JPH05207775A - Servo unit - Google Patents

Abstract

PURPOSE:To halve the number of signal lines by providing a first switch to be controlled by phase A, B, Z signals and a second switch to be controlled by phase U, V, W signals and then turning the switches ON/OFF so that H signals of phase A, B, Z are subjected to amplitude modulation by the phase U, V, W signals. CONSTITUTION:First switch groups 11-31 being controlled with outputs from an optical encoder 1, i.e., phase A, B, Z signals, is connected in series with a second switch group 12-32 being controlled with magnetic pole position signals, i.e., phase U-W signals. Phase U, V, W signals are superposed on phase A, B, Z signals depending on the ON/OFF states of the switch groups 11-31, 12-32 and transmitted on connecting lines to a servo controller 2. In the servo controller 2, comparison is made with respective reference values at first and second comparator groups 15-35, 16-36 in order to detect phase A, B, Z signals and PHA;SE' U, V, W signals and the outputs from the second comparator group 15-36 are made valid only when the outputs from the first comparator group 15-35 are H.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a U-phase, V-phase which is required when a permanent magnet type synchronous motor is applied to a servo motor.
Encoders that output the magnetic pole position signals of the W-phase and W-phase, the A-phase and B-phase signals required for positioning and speed detection, and the Z-phase signal that is the origin signal. The present invention relates to a servo device including a servo control device (servo controller) that controls a servo motor.

[0002]

2. Description of the Related Art Conventionally, in a servo apparatus driven by a permanent magnet type synchronous motor, encoders are used for A phase, B phase, and Z phase.
It is general to detect each of the phase, U-phase, V-phase, and W-phase signals and transmit them to the servo controller using six transmission lines.

[0003]

[Problems to be Solved by the Invention]
6 for transmitting phase, B phase, Z phase, U phase, V phase, W phase signals
Since the book transmission line is used, the number of circuits, cables, connectors, etc. required for the transmission increases, which not only increases the cost but also reduces the reliability. Further, there is a problem that a large amount of work is required when the servo device is first assembled. Therefore, an object of the present invention is to reduce the number of wires between the servo motor and the servo controller to reduce the cost and improve the reliability.

[0004]

In order to solve such a problem, in the first invention, a servo device including an encoder and a servo control device for controlling a servo motor based on an output from the encoder, The encoder receives high-level signals of A-phase, B-phase, and Z-phase indicating the origin position, which signals are composed of high-level and low-level signals and which are obtained through the detector of the encoder, through the detector of the encoder. The servo control device is provided with transmission means for amplitude-modulating each of the U-phase, V-phase, and W-phase magnetic pole position signals obtained as described above and transmitting the three encoder signals. A first comparator group that detects an A-phase signal, a B-phase signal, and a Z-phase signal by comparing the value with a value;
U phase, V compared with the second reference value which is larger than the reference value of
A second comparator group for detecting respective phase and W-phase signals, and validating means for validating the output of the second comparator group corresponding to the second comparator group only when the output of the first comparator group is at a high level It is characterized by having and.

In a second aspect of the invention, the transmission means of the encoder in the first aspect of the invention is provided with an A phase signal, a B phase signal and a Z phase signal.
A first switch group consisting of three switches that are turned on / off according to the low level and high level of the phase signal, and similarly turned on according to the low level and high level of the U-phase signal, V-phase signal and W-phase signal, A second switch group consisting of three switches to be turned off is connected in series, and the other of the first switch group connected in series is grounded, and the other of the second switch group is also connected via a current limiting resistor. Connected to a power supply, and a resistor is connected in parallel to each switch of the second switch group to extract the encoder signal from the connection point of the first and second switch groups connected in series. Is characterized by. In the third invention, in the second invention,
When the first switch group is turned on, a gate means is provided for turning off the second switch group connected in series with the first switch group.

In the fourth invention, the transmission means of the encoder in the first invention is turned on according to the low level and the high level of the A phase signal, the B phase signal and the Z phase signal.
A first switch group consisting of three switches that are turned off,
Similarly, a second switch group including three switches that are turned on and off according to the low level and the high level of the U-phase signal, the V-phase signal, and the W-phase signal, and each of the second switch group. Connect a resistor in series with the switch,
This is connected in parallel with the first switch group, one of which is grounded and the other is connected to a power source through a resistor, and a connection point of the first and second switch groups connected in parallel with the resistor. It is characterized in that the encoder signal is taken out from.

