Permanent magnet hub asymmetric V-shaped built-in external rotor motor

Abstract

A permanent magnet hub asymmetric V-shaped built-in outer rotor motor relates to the technical field of motors, the motor comprises an inner stator and an outer rotor, a plurality of permanent magnet units are built in the outer rotor, and the permanent magnet units are symmetrically arranged around a rotating shaft of the outer rotor, and is characterized in that each permanent magnet unit comprises a V-shaped magnetic steel group; the V-shaped magnetic steel group is composed of two pieces of linear magnetic steel which are symmetrically arranged relative to the d axis, and in the V-shaped magnetic steel group, the width of the linear magnetic steel located on the anticlockwise side of the d axis is a, the width of the linear magnetic steel located on the clockwise side of the d axis is b, and then egt exists; b. The motor provided by the utility model is good in flux-weakening speed expansion capability.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a permanent magnet hub asymmetric V-shaped built-in external rotor motor. Background Technology

[0002] The air gap diameter of the external rotor motor is larger than that of the internal rotor, which has a high power factor, high efficiency, high output torque and rotational inertia. It is suitable for low-speed, high-torque and direct drive applications. However, the cogging torque of the permanent magnet hub motor will cause speed and torque fluctuations, resulting in technical problems such as motor noise, vibration and deterioration of operation.

[0003] like Figure 2 As shown, existing external rotor motors are all surface-mount permanent magnet synchronous motors (SPMSMs), mainly composed of an inner stator 72 and an annular outer rotor 71. The inner stator is located in the annular hole of the outer rotor, and the inner stator and the outer rotor are in clearance fit. Surface-mounted tile-shaped magnets 73 are evenly distributed radially inwardly protruding on the inner annular surface of the outer rotor 71. Because the permeability of the permanent magnets in this type of surface-mount external rotor permanent magnet synchronous motor is close to that of air, the air gaps between the quadrature and direct axes are uniform, and the inductances between the quadrature and direct axes are equal (Ld=Lq), it belongs to a salient pole magnetic circuit and does not generate reluctance torque. Moreover, due to the large equivalent air gap, it is difficult to solve the problem of field weakening and speed extension. A large direct-axis current must be introduced into the stator winding to achieve the purpose of field weakening and speed extension. This method will reduce torque, increase stator losses, reduce drive system efficiency, and may lead to the risk of irreversible demagnetization of permanent magnets. Poor field weakening and speed extension capability is the fundamental reason hindering the development of SPMSMs. Utility Model Content

[0004] In view of the defects existing in the prior art, the technical problem to be solved by this utility model is to provide a permanent magnet hub asymmetric V-type built-in external rotor motor that can reduce motor noise and torque fluctuation.

[0005] To solve the above-mentioned technical problems, this utility model provides an asymmetric V-shaped built-in external rotor motor with a permanent magnet hub, including an inner stator and an outer rotor. The outer rotor has multiple permanent magnet units built in, and each permanent magnet unit is symmetrically arranged around the rotation axis of the outer rotor. The permanent magnet unit is characterized in that: the permanent magnet unit includes a V-shaped magnet group, which is composed of two straight magnets symmetrically arranged relative to the d-axis. Let the width of the straight magnet on the counterclockwise side of the d-axis be a, and the width of the straight magnet on the clockwise side of the d-axis be b, then a>b.

[0006] Furthermore, in the V-shaped magnet assembly, a central permanent magnet groove is provided between the adjacent ends of the two straight magnets, and a side permanent magnet groove is provided at the non-adjacent ends of the two straight magnets.

[0007] Furthermore, in the V-shaped magnet assembly, a pole shoe hole is provided at the pole shoe portion between the two straight magnets.

[0008] Furthermore, each stator tooth end face of the inner stator is provided with a semi-circular groove.

