A multi-pole magnetization method for a permanent magnet synchronous motor rotor

Abstract

The invention discloses a multi-pole magnetization method for a permanent magnet synchronous motor rotor. When the motor rotor is injection molded, the injection molding material in the gap between the outer circumference of a rotor chip and the outer circumference of a permanent magnet is eliminated. When the motor rotor is placed in a magnetization fixture, a magnetization head can move forward to fit and contact the outer circumference of a permanent magnet of the permanent magnet synchronous motor rotor, thereby eliminating the gap and forming a seamless closed magnetic circuit of magnetic silicon steel, permanent magnet, rotor chip, adjacent permanent magnet, adjacent magnetic silicon steel, silicon steel disc, and magnetic silicon steel, thereby eliminating magnetic leakage.

Description

Technical Field

[0001] The present invention relates to the technical field of motor manufacturing, and in particular to a multi-pole magnetization method for a permanent magnet synchronous motor rotor. Background Art

[0002] The principle of multi-pole magnetization is mainly realized by using pulse magnetic field, which is related to the working characteristics of the magnetizer, the magnetizing head and the performance indicators of the magnet itself. This process involves the use of pulse magnetic field generated by instantaneous discharge of large current to magnetize the permanent magnet. The realization of multi-pole magnetization depends on specific magnetizing equipment, which is usually composed of components such as capacitor bank, thyristor, control circuit and charging head. The working principle of the magnetizer is to charge the DC high voltage into the capacitor and then discharge it through a coil with extremely low resistance. During discharge, the peak value of the pulse current can reach tens of thousands of amperes. This current pulse generates a strong magnetic field in the coil, which permanently magnetizes the hard magnetic material placed in the coil. This magnetization method is suitable for high coercive force permanent magnetic materials or complex multi-pole magnetization occasions. It is efficient and reliable, and is widely used in permanent magnetic material production and application enterprises.

[0003] For permanent magnet synchronous motors, the motor rotor chip is plastic-sealed after being assembled with permanent magnets. During magnetization, the plastic-sealed rotor is placed in the center of the magnetization fixture, and the magnetizer is started for magnetization. The magnetization fixture generally contains a magnetization head composed of magnetic silicon steel (i.e., magnetic conductor) and a wire coil. The number of magnetization heads corresponds to the number of rotor poles. In order to automate the rotor magnetization process, there is a certain gap between the rotor and the magnetization fixture when the rotor is placed in the magnetization fixture. After the rotor is assembled with permanent magnets, there is a drop gap between the outer cylindrical surface of the rotor chip and the outer cylindrical surface of the permanent magnet. The drop gap is generally filled with engineering plastics after injection molding. During magnetization, magnetization is directly performed through the injection molding material.

[0004] These two gaps will produce unfavorable factors: due to the gap, the magnetizing fixture magnetizer is not in contact with the permanent magnet, and there is a gap between the two. The magnetic lines of force cannot form a closed loop during magnetization, resulting in leakage magnetic flux; at the same time, the magnetizing fixture magnetizer is not in contact with the permanent magnet, and there is an empty space between the two. Its magnetic permeability is close to 1, forming a large magnetic resistance, which further increases the formation of leakage magnetic flux. Due to the above unfavorable factors, a strong magnetic field is applied during magnetization, resulting in heating of the magnetizing coil and magnetizer and useless energy loss. Summary of the invention

[0005] In order to solve the magnetic leakage problem during magnetization of a permanent magnet synchronous motor rotor, the present invention provides a multi-pole magnetization method for a permanent magnet synchronous motor rotor.

[0006] The present invention provides the following technical solution: a multi-pole magnetization method for a permanent magnet synchronous motor rotor:

[0007] Preparation of motor rotor: When the motor rotor is injection molded, the injection molding material in the gap between the outer cylindrical surface of the rotor chip and the outer cylindrical surface of the permanent magnet is eliminated;

[0008] Prepare a magnetizing fixture: a single magnetizing head is formed by a wire coil and magnetic silicon steel, and multiple magnetizing heads are movably connected to the magnetizing fixture body and distributed in a ring-shaped manner; a silicon steel disc made of silicon steel material is placed at the bottom of the magnetizing head to abut against and connect the magnetic silicon steel, forming a closed magnetic circuit between the magnetic silicon steels of the multiple magnetizing heads; a pushing mechanism is provided on the magnetizing fixture to connect the magnetizing heads, forming a movable connection of the magnetizing heads;

[0009] Magnetization: The motor rotor is placed in the magnetization fixture and fixed. The pushing mechanism pushes the magnetization head. The magnetic silicon steel head of the magnetization head enters the drop gap and contacts the outer cylindrical surface of the permanent magnet, forming a seamless closed magnetic circuit of magnetic silicon steel-permanent magnet-rotor chip-adjacent permanent magnet-adjacent magnetic silicon steel-silicon steel disc-magnetic silicon steel, and the magnetizer is started for magnetization.

