JPS6258892A - Brushless motor and control method thereof - Google Patents

Abstract

PURPOSE:To improve the efficiency of a motor by obstructing the conduction of field currents to a stator coil at the time of low torque conversion efficiency. CONSTITUTION:Two stator coils 16 are connected in series, circuits through transistors as armature current control elements 25 are fitted in parallel, and output terminals for a Hall IC 22 as a magnetoelectric device 21 are connected to bases in each control transistor. When base bias resistors 26 for the control transistors are determined properly and an output from the Hall IC 22 takes voltage such as 3V and the control transistors are conducted, the control transistors are conducted with the exception of predetermined angles before and behind the dead center of torque, and armature currents can be changed into pulsating currents, thus reducing the power consumption of a motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a brushless DC motor that is electronically rectified by a switching circuit using a Hall IC or the like.

[Prior Art] Today, brushless motors that do not generate electrical noise are often used in OAi devices such as personal computers, and small brushless flat motors are used as drive units for thin fans and the like.

As an example of such a small brushless motor, the first
Examples include motors as shown in FIGS. 3 and 14. 1st
3 and 14, the motor 10 has a flat rotor yoke 12, and magnets 15 in which different magnetic poles are sequentially arranged adjacent to each other in the circumferential direction are attached to the lower surface of the rotor yoke 12. The magnet 15 is rotatable by a motor shaft 19. Note that these magnets 15 and rotor yoke 12 constitute the rotor 11. Furthermore, a stator coil 16 is provided facing the magnet 15 of the rotor 11, and one Hall element 23 is arranged to detect the magnetic pole of the magnet 15 of the rotor 11.
Current control is performed to 6.

By the way, in the torque characteristics of a three-phase machine in which three stator coils 16 are provided at 120° intervals, rotational torque can always be generated as shown in FIG. 15, but as the number of stator coils 16 increases, Control of the armature current using a plurality of magnetoelectric conversion elements such as the Hall element 23 becomes relatively complicated.

Furthermore, in a two-phase machine with two or four stator coils 16, the mechanical structure of the motor 10, the number of magnetoelectric transducers used, and the armature current can be easily controlled, but the torque characteristics shown in FIG. As shown, a torque dead center occurs where no rotational torque is generated, and depending on the stopping position of the rotor yoke 12, it may not be possible to start the rotor yoke.

However, various improvements have been made in the two-phase machine of the brushless motor IO, such as adding distortion to the magnetic field generated by the permanent magnet 15 provided on the rotor yoke 12, and stopping the magnet 15 of the rotor 11 using the auxiliary magnet 29. Improvements have been made in which the magnet 15 of the rotor 11 is always stopped at a position away from the torque dead center using other attached parts.
The range of use of two-phase converters is expanding.

[M points to be solved by the invention] 2 of the brushless motor using Hall elements etc. as mentioned above.
The phase machine has a relatively simple structure, and although its starting torque has been improved and it is becoming more widely used, it has the disadvantage that the efficiency of the motor with respect to power consumption during operation is low.

The present invention is a method of increasing the motor efficiency of such a brushless motor, and a motor that allows the method to be easily implemented.

[Means for Solving the Problem] The present invention includes a rotatable rotor in which magnets with different magnetic poles are sequentially arranged adjacent to each other in the circumferential direction, and a plurality of magnets arranged in the circumferential direction to face the rotor. A method for controlling a brushless motor, characterized in that, in a brushless motor consisting of a stator and a stator comprising a stator coil, the stator coil is not energized with M and a machine current during periods of poor torque conversion efficiency, The configuration of a brushless motor that can easily implement this method includes a rotatable rotor in which magnets with different magnetic poles are sequentially arranged adjacent to each other in the circumferential direction, and magnets arranged in the circumferential direction opposite to this rotor. In a brushless motor consisting of a stator made up of multiple stator coils, a part of the magnetized part of the rotor magnet is detected by a magnetoelectric conversion element provided on the stator side to detect the position of the rotor. This brushless motor is characterized in that it has a structure in which the armature current control element is not made conductive when the non-magnetized portion is detected by removing the magnetized portion.

[Function] As described above, the present invention is applicable to periods when torque conversion efficiency is poor ([circle]), i.e., when armature current is applied to the stator coil, no rotational torque is generated, or only a small rotational torque is generated. This is a control method for brushless motors that can reduce motor power consumption and increase motor efficiency by not allowing armature current to pass through the motor. This is a brushless motor in which the timing at which a magnetoelectric conversion element such as an element detects the N pole or S pole of the rotor magnet is shifted, so that when the torque conversion efficiency is poor, the 1st armature current is not easily conducted.

