JPS6027380B2 - Rotation signal detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation signal detection device for detecting the rotation speed and position of a motor.

Conventionally, in order to detect the position of the rotor in a motor,
Generally, a method such as using a Hall element to detect magnetic velocity density is used to generate a position signal from the polar generation of field magnetic flux, and a separate tachogenerator, pulse generator, etc. is used to detect the rotational speed of the rotor. Generally, the detection means is equipped with: As a result, a motor capable of speed detection is required to have a motor main body, a position detecting section, and a speed detecting section, which has the disadvantage that elements other than the motor main body become large. In addition, small-output motors have the disadvantage that they tend to be large in size, such as the volume of the position detection section and speed detection section being equal to the volume of the motor body. This invention has been made in view of the drawbacks of the conventional ones, and is a rotation signal detection device that can realize an extremely small motor by configuring the field magnetic flux of the motor to be used as an energy source for the speed detection section. is intended to provide. The invention will now be explained with reference to the drawings.

In Fig. 1, numeral 1 is a disc fixed to the rotating shaft, and the outer periphery of the disc 1 is carved with unevenness as shown in the figure.This disc 1 is integrally coupled with the rotor field magnetic flux 2. There is. It is assumed that the rotor field magnetic flux 2 has a toroidal shape and is magnetized into eight poles almost equally at every mechanical angle of 45 degrees. 3 is a stator magnetic path village made of soft magnetic material, and M, to M6 are stator windings flatly fixed on the stator magnetic path material 3 at a pitch of 60 degrees.

101 to 103 are Hall elements, and these Hall elements are connected to the stator magnetic path material 3 via insulating materials 501 to 503.
It is fixed at 200 pitch.

Now, FIG. 1b shows a cross section of the Hall element 101. As shown in Figure b, the rotor field magnet 2
In the path of the magnetic flux generated as a magnetomotive force source, the path passing through the Hall element 101 is as follows: it enters the disk 1 from the N pole of the rotor field magnet, passes through the Hall element 101 from the convex part of the disk 1, and passes through the Hall element 101. The path 300 leading to the south pole is mainly considered. In addition, there is also magnetic flux that enters the Hall element from this vicinity, but as a result of integrating the magnetic fluxes passing through these paths, it is assumed that the magnetic flux passing through the Hall element 101 changes sinusoidally as the rotor rotates. In fact, even if a rotor magnet that is attached in a relatively square wave shape is used, the basic component of the magnetic flux passing through the Hall element is approximately the same due to the gap between the Hall element and the disk 1, the size of the magnetizing magnetic flux, etc. It changes as shown in Figure 4a. Now, for example, when the convex part of the disk 1 faces the Hall element 101, the gap between the disk 1 and the Hall element 101 is small, so the magnetic resistance along the path 3001 becomes small as a whole, and the rotor field magnet Among the magnetic flux generated by the magnetomotive force, the amount of magnetic flux passing through the path 300 increases.

Conversely, when the concave portion of the disk 1 faces the Hall element, the magnetic resistance in the path 3001 becomes large, so the amount of magnetic flux passing through the path 300 decreases. Since a Hall electromotive force proportional to the amount of magnetic flux passing through the Hall element is obtained from the Hall element, the Hall electromotive force from the Hall element 101 is obtained as the rotor rotates as shown in FIG. 4b. In other words, if a positive Hall electromotive force is obtained when the polarity of the rotor field magnet 2 is N, then the polarity of the rotor field magnet 2 is N,
As the pole changes from S to S, the electromotive force of the Hall element changes to positive or negative as a low frequency component, and according to the unevenness of the disc 1, the electromotive force is modulated by a frequency component determined by the tooth profile of the disc 1. It pulsates as a high frequency component. Regarding the Hall electromotive force from the other two Hall elements 102 and 103,
The same holds true for the Hall element 101, and as a result, the Hall elements 102 and 103 produce electromotive force waveforms as shown in FIGS. 4c and 4d. And Figure 4 b, c,
There is a phase difference of 2'3 lights in electrical angle between the two lights. In addition, the figure shows a case where the number of teeth on the outer periphery of the disc 1 is 24. Here, a brief explanation of the operation of the Hall element will be given with reference to FIG. As shown in FIG. 3a, the Hall element has input terminals A and B and output terminals P and Q, and the input terminals and output terminals are in a non-insulated state. When input control current lc is caused to flow through terminals A and B and magnetic flux is made orthogonal to the Hall element from the outside, a potential difference V is generated between output terminals P and Q. This potential difference V is the difference between the potential VP of the terminal P with respect to the terminal B and the potential Vo of the terminal Q with the terminal B as the reference, and the situation is shown in FIG. 3b. In other words,
If the direction of the magnetic flux when it passes from the front to the back of the paper in Figure 3a is the 10cm direction of the rattan axis in Figure 3b, then when the magnetic flux is in the 10cm direction, VP is the dotted line in Figure 3b. However, VQ remains almost constant as shown by the two-dot chain line. Conversely, when the magnetic flux is in the -■ direction, VP and Vo exhibit completely opposite characteristics to those in the ten directions. By taking the difference between VP and VQ, V shown by the solid line in FIG. 3b is obtained. 3 shown in Figure 4 b, c, d
The electromotive force waveforms of the three Hall elements are expressed by the potential difference between the two output terminals of each Hall element, and a circuit for extracting signals for detecting position and velocity from these three Hall elements is shown in Figure 1c. The following are possible.

