JPS6312914A - Rotary position detector - Google Patents

Abstract

PURPOSE:To eliminate a phase error component by arranging grooves of two poles of a stator shifted by a prescribed angle so that they face rotor teeth in mutually opposite phase relation, and putting output signals corresponding to the grooves together differentially. CONSTITUTION:The stator 1 has plural poles provided at a prescribed interval in a circumferential direction and a rotor 2 which faces the poles across a gap has plural projection and recess teeth arranged at equal intervals in the circumferential direction. Then the respective poles are varied in magnetic resistance by variation in the correspondence between the respective poles of the stator 1 and respective teeth as the rotor 2 rotates, and currents are induced accordingly at coils L1 and L2 provided on the side of the stator 1. This stator 1 is provided with poles A1-A6 and B1-B6 in pole groups A and B arranged at equal intervals. Then, the respective poles in the pole groups A and B shift by a prescribed angle corresponding to the teeth of the rotor 2 and correspond to each other in mutually opposite phase relation. Then the output signals of the groups are synthesized differentially into an output signal which excludes the influence of a phase error component upon an AC signal phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phase-type rotational position detector, and more particularly to an improvement in a detector that provides a rotor with uneven teeth and detects a rotational position with high resolution.

[Conventional technology]

A multi-tooth variable mountain resistance rotary position detector in which a plurality of concave and convex teeth are provided around the rotor to produce a plurality of cycles of magnetic resistance changes in each type of stator per rotation is disclosed in Japanese Patent Application Laid-Open No. 57-88317. It is shown in the specification of No. As an example of such a detector, as shown in FIG. 6, there is a detector equipped with a six-pole stator 1 and an eight-tooth rotor 2. In this detector, stator poles A1 arranged at 60 degree intervals
+B1 +C1 The correspondence between each type and the rotor teeth is such that the magnetic resistance changes are sequentially shifted by 120 degrees (in this case, one cycle of magnetic resistance change, or 360 degrees, is the rotational displacement of one rotor tooth pitch). ), and stator poles A2 arranged at 60 degree intervals.
+ B2 + "The correspondence between each type and the rotor teeth in 2 is such that the magnetic resistance changes are sequentially shifted by 120 degrees. Therefore, Al and A2 are in phase, B1 and B2 are also in phase, and C1 and C2 are also in phase. Here,
Excite the primary coils of Al and A2 with sinωt,
The primary coils of Bl and B2 are sin (ωt-120°
), and the primary coils of C1 and C2 are excited by sin (ω
t 240' ) and by combining various secondary coil output signals, approximately Y=Ksin(ω t −N θ >
- Output signal Y expressed by the formula <1>
can be obtained. Here, K is a constant, N is the number of teeth of the rotor 2, and θ is the rotation angle. Phase in output signal Y [Problem to be solved by the invention] In such a device, the magnetic resistance change in each type is expressed by a simple trigonometric function (for example, sin N
θ), but includes errors of the second harmonic (sin2Nθ) or the third harmonic (sio3Nθ). In a hexapole type detector, the third harmonic magnetoresistance error is eventually canceled out (for example, see Utility Model Application Publication No. 59-161023), but the second harmonic magnetoresistance error remains. Furthermore, when the primary side is driven at a constant voltage, the excitation current fluctuates due to changes in impedance, and a second harmonic error occurs accordingly. Due to the existence of such a double wave error, the phase shift component in the final output signal Y is simply a linear function Nθ with respect to θ as shown in the above equation.
Instead, it contains an error component of the third harmonic as shown in equation (2) below. Note that e is a coefficient of an error component.

Y = K sin (ωt-Nθ+e sin 3
Nθ)...(2) This invention was made in view of the above points, and improves position detection accuracy by eliminating the above-mentioned phase error component in a rotational position detector equipped with a multi-toothed rotor. The purpose is to improve.

[Means for solving problems]

The present invention provides a stator including a plurality of poles provided at predetermined intervals in the circumferential direction, and a plurality of protrusions and recesses arranged at predetermined equal intervals in the circumferential direction, facing various types of the stator through gaps. A rotor that includes teeth and changes the various magnetic resistances by changing the correspondence between the various stator types and the teeth according to a given rotation, and a rotor that generates an induced current according to the magnetic resistance of the various stator types. In the phase-type rotational position detector comprising a coil provided on the stator side, the configuration of poles in the stator is
a first pole group consisting of a plurality of poles provided at predetermined equal intervals; and a second pole group consisting of the same number of poles provided at equal intervals as the number of poles in the first pole group; 1
The arrangement of the pole group and the second pole group are shifted by a predetermined angle so that they correspond to each other in opposite phases with respect to the rotor teeth, and the output signals corresponding to each pole group are differentially combined. It is characterized by producing a final output signal.

