JPH0792700B2 - Electric motor controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric motor that drives a rotary shaft, and more particularly to an improvement of a position loop switching system that switches from a speed loop to a position loop.

[Conventional technology]

As a control of an electric motor including an orienting operation for stopping and controlling a rotary shaft at a fixed position, for example, Japanese Patent Laid-Open No. 62-2873
JP-B No. 49-9549 and JP-B No. 46-17853.

FIG. 3 shows a conventional motor control device of this type. In the figure, (1) is an electric motor and (2) is this electric motor (1).
A speed detector attached to the motor, (3) a position detector attached to a rotary shaft driven by the electric motor (1), (4) a speed controller for controlling the electric motor (1), and (5) a The orient control unit for controlling the orient operation, (6) is the speed control unit (4) based on the position command and the position feedback.
Is a changeover switch for switching between a speed command and a position command, and (8) is an orientation changeover switch.

The conventional electric motor control device is configured as described above, and during the speed loop, the speed command is given to the speed control unit (4) through the changeover switch (7), thereby the electric motor (1).
Is driven.

Next, when the orientation command is given, the changeover switch (7) is switched to the lower side in the figure, and the orientation control section (5) performs the orientation operation utilizing the deviation between the origin and the current value. Here, the orientation operation is an operation of controlling the spindle shaft (rotating shaft) to stop at a fixed position when switching from speed control to position control in a machine tool such as a machining center. A Z-phase signal that can detect a position indicates that the Z-axis is stopped at a fixed position. When the distance between the origin position and the current position approaches within the parameter value preset as the allowable range, the stop completion signal of the orientation operation turns on, The stop completion signal switches the orientation changeover switch (8) from the orientation control to the position control. The stopping position at the completion of the orientation operation includes an error less than the parameter set value with respect to the origin position, and the speed control In the middle of switching to position control, find the origin position and return the rotary axis to the origin position. Transition to the control is different from the origin return operation possible.

When the orientation operation is completed, the orientation selector switch (8) is switched to the lower side in the figure, and a position loop is formed with the position at that time as the origin. Subsequent position commands are given to the position controller (6), and the difference with the position feedback fed back from the position detector (3) is calculated by the position controller (6) to obtain the speed command, and the speed command is calculated. A command is given to the speed control unit (4) to drive the electric motor (1).

[Problems to be solved by the invention]

In the conventional electric motor control device as described above, when switching from the speed loop to the position loop, it is necessary to switch to the position loop after passing through the orientation operation. There were problems such as appearing. That is, the width of the orient stop point is a parameter of the allowable error set to surely turn on the stop completion signal when confirming that the stop at a certain position in the orient operation, and after the end of the orient stop, When the position loop control is performed with the orientation stop completion position as the origin position when the position loop control is switched, the orientation loop completion position contains an error less than the parameter setting value with respect to the origin position. There is a problem that an error equal to or less than the parameter set value appears between the current stop point given at the orientation stop completion position at the time of control and the target stop point given at the origin position.

The present invention has been made to solve such a problem, and when switching from the orientation stop to the position loop,
To obtain an electric motor control device that eliminates an error within a parameter value set as an allowable range for turning on the stop completion signal during the orientation operation and can easily perform the transition to the position loop control after the stop. To aim.

[Means for solving problems]

An electric motor control device according to the present invention includes an electric motor that drives a rotating shaft, a speed control unit that controls the electric motor, a changeover switch that switches between a speed loop and a position loop, and a position detector attached to the rotating shaft. And a position control unit that performs a position loop control by making a command to the speed control unit by a position feedback returned from the position detector and a position command, and the position control unit switches from the speed loop to the position loop. At that time, an origin return function for returning the rotary shaft to the origin position is provided prior to the position loop control.

[Action]

In the present invention, the position control unit is provided with an origin return function for returning the rotary shaft to the origin position prior to the position loop control when switching from the speed loop to the position loop,
The orientation operation at the time of switching to the position loop is performed as the origin return operation of the position loop. Therefore, the orientation control unit for switching from the velocity loop to the position loop is unnecessary, and there is no problem that the width of the orientation stop point appears as an error from the origin position.

〔Example〕

FIG. 1 shows an embodiment of the present invention. In FIG.
The same reference numerals as those in the drawings indicate the same or corresponding parts. In this embodiment, the position control section (6) has an origin return function for returning the rotary shaft to the original position prior to the position loop control when switching from the speed loop to the position loop. Therefore, the orientation operation at the time of switching to the position loop is performed as the origin returning operation of the position loop, and the orientation control unit (5), which is conventionally essential for switching from the speed loop to the position loop, is omitted.

In the motor control device configured as described above, during the speed loop, the speed command is given to the speed control section (4) through the changeover switch (7) which is switched to the upper side in FIG. The electric motor (1) is controlled by the speed control unit (4).

Next, when switching to the position loop, the changeover switch (7)
Is switched to the lower side in FIG. 1, and the output of the position control unit (6) becomes the input of the speed control unit (4) to control the electric motor (1).