In FIG. 1c, Hall elements 101, 102, 103 are provided with a bias current by resistors R1, R2, R3, respectively, which lead to a common resistor R4. P1,Q
1, P2, Q2 and P3, Q3 are Hall elements 1, respectively.
There are two output terminals, 01, 102, and 103, and the potential difference between these two output terminals is the Hall electromotive force shown in FIG. 4b, c, and d. In FIG. 4, the solid lines e, f, and g in FIG. 4 indicate the potential of each output terminal P1, P2, and P3 with respect to the earth ground, and the solid lines of each output terminal Q1, Q2, and Figure 4e shows the potential of Q3.
, f, g. Comparators 111, 112,
Reference numeral 113 determines the polarity of the Hall electromotive force of the Hall elements 101, 102, and 103, that is, the N and S polarities of the rotor field magnets are determined to detect the rotor position. 1st
In the figure, to obtain the rotational speed signal, diodes D1, D2 are connected at their respective cathodes to a resistor RO.
, D3 are connected to the output terminals P1, P2, and P3 of each Hall element. In other words, Fig. 5 e, f
, g, when the potentials of the output terminals P1, P2, and P3 shown by solid lines are compared in the same phase, P1 has the highest potential among them.
, P2, P3 is conductive, and so-called diode rectification is performed. As a result of repeating this operation, the potential with respect to the ground of the common cathode terminal M of the diodes DI to D3 has a pulsating component determined by the frequency of the tooth profile on the outer periphery of the disk 1 in the DC component as shown by the solid line in FIG. 4h. It will take on the shape of a folded car. By comparing the component shown by the solid line in FIG. 4h with the DC average voltage portion by the comparator 201, an alternating square waveform output as shown in FIG. 4j is obtained from the comparator 201. The pulse shown in FIG. 4J has a frequency proportional to the rotational speed of the rotor, and can be used as a rotational speed signal. In the above, the output terminals of the Hall elements 101-103 connected to the anodes of the diodes DI-3 are PI-P3.

On the other hand, the other output terminals QI to Q3 of the Hall elements 101 to 103 having potentials to the ground as shown by dotted lines in e, f, and g of FIG. 4 are connected to the anode sides of the diodes DI to D3, respectively. Even if they are connected, the potential with respect to the ground at the common cathode terminal M of the diodes DI to D3 becomes a potential as shown by the dotted line in FIG. 4h, and by passing it through a comparator, a pulse shown in FIG. 4i is obtained.
This can be used as a rotational speed signal. FIG. 2 shows another embodiment of the invention.

In FIG. 2, a positive feedback effect using transistors is used as a circuit for extracting signals for detecting speed from three Hall elements. In Figure 2, diodes D4 and D5
, cancel the forward voltage drop of the conductive diode among DI to D3 and the base-emitter voltage of the transistor TR2. Now, the potential of the common cathode terminal M of the diodes D1 to D3 with reference to the cathode terminal K of the diode ○5 is determined based on the same idea as in the first embodiment. It is shown as a solid line in Figure 4h. Therefore, the base of transistor TR2
Assuming that the emitter voltage can be almost ignored, the voltage shown by the solid line in Fig. 4h can be considered as the voltage between the terminals of the resistor R5, and as a result, even at the emitter current of the transistor TR2, that is, almost the collector current iG2. It has a pulsation of a frequency component determined by the tooth profile on the outer periphery of the disk. Since the collector current ic2 of the transistor TR2 is the base current is of the transistor TRI, the h of iB・
The collector current ic of the transistor TRI, which is amplified by a factor of FE and flows, also has a pulsation of a frequency component determined by the tooth profile of the outer circumference of the disk. Therefore, resistor R1
, R2 and R3 to the Hall elements 101, 102 and 1.
Also at each input control current given to 03, i
A pulsation of a frequency component in phase with c, can be seen.
The phase of the pulsations in the respective input control currents applied to the three Hall elements matches the phase of the pulsations in the magnetic flux interlinking the Hall elements formed by the irregularities on the outer periphery of the disk 1. Therefore, since the output of the Hall element is proportional to the product of the input control current to the Hall element and the amount of magnetic flux linked to the Hall element, the output of the rotor field magnet 2 at each electromotive force of the three Hall elements is The so-called low frequency component vibration having a frequency equal to the sacrificial change becomes large, and at the same time, the amplitude of the pulsation having a frequency component determined by the tooth profile on the outer periphery of the disk 1 also becomes large. Therefore,
According to this embodiment, the amplitude of the pulsation having a frequency proportional to the rotational speed of the rotor is larger than that in the first embodiment, so that the amplitude of the output pulse obtained from the comparator 201 is higher as in FIG. 1c. It is possible to obtain a stable rotational speed signal.