[0009] The permanent magnet hub asymmetric V-type built-in external rotor motor provided by this utility model adopts a salient pole structure for the external rotor. A V-type magnet assembly is built into the external rotor, and the V-type magnet assembly forms an asymmetry for each pole, which makes the quadrature axis inductance greater than the direct axis inductance, resulting in a salient pole effect. This allows the motor to add reluctance torque on top of the permanent magnet torque. The presence of reluctance torque helps to weaken the field and extend the speed, and it has the characteristics of good field weakening speed extension capability. It can improve the starting characteristics, overload capacity and power density of the motor, expand the constant power range operation, and obtain better field weakening speed extension capability. Attached Figure Description

[0010] Figure 1 This is a radial cross-sectional schematic diagram of the permanent magnet hub asymmetric V-shaped built-in external rotor motor according to an embodiment of the present invention;

[0011] Figure 2 A schematic diagram of the radial cross-sections of the stator and rotor of an existing surface-mounted external rotor permanent magnet synchronous motor. Detailed Implementation

[0012] The embodiments of this utility model are described in further detail below with reference to the accompanying drawings. However, these embodiments are not intended to limit this utility model. Any similar structures or variations thereof that adopt this utility model should be included in the protection scope of this utility model. The commas in this utility model all indicate a relationship between and.

[0013] like Figure 1-2 As shown in the figure, the permanent magnet hub asymmetric V-shaped built-in external rotor motor provided by this utility model includes an inner stator 1 and an outer rotor 2. The outer rotor 2 has multiple permanent magnet units built in, and each permanent magnet unit is symmetrically arranged around the rotation axis of the outer rotor.

[0014] The permanent magnet unit includes a V-shaped magnet assembly, which is composed of two straight magnets 21 arranged symmetrically relative to the d-axis. In the V-shaped magnet assembly, a central permanent magnet slot 22 is provided between the adjacent ends of the two straight magnets 21, and a side permanent magnet slot 23 is provided at the non-adjacent ends of the two straight magnets 21. A pole shoe hole 24 is opened at the pole shoe part between the two straight magnets to reduce the magnetic field distortion caused by armature reaction, improve the air gap magnetic field waveform, and reduce torque fluctuation.

[0015] Let the width of the straight magnet on the counterclockwise side of the d-axis in the V-shaped magnet group be a, and the width of the straight magnet on the clockwise side of the d-axis be b, then a>b;

[0016] Each stator tooth end face of the inner stator is provided with a semi-circular groove 12.

[0017] The permanent magnet external rotor motor of this embodiment was compared with the existing external rotor surface-mounted permanent magnet hub motor of the same specification. The parameters of the existing built-in double-layer U-shaped permanent magnet rotor motor are: rated power of 3KW, rated current of 19.5A, efficiency of 91.5%, rated speed of 800r / min, maximum speed of 2000r / min, rated torque of 35.8Nm, and maximum torque of 78Nm.

[0018] Compared with existing surface-mounted permanent magnet hub motors of the same specifications, the motor with the permanent magnet external rotor of this utility model has an efficiency that increases from 91.5% to 95.0%, a cogging torque that decreases from 1.75 Nm to 0.72 Nm, a cogging torque fluctuation that decreases from 4.9% to 2.0%, and a constant power speed regulation range that increases from 800-2000 r / min to 800-2800 r / min.

[0019] Therefore, the present invention improves the air gap flux density waveform and reduces motor noise and torque fluctuation.

Claims

1. A permanent magnet hub asymmetric V-shaped built-in external rotor motor, comprising an inner stator and an outer rotor, wherein the outer rotor has multiple permanent magnet units built-in, and each permanent magnet unit is symmetrically arranged around the rotation axis of the outer rotor, characterized in that: The permanent magnet unit includes a V-shaped magnet group, which is composed of two straight magnets symmetrically arranged relative to the d-axis. Let the width of the straight magnet on the counterclockwise side of the d-axis be a, and the width of the straight magnet on the clockwise side of the d-axis be b, then a>b.

2. The permanent magnet hub asymmetric V-shaped built-in external rotor motor according to claim 1, characterized in that: In the V-shaped magnet assembly, a central permanent magnet groove is provided between the adjacent ends of the two straight magnets, and a side permanent magnet groove is provided at the non-adjacent ends of the two straight magnets.

3. The permanent magnet hub asymmetric V-shaped built-in external rotor motor according to claim 1, characterized in that: In the V-shaped magnet assembly, a pole shoe hole is provided at the pole shoe part between the two straight magnets.

4. The permanent magnet hub asymmetric V-shaped built-in external rotor motor according to claim 1, characterized in that: Each stator tooth end face of the inner stator is provided with a semi-circular groove.

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