CN104795957A - Method for reducing cogging torque of asynchronous start permanent magnet synchronous motor - Google Patents

Abstract

The invention discloses a method for reducing the cogging torque of an asynchronous start permanent magnet synchronous motor. The method is suitable for the asynchronous start permanent magnet synchronous motor, the asynchronous start permanent magnet synchronous motor comprises a stator and a rotor, a permanent magnet is arranged in the rotor, a certain gap exists between the two adjacent permanent magnetic poles of the rotor and all the gaps are equal; stator teeth and stator grooves which are alternately arrayed along a circumferential direction are arranged at the inner side of the stator; rotor teeth and rotor grooves which are alternately arrayed along the circumferential direction are arranged at the outer side of the rotor; one side, facing the stator, of each rotor tooth is a rotor tooth crest. The method is characterized in that a proper rotor tooth crest width is selected according to the actual structural parameters of asynchronous start permanent magnet synchronous motor. The method disclosed by the invention is applied to the asynchronous start permanent magnet synchronous motor, and is beneficial to the stable running of the type of motors.

Description

A kind of method reducing asynchronous starting permanent magnet synchronous motor cogging torque

Technical field

The present invention relates to a kind of method reducing asynchronous starting permanent magnet synchronous motor cogging torque.

Background technology

Cogging torque problem is the intrinsic problem of magneto, can affect the stable operation of motor, and the cogging torque how reducing motor is one of emphasis of magneto research always.At present, most cogging torque weakening method is still confined to the magneto of surface-type and the common monolateral fluting of rotor such as built-in.

The bilateral fluting of rotor of asynchronous starting permanent magnet synchronous motor, armature winding is placed with in stator slot, cage-shaped structure winding is there is in rotor, stator and rotor cores is overrided to form by punching, the asynchronous torque that rotor cage winding can be relied on to produce realizes self-starting, and does not usually need controller when stable operation.Asynchronous starting permanent magnet synchronous motor adopts every pole integer groove usually, and the cogging torque of motor is larger.The existence of cogging torque not only can have a negative impact to the self-starting of asynchronous starting permanent magnet synchronous motor, but also can affect the stable operation of motor.

Summary of the invention

The present invention, in order to solve the problem, proposes a kind of method reducing asynchronous starting permanent magnet synchronous motor cogging torque, and this method, while reduction asynchronous starting permanent magnet synchronous motor cogging torque, can't produce larger impact to motor performance.

To achieve these goals, the present invention adopts following technical scheme:

A kind of asynchronous starting permanent magnet synchronous motor, comprise stators and rotators, described internal rotor is placed with permanent magnet, certain intervals is there is between adjacent two permanent magnetism magnetic poles, and all intervals are all equal, there are the stator tooth and stator slot that are along the circumferential direction alternately arranged in the inner side of described stator, and there are the rotor tooth and rotor that are along the circumferential direction alternately arranged in the outside of described rotor.

Described stator tooth is stator tooth top towards the side of rotor, and the width of all stator tooth tops is all equal and be along the circumferential direction uniformly distributed.

Described rotor tooth is rotor tooth top towards the side of stator, and the width of all rotor tooth tops is all equal and be along the circumferential direction uniformly distributed.

Reduce a method for asynchronous starting permanent magnet synchronous motor cogging torque, comprise the following steps:

(1) according to the structural parameters of asynchronous starting permanent magnet synchronous motor, the harmonic amplitude computation model producing cogging torque in the square distribution of air-gap mmf is built;

(2) by making the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf be 0, the rotor addendum width t that effectively can weaken asynchronous starting permanent magnet synchronous motor cogging torque is obtained ₁.

In described step (2), when the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf is 0, rotor addendum width t ₁for:

$t_1=\frac{2\mathrm{k\π}}{\mathrm{LCM}(Q_1,2p)}---\left(1\right)$

Wherein, LCM (Q ₁, 2p) and represent Q ₁with the least common multiple of 2p; Q ₁for the stator number of teeth; P is the number of pole-pairs of motor; K is positive integer.

Operation principle of the present invention is: square distribution that the cogging torque of asynchronous starting permanent magnet synchronous motor can be regarded as the air-gap mmf that the square distribution of the effective air gap length produced by slotted stator and slotted rotor produce interacts and produces, in the square distribution of air-gap mmf, the amplitude of each harmonic is all by the impact of rotor addendum width, by making the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf be 0, the cogging torque of asynchronous starting permanent magnet synchronous motor effectively can be weakened.

Beneficial effect of the present invention is:

(1) by changing the width of rotor tooth top, effectively can weaken the cogging torque of asynchronous starting permanent magnet synchronous motor, the method is easy to realization, Be very effective;

(2) only change the width of rotor tooth top, other structural parameters of motor do not change, and the impact produced motor performance is very little.

