JP2865219B2 - Position detection device using resolver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for detecting the position and angle of a machine tool or the like using a resolver.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of a conventional position detecting device using a resolver, FIG. 4 is a timing chart thereof, and FIG. 5 is a flowchart for explaining the operation of the microcomputer. The excitation synchronizing signal TE is sent from the timing generation circuit 14 to the excitation voltage generation circuit 13, and the excitation voltage E1 is generated by the excitation voltage generation circuit 13 and sent to the resolver 11. The resolver 11 is connected to a rotating shaft (not shown) and includes an excitation winding WE, two-phase detection windings WA (A phase), and WB (B phase). A phase winding W
The electromotive voltages VA and VB generated in the A and B phase windings WB are sent to analog / digital converters 16 and 17 (hereinafter A / D). In the A / Ds 16 and 17, the timing generation circuit 1
4, the analog voltage VA,
VB are sampled, and digital values DA, D
B is sent to the microcomputer 28. Here, assuming that the current flowing through the exciting winding WE is i, when the angle θ between the exciting winding WE and the winding axis of the A-phase winding WA, A
The digital values DA and DB of the electromotive voltages generated in the phase windings WA and B-phase windings WB can be expressed as shown in Expressions 2 and 3.

[0003]

(Equation 2)

(Equation 3) Here, M is the maximum value of the mutual inductance between the exciting winding WE and the A-phase winding WA (or the B-phase winding WB). The microcomputer 28 calculates the angle θ by calculating the equations 4 to 11 based on the A / D conversion end signal TM sent from the timing generation circuit 14 (step S1) (step S2).

[0004]

(Equation 4)

(Equation 5)

(Equation 6)

(Equation 7)

(Equation 8)

(Equation 9)

(Equation 10)

[Equation 11]

[0005]

In the above-described position detecting device using the conventional resolver, when the excitation frequency is increased, the output waveforms such as the voltages VA and VB shown in FIG.
If the sampling is to be performed at a place where the voltage change is small, the sampling is performed when the current i is flowing through the exciting winding WE. As can be seen from Equations 2 and 3, the excitation winding WE
When the current i flows through the voltage VA and VB, the voltage VA and VB have a drawback that a voltage component which causes an error with the resolver speed dθ / dt and the current i flowing through the exciting winding WE and the angle θ as variables is generated. Also, if the input voltage range of the A / D has a margin for the increment of this voltage component, there is a problem that the detectable resolution is reduced. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a position detection device using a resolver having no detection error and high detection resolution.

[0006]

Means for Solving the Problems The present invention provides a resolver having an excitation voltage generator for generating an excitation voltage of one phase, the winding and detection winding to be excited by the excitation voltage generation unit of the one-phase A position detecting device that obtains a position from a voltage generated in the detection winding; and the object of the present invention is to obtain a speed from the position and obtain the resolution from the speed.
This is achieved by providing a means for correcting the offset of the position, which is an error component caused by the speed , or a control means for controlling the amplitude of the excitation voltage according to the speed obtained from the position.

[0007]

In the present invention, the speed is obtained from the position, and the error component generated by the speed is corrected by the coefficient which is the ratio between the obtained speed and the derivative of the exciting current and the exciting current. Thus, highly accurate position detection is possible. Also,
Since the excitation voltage is controlled so that the amplitude of the voltage generated in each phase winding varies depending on the current and speed flowing through the excitation winding, the input voltage range does not exceed the A / D input voltage range. Can be used to the maximum, so that a higher-resolution position detecting device can be obtained.

[0008]

FIG. 1 is a block diagram showing an example of a position detecting apparatus using a resolver according to the present invention, corresponding to FIG. 3, and FIG. 2 is a flowchart for explaining the operation of the microcomputer. Note that the functions and processes of the components denoted by the same reference numerals as those of FIG. 3 described in the related art are the same, and thus description thereof will be omitted. The exciting voltage E1 sent from the exciting voltage generating circuit 13 is proportionally controlled by the exciting voltage control circuit 19 in accordance with the exciting amplitude command value EO given from the microcomputer 18 and sent to the resolver 11 as the exciting voltage E2. The microcomputer 18 reads the digital values DA and DB according to the A / D conversion end signal TM (step S11). Here, when k and ε that define Equations 12 and 13 are defined and substituted into Equations 2 and 3, Equations 14 and 15 are obtained.

