JPS63107483A - Brushless motor - Google Patents

Abstract

PURPOSE:To obtain incrementing function and positioning function by advancing the phase of a phase exciting position signal by a position signal, and energizing a coil by the position signal. CONSTITUTION:A phase exciting position signal is obtained by a noncontact sensor 23 contained in a motor 20, and the position signal is input through position signal amplifiers 24a-24c to a composite circuit 25 and a phase advancing circuit 26. The circuit 25 combines 3-phase signals displaced at 30 deg. of phase, and the circuit 26 leads or lags the phases of the 3-phase exciting position signals in response to a phase advancing instruction amount. A 3-phase sine wave drive circuit 27 supplies currents proportional to the advanced phase exciting position signal to the coils of a 3-phase motor. A phase advancing instruction signal is output by an adder 32 for adding the outputs of an electronic switch 29, a differentiator 30 and an F/V converter 31.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a brushless motor capable of fine positioning and high speed rotation.

Conventional technology Due to the recent development of semiconductor technology and digital technology, industrial
The digitalization of all types of equipment is progressing, and the adoption of microcomputers is being promoted. Motors capable of digital positioning are suitable as the drive source for these devices, and conventionally stepping motors and servo motors have been used.

A conventional steering/sobbing motor will be described below with reference to the drawings. FIG. 15 shows a principle diagram of a conventional permanent magnet (PM> type stepping motor), in which 151 is a stator, ] 52 is a rotor made of magnets,
153 is a coil.

If the coils are excited from the outside in order, the rotor will change its position and move forward depending on the state of energization of the coils.

FIG. 16 shows the torque distribution of the stepping motor shown in FIG. 15, and it can be seen that it has a position holding characteristic and obtains a rotational speed synchronized with an external signal. However, at high speeds, stepping motors are not suitable for high-speed rotation because the rise of current is delayed due to the time constant of the coil and the effects of iron loss, making it impossible to generate torque in a timely manner.

In particular, when the magnetic pole pitch is made finer in order to increase the positional resolution, the switching frequency per rotation increases, which has a large effect.

In addition, in order to overcome the disadvantage described in E of stepping motors, a method is sometimes used in which an encoder is attached externally and the switching of the electric current phase is accelerated according to the speed of the motor to compensate for the delay in the rise of the current. In this method, the encoder is attached to the outside of the motor, so the shape is thick (
Another disadvantage is that the encoder is expensive.

Furthermore, stepping motors generally have a phenomenon in which, when stopping for positioning, they vibrate "shut down" around the upper stop point, as shown in FIG. 17, 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. there were.

Next, a conventional servo motor will be explained. No.181￥
1 shows the positioning control system of the servo motor, and 18
1 is a motor, 182 is an encoder,] 8:3 is a control circuit including a deviation counter, and 184 is a drive circuit.

The positioning servo system configured as described above can operate at high speed according to digital position commands and can obtain positioning characteristics. In addition, electrical damping can be added, so that the stoppage is not vibrational. 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 drawback of not being able to rotate at high speeds and taking a long time to determine the position, and when an encoder is attached to a stepping motor, the size is large and the encoder is expensive. It has the disadvantage of being Furthermore, the servo motor has the disadvantage that the IIIa system and encoder are expensive.

In view of the above-mentioned problems, the present invention provides a brushless motor that has a shape similar to that of conventional stepping motors, has a relatively simple circuit configuration, has a high-resolution positioning function, and has high-speed rotation.

Means for Solving the Problems In order to solve the above problems, the brushless motor of the present invention includes: (1) a rotor made of a magnetic material or a magnet; (2)
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 supports the rotor so that it can freely rotate; and (4) a bearing device that is attached to the stator and that rotates freely. C5) A non-contact sensor that detects a change in the position of the child, converts it into an electrical signal, and outputs a substantially sinusoidal phase excitation position signal with mutually different phases; (6) speed detection means for converting a change in the position signal into a speed signal; (8) Differentiating means that outputs the amount of change in the selected position signal; (9) The speed signal, the selected position signal, the amount of change in the position signal, and the output signal from the outside. a phase advancing means for advancing the phase of the phase excitation position signal as an addition value and a phase advance amount with the command amount; It is equipped with a sine wave type drive circuit.