FIG. 2 is a flowchart showing this switching operation, which will be described below. The flow chart of FIG. 2 shows the process in the transitional period after the position loop switching signal is input until the position loop control is established. During this period, the rotational position changes, At the same time, after confirming that the origin has passed, by calculating the distance until the next origin comes, when the position loop control is established, it will stop at the origin position, and after stopping at the origin position, The position control can be performed by a position command from the outside. First, step S (1
After initializing the position feedback input counter in 1), the step 1 flag is set in step S (12). Next, when this process is executed, since the step 1 flag has already been set, the part after the process of enabling the input counter in step (13) is executed. The flag, the step 3 flag, and the step 4 flag are set one after another, and finally the position loop control of step (25) is executed at regular intervals. The position loop switching signal is
It is given as an input signal of the control device, and when this signal is turned on, the processing of the flowchart of FIG. 2 is executed, and the origin position is detected at the execution stage of each step. That is, when the position loop switching signal is input, the operation of the flowchart shown in FIG.
The input counter which starts counting from the passage of the origin is initialized by the input counter initial, and then the step 1 flag is set in step (12).

Next, in step (13), the input counter is made operable (enable), and the cumulative counter is cleared in step (14). Then, in step (15), the step 2 flag is set.

Then, in step (16), by updating the cumulative counter by the input value of the position feedback, the moving distance after the counter is cleared can be known, that is, the cleared cumulative counter in step (14) is stepped. After the 2 flag is turned on, by adding the position feedback amount of the amount of movement in a fixed time each time this processing is executed, the movement distance after the counter is cleared can be known, and the origin is determined in step (17). Check for passage. If the origin has been passed, the value at the time of passing the origin (= counter value-input counter value, that is, the difference between the cumulative counter value and the input counter at the time of passing the origin is calculated in step (18) to obtain the origin. (The position of can be known) is set in the origin position counter, and the origin passage flag is set in step (19).

Then, in step (20), the origin return distance is calculated and set in the Z counter. In particular,
The origin return distance is set to {(origin counter value + 1 count equivalent to one rotation) -cumulative counter value at present), and this is set in the Z counter. After that, in step (21), the step 3 flag is set.

Next, in step (22), (Z counter value-value corresponding to origin return speed, where the value equivalent to origin return speed means the speed set by the parameter of the origin return speed during the execution of this processing. Since it is rotating at, and the moving distance for a certain period of time corresponds to the speed, it is the value of the amount of change in position feedback by the position detector 3 moved during this processing cycle.) And the Z counter is updated. , Step (23)
When the Z counter becomes 0, the step 4 flag is set in step (24). And then step (2
A position loop is formed by the position command and position feedback by the position loop control of 5).

That is, in the operation of the flowchart shown in FIG. 2, the counter for inputting the position feedback receives the step (13).
The position is always monitored after being enabled in step S4, and the position of the original point is recognized until the step 4 flag is set in step (24), and the original point returning operation for returning to that position is performed. Therefore, at the step (25), the origin position is reached before the shift to the position loop control. However, the origin return is performed when switching to the position loop, and the origin can be accurately indexed and switched to the position loop.

In the above embodiment, the case where the origin return distance in step (20) of FIG. 2 is calculated using the formula of {(origin position counter value + 1 count number equivalent to rotation) -current cumulative counter value) Although shown, the origin shift value, that is, the parameter setting value for making the origin position a position shifted by the set angle from the Z-phase signal that can be detected once per one rotation of the rotation axis, The origin return distance may be calculated using the formula of {(origin position counter value + 1 count equivalent to one rotation + origin shift value) −cumulative counter value at present}.

〔The invention's effect〕

As described above, according to the present invention, in the position control unit, when the speed loop is switched to the position loop, the distance to the home position return is obtained when the home position is passed prior to the position loop control, and the rotary axis is set to the home position in the position loop. There is a return-to-origin function to perform return, and the orientation operation when switching from the speed loop to the position loop is performed as the return-to-origin operation of the position loop, so there is no need for an orientation control unit to switch from the speed loop to the position loop. In addition, there is an effect that the origin can be automatically returned, the origin can be returned in the shortest time that is not wasted as an operation, and further, an accurate control can be realized by eliminating an error at a switching point.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric motor control device showing an embodiment of the present invention, FIG. 2 is a flow chart showing an operation at the time of position loop switching of the present invention, and FIG. 3 is a conventional electric motor control device. It is a figure equivalent to FIG. (1) ... motor, (2) ... position detector, (4) ... speed detector, (6) ... position controller, (7) ... changeover switch. In each figure, the same reference numerals indicate the same or corresponding parts.

Continuation of the front page (56) Reference JP 61-208509 (JP, A) JP 53-131377 (JP, A) JP 55-98083 (JP, A) JP 60-44248 (JP , A) JP-A-57-48449 (JP, A) JP-A-54-57286 (JP, A)

Claims (1)

[Claims] 1. A motor for driving a rotary shaft, a speed control unit for controlling the motor, a changeover switch for switching between a speed loop and a position loop, a position detector attached to the rotary shaft, and a position detector. And a position control unit that performs a position loop control by making a command to the speed control unit based on a position feedback and a position command returned from the device, and the position control unit, when switching from the speed loop to the position loop, Prior to the control, the origin return distance is stored in the Z counter when the origin is passed, and the Z processing is performed from the next processing.
A control device for an electric motor, which has a home-return function for returning the rotary shaft to the home position by incorporating it into a position loop when the counter is continuously updated and the counter value becomes 0.