JPH0552503A - Position detection device using resolver - Google Patents

Abstract

PURPOSE:To provide a position detection device using a resolver without any detection error and with a high detection resolution. CONSTITUTION:A position is obtained from a voltage which is generated at each phase coil windings WE, WA, and WB by a microcomputer 18. Then, a speed is obtained from the position and then an offset of the position is compensated for. An excitation voltage control circuit 19 controls amplitude of an excitation voltage according to the speed.

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 by 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 its timing chart, and FIG. 5 is a flowchart for explaining the operation of the microcomputer. An excitation synchronization signal TE is sent from the timing generation circuit 14 to the excitation voltage generation circuit 13, and an 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, a two-phase detection winding 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 the analog / digital converters 16 and 17 (hereinafter referred to as A / D). Timing generation circuit 1 for A / D 16 and 17
4 by the sample request signal SH, the analog voltage VA,
VB is sampled and digital values DA and D are sampled.
It is converted to B and sent to the microcomputer 28. Here, when the current flowing through the excitation winding WE is i, when the angle θ between the excitation winding WE and the winding axis of the A-phase winding WA is A
The digital values DA and DB of the electromotive voltage generated in the phase winding WA and the B phase winding WB can be expressed as in Equations 2 and 3.

[0003]

[Equation 2]

[Equation 3] However, M is the maximum value of the mutual inductance between the excitation winding WE and the A-phase winding WA (or the B-phase winding WB). In the microcomputer 28, the A / D conversion end signal TM sent from the timing generation circuit 14 (step S1) is used to perform the operations of the expressions 4 to 11 to obtain the angle θ (step S2).

[0004]

[Equation 4]

[Equation 5]

[Equation 6]

[Equation 7]

[Equation 8]

[Equation 9]

[Equation 10]

[Equation 11]

[0005]

In the position detecting device using the conventional resolver described above, when the excitation frequency is increased, output waveforms such as the voltages VA and VB shown in FIG. 4 are obtained.
If an attempt is made to sample in a place where the voltage change is small, sampling will be performed when the current i is flowing through the exciting winding WE. Excitation winding WE as can be seen from equations 2 and 3
When a current i flows through the voltage VA, there is a drawback that the voltage components VA and VB that cause an error with the speed dθ / dt of the resolver, the current i flowing through the excitation winding WE, and the angle θ as variables are generated. Further, if the margin of the increment of this voltage component is maintained in the A / D input voltage range, there is a problem that the detectable resolution is lowered. The present invention has been made under the circumstances described above, 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]

The present invention has an exciting voltage generating section for generating an exciting voltage, and a resolver having a winding and a detecting winding excited by the exciting voltage generating section,
The present invention relates to a position detecting device for obtaining a position from a voltage generated in the detection winding, and the above object of the present invention comprises a means for obtaining a velocity from the position and correcting an offset of the position from the velocity, or This is achieved by including control means for controlling the amplitude of the excitation voltage according to the velocity obtained from the position.

[0007]

In the present invention, the velocity is obtained from the position, and the error component generated by the velocity is corrected by the coefficient which is the ratio of the obtained velocity and the previously obtained exciting current and the differential value of the exciting current. It becomes possible to detect the position with high accuracy. Also,
Since the excitation voltage is controlled so as to suppress the amplitude of the voltage generated in the winding of each phase from changing due to the current and speed flowing in the excitation winding, the input voltage range does not exceed the A / D input voltage range. Since it can be used to the maximum, a position detecting device with higher resolution can be obtained.

[0008]

1 is a block diagram showing an example of a position detecting apparatus using a resolver of the present invention in correspondence with FIG. 3, and FIG. 2 is a flow chart for explaining the operation of the microcomputer. It should be noted that the functions and processings of the components indicated by the same numbers as those in FIG. 3 described in the related art are the same, and thus the description thereof will be omitted. The excitation voltage E1 sent from the excitation voltage generation circuit 13 is proportionally controlled by the excitation voltage control circuit 19 according to the excitation amplitude command value EO given from the microcomputer 18, and is sent to the resolver 11 as the excitation voltage E2. In the microcomputer 18, the digital values DA and DB are read by the A / D conversion end signal TM (step S11). Here, if k and ε that are the equations 12 and 13 are defined and substituted into the equations 2 and 3, the equations 14 and 15 are obtained.

[0009]

[Equation 12]

[Equation 13]

[Equation 14]

[Equation 15] According to the addition theorem, the equations 14 and 15 become the equations 16 and 17. Therefore, the angle θ'obtained by substituting the equations 16 and 17 into the equations 4 to 11 becomes the equation 18 (step S1
2), includes the angle error ε represented by the equations 12 and 13.

[Equation 16]

[Equation 17]

[Equation 18] Here, the angular error ε becomes as shown in Expression 19 from Expressions 12 and 13.

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

[Equation 20] Further, the sampling period ts and the previously calculated angle θ are θ.
1 and the angle θ2, which is the angle θ calculated two times before, the velocity V
(Dθ / dt) is expressed as in Expression 21.

[Equation 21] When the angular error ε obtained by substituting the equations 20 and 21 into the equation 19 is substituted into the equation 18, the equation 22 is obtained (step S13).

[0010]

[Equation 22] Therefore, the angle θ having no error can be obtained by calculating the equation 22 by the microcomputer 18. Here, when k is calculated from the equations 12 and 13, the equation 2 is obtained.
3 and the k is the voltage V according to the equations 16 and 17.
It can be seen that the amplitudes of A and VB are k.

[Equation 23] Therefore, when the amplitudes of the voltages VA and VB when the speed V is zero are divided by the amplitudes when they are not, the following formula 24 is obtained.

[Equation 24] Here, the above-mentioned value represents the reciprocal of the ratio of the amplitude of the voltages VA and VB changing with the speed V. Therefore, by controlling the exciting voltage in proportion to this value, the amplitude change of the voltages VA and VB can be suppressed. You can Therefore, in the present invention, the microcomputer 18 is caused to perform an operation such as
By outputting the result as the excitation amplitude command value EO to the excitation voltage control circuit 19, it is possible to suppress the amplitude change (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 velocity 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, it is possible to provide a position detecting device with higher resolution.

[Brief description of 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 device 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 a conventional device.

[Explanation of symbols]

 19 Excitation voltage control circuit

Claims (4)

[Claims] 1. An exciting voltage generating section for generating an exciting voltage, and a resolver having a winding and a detecting winding excited by the exciting voltage generating section, 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 means for obtaining a speed from the position and correcting an offset of the position from the speed. 2. The resolver according to claim 1, wherein tan ⁻¹ (P · V) calculated by the velocity V and a coefficient P obtained in advance is subtracted from the position to correct the offset of the position. Position detection device using. 3. An exciting voltage generating section for generating an exciting voltage, and a resolver having a winding and a detecting winding excited by the exciting voltage generating section, 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 comprises control means for controlling the amplitude of the exciting voltage in accordance with the speed obtained from the position. 4. The control means obtains a value of equation 1 calculated by the velocity V and a coefficient P obtained in advance, and The position detecting device using a resolver according to claim 3, which is a means for controlling the amplitude of the exciting voltage in proportion to this value.