CN1832301A - Built-in rotor of surface concept permanent magnet motor - Google Patents

Abstract

This invention relates to a built-in rotor of a surface-type concept permanent magnet motor, which replaces two heteropolarity magnets for each pair pole of a general motor with a homopolarity and regular shaped magnet of each pair pole to be inserted in the rotor core, pits are set on the core surfaces of the rotors at both sides of the magnets, so that the d-axis and the quadrature have the same reactance to play the role of a magnet-isolation bridge.

Description

Built-in rotor of surface concept permanent magnet motor

technical field

The invention relates to a rotor of a permanent magnet motor, in particular to a built-in rotor of a surface concept permanent magnet motor.

Background technique

Exploring and selecting a reasonable rotor structure is one of the core issues in the design of permanent magnet motors. It is of great significance to the simplification of the manufacturing process, the reduction of production costs, and the optimization of the design of high-performance permanent magnet motors. There are various rotor structures of permanent magnet motors. As a whole, the most commonly used ones are Surface Mounted Permanent Magnet (SPM) rotor structure and Interior Permanent Magne (IPM) rotor structure.

The surface rotor structure is characterized by saliency ratio ρ=L _q /L _d =1, no reluctance torque, large equivalent air gap, small armature reaction, and good dynamic performance. It is often used in servo motors and traction motors. Surface rotor permanent magnets are usually in the shape of tiles and placed on the surface of the rotor core. Generally, the outer surface of the permanent magnet needs to be covered with a non-magnetic ferrule for protection, or wrapped with a laid-off glass ribbon as a protective layer. The shape of the permanent magnet of this structure is complex, the processing cost is large, and it leads to an increase in the cost of the rotor and an increase in surface loss.

The built-in rotor embeds permanent magnets in the rotor iron core. The processing technology is simple, the shape is regular, and the salient pole ratio is not equal to 1, which is suitable for wide speed regulation occasions.

Contents of the invention

The object of the present invention is to provide a built-in rotor of a surface-type concept permanent magnet motor, so that the built-in rotor has the performance characteristics of a surface-type permanent magnet motor.

In order to achieve the above object, the idea of the present invention is to propose a surface-type permanent magnet motor, which adopts a built-in rotor structure, but has the performance characteristics of a surface-type permanent magnet motor. That is to say, the conventional permanent magnet motor will replace two permanent magnets with different polarity in each pair of poles with one permanent magnet of the same polarity in each pair of poles. The permanent magnets are embedded in the rotor core, which can simplify the processing technology and avoid adding a protective layer on the surface of the permanent magnets. , and can reduce the amount of permanent magnets and reduce costs.

According to above-mentioned inventive concept, the present invention adopts following technical scheme:

A built-in rotor of a surface concept permanent magnet motor, comprising a rotor iron core and a permanent magnet, characterized in that:

(1) All permanent magnets have the same polarity, and the number of permanent magnets is the same as the number of pole pairs of the motor;

(2) The permanent magnet is embedded in the rotor core;

(3) Dimples are provided on the surface of the rotor on both sides of the permanent magnet.

The above-mentioned permanent magnet is rectangular in shape.

The shape and position of the pits on the surface of the rotor on both sides of the above-mentioned permanent magnets should be calculated according to known motor design principles and electromagnetic theory, so that the direct-axis reactance and quadrature-axis reactance of the motor are equal in value and play the role of a magnetic isolation bridge.

The above rotor core shape and air gap distribution should be determined according to the known motor design principles and electromagnetic theory, according to the requirements of the motor for the air gap magnetic field, so as to generate a sine wave air gap magnetic field or a trapezoidal wave air gap magnetic field.

The principle is as follows:

Since there is only one permanent magnet for each pair of poles, assuming that the permanent magnet is an N pole, the main magnetic flux path of the motor is: permanent magnet pole→rotor core upper yoke→air gap→stator core→air gap→rotor core pole→rotor core Lower yoke → back to permanent magnet. The magnetic field path is similar to that of a conventional motor, and the magnetic circuit of each pair of poles remains symmetrical. The difference is that after each pair of poles is changed from two different-polarity permanent magnets to each pair of poles with one same-polarity permanent magnet, this permanent magnet provides the magnetic potential required by a pair of poles. In order to control the size of the quadrature-axis magnetic field, pits are set on the surface of the rotor core on both sides of the permanent magnet, and the shape and size of the pits are accurately calculated by electromagnetic field analysis to ensure that the quadrature-axis reactance is equal to the direct-axis reactance and the salient pole ratio is close to 1. Make the rotor structure of the built-in permanent magnet have the performance characteristics of the surface permanent magnet motor; at the same time, the existence of the pit can prevent the permanent magnetic flux from directly passing through the rotor core to form magnetic flux leakage, and play a role in the conventional built-in permanent magnet The role of the magnetic isolation bridge of the motor.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

(1) From the perspective of electromagnetic design, although the thickness of the permanent magnet in a conventional permanent magnet motor only needs to provide a pole magnetic potential value and anti-demagnetization ability, in most cases the thickness of the permanent magnet depends on the requirements of mechanical strength. After using one permanent magnet for each pair of poles, the thickness of the permanent magnet depends on the magnetic potential and anti-demagnetization ability required by the pair of poles. Generally, the mechanical strength can meet the requirements. Therefore, after adopting this structure, the permanent magnet material is reduced, the shape is a simple rectangle, the number is reduced by half, the processing is convenient, the cost is reduced, and the cost is reduced.

