Technological method for inhibiting eddy current on surface of permanent magnet of rotor of high-speed permanent magnet motor

Abstract

The invention discloses a process method for inhibiting eddy current on the surface of a permanent magnet of a high-speed permanent magnet motor rotor, and belongs to the field of motor design. The problems of heating and demagnetization of the surface of a rotor permanent magnet in the motor are solved; according to the process structure of the permanent magnet of the permanent magnet motor rotor provided by the invention, the conductor on the surface of the permanent magnet is divided into small blocks by carving the shallow grooves on the surface of the permanent magnet, and the generation of large eddy current on the surface of the permanent magnet of the motor rotor is inhibited; the motor is used for reducing heat and loss in the motor and solving the demagnetization problem of the permanent magnet.

Description

Technical Field

[0001] The invention relates to the field of motor design, and in particular to a process method for suppressing eddy currents on the surface of permanent magnets of a high-speed permanent magnet motor rotor. Background Art

[0002] Eddy currents, like general currents, will produce thermal effects, and the heat value generated complies with Joule's law. The iron core (large magnetic permeability) used to enhance the magnetic properties of the coil will generate eddy currents during operation, causing itself to heat up, wasting energy, and even affecting the operation of the equipment. Therefore, in the iron core materials of motors, generators, transformers, AC electromagnets and other equipment, instead of using the entire iron core, silicon steel sheets coated with insulating paint are used. This is because silicon steel contains 2~5% silicon, which can increase the resistivity of the iron core.

[0003] The rotor of a high-speed permanent magnet motor looks like Figure 1 As shown, the surface of the rotor core cylinder is a permanent magnet. During the rotation of the permanent magnet rotor of the high-speed permanent magnet motor, due to the conductive properties of the permanent magnet, eddy currents will be induced on the permanent magnet under the action of the harmonic magnetic field of the stator-rotor air gap. The eddy current i and the equivalent resistance r of the permanent magnet produce a thermal effect, which is expressed as Q=i²r. The eddy current induces a magnetic field in the opposite direction of the harmonic magnetic field, which shields the harmonic magnetic field, causing the intensity of the eddy current to decrease with the depth of the permanent magnet. Most of the eddy currents are confined to the surface of the permanent magnet. The higher the frequency of the harmonic, the shallower the depth of the eddy current. The thermal effect generated by the eddy current increases the temperature of the permanent magnet, reduces the residual magnetism, reduces the air gap magnetic density, reduces the power of the motor, and reduces the efficiency. In severe cases, it can cause irreversible demagnetization of the permanent magnet, so the weaker the eddy current on the surface of the rotor of the high-speed permanent magnet motor, the better. Summary of the invention

[0004] The invention aims to solve the consequences of high temperature and demagnetization caused by large eddy currents on the surface of a permanent magnet rotor of a high-speed permanent magnet motor.

[0005] To this end, the present invention discloses a process method for suppressing eddy currents on the surface of permanent magnets of a high-speed permanent magnet motor rotor, wherein shallow grooves are carved axially on the cylindrical surface of the permanent magnet rotor of the high-speed permanent magnet motor, and the shallow grooves are evenly distributed on the outer surface of the rotor permanent magnets.

[0006] Preferably, the shallow grooves have a depth of less than 1 mm and a spacing of more than 3 mm.

[0007] Preferably, the shallow groove has a width of 0.05-0.2 mm and a depth of 0.5-1 mm.

[0008] More specifically, the shallow grooves have a width of 0.2 mm, a depth of 1 mm, and a spacing of 5 mm.

[0009] Preferably, when machining the surface of the permanent magnet rotor, the shallow grooves are machined by wire cutting to form shallow grooves with equal spacing along the axial direction.

