Permanent magnet synchronous motor and rotor thereof

Abstract

The invention discloses a permanent magnet synchronous motor. A rotor of the permanent magnet synchronous motor comprises an iron core. The iron core is cylindrical. P S-pole magnetic steel sheets and p N-pole magnetic steel sheets are evenly arranged around the axis in the iron core, wherein p is a positive integer. The S-pole magnetic steel sheets and the N-pole magnetic steel sheets are arranged at intervals. Two d-axis surface grooves are formed in the portion, at the position of each magnetic steel sheet, of the surface of the iron core of the rotor. Every two d-axis surface grooves corresponding to the same magnetic steel sheet are symmetrically distributed on the two sides of the center line of the magnetic steel sheet. The distance between the axes of every two d-axis surface grooves corresponding to the same magnetic steel sheet is approximate to the width of the tooth end of a stator tooth of the permanent magnet synchronous motor. The invention further discloses the rotor of the permanent magnet synchronous motor. According to the permanent magnet synchronous motor and the rotor of the permanent magnet synchronous motor, torque fluctuation in a low-torque area can be reduced; in addition, the structure is simple, machining and manufacturing are easy, and cost is low.

Description

technical field [0001] The invention relates to a motor, in particular to a permanent magnet synchronous motor and its rotor. Background technique [0002] Permanent magnet motors have the advantages of high torque density, high power density, high efficiency and wide area, and are the first choice for driving motors for new energy vehicles such as hybrid, pure electric and fuel cells. Especially for permanent magnet synchronous motors with built-in magnets, the reluctance torque generated by the salient pole effect of the rotor can be used to further increase the torque level, expand the field-weakening speed regulation range, and increase the speed. However, the permanent magnet rotor will also bring cogging torque, coupled with the influence of the nonlinear magnetic circuit caused by magnetic saturation, the back EMF harmonic content of the permanent magnet motor is rich, and the torque fluctuation level under load is higher than that of the general asynchronous motor. ...

AI Technical Summary

Problems solved by technology

[0007] 2. The stator behind the chute will increase the difficulty of offline, and the effective length of the winding will increase accordingly, increasing the amount of copper wire;

[0008] 3. Segmented oblique poles of the rotor will shorten the distance between magnetic poles of different polarities between adjacent lamination groups, and increase the magnetic flux leakage between poles, thereby weakening the output performance of the motor, especially for motors with a large degree of inclination, the level of performance decline more obvious;

[0009] 4. For the same motor, the peak torque and power of the motor will drop by about 10% after fully chute and oblique poles. If the original performance level is to be achieved, it is equivalent to increasing the amount of magnetic steel by 10%. At present, permanent magnet synchronous The magnetic steel of the motor is mainly NdFeB. Affected by the price of rare earths, the magnetic steel once accounted for about 50% of the cost of the whole machine, and the amount of magnetic steel is sensitive to the economic impact of the product;

[0010] 5. For the segmented oblique poles of the rotor, generally when the number of segments is ≥3, the degree of weakening of the cogging torque and torque fluctuation does not change much, that is, as long as the number of segments is not infinite, the stator chute cannot be achieved. effect, and some specific cogging torques cannot be weakened by the method of segmented oblique poles;

[0011] 6. For ISG (Integrated Starter Generator, combined starter / generator) and other motors with a relatively short axial length or a relatively small number of slots, it is difficult to implement inclined slots or oblique poles, and the impact ratio of tape leakage at the end is relatively small. Large, the resulting cogging torque cannot be effectively weakened by chute or oblique pole;

[0012] 7. The chute or inclined pole will generate a periodic axial component force on the rotor, which will increase the failure probability of the bearing, shorten the life span, and increase the axial NVH

[0013] A rotor segmented oblique pole permanent magnet synchronous motor used in Nissan Leaf (LEAF) such as image 3 As shown, the rotor segmented skew pole permanent magnet synchronous motor can significantly improve the back EMF waveform, reduce the cogging torque and torque ripple, but it will also weaken the peak performance of the motor, and increase the manufacturing complexity of the rotor at the same time

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