KR20000054867A - BLDC motor - Google Patents

Abstract

PURPOSE: A brushless DC motor is provided to generate a high reluctance torque with changing a form of permanent magnet to be maximum of difference of reluctance in direction of d and q axis. CONSTITUTION: A brushless DC motor comprises a rotor(100) with a permanent magnet(120), a stator(100) with a amateur coil, and a position detection circuit. The rotor(100) is composed of a plurality of permanent magnet(120) having a pair of curvedly cutting portion extended to a predetermined angle for both sides of a body toward the external side of an iron core. The stator(200) is comprised of the amateur coil which interacts with a magnetic field produced by the permanent magnet(120) to form an electric field. The position detection circuit detects the position of the rotor and the stator in order to supply a conducting signal to the amateur coil.

Description

Brushless DC motor {BLDC motor}

The present invention relates to a direct current motor, more specifically a brushless direct current motor (BLDC Motor) having no brush.

In general, the brushless DC motor is widely used because it does not generate electrical and mechanical noise and has a long life since there is no mechanical contact between the commutator and the brush. Such a brushless direct current motor has a rotor with a plurality of permanent magnets for magnetic field formation, a stator and a rotor wound with an amateur coil that generates torque to rotate the rotor by interaction with the magnetic field by the permanent magnet of the rotor. It consists of a position detection circuit etc. which detect an electron position and apply an energization signal to an amateur coil.

A schematic structure of a general brushless DC motor having the above structure is shown in an exploded perspective view in FIG. 1, which will be briefly described as follows.

In the drawings, reference numeral 10 denotes a rotor and 20 denotes a stator.

As shown, the rotor 10 is composed of an iron core 12 and a plurality of permanent magnets (16).

The iron core 12 is formed by stacking a plurality of electrical steel sheets, a shaft hole 13 is formed in the center and a plurality of insertion holes 14 are formed around the shaft hole 13.

The permanent magnet 16 is inserted into the insertion hole 14 of the iron core 12, as shown in FIG. The permanent magnet 16 has a smooth arc shape and is arranged in a circle on the iron core 12.

The stator 20 has a plurality of half-opening slots 20a formed on the inner circumferential surface thereof for winding the armature coil.

In addition, although not shown, a general brushless DC motor is provided with a position detection circuit that detects the position of the rotor and applies an energization signal to the armature coil.

However, in the conventional brushless DC motor as described above, since the permanent magnet has a smooth arc shape and is disposed in a circular shape on the iron core, the magnetoresistance torque which contributes to the improvement of the efficiency of the motor in addition to the basic torque of the permanent magnet is increased. There was a disadvantage that the efficiency of the motor is low. That is, in FIG. 2, when the flux central axis of the permanent magnet 16 is the d-axis (magnet torque axis), and the axis having a phase of 90 ° electric angle (magnetic resistance torque axis) is the q-axis, Since the distance between the outer circumferential surface of the permanent magnet 16 and the inner circumferential surface of the stator 20 is the same in the d-axis and q-axis directions, no magnetoresistive torque is generated (Lq / Ld = 1, where Ld: d-axis inductance, Lq; q-axis inductance). Therefore, improvement of the motor efficiency by magnetoresistance torque cannot be expected.

In order to improve this disadvantage, an example of modifying the shape of the permanent magnet as shown in FIGS. 3A and 3B is known. In this case, the distance between the outer circumferential surface of the permanent magnet 16 and the inner circumferential surface of the stator 20 is different from each other in the d-axis and q-axis directions, so that a certain amount of magnetoresistive torque can be expected. There is a limit to improving the efficiency of the motor.

The present invention has been devised in view of the above, and the brushless DC motor aimed at improving the efficiency by changing the shape of the permanent magnet to the maximum magnetoresistance difference in the d-axis and q-axis directions to generate a large magnetoresistive torque. The purpose is to provide.

1 is an exploded perspective view schematically showing a general brushless DC motor.

FIG. 2 is an assembled plan view of the brushless DC motor shown in FIG. 1. FIG.