[0009]

(Equation 12)

(Equation 13)

[Equation 14]

(Equation 15) According to the addition theorem, Equations 14 and 15 become Equations 16 and 17 respectively. Therefore, the angle θ ′ obtained by substituting Equations 16 and 17 into Equations 4 to 11 becomes Equation 18 (Step S1).
2) Includes an angular error ε expressed by Equations 12 and 13.

(Equation 16)

[Equation 17]

(Equation 18) Here, the angle error ε is as shown in Expression 19 from Expressions 12 and 13.

[Equation 19] Therefore, the exciting current i and its differential value di / dt are obtained in advance and set to Equation 20.

(Equation 20) In addition, the sample period ts and the previously calculated angle θ
1 and θ2 which is the angle θ calculated two times before, the speed V
(Dθ / dt) is expressed as in Expression 21.

(Equation 21) The angle error ε obtained by substituting Equations 20 and 21 into Equation 19 is substituted into Equation 18 and transformed into Equation 22 (Step S13).

[0010]

(Equation 22) Therefore, the angle θ without error can be obtained by performing the operation of Equation 22 by the microcomputer 18. Here, when k is obtained from Expressions 12 and 13, Expression 2 is obtained.
3 and from Equations 16 and 17, this k is equal to the voltage V
It can be seen that the amplitudes of A and VB are k.

(Equation 23) Thus, when the amplitudes of the voltages VA and VB when the speed V is zero is divided by the amplitudes when the speed V is not zero, Equation 24 is obtained.

(Equation 24) Here, since the above values indicate the reciprocal of the ratio at which the amplitudes of the voltages VA and VB change according to the speed V, the change in the amplitudes of the voltages VA and VB is suppressed by controlling the excitation voltage in proportion to this value. Can be. Therefore, in the present invention, the microcomputer 18 is caused to perform an operation as shown in Expression 24,
By outputting the result to the excitation voltage control circuit 19 as the excitation amplitude command value EO, it is possible to suppress a change in amplitude (steps S14 and S15). Although the example in which the excitation voltage is a rectangular wave has been described here, the excitation voltage may be a sine wave, pulse excitation, or another waveform.

[0011]

As described above, according to the position detecting device using the resolver of the present invention, since the error component generated by the speed is corrected, the position can be detected with high accuracy. Further, since the input voltage range can be used to the maximum without exceeding the A / D input voltage range, a position detecting device with higher resolution can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a position detection device using a resolver of the present invention.

FIG. 2 is a flowchart showing a process performed by a main part of the apparatus of the present invention.

FIG. 3 is a block diagram showing an example of a conventional position detecting device using a resolver.

FIG. 4 is a timing chart for explaining the operation of the conventional device.

FIG. 5 is a flowchart showing a process performed by a main part of the conventional device.

[Explanation of symbols]

 19 Excitation voltage control circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 7/00-7/34 G01D 5/245

Claims (4)

(57) [Claims] And 1. A excitation voltage generator for generating an excitation voltage of one phase, wherein and a resolver having a winding and detection winding to be excited by the excitation voltage generation unit of one phase, the detection winding In a position detecting device that obtains a position from a generated voltage,
The speed is determined from the position, and the resolver is determined from the speed.
A position detecting device using a resolver, comprising: means for correcting an offset of the position, which is an error component generated by speed . 2. The resolver according to claim 1, wherein an offset of said position is corrected by subtracting tan ^-1 (PV) calculated by said speed V and a coefficient P obtained in advance from said position. Position detection device using 3. An exciting voltage generating section for generating an exciting voltage, and a resolver having a winding excited by the exciting voltage generating section and a detecting winding, and a position is obtained from a voltage generated in the detecting winding. A position detecting device using a resolver, characterized in that the position detecting device includes control means for controlling the amplitude of the excitation voltage in accordance with the speed obtained from the position. 4. The control means obtains a value of Equation 1 calculated by the speed V and a coefficient P obtained in advance. 4. The position detecting device using a resolver according to claim 3, wherein said position detecting device is means for controlling the amplitude of said exciting voltage in proportion to this value.