[0010] Preferably, the magnetic silicon steel head of the magnetizing head is provided with a protrusion, and the protrusion enters the drop gap and contacts the outer circumferential surface of the permanent magnet.

[0011] Preferably, guide rails and guide grooves are provided between the silicon steel disc and the magnetic silicon steel of the magnetizing head to facilitate the movable displacement of the magnetizing head.

[0012] Preferably, the top of the magnetizing head is movably covered with a silicon steel cover plate which is in contact with the magnetic silicon steel. Guide rails and guide grooves are provided between the silicon steel cover plate and the magnetic silicon steel of the magnetizing head to facilitate the movable displacement of the magnetizing head. The silicon steel disc and the silicon steel cover plate constitute an upper and lower guide and limiting mechanism.

[0013] Preferably, the magnetic silicon steel comprises an arc-shaped plate, a winding plate, and a rear seat plate, and the winding plate is provided with a wire coil.

[0014] Preferably, the pushing mechanism provided on the magnetizing fixture is an electric push rod or a pneumatic push rod, and the movable end of the pushing mechanism is connected to the rear seat plate.

[0015] Preferably, when the motor rotor is injection molded, the method for eliminating the injection molding material in the gap between the outer cylindrical surface of the rotor chip and the outer cylindrical surface of the permanent magnet is to supplement the corresponding gap position on the injection mold so that the injection molding material cannot flow into the gap.

[0016] Preferably, the oblong hole in the rotor chip is extended outwardly, and the length of the oblong hole is 1 to 8 mm, so as to strengthen the fixation of the rotor components during injection molding.

[0017] The beneficial effect of the present invention is that the magnetizing head is fitted and abutted against the outer circumferential surface of the permanent magnet of the permanent magnet synchronous motor rotor, thereby eliminating the gap, so that the magnetic lines of force form a closed loop during magnetization, eliminating magnetic leakage, and reducing the heat generated during the magnetization process.

[0018] By adopting the technical solution of the present invention, the beneficial effects are further clarified as follows:

[0019] (1) When the number of turns of the charging coil, DC resistance, wire diameter and other parameters remain unchanged, the magnetizing current is reduced from the original 12.5KA to 4KA;

[0020] (2) Under continuous operation, the energy consumption and heat generation are reduced due to the reduction of charging current. Without using the cooling circulation system, the temperature rise does not exceed 60°C;

[0021] (3) As the magnetic leakage is greatly reduced, the magnetic conductive silicon steel is in direct contact with the permanent magnet, making the magnetic field distribution on the surface of the magnetized permanent magnet more uniform and consistent, and the magnetic field distribution state formed is closer to the sine distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the use of the magnetizing fixture of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the magnetizing fixture of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the magnetic charging head of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the rotor of the present invention;

[0026] Figure 5 is a schematic diagram of the structure of the rotor chip;

[0027] Figure 6 It is a schematic diagram of the connection structure between the rotor chip and the permanent magnet;

[0028] Figure 7 It is a schematic diagram of the structure of the relative height gap position of the raised part;

[0029] In the figure: a motor rotor 1, a rotor chip 11, a permanent magnet 12, a step gap 13, an oblong hole 111; a magnetizing fixture 2, a magnetizing head 21, a silicon steel disc 22, a pushing mechanism 23, a silicon steel cover disc 24, a wire coil 211, a magnetic silicon steel 212, a protrusion 213, an arc plate 2121, a winding plate 2122, and a rear seat plate 2123. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] The magnetic silicon steel in the existing magnetizing fixture is an annular integral part, and magnetizing poles extend from the ring. After the rotor is placed in the middle, the permanent magnet is magnetized. In order to facilitate the removal and placement of the motor rotor, there must be a gap between the front end of the magnetic silicon steel of the magnetizing pole and the outer cylindrical surface of the rotor. During the magnetization process of the magnetizing fixture, the N pole and the S pole are alternate, and the originally closed magnetic lines of force are affected by the gap between the magnetic silicon steel and the permanent magnet, forming leakage magnetic field.