According to the above-described structure, the present invention advances the phase excitation position signal obtained by the non-contact sensor built into the motor by the position signal selected by the electronic switch means, and the phase-advanced phase excitation position By energizing the coil with a signal, a brushless motor with stepping and positioning functions is obtained. Furthermore, by adding the speed signal to the phase advance command ant, the amount of phase advance of the phase excitation position signal is increased overall according to the speed to cover the delay in the rise of the current and high-speed operation can be performed. Further, by adding the change in the position signal for the phase advance command as a damping signal to the advance and phase ends, vibrations at the time of stopping are suppressed and the time until the position is determined is shortened. By adding an external signal to the phase 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.

FIGS. 1(a) and 1(b) show the mechanism of a brushless motor according to the first embodiment of the present invention, where (a) is a cross-sectional view of the main part, and FIG. ) is a sectional view taken along line A-A.

In the figure, 1-a and 1b are rotor cores with magnetic pole teeth on the circumferential surface, 2 is a stator core with magnetic pole teeth on the surface facing the rotor, and 3 is 2 of 1a and 1b. Magnets stacked on two rotor cores, 4 is 3-phase 12 coils, 5 is 1
This is a non-contact sensor that outputs a substantially sinusoidal signal with a phase shift of 20 degrees.

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 mechanical section of the aforementioned motor, 21 a rotor, and 22a.

22b+22c are three-phase coils, and 23 is a non-contact sensor consisting of a magnetoresistive element. 24a, 24b.

Reference numeral 24c denotes a position signal amplifier that amplifies the three-phase sum excitation position signal output of the non-contact sensor.

25 is a synthesis circuit for synthesizing three-phase signals whose phases are shifted by 30 degrees from three-phase phase excitation position signals, and 26 is a synthesis circuit for synthesizing three-phase signals whose phases are shifted by 30 degrees from three-phase phase excitation position signals. A phase advancing circuit 27 for advancing or delaying is a three-phase sine wave type drive circuit that flows a current proportional to the phase-advanced phase excitation position signal to the coil of the three-phase motor. 28a, 28b,
28C928d, 28e, and 28f are amplifiers that invert six-phase position signals. Reference numeral 29 denotes an electronic switch circuit that receives a step command signal from the outside, selects one signal from a total of 12 signals including a position signal and an inverted position signal, and outputs the selected signal.

30 is a differentiator which takes out and amplifies the change in the position signal for the selected phase advance command. 31 is a frequency-voltage conversion (
(FV conversion) circuit 32 is an adder, the output of which becomes a phase advance command signal for the phase advance device 26.

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

In a reluctance type motor that uses the force generated by the stator and rotor magnetic pole teeth like the motor in this example, the magnetic flux in the air gap between the stator and rotor can be reduced by devising the shape of the magnetic pole teeth. The distribution can be made closer to a sine wave.

When a constant current is passed through each coil phase in this way, the torque due to each phase A, B, and C of the coil is expressed by the tooth pitch (electrical angle 2
It can be expressed as a sine wave with a period of π). In the case of this embodiment, since it is a three-phase motor, each torque distribution is out of phase by 120 degrees.

There are 3 non-contact sensors in one chip consisting of magnetoresistive elements.
Phase sensor elements are configured to detect the position of the magnetic pole teeth of the rotor. Figure 4 shows the sensor arrangement and output. In FIG. 4, 41 is a rotor magnetic pole tooth, and 42 is a non-contact sensor. When the rotor moves in the θ direction, three-phase sensor outputs are obtained due to changes in the relative positions of the centers a, b, and c of each sensor element and the rotor magnetic pole teeth 41. As for the sensor output, a sinusoidal output can be obtained by adjusting the mounting position of the magnetoresistive element and the strength of the bias magnet 43.

The non-contact sensor is basically installed as shown in Figure 5 = In Figure 5, 51 is the stator 1 phase magnetic pole tooth, 52 is the rotor magnetic pole tooth, and 53 is 1 phase corresponding to the stator magnetic pole tooth phase. It is a sensor of When the magnetic pole teeth of the rotor and identifier are facing each other as shown in FIG. 5(a), no torque is generated.

