JPS604425B2 - rotation detection device - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a device that stably detects the rotational speed and rotational direction of a rotating machine simultaneously or individually without any time delay. Various rotational speed detection devices have been proposed for use in constant speed control of rotating machines and in measuring the rotational speed of rotating machines. It has the disadvantage that the proportional output value includes ripples or that the far response is insufficient. Furthermore, detection of the rotational direction also has the same drawbacks as above. The object of the present invention is to eliminate the above-mentioned drawbacks and to minimize ripples and time delays. The details of the present invention will be explained below with reference to the drawings. In the drawings, the same functions or the same members are given the same reference numerals. A conventional example is shown in FIG. 1a. As the rotating machine 1 rotates, a frequency signal is generated from the generator 2 and input to the amplifier 3. The output signal of the amplifier 3 is inputted to a waveform shaping circuit 4, converted into a rectangular wave, triggers a monostable multivibrator 5, and the output signal of the monostable multivibrator 5 is smoothed by an integrating circuit 6. The smoothed relatively small signal is converted into a large signal to drive the next stage by the DC amplifier 7 and drives the rotational speed indicator 8. Further, if the rotating machine 1 is a DC motor, for example, if the DC amplifier 7 has a built-in reference voltage generation circuit and a comparison circuit for comparing the reference voltage and the smoothed signal from the integrating circuit 6, the motor The supply voltage can be controlled and the rotation speed can be kept at a desired constant value. FIG. 1b shows signal waveforms of various parts of the conventional example, and shows how the rotational speed gradually increases. If the source signal from the generator 2 is sinusoidal, the output signal waveform of the amplifier 3 will be S, and after waveform shaping it will be S2. When the monostable multivibrator 5 is triggered at the rising edge of the rectangular signal S2, the output signal waveform of the monostable multivibrator 5 becomes a pulse waveform in which the repetition period T decreases by 4 as time t increases, as shown in S3. The signal S4 is a flat version of the pulse waveform S3,
The voltage is gradually increasing. In the conventional example, the speed change is detected using the signal S.
3, the repetition period is T. Therefore, it is necessary to hold the previously detected value before the arrival of the next pulse waveform, and it is impossible to detect a speed change at least in the hold period. As a result, the final stage signal becomes stepwise as shown in S4, and as a result, it includes ripples. Furthermore, since there is a repetition period T, there is a drawback that the time delay tends to become large. The time delay and the content of ripple components in the signal become particularly noticeable when the rotation speed is low, that is, when the repetition period T is large. For this reason, in electric motors that require low-speed rotation control, special equipment is used to increase the frequency generated per unit time from the speed signal generator corresponding to generator 2, which is expensive and complicated. It becomes. For example, a magnetic head can obtain signals from a rotating body that has been coated with a magnetic coating with high accuracy over the entire area, or an inductance element can be applied to a rotating body that is equipped with a magnetic body that has a large number of mechanical convex poles. There is a device in which devices having two types of inductance are placed opposite each other so that changes in inductance can be extracted as changes in voltage. The present invention does not require the above-mentioned complicated configuration, is therefore inexpensive, and is capable of detecting the rotation speed and rotation direction without time delay with extremely small ripples even during ultra-low speed rotation, as shown in Fig. 2a. A block diagram of the embodiment is shown in FIG. In FIG. 2a, the magnet 11 rotates in a negative relationship with the rotating machine 10, and has a plurality of magnetic poles (in this figure, 8 poles are divided into 8 poles, which are alternately magnetized). The inductance element 12 and the magnetoelectric conversion element 13 are under the magnetic field of the magnet 11, and are arranged at a predetermined distance Qo from the magnet 11 (1/2 of the width of one magnetic pole in this figure, that is, 22.5 degrees). ing. Figure 2b shows the magnetization curve for one pole (vertical axis is magnetic flux density B, horizontal axis is electrical angle 8).