Accompanying drawing explanation

Fig. 1 is the structural representation of asynchronous starting permanent magnet synchronous motor;

Fig. 2 is the structural representation before and after rotor addendum width changes;

Fig. 3 is the cogging torque schematic diagram before and after rotor addendum width changes;

Wherein, 1-stator core, 2-rotor core, 3-stator winding, 4-rotor cage winding, 5-permanent magnet, the interval between adjacent two permanent magnetism magnetic poles of 6-, t ₀-former rotor addendum width, t ₁width after-rotor addendum width changes.

Embodiment:

Below in conjunction with accompanying drawing and embodiment, the invention will be further described.

As Figure 1-Figure 2, a kind of method reducing asynchronous starting permanent magnet synchronous motor cogging torque, there is certain intervals (6), and all intervals (6) is all equal between adjacent two rotor permanent magnet magnetic poles.According to the main structure parameters of asynchronous starting permanent magnet synchronous motor, the width of rotor tooth top is changed into t ₁time, the cogging torque of motor will significantly weaken, wherein:

$t_1=\frac{2\mathrm{k\π}}{\mathrm{LCM}(Q_1,2p)}---\left(1\right)$

Wherein, LCM (Q ₁, 2p) and represent Q ₁with the least common multiple of 2p; Q ₁for the stator number of teeth; P is the number of pole-pairs of motor; K is positive integer.

The former rotor addendum width of asynchronous starting permanent magnet synchronous motor shown in Fig. 1 is 5.8225 °, its stator number of teeth Q ₁=72, number of pole-pairs p=4, can calculate the rotor addendum width that effectively can weaken motor cogging torque is t ₁=5 °.Cogging torque when the rotor addendum width of motor is respectively 5.8225 °, 5 ° as shown in Figure 3, can find out, by changing rotor addendum width, cut down to 20Nm by 38Nm, reduces 47.4% by the cogging torque maximum of motor.

As shown in Figure 2, what the method changed is only rotor addendum width, can not produce considerable influence, and the method is easy to realization, Be very effective to the performance of motor.

The principle that realizes of the present invention is: the square distribution that the cogging torque of asynchronous starting permanent magnet synchronous motor can be regarded as the air-gap mmf that the square distribution of the effective air gap length produced by slotted stator and slotted rotor produce interacts and produces, in the square distribution of air-gap mmf, the amplitude of each harmonic is all by the impact of rotor addendum width, by making the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf be 0, the cogging torque of asynchronous starting permanent magnet synchronous motor effectively can be weakened.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (5)

1. an asynchronous starting permanent magnet synchronous motor, comprises stators and rotators, and described internal rotor is placed with permanent magnet, it is characterized in that: there is certain intervals between adjacent two permanent magnetism magnetic poles, and all intervals are all equal.

2. a kind of asynchronous starting permanent magnet synchronous motor as claimed in claim 1, is characterized in that: there are the stator tooth and stator slot that are along the circumferential direction alternately arranged in the inner side of described stator, and there are the rotor tooth and rotor that are along the circumferential direction alternately arranged in the outside of described rotor.

3. a kind of asynchronous starting permanent magnet synchronous motor as claimed in claim 1, is characterized in that: described stator tooth is stator tooth top towards the side of rotor, and the width of all stator tooth tops is all equal and be along the circumferential direction uniformly distributed; Described rotor tooth is rotor tooth top towards the side of stator, and the width of all rotor tooth tops is all equal and be along the circumferential direction uniformly distributed.

4. reduce a method for asynchronous starting permanent magnet synchronous motor cogging torque, it is characterized in that: comprise the following steps:

(1) according to the structural parameters of asynchronous starting permanent magnet synchronous motor, the harmonic amplitude computation model producing cogging torque in the square distribution of air-gap mmf is built;

(2) by making the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf be 0, the rotor addendum width t that effectively can weaken asynchronous starting permanent magnet synchronous motor cogging torque is obtained ₁.

5. a kind of method reducing asynchronous starting permanent magnet synchronous motor cogging torque as claimed in claim 4, it is characterized in that: in described step (2), when the harmonic amplitude producing cogging torque in the square distribution of air-gap mmf is 0, rotor addendum width t ₁for:

$t_1=\frac{2\mathrm{k\π}}{\mathrm{LCM}(Q_1,2p)}---\left(1\right)$

Wherein, LCM (Q ₁, 2p) and represent Q ₁with the least common multiple of 2p; Q ₁for the stator number of teeth; P is the number of pole-pairs of motor; K is positive integer.