JPH0746880A - Signal transmission method for encoder - Google Patents

Abstract

PURPOSE:To allow reduction in the number of transmission lines by converting an encoder signal, representative of the rotational direction, rotational speed, and pole position, into a three-value variable signal before being transmitted on a transmission line. CONSTITUTION:A rotational speed signal of an AC servo motor, including the rotational direction thereof, is converted into a three-valued variable signal, representative of a low voltage level (L), a high voltage level (H), and a high impedance state (ZH), before it is transmitted on a transmission line. The uppermost waveform represents phase A of the rotational speed signal comprising a two-value variable signal of L and H detected by an encoder. The intermediate waveform represents the phase Z signal, i.e., a two-value variable signal of L and H detected by the encoder. The lowermost waveform represents a three-value variable signal produced from the uppermost and the intermediate waveforms. The lowermost waveform requires only one transmission channel and includes the information of phases A and Z of the two-value variable signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission method of an encoder for knowing a rotation speed including a rotation direction of the AC servo motor and a magnetic pole position when the AC servo motor is controlled at a variable speed.

[0002]

2. Description of the Related Art According to a conventional encoder signal transmission method, a low voltage level detected by the encoder, that is, a low level (L) and a high voltage level, that is, a high level (H ), The binary variable signal is transmitted as it is to the transmission line for transmitting the signal as a binary variable signal of a low voltage level, that is, a low level (L) and a high voltage level, that is, a high level (H). ,
The rotation speed signal including the rotation direction and the magnetic pole position signal are individually transmitted.

[0003]

In the conventional method, since the amount of information transmitted per transmission line is a maximum of two values, the number of transmission lines is increased in order to transmit a desired rotation speed and magnetic pole position signal. There was a problem. An object of the present invention is to provide a signal transmission method for an encoder that reduces the number of transmission lines.

[0004]

In order to solve the above problems, in an encoder for an AC servo motor, in the first invention, a rotation speed signal including the rotation direction of the AC servo motor is transmitted to a transmission line at a low voltage level, that is, Low level (L)
And a high voltage level, that is, a high level (H) and a high impedance state, that is, a high impedance state (ZH). The position signal is converted into a signal of a ternary variable of L, H, and ZH on the transmission line and transmitted, and in the third invention, a rotation speed signal including the rotation direction of the AC servomotor and a magnetic pole position signal. Is converted into a signal of a ternary variable of L, H, and ZH on a transmission line and transmitted.

[0005]

According to the first aspect of the present invention, the rotation speed signal including the rotation direction of the AC servo motor is transmitted to the transmission line by L, H and Z.
In the conventional method, the number of transmission lines is three channels (A phase,
What was required for the B phase, the origin) is possible with the number of transmission lines of 2 channels, and according to the second invention,
The magnetic pole position signal of the AC servo motor is sent to L and H on the transmission line.
In the conventional method, three channels (U-phase, V-phase, W-phase) were required by converting the signals into three-value variable signals of ZH and ZH and transmitting them. According to the third invention, the rotation speed signal including the rotation direction of the AC servomotor and the magnetic pole position signal are converted into a signal of a ternary variable of L, H and ZH on the transmission line. By transmitting, in the conventional method, the number of transmission lines is 6 channels (A phase, B
Phase, origin, U-phase, V-phase, W-phase) is required with four channels of transmission lines.

[0006]

FIG. 1 is a waveform diagram for explaining the first embodiment of the present invention. In FIG. 1, (a) shows the A-phase signal of the rotation speed signal including the rotation direction of the AC servo motor, and shows the waveform of the binary variable signal of L and H detected by the encoder. (B) shows the Z-phase signal, and shows the waveform of the binary variable signal of L and H detected by the encoder. (C) shows the waveform of the transmission line in the signal of the ternary variable of the present invention generated from the signal waveforms of (A) and (B), and the number of transmission lines transmitting the waveform of (C) is 1 channel. The waveform of (c) is A phase and Z in the signal of the binary variable.
Includes phase signal information.