In the positional relationship shown in (b), a torque in the θ direction acts due to the attractive force between the magnetic pole teeth. At the time of re), a torque in the opposite θ direction is generated. Sensors (a) and (b).

As shown in (c), when arranged with respect to the stator magnetic pole teeth, the relationship between the torque distribution of each phase and the sensor output is as shown in Fig. 5 (
As shown in d) and (e), there is a relationship with a phase shift of 90''. However, the excitation sensor signal is phase-advanced by an arbitrary angle by the phase-advance 1 circuit 26.

When using the sine wave type drive circuit 27 as in the present invention,
The coil current of each phase changes according to a sinusoidal excitation position signal.

Since the torque of each phase is distributed sinusoidally with respect to θ, A phase KIIA-6inθ B phase K+-IB-sin(θ--π) C phase K+
-1cm5in(θ--π): Constant IA, la
, rc: Each phase current.

The current in each phase is proportional to the excitation sensor signal, and the excitation sensor signal is out of phase with the torque distribution, so (A = 2.5jn(θ--+α), 1 2 = 2: Constant α: Becomes the phase advance angle of the sensor signal, and the overall torque distribution becomes =-KIK2 · sin a - (1).

Therefore, T=-KIK2 and continuous torque is generated.

The brushless motor of the present invention has positioning characteristics by changing the phase advance amount α in accordance with the position signal synthesized with the phase excitation position signal itself.

A synthetic position signal is synthesized from the phase excitation signals by a synthesis circuit 25. The synthesis circuit 25 has the configuration shown in FIG. 6(a),
Each excitation position signal is added to another inverted excitation position signal, and the value is multiplied by 1/( to obtain a new position signal.

In FIG. 6(a), 61a, 61b, 61c are inverting amplifiers, 62a, 62b, 62c are adders, F3a,
63b and 63c are amplitude adjusters that make ]/(.The synthesized position signal is a 30° phase difference from the excitation three-phase position signal, as shown in the vector diagram of FIG. 6(b). The signal is a shifted three-phase signal.

The second M phase advance circuit 26 is a circuit that advances the phase of the E-sine wave excitation sensor signal according to the phase advance command voltage, and changes the value sinusoidally depending on the method of vector addition of sensor signals or the amount of instruction. It is obtained by multiplying the reference signal and the sensor signal.

The sensor signal is guided to the phase advance circuit 26 for phase excitation and is also used as part of the position signal for phase advance command.

As shown in FIG. 2, each of the six phase position signals is inverted, and a total of 12 signals are input to the electronic switch circuit 29.

As shown in FIG. 7, the electronic switch circuit 29 includes a reversible decimal counter 71 and a decoder 72 that selects one signal from 12 signals based on the output of the counter. With this configuration, 12 signals can be selected in order for phase advance commands in both directions.

Further, the FV conversion circuit 31 is a circuit that generates a voltage according to the speed from a change 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. 8(a) shows a distribution diagram of 12 phase advance signals. The position signals are each inverted to create sinusoidal signals with a phase shift of 30'.

They are expressed as π a = 3 * S i n (θ−−) π a = 3·s i n (θ−−−π), and as shown in FIG. 8(b), a, d.

3 in the order of c, T, b, e, a, H, c, f, T;, e
The phase is shifted by 0°.

It is now assumed that a is selected as the phase advance signal by the electronic switch circuit. Further, if the coefficient of the phase advance command voltage of the phase advancer 26 - the phase advance angle is β, then the torque distribution is expressed as T(θ)=-KIK2s in from equation (1).

As shown in FIG. 9, the shape of this torque distribution changes depending on the value of β of 3, but it shows that it has position retention ability at the point of θ=2π. Also, by changing the value of 3 to β,
It is also shown that 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) = -KIK2s in θ, but the slope near the position holding point at this time is 3 = 1 to β in Fig. 9.
approximately equal to the case of .

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 position holding point can be doubled, reducing positioning errors due to disturbances. be able to.

Now, similarly to the torque distribution in the case of the phase advance signal a, FIG. 10 shows the torque distribution when each phase advance signal is selected when β is set to 3=-.

As can be seen from this figure, a linear torque distribution with 12 position holding points within one pitch of magnetic pole teeth is obtained.