[Effect]

Assuming that the output signal obtained from the coil corresponding to the first pole group is Yl and the output signal obtained from the coil corresponding to the second pole group is Y2, since both are in opposite phase, the sign of their respective amplitude values is is of opposite polarity and the phase error also appears in opposite phase, so from equation (2) above, Y+ = Ksin(ω t −N θ + e st
n 3 N θ ) ・ (3 N Y2= Ks
in(ωt-Nθ-e sin 3 Nθ)...(4)
It can be expressed as Output signal of both groups Y1゜Y
2 are differentially (that is, subtractively) combined, the final output signal is Yl − Y2 = Ksin(ωt−Nθ+e sin
3 Nθ)(-Ksio (ωt-Nθ-e sin
3 Nθ))=2 Ksin(ωt-Nθ)cO3(e
sin3Nθ)...(5). In the above formula, cO5 (esin3Nθ) is “1
” or a value close to it, and 2Ksin(ωt-N
The amplitude of θ) is slightly changed, but the phase is not affected. Therefore, the above equation (5) is substantially the same as the above equation (1) in its phase component. In this way, an output signal is obtained in which the phase error component esin3Nθ is substantially canceled. It goes without saying that phase error components other than the third harmonic can also be canceled out in the same manner.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a rotational position detector according to the present invention. The stator 1 of this rotational position detector has equal intervals (
In other words, six poles Al- arranged at 60 degrees each
A first pole group consisting of A6 and six poles B1 to B6 equally spaced (i.e. 60 degrees apart).
A second pole group is provided consisting of. Rotor 2
has convex rotor teeth with 16 pitches at equal intervals (i.e. 2
Each term Al-As of the first pole group and each Bl# of the second pole group are provided at intervals of 2.5 degrees).
B, respectively, are rotor teeth 1-! - are offset by an angle corresponding to the pitch (i.e. 33.75 degrees). With this arrangement, as is clear from the figure, the first pole group and the second pole group correspond to each other in opposite phases with respect to the rotor teeth.

Incidentally, only the pole A1 is given a reference numeral, and the others are omitted, but in FIG. 1, various A of the stator 1 are shown.

~A6 + A primary coil Ll and a secondary coil -L2 are wound around B1 and B6, respectively.

Next, the detection principle of this rotational position detector will be explained.

Ideally, the function of the change in magnetoresistance of the various A1 to A6 of the first pole group, that is, the function of the permeance PA1 to PA6 with respect to the rotation angle θ of the rotor 2, is as follows.

In the formula, the unit of angle is "degree", N is the number of teeth of the rotor 2, and PO+P1 is a constant.

Pole Al, the primary signal of A4 is Eal, and pole A2.

The primary signal of A5 is Ea2, and the primary signal of pole A3 + 86 is Ea3, and these are set as follows.

That is, each pole group is excited by an alternating current signal having a phase shift corresponding to the phase shift of its magnetoresistive change. In addition, the primary signals E31 to Ea3 of various A1 to A6
The polarity of is set so that the magnetic circuit passes from one pole to the other within the pole group.

If we calculate the composite value Yl of the output signals induced in the secondary coils of various types A and -A of the first group under the conditions of equations (6) and (7) above, ideally the ) should be Yl=Ksin(ωt-Nθ), but as mentioned above, the phase error of the third harmonic is actually included, so Yl is actually the equation (32 As shown in the equation, Yl = Ksin (ωt-Nθ+esin3Nθ).

On the other hand, the functions of the permeances PB1 to PB6 of the poles B and -B of the second pole group are as follows since the first pole group and the second pole group are in opposite phase.

PB□=PB4=Po+P1sln (Nθ-180°)
= Po−P, sin Nθ PBz””PBs=P+)+P1sin(Nθ−120
°-180') = P o-P 1s+n (Nθ-1
20') PB3==PB6=PO+P1sin(Nθ
-240°-1800)" Po -Pl sin (
Nθ-240') The primary signals of poles B1 and B4 are Eb,
, the primary signal of pole B2°B5 is Eb2, and pole B
3. The primary signal of B6 is Eb3, and these are set as follows.

” bl= E a1=sin ωt Eb2=Ea□=sin(ωt-120°) Eb3=E
a,=s1n(ωt-2400) Subject to the above formula,
When calculating the composite value Y2 of the output signals induced in the secondary coils of various B1 to B6 in the second group, ideally it should be Y2 = -Ksin (ωt - Nθ) as described above. , as mentioned above, actually contains the phase error of the third harmonic wave with the opposite phase to Yl, so Y2 is expressed as Y2 = -Ksin (ω t -N θ -e) as in (4) above.
sin 3 N θ ).

The output signals Yl r Y 2 of each group are differentially combined and the phase error component e 5 is calculated as shown in equation (5) above.
An output signal Y is generated that eliminates the influence of in3Nθ on the AC signal phase.