Here, within the S pole, there is a sine magnetization curve B-1 in an interval from 0 degrees to 180 degrees. In the Oka diagram, the electrical angle difference between the magnetoelectric conversion element 13 and the inductance element 12 is 90 degrees. The output signal of the inductance element 12 is amplified by an amplifier 14 to become a signal V2. On the other hand, the output signal of the magnetoelectric conversion element 13 is amplified by an amplifier 15 to become a signal V. The signals V and V2 are individually input to two input terminals of a divider 16, which is an arithmetic unit that executes division, and a signal Vo is output. The signal Vo is now the quotient of V and V2, and its value is V2/V in this case. After the signal Vo is input to the DC amplifier 17, it drives the rotational speed indicator 18. Further, if the rotating machine is a controlled electric motor, the voltage supplied to the electric motor can be controlled in the same manner as explained in the prior art example, and the rotating machine rotates at a constant speed. Here, assuming that the attachment curve of one magnetic pole of the magnet 11 is a sine wave, as the magnet 11 rotates, the change in the magnetic flux density B becomes a trigonometric function including a time element. That is, if time is t, the change in magnetic flux density B over time is B=A.・T of sin can be expressed by [1]. However, Ao is a constant and Ao is the angular velocity. By the way, since the magnetoelectric conversion element directly converts the change in magnetic flux density into a voltage and outputs it, the time change of the output voltage e of the magnetoelectric conversion element is equivalent to the above equation [1], and t of el A, Sin... [2]. However, A is a constant. Furthermore, since the amplifier 15 outputs a voltage V, which is proportional to the e, the voltage V, is V,=
A.・sin wt...[3]. However, A is a constant. Next, the output voltage e2 of the inductance element is determined. Now, the inductance element is a coil that is in the magnetic field of the magnet and has two straight sections (outward path and return path each having a length L) in the direction of the magnet, and the opening of the two straight sections. Assuming that the angle is 3, when the phase difference between the coil center and the magnetoelectric transducer is 90 electrical degrees (T/2), when the magnet 11 rotates in the direction of arrow D, the magnetic flux penetrating the coil surface decreases. = Sha-A. -Sin becomes side t-----[4]. Therefore, when L=1, the coil output voltage e2 is e2i-etc.=false/Sin/...t of Sm...[5-a], where 2,A. , Sin is all constant, so it is secret. If XSin is a new tr constant, the formula [5-a] becomes e2 ni A3,
■, t of Sin...[51b]. Also, the output voltage V2 from the amplifier 14 is equivalent to the formula [5-b], and t of V2 minus A4, ・Sin of
...[6]. A4 is a constant. From the above, the quotient Vo of V and V2 is V. =etc.=Ayun・etc.S device n thing t=sha・■-----[7
], and if the constant A4'A, is K, then V. As shown in [8], Vo is proportional only to the angular velocity. On the other hand, when the magnet 11 rotates in the direction opposite to the arrow D, the above [51a]
The formula is:

[9] is changed. e2=-dimo et al=
-Secretion.・Sin is small Sm... [9-a] Therefore, the output voltage V2 from the amplifier 14 is changed to V2 by changing the equation [6].
2 knees A4●. t of Sin becomes [91b], so that the quotient Vo becomes V. =-Young Yo; Fresh-canned. ...---[10] And since A4/A,=K, in the end, V. Ni-K. of... like [11] [8
] Generates a negative voltage whose absolute value is equal to the equation. The value here is, if the number of rotations of the magnet 11 is M rotations per second and the number of magnetic poles is m, then ■ = 2 shore f = 2 m - tube - M = shore - m - M .・・・． ...[12] becomes. However, f is the frequency. The reason why m is divided by 2 is that a pair of N and S poles constitutes one cycle of the sine wave. As described above, the output Vo takes a value proportional only to the rotation speed, and at the same time, it is possible to determine whether the rotation is normal or reverse based on the positive or negative voltage. By the way, in the case of general dividers, since many of them prohibit the numerator and denominator from taking negative values at the same time, an embodiment in which the numerator and denominator always take a positive value will be described in FIG.
A block diagram is shown in FIG. 3a, where the inductance element 1
2 and the outputs e2 and e of the Shiro conversion element 13 are the amplifier 1.
4 and 15, the signal V2 shown in FIG.
