JPH01174914A - System for correcting detection error of resolver - Google Patents

Abstract

PURPOSE:To enhance the detection accuracy of a position by correcting the position detection error of a resolver, by a method wherein the position correcting data corresponding to an angle of rotation is operated and stored on the basis of the position detection signal of the resolver when an electromotor is rotated at a constant speed and read when the electromotor is controlled to perform correction. CONSTITUTION:In an electromotor control apparatus, a resolver 108 is used as a rotary position detector. The position detection signal of a position detection circuit 102 when a motor 107 is rotated at a constant speed is converted to a speed signal by a differentiator 103. The deviation signal of this signal with a speed order is outputted as the signal corresponding to speed deviation by a speed controller 104 and amplified by a power amplifier 106 to become the drive signal of the motor 107. Further, the position correcting data corresponding to a rotary position is operated from the differentiation signal from the differentiator 103 to be stored in the memory of a memory compensation device 105. At the control time of the motor 107, the position correcting data corresponding to the position detection signal is read to perform correction and the data after correction is used as a position signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resolver detection error correction method in a motor control device using a resolver as a rotational position detector.

[Conventional technology]

In electric motor control, it is necessary to detect the rotational position in order to obtain the positional deviation between the old position and the actual rotational position of the electric motor. One of these rotational position detection means is a resolver. A resolver is a rotating electric machine in which a stator has a primary winding (excitation winding) and a rotor has a secondary winding (detection winding).

FIG. 5 shows the configuration of a general resolver that measures displacement by detecting a phase difference.

In FIG. 5, 201 is an excitation circuit of the resolver 202;
203 is a detection circuit. In the excitation circuit 201, excitation signals α and β having a phase difference of 90° are applied to the two excitation windings 21 and 22 of the resolver 202. Resolver 202
outputs a detection signal γ having a phase difference proportional to the amount of displacement of the moving body from the detection winding 23. The detection circuit 203 outputs a position detection signal θ based on the phase difference between the excitation signal α and the detection signal r.

[Problem that the invention seeks to solve]

By the way, the resolver detection signal should ideally be the same sine wave as the excitation signal, but due to the influence of the shape of the core, material properties of the core, shape of the winding, gap, etc.
The detected waveform may be modulated depending on the rotation of the shaft.

If such modulation occurs, the detected waveform will be distorted, making it impossible to accurately detect the position. Therefore, there are problems in that an error occurs in absolute positioning, and a speed ripple occurs when the position signal is used as a detected speed.

The present invention has been made in view of such conventional problems, and an object of the present invention is to improve the accuracy of position detection by correcting the position detection error of the resolver.

[Means for solving problems]

In order to achieve this objective, the resolver detection error correction method of the present invention, in a motor control device using a resolver as a rotational position detector, differentiates the position detection signal of the resolver when the motor is rotated at a constant speed. From the differential signal,
Position correction data corresponding to the rotational position is calculated and stored in a memory, and when controlling the motor, the position correction data corresponding to the position detection signal of the resolver is read out from the memory and corrected, and the corrected data is It is characterized by being used as a position signal.

[Effect]

FIG. 1 is a control block diagram for removing resolver ripples according to the present invention. In the figure, 101 is the resolver 1
08 is an excitation circuit, 102 is a resolver position detection circuit, and the rotor of the resolver 1 [1B is coupled to the rotating shaft of a motor 107. A position signal output from the position detection circuit 102 is converted into a speed signal by a differentiator 103. The deviation signal between the speed signal and the speed command ω1 is generated by the speed controller 1.
04, and a signal corresponding to the speed deviation is output. The signal is amplified by the power amplifier 106, and the motor 1
07 drive signal.

109 represents the inertial load of the motor 107.

The present invention is characterized in that a compensator 105 is provided which includes a memory for storing correction data.

In FIG. 1, when the inertial load 109 is large relative to the rotor inertia of the motor 107 body and the gain of the speed controller 104 is set small, the frequency characteristics of speed control are suppressed low. In a multi-pole resolver, the highest degree of speed ripple is the ripple that appears as much as the number of pole logs in one rotation, but the frequency characteristic of speed control is set to be sufficiently smaller than the ripple in the number of pole logs during a constant rotation.

Now, assuming that the detection position of the resolver 108 is 06, the detection characteristic of the resolver 108 can be expressed by the following equation.

θ, = θ + E θ. 5in (np θ)
・ ・ ・ (At this point, p:
Number of resolver pole pairs n: Harmonic order θ0: Position error
θ: With the speed control settings mentioned for true position light, the motor is hardly affected by the detection characteristics and rotates at a nearly constant speed.

However, the detected speed signal δ6 is expressed by the following equation including ripple.

+! j d = d + p θacos (p θ>−
f) ・ ・ −(2nd this(
2) The second term on the right side of the equation (higher order abbreviation) is the ripple component.

FIG. 2 is a graph showing part of the detected speed, detected position, and position error during constant speed rotation of the motor.

Here, the speed measurement error 6d-6 and the position error θd-θ
is a sine wave with a phase difference of 90°, and points A6, A I+ r, etc. in the figure are points where the detected value and the true value match. Therefore, since the value of θ0 is calculated based on the velocity error amplitude, the relationship between the detected position θ6 and the true value θ is determined as a function of 06. If the reference point is set to AI, the relationship between θd and θ will be as shown in FIG. 3, and if this relationship is determined in advance, the correspondence between the detected value and the true value can be determined. That is, the compensator 10 of FIG.
The compensation data is stored in the position detector 102.
A value obtained by adding compensation corresponding to the detected position θ6 detected in is outputted to the differentiator 103 as a position signal.

In the case of a multi-pole resolver, this correction may be repeated for the number of pole pairs in one rotation of the mechanical angle. For subsequent control, this corrected detection value is used. In this case, the gain settings of the speed control system, the inertial load, etc. can be set to arbitrary values since the compensation data has been collected.

Furthermore, when considering not only the fundamental wave of n=1 but also harmonics, calculations may be performed by adding the order of the harmonics to equation (2).

〔Example〕

Hereinafter, the present invention will be specifically described based on embodiments shown in the drawings.

FIG. 4 shows a motor speed control system using a microprocessor to which the present invention is applied. In FIG. 4, 501 is a microprocessor processing unit, 5o2 is a correction data calculation unit,
503 is a differentiator. Further, 504 is a memory storing the resolver position detection characteristics, 5o5 is a block representing the resolver position detection characteristics, and 506 is a speed control section. In the figure, the broken line represents the signal path during correction data collection, and the double line represents the signal path during normal operation.

First, when collecting correction data, the initial setting of the speed command ω9 is set to a constant value. In addition, the inertia J is set to be large enough to be unaffected by torque ripple during constant speed rotation.When the motor speed ω matches the speed command ω4, the inertia J is compensated according to the procedure explained in the [Operation] section. The data is calculated and stored in the memory 504.

An example of compensation data in memory 504 is shown in the following table.

In this example, compensation is performed by quantizing 1 electrical angle as 100.

In the table above, the in-memory table stores the value of θ at the memory address corresponding to θ.

After saving the compensation data, set the conditions for normal operation. That is, the proportional gain K of the speed control section 506 is adjusted so that the inertia is maintained at the state during normal operation and the frequency characteristics of the speed control loop shown in FIG. 4 are increased.
Set l, and an integral time constant T, . The subsequent control is
This is done using corrected detection values.

If it becomes necessary to re-collect data due to environmental temperature, changes over time, etc., the desired characteristics can be ensured by repeating the above method.

Note that a nonvolatile memory is used as the memory 504,
In environments where large temperature changes do not occur, there is no need to re-collect data.

〔Effect of the invention〕

As described above, in the present invention, based on the resolver position detection signal when the electric motor is rotated at a constant speed,
Position correction data corresponding to the rotation angle is calculated and the data is stored in the memory.

When controlling the electric motor, position correction data corresponding to the position detection signal of the resolver is read out from the memory and corrected, and the corrected data is used as the position signal. As described above, according to the present invention, position detection characteristics can be significantly improved by simply adding simple calculation and memory functions to a control circuit using a conventional resolver. Furthermore, by re-collecting memory data, it is possible to flexibly respond to changes in characteristics due to temperature or aging.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a graph showing an example of detected speed, detected position, and position error.
FIG. 3 is a graph showing the relationship between detected positions and true values, FIG. 4 is a block diagram showing the structure of an embodiment of the present invention, and FIG. 5 is a block diagram showing the general structure of a resolver. 101: Excitation circuit 102: Position detection circuit 10
3: Differentiator 104: Speed controller 105: Compensator 106: Power amplifier 107: Motor 108: Resolver 109: Inertial load
ω0: Speed command 501: Microprocessor processing unit 502: Correction data calculation unit 503: Differentiator 504; Memory for storing resolver position detection characteristics 505: Block representing resolver position detection characteristics 506: Speed control unit Patent applicant Yasuyo Co., Ltd. Electrical Manufacturing Representative
Person Masu Kobori (2 idiots) Figure 1 Rendo Sairei ω1 Figure 4 Figure 2

Claims (1)

[Claims] 1. In a motor control device that uses a resolver as a rotational position detector, the position detection signal of the resolver is differentiated when the motor is rotated at a constant speed, and position correction data corresponding to the rotational position is calculated from the differentiated signal. and storing the same in a memory, and during motor control, position correction data corresponding to the position detection signal of the resolver is read out from the memory and corrected, and the corrected data is used as the position signal. Error correction method.