[0007]

[Function] Magnetic pole position signals U phase, V phase, W phase signals are A phase, B phase
Since the A-phase, B-phase, and Z-phase signals are at a low level for a shorter period of time than the phase and Z-phase signals, the magnetic pole position signals U-phase, V-phase, and W-phase signals are Phase B
When the phase and Z phase signals are at high level, they are superimposed, that is, A
High-level signals of phase B, phase B, and phase Z for magnetic pole position signal U
By performing amplitude modulation with the phase, V phase, and W phase signals, the number of transmission lines can be reduced to half of the conventional one. Also, A phase, B
Phase and Z phase signals are low level, magnetic pole position signals U phase, V phase,
During the period in which the W-phase signal is not superimposed, the magnetic pole position detection value is not changed (the previous value is held) so that the magnetic pole position can be continuously detected.

[0008]

1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is an encoder, 2 is a servo controller, which are connected by two power lines (P, N) and three signal lines (A ', B', Z '). Encoder 1
Is a first switch group 11, 21, 31 such as a transistor which is turned on / off by A-phase, B-phase and Z-phase signals,
It is composed of second switch groups 12, 22, 32 which are turned on and off by magnetic pole position signals U-phase, V-phase and W-phase signals, and resistors 13, 23, 33 which are short-circuited when the second switch group is turned on. It Here, when the first switch group is turned on, the transmission signals A ′, B ′, Z ′ are connected to 0V of the power source. On the other hand, when the second switch group is turned on, the resistors 13, 23, 3
3 is short-circuited, and if the first switch group is off at this time, the potentials of A ′, B ′ and Z ′ are subtracted from the power supply voltage V _{D by} the voltage drop of the resistor 4 due to the turning on of the second switch group. V _D ′, and the voltage V _D ′ is divided by the resistors 13, 23, 33 on the encoder 1 side and the receiving resistors 14, 24, 34 on the servo controller 2 side by turning off the second switch group. The resistor 4 is a current limiting resistor provided in case both the first and second switch groups are turned on.

The operation of FIG. 1 will be described with reference to FIG. 2 (a) to (f) show outputs of a sensor (not shown) of A-phase, B-phase, Z-phase, U-phase, V-phase, and W-phase signals. Since it is widely known as an optical encoder, its details are omitted,
It is assumed that the signals shown in (a) to (f) are input to the encoder shown in FIG. Now, assume that the first and second switch groups in FIG. 1 are turned on when the input signal is at a low level, the resistance values of the resistors 13, 23, 33 and the resistors 14, 24, 34 are equal to each other, and the current limiting resistance is It should be a sufficiently large value for 4. As a result, the output signals A ′, B ′, Z ′ from the encoder 1 are 0 V as shown in (g) of FIG.
And a three-valued signal of V _D '/ 2 and V _D '. The voltage becomes 0 V when the first switch group is on and the A-phase signal, the B-phase signal, and the Z-phase signal are at the low level. V
_D '/ 2 is when both the first switch group and the second switch group are off, the A phase signal, the B phase signal, and the Z phase signal are at the high level, and the U phase signal and the V phase signal , W phase signal is also at high level. Therefore, the signal voltage of the encoder V _D 'V by dividing by equal resistance to _D' /
It becomes 2. On the other hand, V _D 'becomes when the first switch group is off and the second switch group is on, the A-phase signal, the B-phase signal, and the Z-phase signal are at high level, and U
This is a case where the phase signal, the V phase signal, and the W phase signal are at the low level.

As is clear from (g) to (g) of FIG. 2, thresholds are provided between 0 V and V _D '/ 2, V _D ' / 2 and V _D ', and each signal is It can be seen that the states of the A-phase signal to the W-phase signal can be detected by comparing with these threshold values. Therefore, in this embodiment, the following is performed. First, in the servo controller 2, as a receiving circuit,
The first reference voltage V1 between V and V _D '/ 2 is set, and the first comparator is composed of three comparators 15, 25 and 35 for comparing the reference voltage V1 with the A', B ', Z'signals. Comparator group 5 and reference voltage V2 between V _D '/ 2 and V _D '
Is set, and a second comparator group 6 including three comparators 16, 26, and 36 for comparing the A ′ signal, the B ′ signal, and the Z ′ signal with each other is provided.

In the first comparator group 5, V _D '/ 2
0V or V _D '/ by comparing with smaller V1
Determine if it is 2 or more. That is, it can be seen that the first comparator group 5 can detect whether or not the first switch groups 11, 21, 31 are turned on, that is, the A-phase signal, the B-phase signal, and the Z-phase signal. The output of each comparator is shown in FIG.

