Permanent magnet hub motor hybrid magnetic pole built-in external rotor motor

Abstract

A hybrid magnetic pole built-in external rotor motor of a permanent magnet hub motor relates to the technical field of motors, the motor comprises an inner stator and an outer rotor, and a plurality of permanent magnet units are built in the outer rotor; the permanent magnet motor is characterized in that the permanent magnet units are divided into a group A and a group B, the two groups of permanent magnet units are alternately arranged around a rotating shaft of the outer rotor, the group A of permanent magnet units are arc-shaped magnetic steel symmetrically arranged relative to the d axis, and the group B of permanent magnet units are V-shaped magnetic steel symmetrically arranged relative to the d axis. 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 motor with a hybrid magnetic pole 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 motor with a hybrid magnetic pole built-in external rotor that can reduce motor noise and torque fluctuation.

[0005] To solve the above-mentioned technical problems, this utility model provides a permanent magnet hub motor with a hybrid magnetic pole built-in external rotor, comprising an inner stator and an outer rotor, wherein the outer rotor has multiple permanent magnet units built-in; characterized in that:

[0006] The permanent magnet units are divided into Group A and Group B. The two groups of permanent magnet units are arranged alternately around the rotation axis of the outer rotor. The permanent magnet units in Group A are arc-shaped magnets arranged symmetrically with respect to the d-axis, and the permanent magnet units in Group B are V-shaped magnets arranged symmetrically with respect to the d-axis.

[0007] Furthermore, both ends of the arc-shaped magnet and the V-shaped magnet are provided with air permanent magnet grooves.

[0008] Furthermore, the coercivity of the V-shaped magnet is higher than that of the arc-shaped magnet.

[0009] Furthermore, each stator tooth end face of the inner stator is provided with a semi-circular groove.

[0010] The permanent magnet hub motor provided by this utility model is a hybrid magnetic pole built-in external rotor motor. The external rotor adopts a salient pole structure, and arc-shaped magnets and V-shaped magnets are built into the external rotor, so that the quadrature axis inductance is greater than the direct axis inductance, which has a salient pole effect. This allows the motor to add reluctance torque on the basis of permanent magnet torque. The presence of reluctance torque helps to weaken the field and extend the speed, and 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

[0011] Figure 1 This is a radial cross-sectional schematic diagram of a permanent magnet hub motor with a hybrid magnetic pole built-in external rotor according to an embodiment of the present invention;

[0012] 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

[0013] 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.

[0014] like Figure 1-2 As shown in the figure, the permanent magnet hub motor with hybrid magnetic pole built-in external rotor provided by this utility model includes an inner stator 1 and an outer rotor 2, wherein the outer rotor 2 has multiple permanent magnet units built-in.

[0015] The permanent magnet unit is divided into group A and group B. The two groups of permanent magnet units are arranged alternately around the rotation axis of the outer rotor 2. The permanent magnet unit of group A is an arc-shaped magnet 21 arranged symmetrically with respect to the d-axis, and the permanent magnet unit of group B is a V-shaped magnet 22 arranged symmetrically with respect to the d-axis.

[0016] Both ends of the arc-shaped magnet 21 and the V-shaped magnet 22 are provided with air permanent magnet grooves;

[0017] The coercivity of the V-shaped magnet 22 is higher than that of the arc-shaped magnet 21;

[0018] Each stator tooth end face of the inner stator 1 is provided with a semi-circular groove 12.

[0019] 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.

[0020] 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 94.8%, a cogging torque that decreases from 1.75 Nm to 0.78 Nm, a cogging torque fluctuation that decreases from 4.9% to 2.17%, and a constant power speed regulation range that increases from 800-2000 r / min to 800-2800 r / min.

[0021] Therefore, the present invention improves the air gap flux density waveform and reduces motor noise and torque fluctuation.

Claims

1. A permanent magnet hub motor with a hybrid magnetic pole built-in external rotor, comprising an inner stator and an outer rotor, wherein the outer rotor has multiple permanent magnet units built-in; characterized in that: The permanent magnet units are divided into Group A and Group B. The two groups of permanent magnet units are arranged alternately around the rotation axis of the outer rotor. The permanent magnet units in Group A are arc-shaped magnets arranged symmetrically with respect to the d-axis, and the permanent magnet units in Group B are V-shaped magnets arranged symmetrically with respect to the d-axis.

2. The permanent magnet hub motor with hybrid magnetic poles and an internal external rotor as described in claim 1, characterized in that: Both ends of the arc-shaped magnet and the V-shaped magnet are provided with air permanent magnet grooves.

3. The permanent magnet hub motor with hybrid magnetic poles and an internal external rotor as described in claim 1, characterized in that: The coercivity of the V-shaped magnet is higher than that of the arc-shaped magnet.

4. The permanent magnet hub motor with hybrid magnetic poles and an internal external rotor as described in claim 1, characterized in that: Each stator tooth end face of the inner stator is provided with a semi-circular groove.

Images