JPS62181689A - Brushless motor - Google Patents

Abstract

PURPOSE:To obtain a stepping function and a positioning function by simple constitution by phase-advancing a positional signal from a noncontact sensor built into a motor and energizing a coil by the phase-advanced positional signal. CONSTITUTION:The three-phase positional signal outputs of a noncontact sensor 26 consisting of a magnetoresistance element incorporated to a motor are each transmitted over a phase-advancing circuit 31 and an FV conversion circuit 36 through positional-signal amplifiers 30a-30c. A three-phase sinusoidal type drive circuit 32 flows currents proportional to positional signals phase-advanced in response to the quantity of the command of phase-advancing through coils 25a-25c for the three-phase motor. An adder 37 adds outputs from the FV conversion circuit 36, an electronic switch circuit 33 and a differentiating circuit 35, and outputs the phase-advancing command signal of a phase advancer 31.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to a device capable of positioning operation and high speed rotation. !
: This is related to a brushless motor that moves.

iiC future technology (tr?) Recent semiconductor technology 1: Due to the development of i and digital technology, the digitization of all industrial equipment is progressing, and the adoption of microcomputers is being promoted.Digital is the driving source for these equipment. A motor that can perform positioning operations is suitable, and conventionally, stepping motors have been used.

A conventional stepping motor will be described below with reference to the drawings. FIG. 14 shows a principle diagram of a conventional permanent permanent magnet (P~1) type stepping motor, where 141 is a stator, 142 is a rotor made of magnets, and 143 is a coil.

If the coils are excited from the outside in a sequential order, the rotor will advance by changing the position 1n depending on the state of energization of the coils.

Figure 15 shows the stepping motor shown in Figure 14.
It shows the torque distribution, and it can be seen that the position holding characteristic is achieved and the rotation speed is synchronized with the external signal. However, stepping motors are not suitable for high-speed rotation because the current rises late at high speeds due to the time constant of the coil and iron loss, and torque is not generated in a timely manner.

In particular, when the magnetic pole pitch was made finer in order to increase the position resolution, the switching frequency per revolution increased, which had a significant effect.

In order to overcome the above-mentioned drawbacks of stepping motors, an external encoder is attached to switch the energized phase faster depending on the speed of the motor to compensate for the delay in the rise of the current. However, this method has the disadvantage that the encoder is attached to the outside of the motor, which increases the size of the motor, and that the encoder is expensive.

Furthermore, stepping motors generally have the disadvantage that when stopping for positioning, they vibrate and stop around the stopping point as shown in FIG. 16, and it takes time to determine the position. In order to reduce this vibration and shorten the time required to determine the position, it is necessary to provide mechanical viscous resistance (mechanical damping) to the rotor, which has the disadvantage of complicating the structure. .

Next, we will explain the conventional Noriichi-Bomo Yu. 17th
The figure shows the servo motor positioning system m1), so
+7] is the motor, 172 is the encoder, 173 is I (4
Difference) 1 counter is a control circuit, and 174 is a drive circuit.

In the above-described position control system, it is possible to operate at high speed according to digital position commands, and it is also possible to obtain position control characteristics.It is also possible to add electrical damping. Done and stopped t) Not vibratory.

However, the disadvantages are that the encoder is expensive and the circuit size of the control system is large and expensive.

Problems to be Solved by the Invention As mentioned above, stepping motors have the disadvantage of not being able to rotate at high speeds and taking a long time to determine the position, and if a stepping motor is equipped with an encoder, the size is large and the encoder is expensive. It has the disadvantage of being.

Additionally, servo motors have the disadvantage that the control system and encoder are expensive.

In view of the above problems, the present invention provides a brushless motor with a positioning function and high-speed rotation, which has the same shape as a conventional stepping motor and a relatively simple circuit configuration.
[Ie to do it).

Means for Solving the Problems In order to solve the above problems, the brushless motor of the present invention has: (1) a rotor made of a magnetic material or magnet;
a stator that includes at least a stator core and a plurality of coils that face the rotor through a gap; (3) a bearing device that rotatably supports the rotor; and (4) a bearing device that is attached to the stator and that supports the rotor. (5) a non-contact sensor that detects a change in the position of the motor, converts it into an electrical signal, and outputs a substantially sinusoidal position signal with mutually different phases; and (5) a speed detection means that converts the change in the position signal into a speed signal. (6) electronic switch means that receives a step command signal from the outside and sequentially selects the multi-phase position signals according to the number of step command signals; and (7) outputs the amount of change in the selected position signal. Differentiating means; (8) Phase advancing means for advancing the phase of the position signal as a phase advancer using an added value of the speed signal, the selected position signal, a change in the position signal, and an external command amount. (9) A plurality of coils are driven by the phase-advanced position signal and a sinusoidal wave type drive circuit.