[Outer 1]

[Outside 2]

[Outside 3] On the other hand, in the second comparator group 6, 'by comparing the / 2 greater than V2, V _D' V _D 'to determine, thereby V _D' / 2 or less or V _D in case of the second It is detected that the switch groups 12, 22, 32 are turned on, and it can be seen that the U-phase signal, the V-phase signal, and the W-phase signal are at the low level.

By the way, when the first switch group is turned on,
Since the A ′ signal, the B ′ signal, and the Z ′ signal are 0 V regardless of the second switch group, detection in this case cannot be performed, and
Comparators 16, 26, 36 of the comparator group 6 of
The outer 4, outer 5, and outer 6 signals that are the outputs of FIG.
The part that cannot be detected, such as (Y), is output as a low level. This becomes remarkable especially when combined with the A-phase signal and the B-phase signal as in (W) and (F).

[Outside 4]

[Outside 5]

[Outside 6]

Therefore, when these signals are low level by using the signals of outer 1, outer 2 and outer 3 shown in (nu) to (e) of FIG. 2, that is, when the first switch group is turned on. The output of the second comparator group 6 is invalidated and the previous value is retained. The specific configuration is shown in FIG. This is composed of three latch elements 17, 27 and 37, and is commercially available, for example, as TTL 7475. The input / output relationship (truth table) is shown in FIG.
Shown in. That is, the latch circuit 7 includes the latch element 17,
When the gate signal G for 27 and 37 is at the high level, the input signal D is output as it is, and when it is at the low level, the output value before the low level is held regardless of the input signal.

Therefore, the gate signal of the latch circuit 7 is used as the first to third outer signals and the input signal is the fourth to sixth outer signals.
In order to match the logic with the original U-phase to W-phase signals,
When the following signals from the outside 7 are used as the respective inverted outputs of the latch element, the latch circuit 7 outputs (ta), (re),
It can be seen that the outer 8, outer 9, and outer 10 signals shown in (S) are obtained.

[Outside 7]

[Outside 8]

[Outside 9]

[Outside 10] In addition, in FIG.
The latter is delayed when compared with the signal of (1), but this is because the change point of the A-phase signal and the change point of the U-phase signal generally do not match. Therefore, the signals of the outer 8 and the outer 9 are the maximum of a half cycle of the A-phase signal and the B-phase signal, respectively, and the outer 1
The 0 signal causes a detection error only in the low level section of the Z-phase signal, but these are sufficiently smaller than the U-phase to W-phase signals. Considering how these signals are used, practically no There is no problem.

FIG. 4 shows another embodiment of the present invention. This shows only one phase of the encoder 1, and the same parts as those in FIG. 1 are designated by the same reference numerals. As is clear from the figure, the current limiting resistance is omitted and the NAND gate 18
The feature is that is added. This current limiting resistance is the first
This is necessary when the switch 11 and the second switch 12 are turned on at the same time, and since the U-phase signal and the A-phase signal are unrelated to each other, such a mode always exists. However, when the first switch 11 is turned on by the A-phase signal, the signal of the outside 1 of the encoder 1 becomes the second switch 12
It becomes 0V regardless of ON or OFF of. Therefore, here, when the first switch 11 is turned on, the second switch is always used.
So that the switch 12 of the NAND gate 1 is turned off.
8 is provided to give a high level signal to the second switch 12. From the above, the encoder 1 shown in FIG. 1 uses the magnetic pole position signals U-phase to W-phase for each signal of A-phase to Z-phase.
The phase signals are superimposed and transmitted, that is, the high-level signals of the A phase to Z phase are amplitude-modulated by the U phase to W phase signals and transmitted, and the servo controller 2 demodulates them to transmit the encoder 1 and the servo. It can be said that the number of signal lines between the controllers 2 is reduced.