The electronic switch circuit 29 uses an external clock to input the phase advance sensor signal a ;'d;" Q = T E b d
eE a E ”'Frj:! c′;!f ′;!T
; If it is determined that the signals are selected reversibly in the order of E and e, and the signal a is currently selected, the rotor will stabilize and maintain its position at point ■ in Figure 10 according to the torque distribution determined by Ta. . Next, when a forward phase advance command is input from the outside, the electronic switch circuit 29 selects the sensor signal d.

As a result, a positive torque at point 0 on Td in FIG. 10 is applied to the rotor, and the rotor moves to point 2 and maintains its 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 while the stability is at point ■, the sensor signal a for phase advancement is selected, and the negative torque at point ■ acts on the rotor, causing the rotor to move in the opposite direction and at one point. It can be seen that it is stable and exhibits reversible movement in response to external pulses.

The positioning step at this time is 1/12 of one pitch, which is smaller than that of a normal stepping motor.

Furthermore, if the T-θ characteristic near the position holding point is linearized as shown in FIG. 11(a), it can be considered that it constitutes a feedback system (b) based on sensor signals.

(In Fig. 11, J is the rotor inertia, S is the Laplace operator, and K4 and 5 are constants.) Such 2
In the case of the next servo system, the stability during positioning can be changed by inserting the position differential term KSS into the feedback loop as shown in FIG. 11(C).

Normally, when there is no differential term as in (b), the rotor stops due to the photographic action, but if the value of 5 is set to an appropriate value as in (C), the photographing can be suppressed. , the time until settling can be shortened.

Furthermore, the value of 5 can be adjusted electrically, and does not need to be done mechanically as in the case of a stepping motor.

Now, the positioning characteristics are determined by the torque distribution in equation (1), but if an arbitrary bias voltage of 6 is given to this phase advance amount α from the position fine adjustment input terminal in Fig. 2, 33, the sensor signal a
is selected, the amount of phase advance is α-β・K3・5in(θ-1)+β-KG, and the torque distribution is as follows, and the phase is shifted by 6 from the distribution of equation (2) to β. distribution. 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, the interval between external stepping commands becomes short (and the speed of the rotor increases accordingly).e, the output voltage of the FV converters 3 and 1 increases, and this speed voltage is converted into a phase advancing by the adder 32. The sensor signal for phase excitation has a larger phase advance than when the speed is slow.By appropriately adjusting the level of the FV conversion output, the coil current can be reduced as the switching frequency increases. High-speed operation can be achieved by covering the delay in starting position by advancing the phase of the excitation position signal.

As described above, according to the wooden embodiment, there is a rotor made of a magnetic material with magnetic pole teeth cut at a constant pitch on the circumference, a stator core with a group of magnetic pole teeth, a magnet, and a multiphase coil. a non-contact sensor that outputs an excitation position signal in the form of a substantially sinusoidal wave to match the unevenness of the magnetic poles of the rotor; a means for synthesizing a position signal for position determination from the excitation position signal; and a speed detection device. By providing an electronic switch means, a differentiating means, a position fine adjustment input terminal, a phase advance means, and a sine wave type drive circuit, it is possible to perform a step function in minute steps and fine position adjustment with good stability. It is possible to obtain a small, inexpensive brushless motor that has a positioning function that allows for high-speed rotation.

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

That is, as shown in FIG.
22, a yoke 123, and a coil 124 are installed, the rotor core 125 and the stator core 121 are equipped with magnetic pole teeth, and the non-contact sensor 26 is a brushless motor that detects the irregularities of the magnetic pole teeth of the rotor, and FIG. As shown in the figure, the rotor is composed of a multi-pole magnetized magnet 131, and is equipped with a stator core 132, a coil 133 wound around the stator core, and a non-contact sensor 134 for detecting the magnetic poles of the rotor magnet. brushless motor,
As shown in FIG. 14, the rotor consists of a multi-pole magnet 141 on a disk surface, and the stator consists of a yoke 142 and a coil 143.
It is also possible to use a brushless motor equipped with a non-contact sensor 145 for detecting the magnetic poles of the rotor.

Further, in the embodiment, the positioning signal including the composite signal is made up of 12 signals at intervals of 30 degrees in electrical angle, but these may also be composited into signals at even finer angle intervals.

