JPS6154859A - Brushless motor - Google Patents

Abstract

PURPOSE:To enable to switch armature currents of 2 phases by a Hall element by supplying a current to either one of windings wound on two sets of N-, S- poles of a stator by a current switching circuit controlled by the Hall element. CONSTITUTION:A salient pole type stator 3 is secured to the periphery of a cylindrical support fixed to a body casing, and armature windings 6 of two phases are respectively wound on poles 4a, 4b, 5a, 5b. A current to the windings 6 is controlled through a current switching circuit by the output of a Hall element 11. Ones 5a, 5b of the adjacent poles of the stator 3 are displaced by 20-40 deg. of an electric angle from the equal interval position toward the rotating direction, and the pole width is formed to be 30-60% of the width of the other pole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a two-phase brushless motor that uses a Hall element for position detection.

[Background Art] In recent years, a two-phase brushless DC motor using a Hall element as shown in FIG. 5 has been developed as a fan motor that can be used with battery power and has a long life without brush wear. This type of motor rotates a permanent magnet rotor on the outside or inside of a salient pole type stator with a two-phase armature winding, but it has a torque dead center unique to two-phase DC motors. In order to eliminate this, a cylindrical permanent magnet 12 consisting of a 4-pole part and an 8-pole part is used as a rotor, and
A commutative pole 14 without a winding is provided in the middle of the main pole 13 with a winding on the stator to generate an auxiliary torque having a period of 172 of the fundamental wave, and as shown in FIG. By configuring the motor so that the auxiliary torque T2 takes a maximum value of plus l1llI (rotation direction side) at the phase switching point of the fundamental wave T (θ=π, 2π), a self-starting characteristic is provided. However, this method has the problem that the structure of the permanent magnet rotor is complicated, making it difficult to magnetize it, and the strength of the magnetic poles in the 8-pole portion tends to deteriorate.Additionally, the stator has the same number of complementary poles as the main poles. This poses a problem in that it is difficult to make it smaller and lighter.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide the same self-starting function as the above-mentioned conventional example, and to improve the structure of the stator and permanent magnet rotor. The purpose of the present invention is to provide a two-phase brushless smoker which is extremely simple and suitable for small electric heaters.

[Disclosure of the Invention] The brushless morph of the present invention has a permanent magnet rotor with four poles magnetized alternately and at regular intervals, and a winding current direction is fixed and two adjacent magnetic poles have the same polarity. A stator, a Hall element attached to the stator that detects the polarity of the rotor magnetic poles passing through, and a current flowing through one of the windings controlled by the Hall element and wound around the two sets of NS poles of the stator. and a current switching circuit that supplies a
It is characterized by a degree (electrical angle) deviation and a magnetic pole width of 30 to 60% of Ikegata's magnetic pole.
DenisogoIn a state of zero current, the self-starting characteristic is obtained by utilizing the torque generated between the permanent magnet rotor and the salient stator magnetic poles and shifting this torque curve in the direction of rotation. This is what I did.

1 to 4 show an embodiment of the brushless motor of the present invention. In FIGS. 1(a) and (1), a four-pole salient pole type stator 3 made of a laminated iron core is fixed around a cylindrical support 2 fixed to a main body casing 1, and each magnetic pole 4a4b and 5a5b are provided with a two-phase electric current (paper-mache winding 6).The cylindrical support body 2 holds a rotating shaft 8 via a bearing 7 inside, and this rotating shaft 8
A rotor is constituted by a cup-shaped yoke 9 fixed to one end of the yoke and a cylindrical permanent magnet 10 fixed to the inner circumferential surface of the cup-shaped yoke 9. As shown in FIG.
On the other hand, the stator is composed of wide magnetic poles 4a and 4b having a large magnetic pole width D1 and narrow magnetic poles 5a and 5b having a magnetic pole width D2 of about 172 mm of the wide magnetic pole. The narrow magnetic poles 5a and 5b are offset by 20 to 40 electrical degrees in the rotational direction from the equally spaced positions. Further, a Hall element 11 for detecting the polarity of the passing rotor magnetic pole is located at a location 90 degrees away in electrical angle from the center position of one of the two wide magnetic poles 4a in the rotational direction.
The output of this Hall element 11 controls the two transistors Q1 and Q2 of the current switching circuit shown in FIG. Current is alternately supplied to the windings L1 and L2. The Hall element 11 detects one polarity (in this embodiment, the N pole) and outputs a signal to turn on the transistor Q, thereby turning on the transistor Q1%Q2.
As a result, current flows through the winding L1 and no current flows through L2, so that only the magnetic poles 4a and 5a, which are wound in the winding in figure (b), are turned off. The magnetic poles 4b and 51 which are energized and are wound with the winding L2 are not energized. In this way, any two of the four stator magnetic poles are always magnetized. Next, the operation of the brushless morph of the present invention will be explained using diagram t52. The figure (,) shows a state in which no current flows through the windings L1 and L2, and the narrow magnetic poles 5a and 5b are opposed to the substantially central part of the N or S pole of the rotor. In other words, the magnetic flux at this time is only generated from the permanent magnet, and the induced magnetic charge can move freely in the wide magnetic pole 4a4b, but there is not much freedom in the narrow magnetic pole 5aSb, so this positional relationship The rotor is stopped. Next, when an Isoko current is applied to the winding, the center of magnetization of the wide magnetic pole 4a moves almost to the center of the magnetic pole, as shown in figure (b), and the rotor therefore exerts a repulsive force in the direction of the arrow. receive. If you start the motor with the N pole of the rotor facing pole 4a (N pole) of the stator and the S pole of the rotor facing pole 5a (S pole) of the stator as shown in the same figure, the hall Element 11
detects the N pole of the rotor, so transistor Q1
turns on, current flows through winding L1, the rotor rotates forward (clockwise), passes the position shown in (c), and is further attracted in the clockwise rotation direction to reach the position shown in (d). However, from figure (c), when moving to the state of (, l) [lD, the Hall element detects the S pole of the rotor and winds, and the current is switched from L2 to L2, so the process is repeated in the same way as above. It can continue to rotate.

