickness of 70 mm, and a rated speed of 120 rpm. The permanent magnet 203 of the motor is made of ferrite. When the motor current is set to Id = -7A and Iq = 8.5A, the torque of motors A, B, and C is tested. Among them, the ratio of the maximum height H1 of the magnetic protrusions 202 to the maximum height H2 of the permanent magnet 203 of motors A, B, and C is different.

[0043] Figure 1 shows motor A according to the preferred embodiment of the present invention.

[0044] In the preferred embodiment, the maximum height H1 of the magnetic protrusion 202 is equal to the maximum height H2 of the permanent magnet 203. After testing, the permanent magnet torque of the motor is 8.4 Nm, the reluctance torque is 10 N·m, and the total output torque is 18.4 Nm.

[0045] In another embodiment, the maximum height H1 of the magnetic protrusion 202 is 1.5 times the maximum height H2 of the permanent magnet 203. After testing, the permanent magnet torque of the motor is 5.8 Nm, the reluctance torque is 9.8 Nm, and the total output torque is 15.6 Nm.

[0046] In another embodiment, the maximum height H1 of the magnetic protrusion 202 is 0.5 times the maximum height H2 of the permanent magnet 203. After testing, the permanent magnet torque of the motor is 9.8 Nm, the reluctance torque is 4.3 Nm, and the total output torque is 14.1 Nm.

[0047] Figure 4 shows motor B in Comparative Example 1. The maximum height of the magnetic protrusion 202 of motor B is 1.8 times the maximum height of the permanent magnet 203. After testing, the permanent magnet torque of the motor is 3.6 Nm, the reluctance torque is 9.6 Nm, and the total output torque is 13.2 Nm.

[0048] Figure 5 shows the C motor of Comparative Example 2. The maximum height of the magnetic protrusion 202 of the C motor is equal to 0.3 times the maximum height of the permanent magnet 203. After testing, the permanent magnet torque of the motor is 10 N·m, the reluctance torque is 1.2 N·m, and the total output torque is 11.2 N·m.

[0049] Based on the above experimental data, the total output torque of motor A in the preferred embodiment of the present invention is significantly improved compared with motor B in comparative embodiment one and motor C in comparative embodiment two.

[0050] For the preferred embodiment of motor A, the ratio of the maximum height H1 of the magnetic protrusion 202 to the maximum height H2 of the permanent magnet 203 is 0.5 to 1.5, and the total output torque of motor A is greater. Among them, the total output torque of the best embodiment is the largest, and the total output torque of other embodiments is slightly lower than that of the best embodiment.

[0051] Based on the data analysis shown in Figure 6, for motor B, the ratio of H1 to H2 is too large, resulting in a larger gap between the permanent magnet 203 and the stator teeth 102, and a significant decrease in the permanent magnet torque, leading to a decrease in the total output torque. For motor C, the ratio of H1 to H2 is too small, resulting in a larger gap between the magnetic protrusion 202 and the stator teeth 102, and a significant decrease in the magnetic reluctance torque, leading to a decrease in the total output torque.

[0052] As shown in Figures 1, 7, 8, and 9, the motor is an external rotor motor with uniformly distributed magnetic protrusions 202 on the rotor yoke 201. The motor adopts a 10-pole, 12-slot structure, with an outer diameter of 115 mm, a stack thickness of 70 mm, and a rated speed of 120 rpm. The permanent magnet 203 of the motor is made of ferrite. The ratio of the maximum height H1 of the magnetic protrusion 202 to the maximum height H2 of the permanent magnet 203 is 1. When the motor current is set to Id = -7A and Iq = 8.5A, the torque of motors A, D, and E is tested. Among them, the ratio of the middle width W1 of the magnetic protrusion 202 to the middle width W2 of the stator tooth 102 is different for motors A, D, and E.

[0053] As shown in Figure 1, in the optimal implementation of motor A, the width W1 of the magnetic protrusion 202 is equal to the width W2 of the stator tooth 102. After testing, the permanent magnet torque of motor A is 8.4 Nm, the reluctance torque is 10 N·m, and the total output torque is 18.4 Nm.