In the embodiment, a three-phase coil brushless motor is used, but the same effect can be obtained using other two or more phase coil brushless motors.

Effects of the Invention As described above, the present invention provides a rotor made of a magnetic material or a magnet, a stator including at least a stator core and a plurality of coils, a bearing device, and a non-contact method for detecting the position of the rotor. By providing a sensor, a means for synthesizing sensor signals, a speed detecting means, an electronic switch means for accepting external pulses, a phase advance means, a differentiating circuit, and a sine wave type drive circuit, high resolution and stability can be achieved. A small, inexpensive brushless motor that has a positioning function that allows fine position adjustment from the outside and rotates at high speed in synchronization with an external stepping pulse can be obtained.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view of essential parts of a brushless motor according to a first embodiment of the present invention, FIG. 1(b) is a cross-sectional view taken along line A-A in FIG. 1(a), and FIG. A block diagram of the electric circuit in the first embodiment of the invention, FIG. 3 is a diagram showing the torque distribution of each phase in the first embodiment, and FIGS. 4(a) and (h) show the arrangement of the non-contact sensor. Figures 5(a) to 5(e) are diagrams showing the sensor arrangement and distribution of torque and sensor output, Figure 6(a) is a configuration diagram of the synthesis circuit, and (b) is the waveform with synthesis. Figures 9 (a) to (d) and Figure 10 are diagrams showing the torque distribution of the first embodiment, Figures 1 and 1] (a) to (C).
Figures 12(a) and 12(b) are diagrams explaining the damping part.
), Figure 13(a). (h), FIGS. 14<a) and (b) are diagrams showing the main mechanical parts of a motor according to another embodiment of the present invention, FIG. 15 is a principle diagram of a conventional stepping motor, and FIG. 16 is a diagram showing the principle of a conventional stepping motor. FIG. 17 is a diagram showing the stability of a stepping motor, and FIG. 18 is a diagram showing a conventional servo motor control system. 1 a, 1 b...Rotor core, 2,1
21.132... Stator core, 3,122...
...Magnet, 4,124°133.143...
・Coil, 5.23, 126° 134.145...
...Non-contact sensor, 20...Motor section, 25.
...Synthesizing circuit, 26... Phase advance circuit, 27
... Sine wave type drive circuit, 29 ... Electronic switch circuit, 30 ... Differentiator, 31 ...
...FV converter, 41°52...Rotor magnetic pole tooth, 51...Stator magnetic pole tooth. Name of agent Patent attorney Toshio Nakao and one other person Figure 1 1a, Ib-
Rotor] Aku m-1 Stator core 4---': l-i! 5 --- 1 to 1 concubine touch se〉7 (Q) Figure 3 ToIL Figure 4 Figure 5 z 1) L7 1? 〉Aeka Fig. 6 1) + a Fig. 7 L J Fig. 8 (a) Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 (a) Fig. 14 Fig. 1 152 +53 Fig. 16 Torque Fig. 17 θ

Claims (5)

[Claims] (1) A rotor made of a magnetic material or magnets, a stator that faces the rotor through a gap and includes at least a stator core and a plurality of coils, and a bearing device that supports the rotor in a freely rotatable manner. and a non-contact sensor attached to the stator, which detects a change in the position of the rotor, converts it into an electrical signal, and outputs a position signal for phase excitation of substantially sinusoidal coils having mutually different phases; A means for synthesizing a position signal for positioning from a position signal for phase excitation, a speed detection means for converting a change in the position signal into a speed signal, and a means for receiving a step command signal from the outside, electronic switch means for selecting the position signals in order; differentiating means for outputting the amount of change in the selected position signal; and the speed signal, the selected position signal, the amount of change in the position signal, and an external command amount. a phase advancing means for advancing the phase of the phase excitation position signal using an added value as a phase advance amount; and a sine wave type drive circuit that energizes the plurality of coils by the phase advanced phase excitation position signal. Brushless motor with. (2) 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. Child core and
2. The brushless motor according to claim 1, wherein the brushless motor comprises 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 the detected irregularities into electrical signals. (3) The rotor is made of a magnetic material with magnetic pole teeth cut at a constant pitch on the circumference, and the stator has a stator core equipped with 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. (4) The rotor consists of magnets magnetized with multiple poles 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 a plurality of 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.