3A and 3B are plan views showing another example of a conventionally known brushless DC motor.

Figure 4 is an exploded perspective view showing a brushless DC motor according to an embodiment of the present invention.

5 is an assembled plan view of the brushless DC motor shown in FIG. 4.

FIG. 6 is a plan view of a main part of the magnetic flux concentration effect of the permanent magnet of the brushless DC motor shown in FIG. 5; FIG.

Explanation of symbols on the main parts of the drawings

100; Rotor 110; Iron core

120; Permanent magnet 122; Body of permanent magnet

124; Bend of the permanent magnet 200; Stator

A brushless direct current motor according to the present invention for achieving the above object is inserted into the iron core formed by stacking a plurality of thin steel plates and a plurality of insertion holes formed around the shaft hole of the iron core to form a magnetic field, A rotor consisting of a plurality of permanent magnets having a body portion disposed at right angles to the radial direction of the iron core and a pair of bent portions extending from both sides of the body portion at an angle toward the outside of the iron core; A stator having an amateur coil that forms an electric field that generates torque by interacting with a magnetic field by a permanent magnet; And a position detection circuit for detecting a position of the rotor and applying an energization signal to the amateur coil. Here, the angle formed by the bent portion of the permanent magnet is preferably 120 to 150 °, the number of the permanent magnet is preferably four.

According to this, since the distance between the outer surface of the permanent magnet and the inner circumferential surface of the stator in the d-axis (magnet torque axis) and q-axis (magnetic resistance torque axis) direction is different from each other, Magnetoresistance torque is largely generated. Therefore, a large magnetoresistive torque is generated in addition to the basic torque generated by the permanent magnet, thereby greatly improving the efficiency of the motor.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

4 is an exploded perspective view of a brushless DC motor according to an exemplary embodiment of the present invention, FIG. 5 is an assembled plan view of the motor shown in FIG. 4, and FIG. 6 is a magnetic flux concentration of a permanent magnet of the motor shown in FIG. 5. The main part plan which showed the effect.

In the drawings, reference numeral 100 is a rotor, 200 is a stator, 110 is an iron core, 120 is a permanent magnet.

As shown, the brushless DC motor according to an embodiment of the present invention, the magnetic field by the rotor 100, the permanent magnet 120 of the rotor 100 is mounted with a plurality of permanent magnets 120 Position detection circuit (not shown) which detects the position of the stator 200 and the rotor 100 in which the Amateur coil, which forms an electric field generating torque by the interaction of the coil, and applies an energization signal to the Amateur coil. The basic structure including the same as the configuration of the conventional brushless DC motor described above. The feature of the present invention is that the shape of the permanent magnet 120 of the rotor 100 is a shape that can generate a large magnetoresistance torque.

That is, as shown in Figures 4 and 5, the permanent magnet 120 is inserted into the plurality of insertion holes 112 formed around the shaft hole 111 of the iron core 110, respectively, the body portion 122 and It has a pair of bends 124. The body portion 122 is arranged at a right angle with respect to the radial direction of the iron core 110, the bent portion 124 extends at a predetermined angle toward the outside of the iron core 110 from both side ends of the body portion 122 It is. Here, the angle between the body portion 122 and the bent portion 124 is approximately 120 ° to 150 °, and preferably 135 °. In addition, the number of permanent magnets 120 is preferably four.

In the brushless DC motor according to the embodiment of the present invention, the magnetoresistive torque is largely generated, and thus the efficiency of the motor may be improved. The conventional motor shown in FIG. 2 has the same magnetoresistance as the distance between the outer circumferential surface of the permanent magnet 16 and the inner circumferential surface of the stator 20 in the magnet torque axis (d-axis) and magnetoresistance torque axis (q-axis) directions is the same. No torque is generated. However, the motor according to the exemplary embodiment of the present invention illustrated in FIG. 4 includes an outer circumferential surface of the permanent magnet 120 and an inner circumferential surface of the stator 200 in the magnet torque axis (d-axis) and magnetoresistive torque axis (q-axis) directions. Since the distance between them is different, the magnetoresistive torque is largely generated (Lq / Ld> 1). Therefore, compared with the conventional motor, since the torque generated by the magnetic resistance is generated in addition to the basic torque by the permanent magnet 120, the motor efficiency can be improved.

