JPS61221595A - Pulse motor drive monitoring system - Google Patents

Abstract

PURPOSE:To prevent a pulse motor from being burned out by providing a counter, detecting the abnormal state of a pulse motor, and cutting the drive current of the motor. CONSTITUTION:A microprocessor 1 sets the prescribed value in a counter 20 to monitor in the stop control of a pulse motor 4. The counter 20 counts down by a pulse signal of a signal line 13. The microprocessor 1 periodically reads out the content of the counter 20, and resets the counter 20 so that the pulse signal 13 is normally generated if the counted value is reduced by the prescribed amount from the set value. If the counted value of the counter 20 is not varied from the set value, it is judged as an abnormal state that the pulse signal 13 is not generated, and the prescribed error process is started.

Description

[Detailed Description of the Invention] (Summary) This is a method for monitoring the drive of a pulse motor when it is stopped.When performing so-called weak excitation, the energization time rate of the excitation current is controlled by a pulse signal of a predetermined period. , by providing a counter operated by the pulse signal for monitoring and monitoring whether or not the counter value changes,
Detects an abnormality in the excitation state.

[Industrial application field]

The present invention relates to a method for monitoring the driving state of an excitation current when a pulse motor is stopped, in order to prevent burnout or the like of a pulse motor.

As is well known, a pulse motor is rotated by, for example, switching excitation current from four-phase coils in a predetermined order.

In order to stop this rotation correctly at the required rotation angle, it is necessary to excite the required one phase continuously for m at the time of stop, but if the drive current during rotation is continuously applied to the same wire wheel, the temperature will rise. Since the current consumption is also large, a method is adopted in which the average current is reduced by intermittently energizing the motor under control using a pulse signal of an appropriate period while the motor is stopped.

Excitation caused by such an energized state is called weak excitation.

Therefore, if continuous energization is performed without weak excitation due to some kind of control failure, there is a possibility that the motor will burn out, and when such a situation occurs, as a minimum measure, It is desirable to turn off the power immediately.

[Prior art and problems to be solved by the invention] FIG. 2 is a block diagram showing an example of the configuration of a pulse motor control section.

The control section is controlled by a microprocessor 1 using a microprogram control system.

First, the microprocessor 1 sets a predetermined value in the register 2, thereby turning on the output line 3 of the register 2.

The power supply section is controlled by this signal, and +24 volts, for example, for driving the pulse motor 4 is supplied to necessary parts.

The pulse motor 4 is the same regardless of the number of phases, but here it is assumed to have four-phase drive line wheels driven by drive lines 8-1, 8-2, 8-3, and 8-4. .

In driving the pulse motor, the microprocessor 1
By setting the required time in the timer section 5, and starting each time an interrupt is generated by the interrupt signal 6 generated from the timer section 5 as the time elapses, and setting the register 7 to the required contents. , controls the drive of the pulse motor.

During normal rotational driving, the microprocessor l is
For example, by setting the timer section 5 to generate an interrupt every 4 milliseconds, and setting the register 7 by a control program activated by this interrupt, the signal line 9-1.9- of the output of the register 7 is set. 2.9-3.
The two adjacent lines of signal line 9-4 are turned on by shifting one line at a time for each interrupt (assuming that signal line 9-1 follows signal line 9-4), and the others are turned off. Also, during this time, signal line 1
0 turns it off.

Therefore, only the outputs of two adjacent gates of 11-1 to 11-4 (logical product game) are turned on, and the drive lines 8-1 to 8-
The drive circuit 12 causes a drive current to flow through two of the four drive lines corresponding to this ON signal.

By repeating the above control, the pulse motor 4 rotates in the desired direction.

When stopping this pulse motor, the microprocessor 1 sets the register 7 to
Turn on only one line determined by the stopping angle,
Also, turn on the signal line lO.

At the same time, the timer section 5 is controlled to send out a required repetitive pulse signal to the signal line 13. This signal is a repetitive pulse signal with an on/off ratio of 1, for example, with a period of 50 microseconds.

Since the signal on signal line 10 is on, the AND game) 1
1-1 to 11-4 are controlled by a signal on a signal line 13, and an intermittent drive current flows through only one of the drive lines 8-1 to 8-4 via the drive circuit 12.

In this state, the average current flowing through one drive wire of the pulse motor is lower than the drive current during rotation, and even if the same wire is continuously energized in this state, the temperature rise will be within a low range that does not cause burnout. It can be suppressed within.