Further, as in FIG. 1c, each output terminal P1, Q1, P2, Q2 and P3 of the Hall elements 101, 102 and 103,
By inputting Q3 to the comparators 111, 112, and 113, the level of the position detection signal obtained as an output from each comparator becomes higher than that in the first embodiment, so it can be used as a stable position signal. . Note that the resistor R5 is for controlling the collector current of the transistor TRI, and as a result, the magnitude of the output from each Hall element is also controlled. Also, the transistor TR
Even when I is off, the Hall elements 101 to 103
A relatively high resistance resistor R6, shown in dotted lines in FIG. 2, may be included to ensure a minimum input control current for the current. Furthermore, in this embodiment, the same effect can be obtained even if the output terminals of the Hall elements 101 to 103 connected to the anodes of the diodes DI to D3 are QI to Q3.

FIG. 5 shows another embodiment of the present invention. FIG. This is slightly modified compared to the one shown in FIG. 1A, and the distribution of the unevenness of the disk 1 per one magnetic pole of the rotor field magnet is changed between the N magnetic pole and the S magnetic pole.

In other words, when the number of convex portions of the disk 1 at one magnetic pole is 3, the convex portion of the disk at the N pole starts carving from the switching position from the S pole to the N pole, whereas the circle at the S pole The convex part of the plate is am (o) in mechanical angle from the switching position from N pole to S pole.
This is so that the engraving starts later. FIG. 5b shows a circuit for extracting a signal for detecting the rotational speed of the rotor from the outputs of the Hall elements 101 to 103, 211,
221 is a comparator, and 600 is an exclusive OR gate circuit. In this embodiment, the Hall element 101,1
02 and 103, each one output terminal P1, P2, P3
The ground potentials of are shown by the solid lines in Figure 6 a, b, and c, where they have a phase difference of 2/3 electrical degrees from each other.
The other output terminals Q1, Q2, Q of the three Hall elements
The ground potentials of 3 are shown by the dotted lines in FIG. 6 a, b, and c, and these also have a phase difference of 2/3 in electrical angle.

Therefore, the potential of the terminal M with respect to the ground, taking into account the voltage drop of any one of the diodes DII to 031, is as shown by the solid line in Figure 6d, and this solid line is determined by the tooth profile on the outer circumference of the disk. It has pulsations of frequency components. Similarly, the potential of the common cathode terminal N of the diodes D12, D22, and D32 with respect to the ground is indicated by the dotted line in Fig. 6d, and the output at point N' indicated by this dotted line is also
While maintaining the phase difference with the M point output shown by the solid line, it has a pulsation of a frequency component determined by the tooth profile on the outer periphery of the disk. 6th
The comparator 211 compares the output at point M, indicated by the solid line in FIG. d, with the average DC component, thereby obtaining an alternating square waveform output shown in FIG. 6e from the comparator 211. At the same time, an alternating rectangular waveform output as shown in FIG. 6f is obtained from the result 221 of comparing the N point output shown by the dotted line in FIG. 6d with the average DC component by the comparator 221. The pulses in FIGS. 6e and 6f each have a frequency proportional to the rotational speed of the rotor (here 24 pulses per rotor rotation). Here, at any om of the mechanical angle of the convex part of the disc 1 shown in Fig. 5a, 8 m: trench (N; number of convex parts of the disc at the work pole 4? middle') is satisfied. In other words, since N=3 here, by setting 8m so that 8m=7.50, pulses having the phase relationship shown in FIG. 6e and f can be obtained.