FIG. 5 is a block diagram showing still another embodiment of the present invention. Here, a first switch group 1 which is turned on / off at low level and high level of A phase, B phase, and Z phase
1, 21 and 31 are resistors 14 on the servo controller 2 side,
24 and 34 are connected in series, the other of the switch groups is grounded, and the resistor group is connected to the power supply side. This is a signal transmission method generally called an open collector method. Now, assuming that the signal is low level and the switch turns on, A
When the phase, B phase, and Z phase signals are at low level, A ',
The B'and Z'lines are also grounded and become low level. On the other hand, it is connected in series with the resistors 13, 23 and 33, and the U phase, V phase, W
The second switch group 12, 22, which is turned on and off by the phase signal,
32 is connected in parallel to the first switch group 11, 21, 31. By doing so, the encoder signals of the A ′, B ′, and Z ′ lines can be changed by turning on and off the second switch group only when the first switch group is off. That is, when the U-phase, V-phase, and W-phase signals are at a low level and the second switch group is turned on, the signal voltage from the encoder is the resistors 14, 2 on the servo controller side.
4, 34 and the resistors 13, 23, 33 on the encoder side are determined by the voltage division ratio, and if the resistance values are the same as in FIG.
It is half of the power supply. As a result, the encoder signal is
(G), (H), (L), and demodulation can be performed in the same manner as in the case of FIG. However, the encoder signals in FIG. 5 are the same as (G), (H), and (L) in FIG.
The difference is that the relationship between V _D 'and V _D ' / 2 is reversed.

[0017]

According to the present invention, the first switch controlled by the A-phase, B-phase and Z-phase signals and the second switch controlled by the U-phase, V-phase and W-phase signals are connected in series. Alternatively, since they are connected in parallel and the high-level signals of the A phase, B phase, and Z phase are amplitude-modulated by the U phase, V phase, and W phase signals by turning them on and off, the number of signal lines from the encoder It is possible to halve the number from 6 to 3, and it is possible to reduce cost and improve reliability. Further, when the first switch and the second switch are connected in series and the second switch is not turned on when the first switch is on, the short circuit of the power supply in the encoder is eliminated and the short-circuit limit is eliminated. The flow resistance is not required, and the loss can be greatly reduced, and the voltage drop due to the current limiting resistance is eliminated, so that the detection accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a waveform chart of each part for explaining the operation of FIG.

FIG. 3 is a partial configuration diagram showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a relationship between a latch circuit and its input / output signals.

FIG. 5 is a configuration diagram showing still another embodiment of the present invention.

[Explanation of symbols]

1 ... Encoder, 2 ... Servo controller, 4, 13,
23, 33, 14, 24, 34 ... Resistors, 5, 6 ... Comparator group, 7 ... Latch circuit, 11, 12, 21, 22, 22
31, 32 ... Switch, 15, 16, 25, 26, 3
5, 36 ... Comparator, 17, 27, 37 ... Latch element, 18 ... NAND gate

Claims (4)

[Claims] 1. A servo device comprising an encoder and a servo control device for controlling a servo motor based on an output from the encoder, wherein the encoder includes a detection part of the encoder which is composed of a high level signal and a low level signal. A-phase, B-phase, and Z-phase high-level signals obtained via the encoder are respectively amplified by U-phase, V-phase, and W-phase magnetic pole position signals obtained via the encoder detection unit. The servo control device detects the A-phase signal, the B-phase signal, and the Z-phase signal by comparing the encoder signal with a first reference value while providing a transmission unit that modulates and transmits as three encoder signals. Detecting U-phase, V-phase, and W-phase signals by comparing a first comparator group and the encoder signal with a second reference value that is larger than the first reference value A second comparator group and a validating means for validating the output of the second comparator group corresponding to the second comparator group only when the output of the first comparator group is at a high level. Servo device. 2. A first switch group consisting of three switches that turn on and off the transmission means of the encoder according to the low level and high level of the A-phase signal, the B-phase signal and the Z-phase signal, and the same U switch. Turns on and off according to the low level and high level of the phase signal, V phase signal and W phase signal 3
A second switch group consisting of two switches is connected in series, and the other of the first switch groups connected in series is grounded, and the other of the second switch group is also connected to the power source via a current limiting resistor. And a resistor is connected in parallel to each switch of the second switch group, and the first and second switches connected in series are connected.
The servo device according to claim 1, wherein the encoder signal is taken out from a connection point of the switch group. 3. A gate means is provided for turning off the second switch group connected in series with the first switch group when the first switch group is turned on.
Servo device described in. 4. A first switch group including three switches that turn on and off the transmission means of the encoder according to the low level and high level of the A-phase signal, the B-phase signal, and the Z-phase signal, and the same U switch. Turns on and off according to the low level and high level of the phase signal, V phase signal and W phase signal 3
And a resistor connected in series to each switch of the second switch group, which is connected in parallel with the first switch group, one of which Is grounded and the other is connected to a power source via a resistor, and the encoder signal is taken out from a connection point of the first and second switch groups connected in parallel with the resistor. Servo device.