Permanent magnet hub motor built-in groove-added external rotor motor

Abstract

A permanent magnet hub motor built-in slot-increasing outer rotor motor relates to the technical field of motors, the motor comprises an inner stator and an outer rotor, a plurality of V-shaped magnetic steel groups symmetrically arranged around a rotating shaft of the outer rotor are built in the outer rotor, each V-shaped magnetic steel group is composed of two linear magnetic steels symmetrically arranged relative to a d shaft, and the linear magnetic steels are arranged in the inner stator and the outer rotor. The rotor is characterized in that a plurality of arc-shaped grooves which are distributed at intervals in the circumferential direction of the outer rotor are formed in the inner ring face of the outer rotor, three arc-shaped grooves form a group, and the three arc-shaped grooves in the same group are symmetrically distributed 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 an internal slotted external rotor. 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 built-in slotted 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 an internal slotted external rotor, comprising an inner stator and an outer rotor. The outer rotor has multiple V-shaped magnet groups symmetrically arranged around its axis of rotation. Each V-shaped magnet group is composed of two straight magnets symmetrically arranged relative to the d-axis. The invention is characterized by:

[0006] The inner ring surface of the outer rotor is provided with multiple arc-shaped grooves arranged at intervals along the circumference of the outer rotor. The arc-shaped grooves are arranged in groups of three, and the three arc-shaped grooves in the same group are symmetrically arranged relative to the d-axis.

[0007] Furthermore, each stator tooth end face of the inner stator is provided with a semi-circular groove.

[0008] Furthermore, in the V-shaped magnet assembly, the non-adjacent ends of the two straight magnets are provided with side permanent magnet slots.

[0009] The permanent magnet hub motor with built-in slotted external rotor provided by this utility model adopts a salient pole structure. V-shaped magnets are built into the external rotor, and circular slots are opened on the surface of the pole shoes to form an uneven air gap with the stator. This 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, resulting in good field weakening speed extension capability. It can improve the motor's starting characteristics, overload capacity and power density, 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 a permanent magnet hub motor with built-in slotted external rotor 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 As shown in the embodiment of this utility model, a permanent magnet hub motor with built-in slotted external rotor includes an inner stator 1 and an outer rotor 2. The outer rotor 2 has multiple V-shaped magnet groups 21 symmetrically arranged around the rotation axis of the outer rotor 2. The V-shaped magnet group 21 is composed of two straight magnets symmetrically arranged relative to the d-axis. In the V-shaped magnet group 21, the non-adjacent ends of the two straight magnets are provided with side permanent magnet slots 22.

[0014] The inner ring surface of the outer rotor 2 is provided with a plurality of arc-shaped grooves 23 arranged at intervals along the circumference of the outer rotor. The arc-shaped grooves 23 are arranged in groups of three, and the three arc-shaped grooves 23 in the same group are symmetrically arranged with respect to the d-axis.

[0015] Each stator tooth end face of the inner stator is provided with a semi-circular groove 12.

[0016] 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.

[0017] 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.

[0018] Therefore, the present invention improves the air gap flux density waveform and reduces motor noise and torque fluctuation.

Claims

1. A permanent magnet wheel hub motor built-in slot-increased outer rotor motor, comprising an inner stator and an outer rotor, a plurality of V-shaped magnetic steel groups are built-in on the outer rotor and symmetrically arranged around the rotation axis of the outer rotor, the V-shaped magnetic steel group is composed of two opposite d-axis symmetrically arranged single magnetic steels, characterized in that: a plurality of arc-shaped grooves are arranged on the inner ring surface of the outer rotor and spaced along the circumferential direction of the outer rotor, the arc-shaped grooves are grouped into three, and the three arc-shaped grooves in the same group are symmetrically arranged with respect to the d-axis. The end surface of each stator tooth of the inner stator is provided with a semicircular groove.

2. The permanent-magnet wheel-hub- motor-embedded slot-increased outer-rotor motor according to claim 1, characterized in that: In the V-shaped magnetic steel group, the non-adjacent ends of the two single magnetic steels are provided with side permanent magnet grooves.

3. The permanent magnet wheel-hub motor built-in slot-increase outer rotor motor of claim 1, wherein: ​

Images