(In other words, 8m corresponds to the nasal synchronous portion of the uneven wave. Both pulses e and f in FIG. 6 are connected to the exclusive OR gate circuit 600.
600, the pulse output shown in FIG. 6g is obtained. The pulse output shown in Fig. 6g has a frequency twice the total number of teeth on the outer periphery of the disc 1 (here, 48 pulses per rotor rotation), and can be used as a rotational speed signal. I can do it. In addition, if the polarity of each Hall electromotive force between the two output terminals P1, Q1, P2, Q2 and P3, Q3 of the Hall elements 101, 102 and 103 is determined using a comparator, it can be used as a rotor position signal. I can do it.

As described above, according to this embodiment, the signal used to detect the rotational speed of the rotor is obtained at twice the frequency compared to the first, second, and third embodiments, so that more precise rotation can be achieved. Speed detection becomes possible.

Furthermore, in FIG. 5a. Exactly the same effect can be obtained by using a magnet in which the N pole is changed to the S pole and the S pole is changed to the N pole. Note that when using a magnetoresistive element instead of a Hall element, the magnetoresistive element cannot determine the polarity of the magnetic flux passing through it.
There is no problem in using it for speed detection, but in order to use it for detecting position signals, it is necessary to place the magnetoresistive element on a separate magnetomotive force source for magnetic bias such as a permanent magnet, so that the rotor field magnet is It is necessary to perform processing such as providing a relative difference in the amount of magnetic bias applied to the magnetoresistive element between the north pole and the south pole.

However, as long as the element is processed to enable rotor sacrifice detection in this way, the Hall element can be replaced with a magnetoresistive element in the explanations of the first, second, and third embodiments above. I can do it. As explained above, according to the present invention, the magnetic flux generated by the field magnet, which is a source of magnetomotive force, can be used as an energy source for detecting the rotational speed of the motor, and a plurality of magnetically sensitive elements that receive this magnetic flux can be used as an energy source. By creating density and density in the magnetic flux passing through the magnetic flux using a magnetic flux changing means, and by rectifying each output from these multiple magnetic sensing elements, it is possible to extract a frequency component proportional to the rotation speed of the motor. There is no need to provide rotation detection means.

Therefore, the motor configuration can be made smaller. Furthermore, when the magnetic flux passing through the magnetically sensitive element is made to be dense or dense by the magnetic flux changing means, the output of the magnetically sensitive element is amplified by the amplifying means, and the output from the amplifying means is used to control the input control current to the magnetically sensitive element. None, as a result of which the output of at least one magnetically sensitive element is amplified in a positive feedback manner. Therefore, since the gain of the AC component having a frequency proportional to the rotational speed of the motor increases, stable rotational speed detection is performed. Furthermore, a stable signal can be obtained for simultaneous rotor position detection.

[Brief explanation of drawings]

Figures 1a, b and c are top views, side views and circuit diagrams showing a first embodiment of the invention, Figure 2 is a circuit diagram showing a second embodiment of the invention, and Figures 3a and 3 are diagrams showing a second embodiment of the invention. b is a circuit diagram and characteristic diagram explaining the principle of the Hall element, FIG. 4 is a waveform diagram explaining the operation of the motor in FIGS. 1 to 3, and FIG. 6 is a waveform diagram for explaining the operation of the motor in FIG. 5. In the figure, 1 is a disk, 2 is a rotor field magnet, and 3 is a stator. Magnetic path material, 101 to 103 are Hall elements, P1, Q1, P2
, Q2 and P3, Q3 are Hall elements 101 and 1, respectively.
These are the output terminals of 02 and 103. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 1 Figure 3 Figure 2 Figure 4 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. A magnetic flux source on a rotating body and magnetized into multiple poles;
A soft magnetic material that is fixed integrally with the magnetic flux source and has unevenness of equal pitch in the rotational circumferential direction at a pitch shorter than the magnetization pitch of the magnetic flux source to partially change the magnetic flux of the magnetic flux source to be denser or denser. a magnetic flux changing means, a plurality of magnetic sensing elements for detecting the magnetic flux of the magnetic flux source, which is located on a stationary body at a position facing the magnetic flux changing means and is partially changed in density by the magnetic flux changing means; A rotation signal detection device comprising means for rectifying and adding the outputs of the plurality of magnetic sensing elements to obtain a rotation speed signal generated by the magnetic flux changing means. 2. Claim 1, wherein the input current supply amount of the plurality of magnetic sensing elements is controlled by the current supply means in response to the output of the means for extracting the rotational speed signal.
The rotation signal detection device described in .