KR20020081622A - Brushless dc motor - Google Patents

Abstract

PURPOSE: A brushless DC(Direct Current) motor is provided to reduce a cogging torque and improve an initial starting performance by arraying an interval between a horizontal junction width and a vertical junction width, asymmetrically. CONSTITUTION: A brushless DC motor is formed with four separative C type permanent magnets(2), a rotator(5), a stator core(1), and a yoke(4). The C type permanent magnets(2) are loaded on the rotator(5). The stator core(1) is formed by combining 9 slots(6). A coil(3) is wound around the stator core(1). The C type permanent magnets(2) are covered by the yoke(4). A horizontal junction width and a vertical junction width of the separative C typed permanent magnet(2) is asymmetrically arrayed among the separative C type permanent magnets(2) and the slots(6) of the stator core(1) in order to reduce a cogging torque generated from a magnetic unbalance. The horizontal junction width and the vertical junction width are asymmetrically arrayed as much as 150 percents.

Description

Brushless DC Motor

The present invention provides a brushless DC motor having a C-type permanent magnet in which the permanent magnet is asymmetrically arranged in the yoke inner circumference so as to reduce magnetic inequality generated in the rotor permanent magnet and the slot opening of the stator core. direct current motor with C type permanent magnet).

More specifically, the present invention relates to a brushless DC motor which can reduce cogging torque due to a decrease in magnet density of the pores of the permanent magnet junction by asymmetrically arranging the lateral and longitudinal gaps of the permanent magnet. .

In general, the brushless DC motor has a long lifespan, and has the advantage that the electrical and mechanical noise does not occur according to the structure in which the commutator and the brush is removed, so as to the home appliances of various electrical and electronic products, as well as office equipment, automotive electronics It is widely used as a driving motor for the back. In other words, the brushless DC motor uses a permanent magnet having a high energy density, so the output is high, and thus it is widely used as a driving motor for electric and electronic products, office equipment, and automotive electronics.

1 is a schematic cross-sectional view of a brushless DC motor according to the prior art.

As shown, a brushless direct current motor having a C-type permanent magnet is provided with a rotor 5 and a stator core 1, and as the rotor 5 an inner circumferential surface of the yoke 4. The C-type permanent magnet (2) mounted in a substantially fan-shaped shape on the stator core (1) is configured to have two N-poles and S-poles or two S-poles and N-poles per piece to form 12 poles. Provides a space so that the rotor 5 is positioned while maintaining an air gap, and the coil 3 is provided so that electricity can be supplied to the insulated thin silicon steel sheet after being pressed. Winding.

Therefore, when a power supply voltage is applied to the coil 3 of the stator core 1, a magnetomotive force is formed, and in order to obtain proper interaction with the magnetic flux according to the pole change of the permanent magnet 2, the direction of each coil 3 current and The yoke 4 including the permanent magnet 2 used as the rotor 5 by the interaction between the magnetic field of the stator core 1 and the magnetic field of the permanent magnet 2, if the order is properly exchanged and applied. The rotation torque is generated in one direction to obtain the rotational force.

However, in the brushless DC motor of the prior art as described above, the magnetoresistance is not constant due to maintaining a constant distance between the pieces of the permanent magnet for manufacturing convenience, the magnetic accompanying energy by the permanent magnet during rotation The cogging torque generated while changing by rotation is pointed out as a big problem.

That is, the cogging torque generated by the slot 6 of the permanent magnet 2 and the stator core 1, as shown in the graph showing the cogging torque characteristics according to the conventional rotor rotation position shown in FIG. It can be confirmed that the maximum value of each cycle is uniformly represented as 220 (gcm).

Such cogging torque is a magnetic energy is changed according to the relative position between the stator core (1) and the rotor (5) has a problem that causes vibration and noise during the rotation of the DC motor.

Accordingly, an object of the present invention is to coke torque, which is a cause of noise and vibration generated in a brushless DC motor due to a decrease in the magnet density of the pores of the permanent magnet junction by asymmetrically arranging the lateral and longitudinal gaps of the permanent magnet. It is to provide a brushless DC motor to reduce the, and to improve the initial startability.

1 is a schematic cross-sectional view of a brushless DC motor according to the prior art,

2 is a schematic cross-sectional view of a brushless DC motor having an asymmetrical arrangement of a C-type permanent magnet according to the present invention;

3 is a graph showing the distribution of the radial magnetic flux density radial components according to the permanent magnet spacing,

Figure 4 is a graph showing the cogging torque characteristics according to the rotor rotation position of the brushless DC motor of the prior art,

5 is a graph showing the cogging torque characteristics according to the rotor rotation position of the brushless DC motor according to the present invention.