Operation According to the above-described structure, the present invention phase-excites the position signal 11q obtained by the non-contact sensor incorporated in the motor by the position signal itself selected by the electronic switch means.
f By advancing the phase of the Ft multiplication signal and energizing the coil by the position signal that is flattened to -, the stepping function and the position 1 are activated.
A brushless motor with two functions has been obtained. Furthermore, by adding the speed signal to the phase advance command;
According to the speed, the overall phase advance amount of the position signal is increased to reduce the delay in the rise of the current by h, making it possible to perform high-speed operation. Further, by adding the change in the phase advance command position signal to the phase advance amount as a damping signal, vibrations at the time of stopping are suppressed and the time until the position is determined is shortened. By adding the external signal to the advance amount, the stop position can be moved in accordance with the external signal.

Embodiments Hereinafter, brushless motors according to embodiments of the present invention will be described with reference to the drawings.

1 shows the mechanism of a brushless motor according to a first embodiment of the present invention, (a) is a perspective view of the main part, (b)
) is a cross-sectional view.

In Fig. 1, 1 is a rotor with magnetic pole teeth on its circumferential surface, 2 is a stator core with magnetic pole teeth on the surface facing the rotor, 3 is a magnet, and 4 is a joint constituting a magnetic circuit. Iron, 5 is 3 phase 1
The two coils 6 are non-contact sensors that output substantially sinusoidal signals with a phase shift of 120°.

FIG. 2 is a block diagram of the electric circuit section of the brushless motor of the first embodiment. In FIG. 2, reference numeral 20 denotes a mechanism section of the aforementioned motor, 21 a rotor, and 25a.

25b and 25c are three-phase coils, and 26 is a non-contact sensor made of a magnetoresistive scale. 30a, 30b.

:30c is a position signal amplifier that increases the three-phase position signal output of each of the non-contact sensors. 31 is a phase advance command (3t depending on the product); 32 is a phase advance circuit that advances or delays the phase of the position signal in 1; 32 is a phase advance command (3t depending on the product); It is a three-phase sine wave type drive circuit. 34a.

34b and 34c are amplifiers that invert the three-phase position signals. 33 is an electronic switch circuit that receives a step command signal from the outside, selects one signal from a total of six signals including a position signal and an inverted position signal, and outputs the selected signal.

35 is a differentiator which extracts and amplifies the change in the position signal for the selected phase advance command. 36 is a frequency-voltage conversion (FV conversion) circuit that converts a change in the position signal from the non-contact sensor 1) into a speed signal, and 37 is an adder whose output is the phase advance toxicity signal of the phase advancer 31. Become.

The operation of the brushless motor configured as above will be described below.

In a reluctan type motor that utilizes the force generated by the stator and rotor magnetic pole peaks like the motor in this example, the magnetic flux in the air gap between the stator and the rotor is improved by devising the shape of the magnetic pole teeth. It is possible to make the distribution closer to a sine wave.

In this case, if a constant electric current lΔr is applied to each coil phase, the torque due to each phase of the coil, A, B, and C, is as follows:
3 As shown in i'21, r for the electrical angle θ in the rotor direction
H pitch τ1 (can be expressed as a sine wave with a period of 5 air angles 2π. In the case of this embodiment, since it is a three-phase motor, each torque distribution is out of phase by 1.20°.

A non-contact sensor consisting of a magnetoresistive element 1'-- has sensor elements for three phases in one chip, and detects the position of the magnetic field 14m of the rotor. Figure 4 shows the sensor 1) arrangement i't and output. In FIG. 4, 41 is a rotor magnetic field i1', and /12 is a non-contact sensor. When the rotor moves in the θ direction, the centers of each sensor element a, b, c
By changing the relative position of the rotor magnetic pole teeth, a senna output of 3 tll is obtained. Sen output power resistance me 1
By adjusting the mounting position of the magnet and the strength of the bias magnet 43, a more sinusoidal output can be obtained.