FIG. 2 is a waveform diagram for explaining the second embodiment of the present invention. In FIG. 2, (a) shows the U-phase signal of the magnetic pole position signal of the AC servo motor, and shows the waveform of the binary variable signal of L and H detected by the encoder. (B) shows a V-phase signal, which is a waveform of a binary variable signal of L and H detected by the encoder. (C)
Indicates a W-phase signal, and shows a waveform of a binary variable signal of L and H detected by the encoder. These magnetic pole position signals (U phase, V phase, W phase) have a phase relationship of 120 degrees in electrical angle. (D) and (e) are (a), (b) and (c)
3 shows a waveform of a transmission line with a signal of a ternary variable of the present invention generated from the signal waveform of FIG. U for binary variable signals
Phase, V phase, W phase signal (U, V, W) = (L, L, H),
(H, L, H), (H, L, L), (H, H, L),
There are 6 types of (L, H, L) and (L, H, H). These are the signal (d) of the ternary variable as the X signal, (e) as the Y signal,
In the order of (U, V, W), (X, Y) = (ZH,
L), (H, L), (H, H), (ZH, H), (L,
H) and (L, L), the number of transmission lines may be two channels.

FIG. 3 is a waveform diagram for explaining the third embodiment of the present invention. In FIG. 3, (a) shows the A-phase signal of the rotation speed signal including the rotation direction of the AC servomotor, and shows the waveform of the binary variable signal of L and H detected by the encoder. (B) shows the B-phase signal, and shows the waveform of the binary variable signal of L and H detected by the encoder. The phase A signal and the phase B signal have a phase relationship of 90 degrees. (C) shows the U-phase signal of the magnetic pole position signal of the AC servomotor, and shows the waveform of the binary variable signal of L and H detected by the encoder. (D) shows a V-phase signal, and shows a waveform with a binary variable signal of L and H detected by the encoder. (E) shows a W-phase signal, and shows a waveform of a binary variable signal of L and H detected by the encoder.
These magnetic pole position signals (U phase, V phase, W phase) have a phase relationship of 120 degrees in electrical angle.

(F), (to), and (h) are signals of the three-valued variable of the present invention generated from the signal waveforms of (a), (b), (c), (d), and (e). Shows the waveform of the transmission line at, and the number of transmission lines for transmitting the waveforms of (f), (to), and (h) may be 3 channels, and the waveforms of (f), (to), and (h) may be 2 A-phase, B-phase, U-phase, V-phase, and W in the signal of the value variable
Each signal information of the phase is included.

Although not shown in FIG. 3, as an encoder of the AC servo motor, in addition to the above signals, Z
Since a phase signal is also required, a total of four channels of transmission lines are required in the third invention. Further, the conversion from the binary variable signal to the ternary variable signal in the embodiments of FIGS. 1, 2 and 3 shows one combination example and one conversion example, and is not shown. Of course, a combination example and a conversion example are also possible.

[0011]

According to the present invention, the encoder signal for knowing the rotational speed including the rotational direction of the AC servomotor and the magnetic pole position is converted into a signal of three-valued variables of L, H and ZH on the transmission line for transmission. By converting and transmitting, the number of transmission lines can be reduced, which can contribute to wiring saving of the control device, improvement of reliability, and cost reduction.

[Brief description of drawings]

FIG. 1 is a waveform diagram illustrating a first embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating a second embodiment of the present invention.

FIG. 3 is a waveform diagram illustrating a third embodiment of the present invention.

[Explanation of symbols]

 L …… Low level H …… High level ZH …… High impedance

Claims (3)

[Claims] 1. An encoder for an AC servo motor, wherein a rotation speed signal including a rotation direction of the AC servo motor is converted into a signal of a ternary variable of low level, high level and high impedance and transmitted to a transmission line. And encoder signal transmission method. 2. An encoder for an AC servo motor, characterized in that a magnetic pole position signal of the AC servo motor is converted into a signal of a ternary variable of low level, high level and high impedance and transmitted to a transmission line. Signal transmission method. 3. In an encoder for an AC servo motor, a rotation speed signal including a rotation direction of the AC servo motor and a magnetic pole position signal are converted into a signal of a ternary variable of low level, high level and high impedance on a transmission line and transmitted. A signal transmission method for an encoder, comprising: