A Rotor Structure for Improving Air Gap Flux Density Waveform of 2-pole Self-starting Permanent Magnet Motor

Abstract

The invention, which belongs to the technical field of motor fittings, particularly relates to a rotor structure capable of improving a gap flux density waveform of a two-pole self-starting permanent-magnet motor. The rotor structure comprises a rotor iron core having a plurality of mouse case slots and permanent magnets installed in permanent-magnet slots. The permanent magnets under two poles employ three-segment type inverted-U-shaped magnetic circuit structures and each of the permanent magnets includes an intermediate-segment permanent magnet and two segments of side permanent magnets; air slots are formed between the two adjacent segments of permanent magnets; the three segments of permanent magnets are arranged in a left-right symmetric mode relative to the central lines of the intermediate-segment permanent magnets; and end portions, far away from mounting slots of the intermediate-segment permanent magnets, of mounting slots of the two segments of side permanent magnets are non-magnetic-conductive material filling parts. The whole rotor structure is in a left-right-symmetric mode relative to the central lines of the intermediate-segment permanent magnets and the rotor is installed at a rotating shaft. Therefore, the gap flux density waveform of the motor can be optimized. On the basis of sinusoidal processing of the gap flux density waveform of the motor, the harmonic contents in the air-gap field and the stator winding can be reduced, the counter-electromotive-force waveform can be optimized, the motor efficiency can be improved; and the motor torque pulsation can be reduced.

Description

technical field [0001] The invention belongs to the technical field of motor accessories, and in particular relates to a rotor structure for improving the air-gap magnetic density waveform of a 2-pole self-starting permanent magnet motor. Background technique [0002] Due to the advantages of simple structure and low price of asynchronous motors, AC asynchronous motors have been widely used in various industrial fields. However, the asynchronous motor needs excitation current provided by the stator winding, and its power factor is low, and due to the existence of rotor aluminum loss (copper loss), the efficiency of the motor is not high, especially for small asynchronous motors or when the motor is lightly loaded. Compared with asynchronous motors, self-starting permanent magnet motors have obvious advantages. It has the characteristics of high efficiency, high power factor, good force index, small size, light weight, and low temperature rise. It is an ideal choice to replac...

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Problems solved by technology

[0004] At present, most self-starting permanent magnet motors adopt a uniform air gap structure, and the air gap magnetic field contains a large number of harmonics. When the permanent magnets are arranged unreasonably in the rotor, the harmonics in the air gap flux density will be more serious, making the permanent magnet The harmonic content in the electromotive force of the motor is relatively large, which increases the harmonic current in the motor stator, the harmonic copper loss and the harmonic loss in the stator core, and there are also harmonic iron loss, harmonic current and harmonic copper loss in the rotor. consumption, which affects the further improvement of the efficiency of the permanent magnet motor; in addition, the harmonic magnetic field and harmonic current will also generate additional torque fluctuations, causing vibration and noise of the motor

[0005] Due to the particularity of the rotor structure of the 2-pole self-starting permanent magnet motor, in order to increase the amount of magnetic steel placed in the rotor, the magnetic pole structure is generally more complicated. The traditional "one", "U", "V" and "W" structures are very complex. Difficult to meet the design requirements, it is necessary to adopt a combination of various structures

[0006] At present, in order to reduce the influence of the magnetic wave magnetic field in the no-load air gap magnetic field on the performance of the motor, the self-starting permanent magnet motor mainly uses the arrangement of the permanent magnets in the rotor and the reasonable design of the pole arc width to weaken the harmonic in the air gap. Wave magnetic field and the purpose of reducing torque ripple, but the weakening effect of this method is limited

In order to make the magnetic field of the motor closer to sinusoidal, Xu Yinglei of Southwest Jiaotong University proposed a self-starting permanent magnet motor with an eccentric air gap structure whose magnetic pole shape is a single arc, and Liu Mingji of North China Electric Power University proposed a rotor structure with three The self-starting permanent magnet motor with a segmented arc structure optimizes the air gap flux density waveform through the pole arc eccentric method. Although the optimization goal is achieved, the outer circle shape of the rotor of the motor is complex, which increases the difficulty of processing the motor.

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