, V, is the same as in FIG. 2 above. The sine wave signals V, , V2 are so-called alternating current signals that alternately repeat positive and negative values, so in order to always take a positive value of 0 or more, the signals V, , V2 are connected to a full-wave rectifier circuit 20,
30 is input. The output signals from the full-wave rectifier circuits 20, 30 are V, . ,V
22, resulting in a signal waveform as shown in Figure 3b. Here, it is assumed that the rotational speed gradually increases as in the explanation of FIG. Here, there are places where the magnet's magnetization is uneven,
If the magnetic flux density were to decrease at the magnetic pole, the amplitude would decrease as at point P in VI and point P2 in V2 despite the increase in rotational speed. Therefore, the full-wave rectified signal V, . ,V2
Also P,. Points such as point P22 appear where the amplitude decreases. 'The full-wave rectified signals V, . , V22 are inputted to the divider 16 and are converted to Vo, that is, V22/V, . Output the calculated value. The waveform of the signal Vo becomes a direct current voltage proportional to the rotational speed without pulsation as shown in FIG. 3b. By the way, the time change in the magnetic flux density B at the location where the magnetic flux density has decreased cannot be expressed by the above equation [1], but the following equation B2A has a changed term indicating the amplitude.・The t of the ship's side, Sin...becomes like [13]. The Buddha is considered a lower rate. As a result, the full-wave rectified signals V, .
, the amplitude of V22 was also indicated by the rate of decline of the aircraft.
Equations 3] and [6] are changed as follows. V,. :fA.・Buddha・sin's tl...[1's V
Shigeru! A4-'s. Buddha. tl of Sin...[15] The absolute value signal in the above equation is due to full-wave rectification. Even though the amplitude term has been changed, the quotient V〇 is v. = Thread IA4. of. Buddha. Sin's tl-EAI. As in tl-shaW skin of Buddha desk n [16], Muko becomes an unrelated value and becomes the same as the formula [7]. Therefore, in FIG. 3M, the signal Vo shows the DC voltage as the rotational speed increases even in the portion where the magnetic flux density decreases. Vo, which is a gradually increasing straight line in Figure 3b, shows places where there are intermittent trigger pulse-like changes.
This is because the output value becomes unstable when the quotient becomes 0/0. However, in principle, the time during which rotation can be zero is 0 seconds, and the parts where the trigger pulse changes as shown in the diagram are not shown in this diagram, and can be ignored in practice. . As mentioned above, according to this embodiment, it is possible to output the rotational speed as a voltage signal without time delay and without including ripple using a general divider, but it is possible to output the rotation speed as a voltage signal without any time delay or ripple. Although it is not possible to detect the direction of rotation in this case due to the presence of the rotational speed, it is extremely effective in detecting the rotational speed. In addition, in FIG. 3, the stage up to the stage that outputs the signal Vo is shown, but "
The steps subsequent to this are the same as those shown in FIG. 2, and will therefore be omitted. Second
According to the explanation in FIG. 3 and FIG. 3, it is assumed that the magnetization curve is a sine wave.