Table 1 shows experimental data comparing the efficiency of a brushless DC motor and a conventional brushless DC motor according to an embodiment of the present invention. For reference, the conventional permanent magnet shape compared to the motor of the present invention in Table 1 is the case shown in Figure 3b, the comparison data when the same winding specifications.

Conventional The present invention Revolutions talk electric current Voltage Output power Input power efficiency talk electric current Voltage Output power Input power efficiency 3502 16.570 5.401 100.46 595.95 706.40 84.364 16.519 5.129 94.84 594.09 685.20 86.703 3502 16.601 5.389 100.52 596.97 705.10 84.665 16.489 5.127 94.83 592.94 684.70 86.599 3502 16.591 5.393 100.57 596.59 705.80 84.527 16.530 5.128 94.85 594.47 684.80 86.809 3502 16.581 5.393 100.63 596.25 705.60 84.503 16.479 5.126 94.80 592.57 684.50 86.570 3502 16.560 5.395 100.65 595.49 705.80 84.371 16.499 5.131 84.85 593.33 684.20 86.592 3502 16.550 5.398 100.64 595.19 705.60 84.233 16.458 5.121 94.79 591.90 683.20 86.636 3502 16.601 5.390 100.65 596.98 705.00 84.678 16.468 5.123 94.79 592.23 684.00 86.583 5005 16.489 5.524 141.72 847.53 1027.40 82.493 16.591 5.258 134.36 852.68 1000.90 85.191 5005 16.519 5.525 141.75 849.10 1026.60 82.710 16.591 5.257 134.34 852.72 1000.70 85.212 5005 16.499 5.522 141.73 848.00 1027.20 82.555 16.601 5.258 134.35 852.71 1001.70 85.176 5005 16.499 5.525 141.78 848.04 1027.30 82.550 16.581 5.257 134.36 852.25 1000.50 85.182 5005 16.489 5.526 141.73 847.52 1027.20 82.508 16.621 5.262 134.39 852.29 1002.30 85.233 5005 16.519 5.531 141.81 849.10 1027.40 82.646 Motor Voltage 220.00 Gear Ratio 1: 3 Voltage Range 1 AC 240V Current Range 1 AC 30A Voltage Range 2 AC 470V Current Range 2 AC 30A Voltage Range 3 AC 470V Current Range 3 AC 30A

According to the above experimental data, the average efficiency of the conventional motor is 83.6%, the efficiency of the motor according to the present invention is 86.04%, it can be seen that the motor of the present invention is approximately 2.44% higher efficiency than the conventional.

As described above, the motor according to the present invention has a merit that the magnetoresistive torque is largely generated in addition to the basic torque caused by the permanent magnet, and thus the efficiency is improved.

In addition, in the present invention, the magnetic flux in the radial direction can be effectively concentrated on the stator 200 by magnetizing the permanent magnet 120 as shown in FIG. 6, and the thickness (t) of the bent portion 124 of the permanent magnet 120. By increasing this value, the motor efficiency can be improved by increasing the volume.

In the above, certain preferred embodiments of the present invention have been illustrated and described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. .

Claims (3)

A body portion arranged at right angles to the radial direction of the iron core and both sides of the body portion by inserting a plurality of thin steel sheets stacked in the core and a plurality of insertion holes formed around the shaft hole of the iron core to form a magnetic field. A rotor consisting of a plurality of permanent magnets having a pair of bent portions extending at an angle toward the outside of the iron core; A stator having an amateur coil that forms an electric field that generates torque by interaction with a magnetic field by the permanent magnet; And And a position detection circuit for detecting a position of the rotor and applying an energization signal to the armature coil. The brushless direct current motor according to claim 1, wherein the predetermined angle is 120 to 150 degrees. The brushless direct current motor according to claim 1, wherein the number of permanent magnets is four.