JPH11271009A - Conversion method for angle of resolver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a conversion method in which the positioning accuracy of a resolver is increased when the frequency of an exciting signal is made low and whose responsivity is increased when the frequency of the exciting signal is made high by a method wherein the rotational-speed signal of a motor connected to the resolver is applied to an oscillation circuit and the exciting frequency of the exciting signal is made variable according to the rotational-speed signal. SOLUTION: When a rotational-speed signal (v) from a motor is input, an oscillation circuit 1 makes variable the frequency of an exciting signal 1a which is output according to the level of an input voltage. When the motor is in a low-speed region, a low frequency is output. When it is in an intermediate-speed region, a frequency which is proportional to its rotational speed is output. When it is in a high-speed region, a high frequency is output. Two-phase resolver outputs 3A, 3B which are output from a two-phase output coil 3b in a resolver 3 are input to a resolver/digital converter 6 so as to be converted into a digital output 6A. Then, when the rotation of the motor is low, the frequency (f) of the exciting signal 1a is low. As a result, the positioning accuracy of the resolver 3 with reference to the motor is increased. When the rotation of the motor is high, the frequency (f) of the exciting coil 1a becomes high. Thereby, the frequency responsivity of the resolver 3 with reference to the motor can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resolver angle conversion method, and more particularly, to a method in which the frequency of an excitation signal is made variable by using a rotation speed signal of a motor connected to a resolver and the positioning accuracy is high when the frequency is low. The present invention relates to a novel improvement for improving the response when a high frequency is set.

[0002]

2. Description of the Related Art Conventionally, as a resolver angle conversion method of this kind, a method shown in FIG. 2 has been employed. That is, in FIG. 2, what is indicated by reference numeral 1 is an oscillation circuit having a constant frequency, and an excitation signal 1a composed of an AC voltage from the oscillation circuit 1 is applied to a one-phase excitation coil 3a of a resolver 3 via an amplifier 2. Have been. The two-phase resolver outputs 3A and 3B output from the two-phase output coil 3b of the resolver 3 are input to the resolver / digital converter 6 via the amplifiers 4 and 5, and are converted to a digital output 6A. The excitation signal 1a from the amplifier 2 is supplied to the resolver / digital converter 6 by a reference signal Ref.
Is entered as

[0003]

Since the conventional resolver angle conversion method is configured as described above, the following problems exist. That is, the accuracy of the resolver changes depending on the frequency of the excitation signal, and the accuracy decreases as the frequency increases. On the other hand, the frequency response of the resolver / digital converter affects the characteristics of the servo system from the viewpoint of controllability, that is, responsiveness. Since the frequency response of the resolver / digital converter is affected by the excitation frequency of the resolver, the higher the excitation frequency, the better the controllability of the servo system. Therefore, in the conventional method, since the excitation frequency is constant, it is impossible to maintain both the accuracy at the time of low speed and the response at the time of high speed at high performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in particular, the frequency of an excitation signal is made variable using a rotation speed signal of a motor connected to a resolver.
It is an object of the present invention to provide a resolver angle conversion method in which the positioning accuracy is high when the frequency is low and the response is high when the frequency is high.

[0005]

According to the resolver angle conversion method of the present invention, an AC voltage from an oscillation circuit is input to a resolver as an excitation signal, and the output voltage of the resolver is adjusted.
In a resolver angle conversion method in which a resolver output of a phase is obtained as a digital angle output by a resolver / digital converter, a rotation speed signal of a motor connected to the resolver is applied to the oscillation circuit, and the rotation speed signal is determined according to the rotation speed signal. The excitation frequency of the excitation signal is made variable.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a resolver angle conversion method according to the present invention will be described below with reference to the drawings. Note that the same or equivalent parts as those in the conventional example will be described using the same reference numerals. In FIG. 1, what is indicated by reference numeral 1 is an oscillation circuit, which is different from the conventional configuration, when a rotation speed signal v from a motor (not shown) connected to a resolver 3 is input, a known circuit is provided. The frequency f of the excitation signal 1a output according to the input voltage level is made variable, so that the motor has a low frequency in the low speed range, a frequency proportional to the rotation speed in the middle speed range, and a high frequency in the high speed range. Is output. The AC voltage of the excitation signal 1a is applied to the differential amplifier 2 connected to the excitation coil 3a.
The current is supplied to the exciting coil 3a through a well-known constant current circuit 22 composed of 0 and a reference power supply 21, and a constant current excitation method is used.

The two-phase resolver outputs 3A and 3B output from the two-phase output coil 3b of the resolver 3 are input to the resolver / digital converter 6 via the amplifiers 4 and 5, and are converted into a digital output 6A. . The excitation signal 1a from the amplifier 2 is input to the resolver / digital converter 6 as a reference signal Ref.

Therefore, in the above configuration, the resolver 3
When the rotation of the motor (not shown) connected to
As shown by, the frequency f of the excitation signal 1a is low, so that the positioning accuracy with respect to the motor is high. When the rotation is high, the frequency f of the excitation signal 1a is high, so that the frequency response to the motor can be increased. .

[0009]

The resolver angle conversion method according to the present invention comprises:
With the above configuration, the following effects can be obtained. That is, since the frequency of the excitation signal is made variable in accordance with the rotation speed of the motor, it is possible to achieve an improvement in positioning accuracy at low speeds and an improvement in responsiveness at high speeds, which were conventionally incompatible. In addition, the performance of the resolver motor can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a resolver angle conversion method according to the present invention.

FIG. 2 is a block diagram illustrating a conventional resolver angle conversion method.

FIG. 3 is a block diagram of a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillation circuit 1a Excitation signal 3 Resolver 3A, 3B Resolver output v Rotational speed signal 6 Resolver / digital converter 6A Digital angle output

Claims (1)

[Claims] An AC signal from an oscillation circuit (1) is used as an excitation signal.
(1a) is input to the resolver (3), and the two-phase resolver outputs (3A, 3B) output from the resolver (3) are input to the resolver /
In a resolver angle conversion method in which a digital converter (6) obtains a digital angle output (6A), a rotation speed signal (v) of a motor connected to the resolver (3) is applied to the oscillation circuit (1). A method of converting the resolver angle, characterized in that the excitation frequency of the excitation signal (1a) is made variable in accordance with the rotation speed signal (v).