By changing the distance from the magnet 11 along the magnetization direction, it is possible to generate a sine wave response depending on the degree of diffusion of the lines of magnetic force. Therefore, it is clear that even if the magnetization curve itself is not a sine wave, it is sufficient that the signals V, V2 become sine waves as a result. It is also possible to handle the signals V, , V2 with other functions. Now, change the magnetic flux density that changes with time to equation [1] and write Bd A〇. e of t state,. ．． [1
7] and also change the formula [3] to obtain the VI-AI-e [
...If it is [18], then [4] formula [
Rule t Jusenjukai-e■keai-kai...[19] The formula [5-a] becomes ``If L=1, then e2=-published. Shoes t. -Each...[20] Therefore, the formula [6] is, If e love - many - e body + many = A5 (A5 is a constant), then V2 d A5, ■. [21], and in the end, the quotient Vo is V.=Sheep Akimu=Samurai's -...--[22], so A5JA,
=K, then V. NiKIO's. ．． … [23]
Therefore, Vo is proportional to the angular velocity. Therefore, it is also possible to use an exponential function like this.By the way, the opening degree B of the two straight parts of the coil described above is
When it is equal to the opening angle of one magnetic pole, that is, when the electrical angle in Figure 2b is 8; 180 degrees = lamp, then if the magnetic flux density that changes with time is denoted by B (t), the equation [4] is ~ Therefore, the formula [5-a] is expressed as: B(t)・
If d('s t)=F('s t), then -most [F('s t+
Bamboo) - F (t)] t) [: - no -d deficiency;] ......[2
5], and here, in the magnet 11, if the magnetic flux densities of the parts whose phases differ by bamboo (that is, the parts of the same phase in the adjacent poles) are equal (but the polarities are opposite), then t+ of B(
m)=-B(■t), so the formula [25] is e2d2's・B('st), . ．． 、． ．． [26], so the formula [6] is V2 ni A6, ・B(■t
) ... will be changed to [27]. Public is a constant. At this time, V in formula [3] is VI NiA
7.B (mountain t) ......[28], so (
is a constant), and the quotient Vo in formula [7] is V. = Spicy A poisonous effect. A6 = Clothes...'' [29] If A6'A7 = K2, in the end, as in equation [8], V. NiK2.... [30], and Vo is the angular velocity. Here, B (t) is not a particularly specified function, but as mentioned above, the phase difference is proportional to As mentioned earlier, in this case, the opening angle of the straight part of the coil is equal to that in the magnetic pole, so the back electromotive force (magnetic flux) from the armature coil configured with an opening angle equal to that in the magnetic pole (proportional to the product of density and angular velocity)
can be used as a signal for the inductance element. As is clear from the above description, according to the present invention, it is possible to detect the rotation speed and rotation direction of a rotating machine without time delay and without ripples, even from ultra-low speed rotation. In the case of a magnet rotor type motor, the rotor itself may be used as the magnet 11, and if the magnet rotor type motor is a DC machine equipped with a position sensing element, the position sensing element may be used as a magnetoelectric conversion element. Then, the signal V can be obtained from the magnetoelectric conversion element,
It is extremely simple and can be implemented at low cost, and the purpose stated at the beginning is achieved and the effect is remarkable.

[Brief explanation of drawings]

Figure 1 a and b are block diagrams and waveform diagrams of the conventional example, Figure 2 a
is a block diagram of an embodiment according to the present invention, FIG. 2b is a diagram of the relative relationship between the magnetization curve and the detection element, FIG. The waveform diagrams of 1, 10... Rotating machine, 2... Generator, 3, 7,
14, 15, 17... Multiplier, 8, 18...
... Rotation speed indicator, 1 1... Magnet, 12...
...To inductance element, 13... Magnetoelectric conversion element, 16... Divider, 20, 30.
...Full wave rectifier circuit. Younger brother '1 Zero 2nd grandchild 3rd figure

Claims (1)

[Scope of Claims] 1. A magnet having a plurality of magnetic poles that rotates together with the rotating shaft of a rotating machine, a magnetoelectric transducer arranged in the magnetic field of the magnet, and a magnetoelectric transducer arranged at a predetermined interval from the magnetoelectric transducer. It is characterized by being comprised of an inductance element disposed in a magnetic field, and an arithmetic unit that calculates the quotient of a signal proportional to the output voltage of the magnetoelectric conversion element and a signal proportional to the output voltage of the inductance element. rotation detection device. 2. The rotation detection device according to claim 1, wherein the rotating machine is a DC motor, and the magnet is a rotor of the DC motor. 3. The rotation detection device according to claim 1, wherein the magnetoelectric conversion element is a position detection element of the DC motor. 4. Claim 1, wherein during rotation of the magnet, each of the signal proportional to the output voltage of the magnetoelectric conversion element and the signal proportional to the output voltage of the inductance element is a sine wave. The rotation detection device described. 5. Claim 1, wherein during rotation of the magnet, each of the signal proportional to the output voltage of the magnetoelectric conversion element and the signal proportional to the output voltage of the inductance element is an exponential wave. Rotation detection device as described in section.