[0010] After the implementation of the above technical solutions, the eddy current loss on the surface of the rotor of the high-speed permanent magnet motor can be effectively suppressed. Because after the surface of the rotor permanent magnet is grooved, the conductor on the surface of the permanent magnet is divided into small pieces, and the equivalent resistance is very large, which limits the eddy current on the surface of the permanent magnet to a very small thin film area, thereby reducing the overall eddy current loss, reducing heat, reducing energy consumption, improving efficiency, and reducing the risk of permanent magnet demagnetization. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the motor rotor appearance before shallow grooves are carved; Figure 2 Schematic diagram of the appearance of the motor rotor after shallow grooves are carved; Figure 3 Schematic diagram of large eddy currents on the surface of the motor rotor before shallow grooves are carved; Figure 4 Schematic diagram of small eddy currents on a single circular arc surface of the rotor surface after shallow grooves are carved; Figure 5 Schematic diagram of eddy currents on the surface of a motor rotor after shallow grooves are engraved. Specific embodiments

[0012] This embodiment discloses a process for suppressing eddy current on the surface of permanent magnets of a high-speed permanent magnet motor rotor. Shallow grooves are evenly distributed along the axial direction on the cylindrical surface of the permanent magnets of the rotor of the high-speed permanent magnet motor. Before the shallow grooves are carved, the appearance of the original motor rotor is as follows: Figure 1 As shown; when the motor is running, the large eddy current on the rotor surface is as follows Figure 3 as shown; Figure 1 After cutting and grooving, the surface of the motor rotor shown in the figure becomes Figure 2 The motor rotor with shallow grooves shown in the figure, therefore, the shallow grooves before Figure 3 The large vortex shown is cut into Figure 5 The small vortices on the surface of each small arc piece are as shown in Figure 4 shown.

[0013] In this embodiment, when processing the permanent magnet, the surface of the rotor is processed by wire cutting to form the following Figure 2 The shallow grooves are equally spaced along the axial direction as shown. Of course, other methods can also be used to cut the grooves, such as laser cutting, when appropriate.

[0014] Although the depth of the shallow groove is less than 1 mm, the interval is more than 3 mm, and the width is 0.05-0.2 mm, in the present embodiment, the width of the shallow groove is 0.2 mm, the depth is 1 mm, and the interval is 5 mm.

[0015] The present invention is an ingenious improvement of the process structure based on the principle of the motor. The practical effect of the above embodiment is that after the shallow grooves are engraved along the axial direction on the rotor surface of the high-speed permanent magnet motor, the heat generated on the rotor surface is greatly reduced during the operation of the motor, so that the performance and life of the motor are effectively maintained.

Claims

1. A process for suppressing eddy currents on the surface of permanent magnets of a high-speed permanent magnet motor rotor, characterized in that: Shallow grooves are engraved along the axial direction on the cylindrical surface of the rotor permanent magnet of the high-speed permanent magnet motor, and the shallow grooves are evenly distributed on the outer surface of the rotor permanent magnet.

2. The process for suppressing eddy current on the surface of permanent magnets of a high-speed permanent magnet motor rotor according to claim 1, characterized in that: The depth of the shallow grooves is less than 1 mm, and the intervals are more than 3 mm.

3. The process for suppressing eddy current on the surface of permanent magnet of a high-speed permanent magnet motor rotor according to claim 2, characterized in that: The width of the shallow groove is 0.05-0.2 mm, and the depth is 0.5-1 mm.

4. The process for suppressing eddy current on the surface of permanent magnets of a high-speed permanent magnet motor rotor according to claim 3, characterized in that: The width of the shallow groove is 0.2 mm, the depth is 1 mm, and the interval is 5 mm.

5. The process for suppressing eddy current on the surface of permanent magnets of a high-speed permanent magnet motor rotor as claimed in any one of the preceding claims, characterized in that: When processing the surface of the permanent magnet rotor, the shallow grooves are processed by wire cutting to form shallow grooves with equal spacing along the axial direction.

6. The process for suppressing eddy current on the surface of permanent magnets of a high-speed permanent magnet motor rotor as claimed in any one of the above claims, characterized in that: The evenly distributed shallow grooves are cut by laser.

Images