[0054] In another embodiment, the width W1 of the magnetic protrusion 202 is 1.5 times the width W2 of the stator tooth 102. After testing, the permanent magnet torque of motor A is 6.5 Nm, the reluctance torque is 8.8 Nm, and the total output torque is 15.3 Nm.

[0055] In another embodiment, the width W1 of the magnetic protrusion 202 is 0.3 times the width W2 of the stator tooth 102. After testing, the permanent magnet torque of motor A is 9.6 Nm, the reluctance torque is 7.1 Nm, and the total output torque is 16.7 Nm.

[0056] Figure 7 shows the D motor of Comparative Embodiment 3. The width W1 of the magnetic protrusion 202 of the D motor is 1.8 times the width W2 of the stator tooth 102. After testing, the permanent magnet torque of the D motor is 5 N·m, the reluctance torque is 8.3 N·m, and the total output torque is 13.3 N·m.

[0057] Figure 8 shows the E motor of Comparative Example 4. The width W1 of the magnetic protrusion 202 of the E motor is 0.1 times the width W2 of the stator tooth 102. After testing, the permanent magnet torque of the E motor is 10 N·m, the reluctance torque is 6 N·m, and the total output torque is 16 N·m.

[0058] Based on the above experimental data, the total output torque of motor A in the preferred embodiment of the present invention is significantly improved compared with motor D in comparative embodiment three and motor E in comparative embodiment four.

[0059] For the preferred embodiment of motor A, with the ratio of the maximum height H1 of the magnetic protrusion 202 to the maximum height H2 of the permanent magnet 203 set to 0.5 to 1.5, the ratio of the middle width W1 of the magnetic protrusion 202 to the middle width W2 of the stator teeth 102 of the stator core 101 is set to 0.3 to 1.5, further increasing the torque of motor A. The optimal embodiment has the highest total output torque, while the other embodiments have slightly lower total output torques.

[0060] [Corrected according to Rule 91, 09.12.2025] As shown in the data analysis in Figure 9, for motor D, the ratio of W1 to W2 is too large, resulting in a reduction in the amount of permanent magnet 203 used in motor D, a significant decrease in permanent magnet torque, and thus a decrease in total output torque. For motor E, the ratio of W1 to W2 is too small, resulting in a significant narrowing of the width of the magnetic protrusion 202 in motor E, a decrease in magnetic permeability, a significant decrease in reluctance torque, and thus a decrease in total output torque.

[0061] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two elements; they can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0062] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all implementation methods here, and the obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A high-torque external rotor motor, comprising: A stator assembly, the stator assembly including a stator core, the stator core being provided with a plurality of stator teeth; A rotor assembly, the rotor assembly including an annular rotor yoke, Its features are: The inner surface of the rotor yoke is provided with a plurality of magnetically conductive protrusions, which are evenly distributed circumferentially along the inner surface of the rotor yoke. A permanent magnet is disposed between two adjacent magnetically conductive protrusions. The ratio of the maximum height of the magnetically conductive protrusion to the maximum height of the permanent magnet is 0.5 to 1.

5. The ratio of the middle width of the magnetic protrusion to the middle width of the stator tooth is 0.3 to 1.

5.

2. The high-torque external rotor motor as described in claim 1, characterized in that, The maximum height of the magnetically conductive protrusion is equal to the maximum height of the permanent magnet.

3. The high-torque external rotor motor as described in claim 2, characterized in that, The width of the magnetically conductive protrusion is equal to the width of the stator tooth.

4. The high-torque external rotor motor as described in claim 1, characterized in that, The magnetic protrusion is fixedly connected to the rotor yoke.

5. The high-torque external rotor motor as described in claim 1, characterized in that, The permanent magnet is a ferrite.

6. The high-torque external rotor motor as described in claim 1, characterized in that, The rotor assembly is disposed outside the stator assembly.

7. The high-torque external rotor motor as described in claim 1, characterized in that, The stator core is equipped with windings.

Images