JPS645204Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an output error correction device for a variable magnetic resistance type position detection device.

For example, as shown in FIG. 1, a variable magnetic resistance type position detection device has a stator 1 with a plurality of poles A, B,
C, D, and primary coils 2A to 2 for each pole A to D.
D and secondary coils 3A to 3D are wound around the poles A to D, and the reluctance of each pole A to D is changed according to the rotation angle θ of a rotor (for example, an eccentric rotor) 4. Primary coils 2A to 2D and secondary coil 3
The circuit configuration of A to 3D is as shown in Figure 2, for example, where the paired poles A and C and B and D are individually connected to sine waves and cosine waves to bring about differential reluctance changes. And the voltages e _A to e _D induced in each of the secondary coils 3A to 3D by being excited in the opposite phase.
are added and synthesized to obtain a secondary output signal E. As shown in FIG. 1, if the rotation angle θ when the eccentric rotor 4 is closest to the pole D is 0 degrees, the permeance of each pole A to D with respect to a change in the rotation angle θ is
It can be expressed as sinθ, -cosθ, and cosθ. Therefore,
The secondary output signal E ideally includes a phase shift corresponding to the rotation angle θ as follows: E=e _A +e _C −e _B −e _D =Ksin(ωt−θ) (1). This detailed analysis is shown in Japanese Patent Application No. 147425/1982. However, in reality, mechanical angle (rotation angle) and electrical angle (output signal E
(phase shift) is not easily the same, and an error occurs. At this time, most of the error occurs between each pole in the pole pair set to bring about a differential reluctance change as follows.

{e _A +e _C = −Kcosωtsinθ+Δe _AC −e _B −e _D =Ksinωtcosθ+Δe _BD } ...(2) Here, Δe _AC is the error voltage generated at one pole pair A, C, and Δe _BD is the other pole pair B , D. Therefore, the secondary output signal E
contains errors as follows.

E = Ksin (ωt - θ) + Δe _AC + Δe _BD ... (3) The reason why such an error occurs is that the bias voltages of the induced voltages e _A to e D of each pole A to _D are not uniform, and it is inevitable that As a result, the difference between these bias voltages appears as an error voltage.

The object of this invention is to provide a device capable of correcting the above-mentioned error in the output signal in a variable magnetoresistive position detection device.

An embodiment of this invention will be described below with reference to the accompanying drawings.

Similarly to FIG. 2, FIG.
～D primary coil 2A～2D and secondary coil 3A～
This figure shows a 3D circuit configuration, and this idea includes balanced variable resistors BVR1 and BVR2 installed in parallel with secondary coils 3A, 3C and 3B, 3D corresponding to pole pairs A, C and B, D, respectively. This corresponds to such an error correction device. With this configuration, each of the secondary coils 3A to 3D is provided with an adjustable load resistance, and the impedance on the secondary side of each pole A to D changes according to the value of this load resistance. The impedance on the primary side of each pole A to D changes accordingly. Therefore, for one pole pair A, C which is excited by a sine wave, the impedance of the primary coils 2A, 2C can be balanced by adjusting the resistor BVR1. The voltages (bias voltages) applied to the coils 2A and 2C can be changed.
Similarly, regarding the other pole pair B and D excited by the cosine wave, the bias voltages of the primary coils 2B and 2D can be variably adjusted by adjusting the resistor BVR2. In other words, each resistor BVR is adjusted so that the error voltages Δe _AC and Δe _BD are eliminated.
1. Just adjust BVR2.

To show an example of adjustment, first, the rotor 4 (FIG. 1) is positioned at a rotation angle θ=0 degree. In this position,
Since the reluctances of both poles of the pole pair A and C that are excited by a sine wave are equal and are in opposite phase excitation, the induced voltages e _A and e _C of both poles are canceled out, and "e _A + e _C = 0" should be obtained. It is. In addition, the output signal E is only the induced voltages e B and e _D of the pole pair B and _D excited by the cosine wave, and since cos θ = 1 (θ = 0°) in the above equation (2), the output signal E becomes sinωt, and there should be no electrical angle phase shift. Output signal E at this time
(the measurement circuit is not shown), and if the phase shift is not 0, then the pole pair A,
Adjust resistor BVR1 corresponding to C. By doing so, errors regarding the pole pair A and C can be corrected.

Next, the rotor 4 is positioned at a rotation angle θ=90 degrees. At this position, contrary to the above, the induced voltages e _B and e _{D of the pole pair B and D} should cancel each other out, so that "e _B +e _D = 0". In addition, the output signal E is only for "e _A + e _C ", and since sin θ = 1 (θ = 90°) in the above equation (2), the signal E becomes -cos ωt, that is, sin(ωt
-π/2), and the electrical angle phase shift θ should be π/2 (90 degrees). Measure the phase shift of the output signal E at this time, and adjust the resistor BVR2 of the pole pair B and D so that θ=π/2. Thus, polar pair B,
Errors related to D can be corrected.

Note that the variable magnetic resistance type position detection device is not limited to the rotary type as shown in FIG. 1, but may be a linear type. Further, the structure of the rotary detection device is not limited to the one shown in FIG. 1, and there are various structures. In addition, the output error adjustment resistor is not limited to the balanced type;
It may be a variable resistor provided individually in the secondary coils 3A to 3D.

As explained above, this invention has the excellent effect of being able to reliably correct the output error of the variable magnetic resistance type position detection device and contributing to accurate position detection.

[Brief explanation of the drawing]

Fig. 1 is a radial cross-sectional view showing an example of a rotation angle detector using an eccentric rotor as an example of a variable magnetic resistance type position detection device, and Fig. 2 is a general view of the primary coil and secondary coil in Fig. 1. FIG. 3 is a circuit diagram showing an embodiment of the output error correction device according to the invention, and shows an example applied to the circuit of FIG. 2. 1...Stator, A~D...Pole, 2A~2D...
...Primary coil, 3A~3D...Secondary coil, 4...
...Rotor, BVR1, BVR2... Balanced variable resistor.

Claims (1)

[Claims for Utility Model Registration] A plurality of primary coils and two corresponding to each primary coil.
a stator section including a secondary coil; and a movable section that is displaced relative to the stator section and changes the reluctance of the magnetic path passing through the primary coil in accordance with the displacement. In the detection device, the stator section includes a plurality of pairs of poles facing each other in the radial direction at predetermined intervals in the circumferential direction, the primary coil and the secondary coil are wound around each of the poles, and The two primary coils in each pole pair are excited in opposite phases, and by shifting the phase of the excitation signal of the primary coil between each pole pair, the rotational position of the movable part with respect to the stator part is controlled. a balanced variable resistor for adjusting the impedance of the two secondary coils corresponding to each pole pair so that an alternating current signal having an electrical phase shift is obtained on the secondary coil side according to the pole pair; provided for each pair of poles,
An output error correction device for a variable magnetoresistive position detection device, which corrects output errors by adjusting the bias voltage of each secondary coil output using this variable resistor.