Y=Yl-Y2=2Ksin(ωt-Nθ) cos
(e 5in3Nθ) The AC component in the output signal Y obtained in this way is sin
(ωt−Nθ), and the electrical phase shift amount with respect to the reference AC signal sinωt is Nθ. In this way, the phase shift Nθ in the final output signal Y becomes a linear function with respect to the rotation angle θ of the rotor 2, and does not include an error component. As is clear, this electrical phase shift angle Nθ is the actual rotation angle θ multiplied by the number of teeth (in Fig. 1, N=
16 times), and the resolution is expanded.

Figures 2 and 3 show various AI-A6+Bl of each group.
- Fig. 6 shows examples of the connections of the primary coil L1 of B6. With this connection, by simply using two alternating current signals sinωt and sio (ωt-60) with a phase shift of 60 degrees, it is possible to generate three AC signals with a phase shift of 120 degrees as in equation (7).
two AC signals “a1~”33+,”bI~El)
3, which can excite the primary coil of a predetermined pole.

Figures 4 and 5 show various types of A1 to A, B, of each group.
-B6 respectively show connection examples of the secondary coil L2. In FIG. 4, the secondary coil connections of the first group and the second group are connected in reverse phase series, and in FIG. 5, the secondary coil connections of both groups are connected in reverse phase parallel connection. In either case, the output signal Y1 of the first group and the output signal Y2 of the second group are differentially combined so that Y, -Y2 are obtained as the final output signal Y.

The finally obtained output signal Y is supplied to a phase shift measuring circuit (not shown), where the phase shift Nθ is measured, and data corresponding to the rotation angle θ of the rotor 2 is determined by the phase shift measurement.

In the above embodiment, the primary signal Ea□ of the first pole group
~Ea3 and the primary signals Eb1 to Eb3 of the second pole group
are in phase, and the composite value Yl of the output signals in the first pole group and the composite value Y2 of the output signals in the second pole group are subtractively synthesized.
Exactly the same result can be obtained even if a3 and Eb1 to Eb3 are set to have opposite phases, and Yl and Y2 are added and combined.

Further, in this embodiment, the first pole group and the second pole group each consist of six poles, the rotor teeth have a pitch of 16, and the arrangement of the first pole group and the second pole group is the same as that of the rotor teeth. 1-! - the number of poles in a pole group, the number of pitches of the rotor teeth, the arrangement of the first and second pole groups, although they are offset by an angle corresponding to the pitch;
It is not limited to this. The point is that the first pole group consists of a plurality of poles arranged at predetermined equal intervals, and the second
The pole group consists of the same number of equally spaced poles as the first pole group, and the first pole group and the second pole group
It is only necessary that the pole groups are arranged at a predetermined angle so that they correspond to the rotor teeth in opposite phases.

〔Effect of the invention〕

As mentioned above, according to the rotational position detector according to the present invention,
Since the phase error component can be removed from the output signal, it is possible to further improve the position detection accuracy when detecting the rotational position according to the phase shift between the output signal and the reference AC signal. .

[Brief explanation of drawings]

FIG. 1 is a radial cross-sectional view showing one embodiment of a rotational position detector according to the present invention, and FIGS. 2 and 3 show examples of connections of various primary coils of the rotational position detector of FIG. 1, respectively. Figure shown, 4th
5 and 5 are diagrams showing connection examples of various secondary coils of the rotational position detector of FIG. 1, respectively, and FIG. 6 is a typical example of a conventional long-tooth variable magnetic resistance type rotational position detector. FIG. 3 is a radial cross-sectional view. 1. Stator, 2.. Rotor, A1 to A6... 1st
Pole group, Bl"""'B8...Second pole group, Ll...Primary coil, "2...Secondary coil. Figure 4 Figure 5

Claims (2)

[Claims] 1. The stator includes a plurality of poles arranged at predetermined intervals in the circumferential direction, and a plurality of uneven teeth arranged at predetermined equal intervals in the circumferential direction, facing each pole of the stator with a gap therebetween. , a rotor that changes the magnetic resistance of each pole by changing the correspondence between each pole of the stator and the teeth according to a given rotation; and a rotor for generating an induced current according to the magnetic resistance of each pole of the stator. A rotational position detector comprising a plurality of coils provided on the stator side and generating an output signal whose phase is shifted from a predetermined reference AC signal according to the rotational position of the rotor, The configuration includes a first pole group consisting of a plurality of poles provided at predetermined equal intervals;
a second pole group consisting of the same number of equally spaced poles as the poles of the pole group;
The arrangement of the pole groups is shifted by a predetermined angle so that they correspond to each other in opposite phases with respect to the rotor teeth, and the output signals corresponding to each pole group are differentially synthesized to generate the final output signal. A rotational position detector characterized in that: 2. The first pole group and the second pole group each consist of six poles, the rotor teeth have a pitch of 16, and the arrangement of the first pole group and the second pole group is 11/2 of the rotor teeth. The rotational position detector according to claim 1, which is shifted by an angle corresponding to the pitch.