* Explanation of symbols used in the main part of the drawing *

One; Stator core

2; Permanent magnet

3; Coil

4; Rotor back-yoke

A; Transverse Permanent Magnet Spacing

B; Longitudinal permanent magnet spacing

The object of the present invention described above is a four-part permanent magnet, a rotor on which a C-type permanent magnet is mounted, a stator core formed by nine slot combinations, and a coil for applying current, and a permanent magnet. In brushless DC motors with a yoke, the longitudinal joining width of the permanent magnet and the transverse joining width of the permanent magnet are reduced to reduce cogging torque caused by magnetic unbalance between the permanent magnet and the stator core slot. It is achieved by providing a brushless direct current motor, characterized in that arranged asymmetrically.

According to a preferred embodiment, the longitudinal and transverse arrangements of the permanent magnets described above are arranged asymmetrically by 150% or more.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, which are intended to be described in detail to be easily carried out by those skilled in the art to which the present invention pertains, and thus the present invention It does not mean that the technical scope and spirit of the is limited.

2 is a schematic cross-sectional view of a brushless DC motor according to the present invention.

As shown, four divided permanent magnets (2), a rotor (5) on which the C-type permanent magnets (2) are mounted, and nine slots (6) are combined to form a current applying coil (3). ) Is applied to a brushless DC motor having a stator core (1) wound around and a yoke (4) surrounding the permanent magnet (2), which is applied substantially the same as that shown in FIG. The detailed description of the operation is omitted, and it is noted that duplicate reference numerals are the same.

Therefore, according to a preferred embodiment of the present invention, the above-described permanent magnet 2 and press-formed thin silicon, which are configured to have two N-poles and S-poles or two S-poles and N-poles per piece, to form 12 poles Longitudinal joining width of permanent magnets (2) and permanent magnets (2) to reduce cogging torque caused by magnetic unbalance between slots (6) of stator cores (1) laminated with multiple sheets of steel The transverse bond width of is arranged asymmetrically, but preferably the arrangement in the longitudinal direction and the transverse direction of the above-mentioned permanent magnet 2 is asymmetrically arranged at least 150%.

Figure 3 is a graph showing the distribution of the pore flux density radial component according to the permanent magnet spacing.

As shown, it can be seen that as the longitudinal and transverse spacing of the permanent magnets are arranged asymmetrically, the inclination of the magnetic flux density of the voids in the permanent magnet junction appears differently. That is, the middle band of the graph that generates the driving torque coincides with the arrangement of the permanent magnets, so the torque generated during actual rotation is the same.

However, the cogging torque generated by the slots of the stator core and the permanent magnets is reduced by decreasing the pore magnet density of the permanent magnet junction. In other words, when the longitudinal and transverse spacings of permanent magnets are fixed in an asymmetrical arrangement, the driving torque that must be obtained during actual rotation does not change, but the cogging torque that causes vibration and noise is reduced due to the reduction of the magnetic flux density of the gap between the permanent magnets. It can be reduced.

That is, as shown in the graph showing the cogging torque characteristic according to the rotational position of the rotor shown in Figure 5, when the arrangement of the permanent permanent magnet and the transverse permanent magnet 150% asymmetrical arrangement and the permanent magnet (2) and The maximum value of the cogging torque generated by the slot 6 of the stator core 1 is reduced to 200 (gcm) (illustrated by a line), and the arrangement of the longitudinal permanent magnets and the transverse permanent magnets is 190 When arranged in% asymmetry, the maximum value of the cogging torque was reduced to 180 (gcm) (shown by the b-line) to confirm that it appeared aperiodically.

As mentioned above, according to a preferable embodiment, it has the following advantages.

By asymmetrically arranging the transverse and longitudinal spacings of the permanent magnets, the cogging torque is reduced due to the decrease in the magnet density of the pores of the permanent magnet joints, thereby reducing the vibration caused by the torque ripple generated when the DC motor is actually driven. This reduces the noise and vibration of the DC motor and improves the starting performance.

Claims (2)

Brushless direct current with four split permanent magnets, a rotor on which the C permanent magnets are mounted, a stator core formed by nine slot combinations and a coil for applying current, and a yoke surrounding the permanent magnets. In the motor: Characterized in that the longitudinal joining width of the permanent magnet and the transverse joining width of the permanent magnet are asymmetrically arranged so as to reduce cogging torque caused by magnetic unbalance between the permanent magnet and the slot of the stator core. Brushless DC motor. The brushless DC motor according to claim 1, wherein the longitudinal and transverse directions of the permanent magnet are arranged asymmetrically by 150% or more.