(2) The permanent magnet is embedded in the rotor core, so there is no need to add a non-magnetic hoop or latitude-free glass ribbon as a protective layer outside the permanent magnet like a surface-type permanent magnet motor, which simplifies the processing technology and avoids surface loss and latitude during high-speed operation. The possible damage of the glass ribbon improves the reliability of the motor.

(3) For the situation where a non-uniform air gap is required to generate a sine wave magnetic field, the surface type rotor structure permanent magnet is difficult to process, the accuracy is difficult to guarantee, and the amount of permanent magnet material is large; the built-in permanent magnet proposed by the present invention has regular shape and low processing cost , the non-uniform air gap is determined by the shape of the rotor punch, the precision is easy to control, and it is suitable for application in high-performance servo systems.

Description of drawings

FIG. 1 is a schematic structural view of a surface type permanent magnet motor rotor in the prior art.

Fig. 2 Schematic diagram of the structure of the built-in rotor of the surface concept permanent magnet motor.

Fig. 3 The magnetic circuit diagram of the built-in rotor direct axis of the surface concept permanent magnet motor.

Fig. 4 The magnetic circuit diagram of the quadrature axis of the built-in rotor of the surface concept permanent magnet motor.

Fig. 5 The magnetic circuit diagram of the surface-type concept permanent magnet motor built-in rotor interpole leakage.

Fig. 6 Schematic diagram of the structure of the non-uniform air gap rotor of the surface concept permanent magnet motor.

Specific implementation method

The built-in rotor of the surface concept permanent magnet motor of the present invention will be further described in detail in conjunction with the accompanying drawings and a preferred implementation example:

The prior art surface-type rotor is shown in Fig. 1 (taking a four-pole motor as an example), tile-shaped N poles (3) and S poles (1) are alternately placed on the surface of the rotor core (2).

The built-in rotor of the surface concept permanent magnet motor of the present embodiment is as shown in Figure 2. Compared with the surface rotor structure, the number of permanent magnet blocks is reduced by half, the polarity is the same, and the shape is a regular rectangular permanent magnet (4) ( N poles or S poles) are evenly distributed and embedded in the rotor iron core (7), and pits (5) and (6) are arranged on both sides of each permanent magnet. The path of the direct-axis magnetic circuit is: starting from the N pole (4) of the permanent magnet, passing through the upper yoke (9) of the rotor core, the air gap, the stator core (8), the air gap, the rotor core pole (10), the rotor core The lower yoke (11) returns to the permanent magnet (4), specifically as shown in Figure 3. The path of the quadrature-axis magnetic circuit is: the rotor core (7), the pit (5), the air gap, the stator (8), the air gap, and the pit (6) form a circuit, as shown in FIG. 4 .

The shape and position of the pits (5), (6) need to be based on the size of the motor, according to the known motor design principles and magnetic field theory, to carry out electromagnetic field analysis and calculation: between the pits (5), (6) and the end of the permanent magnet The gap is determined according to the requirements of the magnetic bridge in the built-in rotor structure (as shown in Figure 5); the width of the pits (5), (6) is determined by the requirements of the pole arc coefficient; the width of the pits (5), (6) The depth is determined by the salient pole ratio. Generally, the reluctance of the direct axis and the quadrature axis of the motor are required to be approximately equal.

The outer dimensions of the rotor core are determined by the requirements of the air-gap magnetic field waveform: a rectangular or trapezoidal wave air-gap magnetic field adopts a uniform air gap; a sine wave air-gap magnetic field adopts a non-uniform air gap, and the specific shape and size need to be determined by magnetic field calculation, as shown in Figure 6 shown.

Claims (4)

1. the built-in rotor of a surface concept permanent-magnet machine comprises rotor core (7) and permanent magnet (4), it is characterized in that:

(1) all permanent magnet (4) polarity is identical, and the piece number of permanent magnet (4) is identical with the number of pole-pairs of motor;

(2) permanent magnet (4) embeds in the rotor core (7);

(3) rotor surface of permanent magnet (4) both sides is provided with pit (5,6).

2. the built-in rotor of surface concept permanent-magnet machine according to claim 1 is characterized in that the rectangle that is shaped as of permanent magnet (4).

3. the built-in rotor of surface concept permanent-magnet machine according to claim 1 and 2, the shape and the position that it is characterized in that permanent magnet both sides rotor surface pit (5,6), the d-axis reactance of motor is equated with quadrature axis reactance numerical value, and play effect every magnetic bridge.

4. the built-in rotor of surface concept permanent-magnet machine according to claim 3 is characterized in that the distribution of rotor core (7) profile and air gap should be able to produce sinusoidal wave air-gap field or trapezoidal wave air-gap field.

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