[Example] As an example of the present invention, a four-pole two-phase Hall motor using a linear Hall IC will first be described.

In this embodiment, as shown in FIG.
Four stator coils 1B are arranged at 90° intervals on the stator yoke 17-L, which is magnetized into four poles with a pole and an S pole, and are opposed to the magnets 15 of the rotor 11. These stator coil 16 and stator yoke 17 constitute a stator 18. Then, a Hall IC 22 is provided as a magnetoelectric transducer 21 at a mechanically intermediate position of the stator coil 16, and in a part of the magnet 15 of the rotor 11 detected by the magnetoelectric transducer 21, an N pole and an S pole are connected. The magnetized portion is removed so as to provide a notch 13 of an appropriate width having a required angle α in front and behind the boundary line 30.

The angle α of this notch 13 is preferably determined as follows.

That is, as shown in FIG. 1, passing through the center of the stator 18,
A straight line 31 in the radial direction passing through an intermediate position between two adjacent coils 16 (Fig. 1 shows a state in which the position of the boundary line 30 where different poles of the magnets 15 touch coincides with the position of this straight line 31. ) and a straight line 32 in the radial direction that passes through the center of the stator 18 and touches the outermost side of the coil 16 located on both sides of the straight line 31 is defined as β, then the angle α is equal to the angle β. Alternatively, it is preferable to make the angle α a required amount larger than the angle β, as in the position of the straight line 33 shown in the figure.The upper limit value of this angle α is determined according to the torque characteristics of the motor 10 when the notch 13 is not provided. It is preferable to set the torque at an appropriate position within a range where the torque is smaller than the maximum torque.

The reason for determining this is that when the boundary line 3° of the magnet 15 is located within the range of the angle β, the magnet 15 is attached to the coil IB.
Since both the N and S poles do not straddle, no torque is generated, and even if the stator coil 16 is energized within this range, the motor 10 does not perform any work, so it is useless. That is, the angle β
The range indicated by is the torque dead center. Note that this angle β is normally designed to be extremely small.

In FIG. 1, when the angle formed by the two radial straight lines 34 and 35 passing through the center of the stator 18 and touching the inner peripheral edge of the coil 16 is γ, the torque is
When the boundary line 30 of No. 5 is located within the range of this angle γ, the angle becomes maximum. Then, as the magnet 15 rotates, the boundary line 3o of the magnet 15 gradually becomes smaller as it passes the straight line 35 on the side that lags behind the rotation direction, and when it reaches the straight line 32, the torque becomes O. (zero).Of course, on the contrary, when the boundary line 30 of the magnet 15 is rotating close to the straight line 34 on the preceding side with respect to the rotation direction, the generated torque gradually increases, When it reaches straight line 34, it becomes maximum. Therefore, even in the range where the torque is decreasing or increasing, it is desirable to cut out the range where the angle of occurrence approaches zero.

The electric circuit of the magnetoelectric conversion element 21 and the stator coil 16 consists of two stator coils 16 connected in series as shown in FIG. Delimiter coils 1 facing each other at 180° intervals in the figure
It is 6. ), furthermore, a circuit is provided in parallel via a transistor which is the armature current control element 25, and the magnetoelectric conversion element 21
The output terminal of the Hall IC 22 is connected to the base of each control transistor.

This Hall IC 22 includes a Hall element 23 and an appropriate amplifying section 2.
As shown in FIG. 3, the linear Hall IC 22 has a symmetrical output characteristic in which two output voltages intersect when the magnetic flux density to the magnetic detection section is zero.

When the magnetic pole of the magnet 15 of the rotor 11 having the notch 13 at the magnetic pole boundary as described above is detected using the Hall IC 22 having such characteristics, the magnetic flux that crosses the Hall IC 22 when the notch 13 is located at the Hall IC 22 position is generated. becomes zero, and the point at which the re-output voltages match becomes longer in the output of the Hall IC 22, as shown in FIG. 4, depending on the length of the notch 13 of the rotor. Therefore, by appropriately setting the base bias resistance 26 of the control transistor in such a state, for example, the hole I
If the control transistor is set to conduct when the output of C22 is 3V, the control transistor will be conductive except for a predetermined angle α before and after the torque dead center, and the armature current can be made into a pulsating flow as shown in Fig. 5. can. The non-conducting portion of the armature current is near the torque dead center in the torque characteristics shown in FIG. 16, and when the armature current is non-conducting, it is synchronized with the torque dead center. As shown in FIG. 6, the output characteristics of the motor 10 are such that, although the width of the torque dead center is slightly wider and the output is slightly lower, the power consumption of the motor 10 is significantly reduced, and the efficiency of the motor 10 can be increased.