Basically, attach the non-contact sensor as shown in Figure 5. In FIG. 5, 51 is a stator 1-phase magnetic pole tooth, 52 is a rotor magnetic pole tooth, and 53 is a 1-phase sensor corresponding to the stator magnetic pole tooth phase. When the rotation j'- and the magnetic pole teeth of the stator are opposed to each other as shown in FIG. 5(a), no torque is generated.

([)) When the relationship is iNi, a torque in the θ direction acts due to the attractive force between the magnetic tJ (9). In the case of (c), a torque in the opposite direction to 0 is generated. ,(b)
.

As shown in FIG. 5(c), when arranged with respect to the stator magnetic pole 1'11, the relationship between the torque distribution of each phase and the sensor output is as shown in FIG. 5(d) and (e). ] The relationship is 0° out of phase. However, the excitation phase sensor Nobutomi= is the phase advancer 31
Therefore, the phase can be advanced by an arbitrary angle.

When a sinusoidal drive circuit is used as in the present invention, the coil current of each phase changes according to a sinusoidal position signal.

Therefore, the torque of each phase is A phase KIIA-sinθ C phase) (+-1n-sin(θ--π〉C phase K
I・IC-5in (θ−−π〉■＜1. Constant IA
', ln, IC: Each phase current.

Since the current of each phase is proportional to the sensor signal, IA=2・s
i n (θ−−+α)■＜2: Constant α・sen→
The phase advance angle of the noise signal becomes the overall torque distribution as T (θ) = Kl - K 2 ts
i n (θ−−+cz)・ヱ
+ K2 ・s to J-
i na −(1).

A normal brushless motor generates continuous torque when α-- (eyes: 3 hits, T-1 and +2).

In the brushless motor of the present invention, positioning characteristics can be achieved by changing the phase advance α according to the sensor signal itself.

The phase advancing circuit 31 in FIG. 2 is a circuit that advances the phase of the sine wave, magnetic hinge → J signal according to the phase advancing command voltage. )
11 by a method using a vehicle between a reference signal and a sensor signal whose values change sinusoidally.

The sensor signal is guided to the phase advance circuit 31 for phase excitation and is also used for phase advance command.

As shown in FIG. 2, the three-phase sentry signals are each inverted, and a total of six signals are input to the electronic switch circuit 3;

As shown in FIG.
It is comprised of a decoder 62 that selects one. With this configuration, six signals f can be selected in good order for phase advance commands in both directions.

Further, the FV conversion circuit 36 is a circuit that generates a voltage according to the speed from changes in the sensor signal, and is composed of a circuit mainly including a differentiator.

Now, the operation of the brushless motor of the present invention will be described when the interval between external pulse commands is long and the speed voltage is almost negligible.

FIG. 7 shows a distribution diagram of the six signals of the phase advancer. The senry signals are each inverted to create sine wave signals with a phase shift of 60 degrees.

They are π See = 3@5ln(θ--) π = 3.5 inches (θ-1) π 4 π a = 3・s i n (θ−−−π)π = 3・5in (θ−−−π) It can be expressed as

It is now assumed that a is selected as the phase advance signal by the electronic switch circuit. Furthermore, if the coefficient of the phase advance command voltage - phase advance angle of the phase advancer 31 is β, the torque distribution is calculated from equation (1) as follows: T(θ)=-KIK2S i n (β-J(3-sin(θ) --) l-(2).

As shown in FIG. 8, this torque distribution changes shape depending on the value of 2 for β, but it shows that it has a position holding characteristic at the point θ=−−π. Also, by changing the value of 3 to β, the slope of the torque distribution near the positioning point (T-θ characteristic), which is important for positioning characteristics, can be changed. That is, in a normal stepping motor, the torque distribution is T' (θ) − K I K2 sin θ7, but the slope near the position holding point at this time is as follows when 3=1 for β in Fig. 8. Almost equal.

However, in the case of the brushless motor of the present invention, by setting β to about 3-1, the T-θ characteristic near the 16th holding point can be approximately doubled, and the positioning error due to disturbances can be reduced. be able to.

Now, in the same way as the torque distribution in the case of phase advance signal a, βI
<3- a, b, c, a, T) when tied together.

FIG. 9 shows the torque distribution when the phase leading signal of τ is selected. As can be seen from this figure, a torque distribution with six position holding points within one pitch of the magnetic pole teeth is obtained.

The electronic switch circuit converts the phase-advanced 11-lenser signal to a 8 e E b-π-! using an external clock. If it is determined that the selection is reversible in the order of Ct:=U, and Shinso of a is currently selected, the rotor will stabilize at point 1 in Figure 9 according to the torque distribution determined by Ta. Keep it at one place.