However, in this control state, if a situation occurs such as the signal line 12 being continuously held in the ON signal state due to some kind of failure, the drive current will continuously flow through one wire of the pulse motor, causing the pulse motor to malfunction. The amount of heat generated will be greater than during normal stop control, and if this state of energization continues, there is a possibility of burnout.

Therefore, when such an abnormal condition occurs, it is desirable to cut off the motor drive current as soon as possible.
Conventionally, there was no easy way to directly detect such a state, so they were used with the risk of burnout.

[Means for solving problems]

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

20 is a counter that counts based on the pulse signal 13.

The counter 20 is connected to the microprocessor I for setting the count value or reading the count value and performing the necessary processing.

[Effect]

In controlling the stop of the pulse motor 4, the microprocessor 1 sets a predetermined value in the counter 20 for monitoring.

The counter 20 has a signal line 1 which is input via a signal line 21.
For example, it is configured to count down from a set value using a pulse signal of 3.

This set value is determined by the microprocessor 1 using the counter 20.
For example, "0'"
be selected so that it is counted down to.

The microprocessor 1 periodically reads the contents of the counter 20, and if the counted value decreases by a predetermined amount from the set value, it is assumed that the pulse signal 13 is generated normally.
Reset the counter 20.

If the count value of the counter 20 does not change from the set value, it is determined that there is an abnormal state in which no pulse signal is generated on the signal line 13, and necessary error processing is started.

With the above configuration, abnormalities in the weakly excited state can be detected early and appropriate processing can be performed.

〔Example〕

In FIG. 1, a microprocessor 1 executes rotation/stop control of a pulse motor as in the conventional case.

However, in the stop control, the microprocessor 1 sets the counter 20 to a constant value.

The counter 20 is constituted by a counting circuit that decrements from a set value to 0° in response to a pulse signal input from a signal line 21. When the value reaches "0" due to the subtraction, a counter
Turn off.

The signal on signal line 22 blocks the signal on signal line 3 as shown to de-energize the pulse motor and also generates an interrupt signal to the microprocessor l of a type that cannot be masked.

These are effective as protection measures in the event that the monitoring operation of the microprocessor 1 described below is not executed normally.

As mentioned above, the counter 2 is set by the microprocessor 1.
The value set to 0 is such that when a repetitive pulse signal is normally generated on the signal line 13, the pulse signal is input to the counter 20 from the signal line 21 and the counter 20 is decremented.

For example, if the microprocessor 1 is set to generate an interrupt from the timer section 5 every 4 milliseconds as described above, the timer 20 will have a count that decrements to 0 degrees in 6 milliseconds. Set the count value so that

In this way, the microprocessor 1 reads the count value of the counter 20 at the interrupt every 4 milliseconds, and if the count value has decreased from the initial set value, a normal pulse signal is output on the signal line 13. The same count value as the previous time is set in the counter 20, and monitoring is restarted anew.

If the count value read from the counter 20 does not decrease from the set value, it means that the signal line 13 is in an abnormal state, such as a continuous ON or OFF signal, and the microprocessor immediately begins error handling.

In error processing, the microprocessor 1 resets at least the register 2 and the register 7, thereby cutting off the drive power of the pulse motor.

If the microprocessor 1 stops or goes out of control after the pulse motor stop control is performed and the counter 20 is not monitored, the counter 20 will not be reset when 4 milliseconds have elapsed. Therefore, for example, the count value reaches "0" after 6 milliseconds have elapsed. Therefore, the signal line 22 indicating this state is connected to the microprocessor l as described above.
If the counter 20 is used to generate a non-maskable interrupt signal and to turn off the power, the counter 20 can also be used to monitor the microprocessor 1.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, burnout of the pulse motor can be easily prevented by adding a counter, and furthermore, this counter can also be used to monitor the microprocessor, so that the pulse motor drive control can be controlled. It has a significant industrial effect of improving reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a configuration of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional configuration example. In the figure, 1 is a microprocessor;

Claims (1)

[Claims] The energization time rate of the excitation current for stopping the pulse motor is
When controlled by a pulse signal (13) of a predetermined period, a counter (20) counts according to the pulse signal (13).
, and setting the count value of the counter (20) to a predetermined value at a predetermined time interval, and detecting that the count value of the counter (20) has not changed from the predetermined value after the time interval. A pulse motor drive monitoring system characterized by comprising means (1) for starting error processing.