In addition, by providing an auxiliary magnet 29 at a position of the motor case at 180 degrees from the magnetoelectric conversion element 21, for example, the stopping position of the magnet 15 of the rotor 11 is removed from the torque dead center, so that starting torque can always be generated. Needless to say, this has been the case.

Also, the above embodiment is a rotor! A notch 13 is provided around the magnet 15 of 1, but since the notch 13 is used to create a rotational position of the rotor where the Hall IC 22 does not detect magnetism, the notch 13 is replaced with the one shown in FIG. Similarly, there are cases where the magnets 15 of the rotor 11 are not magnetized to remove the magnetization, thereby forming the non-magnetized portion 14.

Further, as the magnetoelectric conversion element 21, the Hall IC 2 in the above embodiment is used.
2 was used to set the base bias of the control transistor, but a relatively simple method that sequentially increases the output voltage according to the Hall resistance or the direction of the magnetic field and magnetic flux density as shown in FIG. When the Hall element 23 is used, it may be sufficient to insert a control resistor 27 as shown in FIG. 9 in some cases.

Furthermore, the magnets 15 of the rotor 11 may be magnetized with six poles for each BO3 as shown in Fig. 1O, or may be a multi-pole machine with six or more poles to reduce vibrations caused by rotational torque.
The stator coil for the magnet 15 of this six-pole magnetized rotor 11! 6 may be provided at 600 intervals, or two stator coils IB may be used as image coils at two locations, or two stator coils 1B may be used with four locations as image coils.

Although the shape of the rotor 11 in the above embodiment was a disk shape, it may also be a cylindrical rotor with an inner rotor shape as shown in FIG. 11 or an outer rotor shape as shown in FIG. 12. Needless to say, there is nothing to gain.

Furthermore, the transistor that serves as the current control element 25 for the current seed 'f1 is not limited to a normal transistor, and an element such as an FET may also be used.

[Effects of the Invention] As described above, the present invention is a brushless motor control method that does not allow armature current to conduct during periods when torque conversion efficiency is poor. This is a method that can easily increase the efficiency by reducing the power consumption of the motor, and also because it is a brushless motor that has a non-magnetized part formed in a part of the rotor and has a period when no magnetic flux is applied to the magnetoelectric conversion element. Therefore, it is possible to easily make the "N" and "A" current open current control elements pass in synchronization with the torque dead center, and it is possible to provide a brushless motor that is easy to manufacture and has high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts showing the rotor, circumferential stator coil, magnetoelectric conversion element, etc. of the brushless motor according to the present invention, FIG. 2 is a diagram showing an example of the electric circuit of the brushless motor according to the present invention, and FIG. is a diagram showing the output characteristics of the Hall IC, Figure 4 is a diagram showing the Hall IC output when used in the present invention, and Figures 5 and 6 are diagrams showing the armature current and rotational torque, respectively. 7 and 10 to 12 are diagrams showing the rotor of other embodiments, FIG. 8 is a diagram showing the output characteristics of the Hall element, and FIG. 9 is a diagram showing the electric circuit of another embodiment. FIG. 13 is a sectional view of a conventional general Ptesires M motor, and FIG. 14 is a plan view of its rotor.
Figures 15 and 16 show general three-phase machines and ? It is a figure which shows each torque characteristic of a cardinal. 10=brushless motor, 11=rotor, 12=
Rotor yoke, 13=notch, 14=non-magnetized portion, 15=magnet, 16=stator coil, 17=stator yoke, 18=stator, ! 9=motor shaft, 21=magnetoelectric conversion element,
25=armature current control element, 26=bias resistance, 27=control resistance, 29=auxiliary magnet. Sai 3 Illustration 4 Illustration 5 Illustration Su vM Chutai f Sai U Illustration 12 Illustration 2 〒-l-2 0To υ O L5 Illustration O [G Figure Procedure Amendment Book October 16, 1980

Claims (2)

[Claims] (1) A rotatable rotor made up of magnets with different magnetic poles arranged adjacently in sequence in the circumferential direction, and a stator made up of a plurality of stator coils arranged circumferentially facing the rotor. A control method for a brushless motor, characterized in that a field current is not applied to a stator coil during periods when torque conversion efficiency is poor. (2) A rotatable rotor made up of magnets with different magnetic poles arranged adjacently in sequence in the circumferential direction, and a stator made up of a plurality of stator coils arranged circumferentially facing the rotor. In the brushless motor configured, a part of the magnetized part of the rotor magnet, which is detected by the magnetoelectric conversion element provided on the stator side in order to detect the rotor position, is removed to make it a non-magnetized part, and A brushless motor characterized by having a structure in which a field current control element does not conduct when a non-magnetized portion is detected.