FIG. 3 shows the operation of the brushless motor of the present invention. In the figure, the torque curve T1, which is caused only by the interaction between the magnetic flux generated by the armature current and the rotor, has an upper half waveform in which the fundamental wave is switched every half cycle. The auxiliary torque curve T2 due to the interaction between the permanent magnet and the stator salient magnetic poles in the state of zero armature current is 1/2 of the fundamental wave T.
The point θ1θ2, which cuts the coordinate axis from positive to negative, is the stable stopping point. If the magnetic poles of the stator were provided at equal intervals, this stable stopping point would coincide with the zero point of the fundamental wave T1, but by deflecting the narrow magnetic poles 5a5b, the auxiliary torque curve T2 can be rotated in the forward direction. shift in the direction,
The stable stopping point θ1θ2 is the fundamental wave T.

It is located slightly to the right of the zero point of
The resultant torque curves T and +T2 are always positive and have no dead center. In this way, at startup, that is, when the armature current is zero, the rotor stops at a position slightly rotated in the forward rotation direction, as shown in Figure 2(a), because the magnetic poles 5a and 5b are biased. This effect is due to the fact that the magnetic pole width is small. There are two possible positions of the rotor at startup, as shown in Figure 2(a) and Figure 4(a).In the case of Figure 4(a), the Hall element is in the position of the rotor at startup. Since the S pole of is detected, current flows only through winding L2, and pole 4b (S pole) and pole 5b (N pole) are excited, and the rotor also rotates forward to the state shown in the same figure (b). It will move on.

[Effect of the invention 1 As described above, the brushless motor according to the present invention is configured such that the current direction of the stator winding is fixed so that two adjacent magnetic poles have the same polarity, and is controlled by a Hall element. Since the current switching circuit supplies current to either one of the windings wound around the two sets of NS poles of the stator, the circuit that switches the two-phase armature current with one Hall element is extremely simple. It is easy to configure, and one of the adjacent magnetic poles of the stator is offset by 20 to 40 degrees (electrical angle) from the equally spaced position toward the rotation direction, and the width of the magnetic pole is 30 to 40 degrees (electrical angle) from the other magnetic pole.
60%, there is no need to provide a commutating pole on the stator or configure the permanent magnet with 4 poles and 8 poles as in the past, and the advantage is that a lightweight brushless motor with a simple structure can be realized. be.

[Brief Description of the Drawings] Fig. 1 shows an embodiment of the brushless motor of the present invention, in which (a) is a longitudinal cross-sectional view, (b) is a cross-sectional view of main parts, and (c) is a longitudinal cross-sectional view.
) is a circuit diagram, Fig. 2(,)(b)(c)(d) is a cross-sectional view of the main part showing the operation of the same as above, Fig. 3 is an operation characteristic diagram of the same as above, Fig. 4(,)(b) 5 is a sectional view of a main part for supplementary explanation of the same operation as above, and FIG. 5 shows a conventional example, in which (a) is a schematic perspective view of a rotor, and (b) is a schematic plan view of a stator. 1 is the main body casing, 2 is the cylindrical support, 3 is the salient pole type stator, 4a4b is the wide magnetic pole, 5a5t+ is the narrow magnetic pole.
6 is an electron winding, 7 is a bearing, 8 is a rotating shaft, 9 is a cup-shaped yoke, 10 is a permanent magnet, and 11 is a Hall element.

Claims (1)

[Claims] (1) NS: A permanent magnet rotor with four poles that are magnetized alternately and at equal intervals, a stator in which the current direction of the windings is fixed and two adjacent magnetic poles have the same polarity, and a rotor that is attached to the stator and passes through. a Hall element that detects the polarity of the rotor magnetic poles, and a current switching circuit that is controlled by the Hall element and supplies current to either one of the windings wound around the two sets of NS poles of the stator, A brushless brushless device characterized in that one of the adjacent magnetic poles of the stator is offset by 20 to 40 degrees (electrical angle) in the rotational direction from the equally spaced position, and the width of the magnetic pole is 30 to 60% of the other magnetic pole. motor.