Next, a phase advance command in the positive direction is selected from the outside by a sensor signal using an electronic switch.

As a result, the two positive tortors on the rotor in Fig. 9 act on the rotor, and it moves to the 13th point and holds the position.

In this way, the rotor advances in accordance with the number of external pulses. If a step command in the negative direction/＼ is input when the three points are stable, the phase advance signal -;-a is selected, and the four points of negative I/lurk act on the rotor. moves in the opposite direction and 11. It is stable in the central position, and you can see that it moves in certain places in response to external pulses.

In addition, the T-θ characteristics near the position holding point are shown in Figure 10 (, -1
), it can be considered that the sensor signal constitutes the foot-pull system (b).

(In Figure 10, J is the rotor inertia, S is the Laplace operator, and K+ and Ks are constants.) In the case of such a quadratic system, the position is as shown in Figure 10 (C). By inserting the differential term K 5 S into the feedback loop, it is possible to change the stability during positioning.

Normally, when there is no differential term as in (b), the rotor vibrates as +I = '': However, if the value of Ks is set to an appropriate value (1/j) as in (c), the vibration can be reduced. The time required for settling can be shortened.

Further, the value of 5 can be adjusted electrically, and there is no need to manually adjust it as in the case of a stepping motor.

Now, the positioning characteristics are determined by the torque external teeth in equation (1), but if an arbitrary bias voltage KG is applied to this phase advance amount α from the position fine adjustment input terminal 38 in Figure 2, the sensor signal a If 'h< is selected, the phase advance amount is π α −β ・K3 ・5in(θ −−)
+ β ・I (6, and the i・lux distribution is T (θ ) −−KI K2 s i
n l β K3 · sin π (θ−1)+β·K 61− (3), resulting in a distribution whose phase is shifted by 6 from the distribution of equation (2) to β. Therefore, the stable point of the torque θ, that is, the stopping position of the rotor, can be arbitrarily and continuously changed by the value of the position fine adjustment input.

Next, when the interval between stepping commands in the evening period becomes shorter and the speed of the rotor increases accordingly, the output voltage of the FV converter 36 increases, and this speed voltage is added to the adder 37 to
The sensor signal for phase excitation, which is added to the position voltage for phase advancement, is
The amount of phase advance is larger than when the speed is slow. By appropriately adjusting the level of the FV conversion output, it is possible to compensate for the delay in the rise of the coil current due to an increase in the switching frequency by increasing the phase of the excitation position signal, thereby achieving high-speed operation.

As described above, according to this embodiment, a rotor made of a magnetic material is provided with magnetic poles m cut at -7 pitches on the circumference;
Magnetism 14 (J: A stator consisting of a stator core with J groups, magnets, and multi-phase coils, and a non-contact sensor that detects the unevenness of the magnetic poles of the rotor and outputs a signal approximately equal to a sine wave. , a speed detection means, an electronic switch means, a differentiator, and a position 1
By providing a fine adjustment input terminal, a phase advance means, and a sine wave type drive circuit, a stepping function and a positioning function with good stability and fine position adjustment are provided. I wish I could get an inexpensive brushless motor.

In addition, in the above-mentioned embodiment, all conventional brushless motors can be applied to the mechanical part of the motor.

That is, as shown in FIG. 11, magnets 112 are arranged on the rotor, and the rotor core 111, stator core 113, and magnet 4'
& 7B brushless motors, brushless motors in which the rotor is made up of multi-pole magnetized magnets as shown in Figure 12, and brushless motors in which the rotor is made up of multi-pole magnetized magnets on a disk surface as shown in Fig. 13. It would be better to use a brushless motor with a rotor. In addition, in the embodiment, a brushless motor with a three-phase coil is used, but the effects of (t) and (R) can be obtained by using other brushless motors with two or more phases.
4 is a coil, and 115 is a non-contact sensor +J-. Also,
In FIG. 12, 121 is a stator core, 122 is a magnet, 123 is a coil, and 1211 is a non-contact sensor.

Furthermore, in FIG. 13, 131 is a rotor magnet;
2 is a stator yoke, 1:33 is a coil, and 134 is a non-contact sensor.