[0032] In order to solve the above problems, the present invention newly sets up a magnetizing fixture 2, such as Figures 1 to 4 As shown. The original annular magnetic silicon steel is divided according to the number of magnetizing heads, and a separate magnetizing head 21 is formed for each wire coil 211 and magnetic silicon steel 212, which are distributed in an annular manner, and the number of magnetizing heads matches the number of rotor poles. The magnetic silicon steel 212 includes an arc plate 2121, a winding plate 2122, and a rear seat plate 2123, and the winding plate 2122 is provided with a wire coil 211. The arc plate 2121 corresponds to the rotor permanent magnet 12 that needs to be magnetized. Considering the circular shape of the rotor, the shape of the arc plate 2121 is set to an arc. The rear seat plate 2123 is movably connected to the magnetizing fixture body. A pushing mechanism 23 is provided on the magnetizing fixture to connect the magnetizing head, forming a movable connection of the magnetizing head. In this way, the magnetizing head on the magnetizing fixture can be displaced forward by the pushing mechanism to contact the outer cylindrical surface of the rotor, thereby eliminating the gap between the front end of the magnetic silicon steel and the outer cylindrical surface of the rotor. The pushing mechanism provided on the magnetizing fixture is an electric push rod or a pneumatic push rod, and the movable end of the pushing mechanism is connected to the rear seat plate.

[0033] Due to the movable setting of the magnetizing head, the connection between adjacent magnetizing heads is disconnected, and a complete closed magnetic circuit cannot be formed. For this purpose, a silicon steel disc 22 made of silicon steel material is placed at the bottom of the magnetizing head to contact and connect the magnetic silicon steel, forming a closed magnetic circuit between the magnetic silicon steels of multiple magnetizing heads. Taking into account the limit and guidance of the activity, guide rails and guide grooves are provided between the silicon steel disc and the magnetic silicon steel of the magnetizing head to facilitate the movable displacement of the magnetizing head. Specifically, a T-shaped guide rail or a straight guide rail can be provided on the magnetic silicon steel of the magnetizing head, and the number of guide rails is equal to the number of magnetizing heads. Furthermore, the magnetic silicon steel and the guide rail are integrated during manufacturing. The silicon steel disc is matched with a guide groove and the guide groove is distributed axially on the silicon steel disc.

[0034] In order to ensure the smooth movement of the magnetizing head, the design of the upper and lower two-layer guide and limit mechanism is considered, and the arrangement is as follows: the top of the magnetizing head is covered with a silicon steel cover plate 24 that contacts the magnetic silicon steel, and a guide rail and a guide groove are provided between the silicon steel cover plate and the magnetic silicon steel of the magnetizing head to facilitate the movement and displacement of the magnetizing head. The silicon steel disk and the silicon steel cover plate constitute the upper and lower two-layer guide and limit mechanism. However, because the upper layer needs to take and place the electronic rotor, there is a circular operating cavity in the middle of the silicon steel cover plate 24.

[0035] like Figures 5 and 6As shown, when the rotor chip and the permanent magnet are assembled in the prior art, a rectangular installation groove for installing the permanent magnet is opened on the rotor chip, and the permanent magnet is embedded in the rectangular installation groove of the rotor chip, and the outer edge of the rotor chip is integrally provided with strip-shaped raised edges located on both sides of the rectangular installation groove as limiting edges. Then after assembly, the outer cylindrical surface of the permanent magnet is slightly lower than the outer cylindrical surface of the rotor, forming a drop gap 13. The drop gap is generally filled with white engineering plastic after injection molding, and magnetization is directly performed across the injection molding material. This drop gap 13 forms the second gap in the present invention that hinders the closure of the magnetic circuit. Because of the injection molding material, the movable magnetizing head can only contact the injection molding material. In order to solve the above problem, when the motor rotor 1 is injection molded, the injection molding material in the drop gap 13 between the outer cylindrical surface of the rotor chip 11 and the outer cylindrical surface of the permanent magnet 12 is eliminated. This embodiment adopts: supplementing the corresponding drop gap position on the injection mold so that the injection molding material cannot flow into the drop gap, so that the drop gap 13 on the rotor is naturally vacant and not filled with engineering plastic during demoulding. Furthermore, the magnetic silicon steel head of the magnetizing head is provided with a protrusion 213, and the protrusion enters the drop gap and contacts the outer circumferential surface of the permanent magnet. Figure 7 shown.

[0036] Since the injection molding material outside the permanent magnet is missing, the oblong hole 111 in the rotor core is extended outward, and the length of the oblong hole is 1-8 mm to strengthen the fixation of the rotor components during injection molding. In this embodiment, 8 mm is used.

[0037] By improving the injection molding of the motor rotor and designing a new structure for the magnetizing fixture, the present invention provides a multi-pole magnetizing method for the rotor of a permanent magnet synchronous motor:

[0038] Preparation of motor rotor: On the basis of the existing preparation method, when the motor rotor 1 is injection molded, the injection molding material in the drop gap 13 between the outer cylindrical surface of the rotor chip 11 and the outer cylindrical surface of the permanent magnet 12 is eliminated, and the corresponding drop gap position on the injection mold is supplemented so that the injection molding material cannot flow into the drop gap. Then, when demolding, the drop gap 13 on the rotor is naturally vacant and is not filled with engineering plastic;

[0039] Prepare a magnetizing fixture 2: A wire coil 211 and a magnetic silicon steel 212 form a single magnetizing head 21, and multiple magnetizing heads are movably connected to the magnetizing fixture body and distributed in a ring-shaped interval; a silicon steel disc 22 made of silicon steel material is placed at the bottom of the magnetizing head to abut against and connect the magnetic silicon steel, forming a closed magnetic circuit between the magnetic silicon steels of the multiple magnetizing heads; a pushing mechanism 23 is provided on the magnetizing fixture to connect the magnetizing heads, forming a movable connection of the magnetizing heads;

[0040] Magnetization: The motor rotor is placed in the magnetization fixture and fixed. The pushing mechanism pushes the magnetization head. The magnetic silicon steel head of the magnetization head enters the drop gap and contacts the outer cylindrical surface of the permanent magnet, forming a seamless closed magnetic circuit of magnetic silicon steel-permanent magnet-rotor chip-adjacent permanent magnet-adjacent magnetic silicon steel-silicon steel disc-magnetic silicon steel, and the magnetizer is started for magnetization.

[0041] Taking barium strontium ferrite permanent magnet as an example, its remanence is about 1.2T. When both sides are magnetized magnetic silicon steel, a magnetizing magnetic field of 7.2T is sufficient. The prior art needs to reach more than 25T due to leakage magnetic field and air gap in the closed loop, but only 7.2T is sufficient through the technology of the present invention.

Claims

1. A multi-pole magnetization method for a permanent magnet synchronous motor rotor, characterized in that: Preparation of a motor rotor: when the motor rotor (1) is injection molded, the injection molding material in the gap (13) between the outer cylindrical surface of the rotor chip (11) and the outer cylindrical surface of the permanent magnet (12) is eliminated; Preparation of a magnetizing fixture (2): A wire coil (211) and a magnetic silicon steel (212) are used to form a single magnetizing head (21); a plurality of magnetizing heads are movably connected to a magnetizing fixture body and are distributed in a ring-shaped manner; a silicon steel disc (22) made of silicon steel is placed at the bottom of the magnetizing head to abut against and connect the magnetic silicon steel, thereby forming a closed magnetic circuit between the magnetic silicon steels of the plurality of magnetizing heads; a pushing mechanism (23) is provided on the magnetizing fixture to connect the magnetizing heads, thereby forming a movable connection of the magnetizing heads; Magnetization: The motor rotor is placed in the magnetization fixture and fixed. The pushing mechanism pushes the magnetization head. The magnetic silicon steel head of the magnetization head enters the drop gap and contacts the outer cylindrical surface of the permanent magnet, forming a seamless closed magnetic circuit of magnetic silicon steel-permanent magnet-rotor chip-adjacent permanent magnet-adjacent magnetic silicon steel-silicon steel disc-magnetic silicon steel, and the magnetizer is started for magnetization.

2. A multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 1, characterized in that: The magnetic silicon steel head of the magnetizing head is provided with a protrusion (213), and the protrusion enters the drop gap and contacts the outer circumferential surface of the permanent magnet.

3. The multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 1, characterized in that: A guide rail and a guide groove are arranged between the silicon steel disc and the magnetic silicon steel of the magnetizing head to facilitate the movable displacement of the magnetizing head.

4. A multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 3, characterized in that: The top of the magnetizing head is movably covered with a silicon steel cover plate (24) which abuts against the magnetic silicon steel. A guide rail and a guide groove are arranged between the silicon steel cover plate and the magnetic silicon steel of the magnetizing head to facilitate the movable displacement of the magnetizing head. The silicon steel disc and the silicon steel cover plate form an upper and lower guide limit mechanism.

5. A multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 4, characterized in that: The magnetic silicon steel comprises an arc-shaped plate (2121), a winding plate (2122), and a rear seat plate (2123), wherein a wire coil is provided on the winding plate.

6. A multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 5, characterized in that: The pushing mechanism provided on the magnetizing fixture is an electric push rod or a pneumatic push rod, and the movable end of the pushing mechanism is connected to the rear seat plate.

7. The multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 1, characterized in that: When the motor rotor is injection molded, the method for eliminating the injection material in the gap between the outer cylindrical surface of the rotor chip and the outer cylindrical surface of the permanent magnet is to supplement the corresponding gap position on the injection mold so that the injection material cannot flow into the gap.

8. A multi-pole magnetization method for a permanent magnet synchronous motor rotor according to claim 7, characterized in that: The oblong hole (111) in the rotor chip is extended outwardly, and the length of the oblong hole is 1 to 8 mm, so as to strengthen the fixation of the rotor components during injection molding.

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