Effects of the Invention As described above, the present invention includes a rotor made of a magnetic material or magnets, a stator including a stator core and a plurality of coils, a bearing device, and a rotor position 1a. By providing a non-contact sensor, a speed detection means, an electronic switch means for accepting external pulses, a phase advance means, a differentiator, and a sine wave type drive circuit, it has good stability and can be easily positioned from outside. I? A small, inexpensive brushless motor that has a positioning function that allows ttYa adjustment and rotates at high speed in synchronization with an external stepping pulse can be obtained.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are perspective views and sectional views of essential parts of a brushless motor according to a first embodiment of the present invention, and FIG. 2 is a block diagram of an electric circuit according to a first embodiment of the present invention. figure,
FIG. 3 is a diagram showing the torque distribution of each phase in the first embodiment, FIGS. 4(a) and (b) are diagrams showing the arrangement and output of the non-welding sensor, and FIGS. 5(a) to ( e) Sen IP placement? FIG. 6 is a diagram showing the configuration of the electronic switch means of the first embodiment, FIG. 7 is a diagram showing the waveform of the advance position signal, and FIG. (a) to (d), FIG. 9 is a diagram showing the torque distribution of the first embodiment, and FIG. 10 (a) to
(c) is a diagram explaining the damping part, Figure 11, Figure 1.
2 and 13 are diagrams showing the main mechanical parts of a motor according to another embodiment of the present invention, FIG. 14 is a diagram showing the principle of a conventional stepping motor, and FIG. 15 is a diagram showing the torque distribution of the motor in FIG. 14. , FIG. 16 is a diagram showing the stability of the stepping motor,
FIG. 17 is a diagram showing a conventional servo motor control system. 1...Rotor, 2,113.121...
・Stator core, 3.112...Magnet, 5,11
4,123°133... Coil, 6.26,1
15,124°134...Non-contact sensor, 20
...Motor section, 31... Phase advance circuit, 3
2... Sine wave type drive circuit, 33... Electronic switch circuit, 35... Differentiator, 36...
...l'' V converter, 41.52... Rotor magnetic pole tooth, 51... Stator magnetic pole tooth. Fig. 3 Fig. 4 1λ Fig. 5 J Figure 6 Figure 7 Figure 8 A-10 Figure 11 Figure 14 θ To 11-11, 14Z, /43 14,: IF Figure 0 is the previous edition] Figure 6 fire

Claims (1)

[Scope of Claims] (1) A rotor made of a magnetic material or a magnet, a stator including at least a stator core and a plurality of coils facing the rotor through an air gap, and a stator that rotates the rotor. a bearing device that freely supports the rotor; a non-contact sensor that is attached to the stator and detects a change in the position of the rotor, converts it into an electrical signal, and outputs substantially sinusoidal position signals having mutually different phases; speed detection means for converting a change in the position signal into a speed signal; electronic switch means for receiving a step command signal from the outside and sequentially selecting the plurality of position signals according to the number of step command signals; Differentiating means outputs the amount of change in the position signal, and advances the phase of the position signal by using the sum of the speed signal, the selected position signal, the amount of change in the position signal, and the external command amount as a phase advance amount. and a sine wave drive circuit that energizes the plurality of coils using the phase-advanced position signal. (2) The rotor is made of a magnetic material having magnetic pole teeth cut at a constant pitch on the circumference, and the stator has a stator core having a group of magnetic pole teeth on the surface facing the rotor. The non-contact sensor is composed of a magnet attached to a stator core and a plurality of coils wound around the stator core, and the non-contact sensor detects irregularities of the magnetic pole teeth of the rotor and converts them into electrical signals. Brushless motor as described in Range 1. (3) The rotor is equipped with magnets, a magnetic body laminating the magnets from both sides, and magnetic pole teeth notched on the circumference of the magnetic body, and the stator is a stationary member with a group of magnetic pole teeth on the surface facing the rotor. The non-contact sensor is composed of a child core and a plurality of coils wound around the stator core, and the non-contact sensor detects the unevenness of the magnetic pole teeth of the rotor and converts it into an electrical signal. brushless motor. (4) The rotor consists of magnets with multi-pole magnetization on the inner or outer circumferential surface, and the stator consists of a stator with poles on the opposing surface of the rotor circumference and multiple coils, and is non-contact. 2. The brushless motor according to claim 1, wherein the sensor detects the magnetic pole of the rotor and converts it into an electric signal. (5) The rotor consists of multi-pole magnets on a disc,
The stator is composed of a plurality of coils arranged on opposing surfaces of the rotor disk and a yoke, and the non-contact sensor detects the magnetic poles of the rotor and converts them into electrical signals. The brushless motor described in item 1.