JPH0328159B2 - - Google Patents

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 by controlling the energization time rate of the excitation current using a pulse signal of a predetermined period, a counter operated by the pulse signal is provided for monitoring, and the counter value changes. An abnormality in the excitation state is detected by monitoring whether or not the excitation state is abnormal.

[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 continuously excite the required one phase when stopping, but if the drive current during rotation is continuously applied to the same wire wheel, the temperature will rise. Since the power consumption is large and the current consumption is large, a method is used 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. As a countermeasure, it is desirable to immediately turn off the power.

[Problems to be solved by conventional technology and 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 microprogram control system by a microprocessor 1.

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

This signal controls the power supply unit, and for example, +24 volts to drive the pulse motor 4.
Supplied to the required parts.

The pulse motor 4 is the same regardless of the phase, but here the drive lines 8-1, 8-2, 8-3, 8
It has a four-phase drive line wheel driven by -4.

When driving the pulse motor, the microprocessor 1 sets the required time in the timer section 5, and as the time elapses, the timer section 5 generates a
The pulse motor is activated by the interrupt signal 6 every time an interrupt is generated, and the register 7 is set to the required contents, thereby controlling the drive of the pulse motor.

During normal rotational driving, the microprocessor 1 sets the timer unit 5 to generate an interrupt every 4 milliseconds, and sets the register 7 by a control program activated by this interrupt. By doing this, the two adjacent signal lines 9-1, 9-2, 9-3, and 9-4 of the output of the register 7 are turned on by sequentially shifting one line at a time for each interrupt (signal lines 9-1, 9-2, 9-3, and 9-4) 4 is assumed to be followed by 9-1), and the others are turned off. Also, during this time, the signal line 10 is turned off.

Therefore, only the outputs of two adjacent AND gates 11-1 to 11-4 are turned on, and two drive lines corresponding to this on signal among drive lines 8-1 to 8-4 are driven. A drive current flows through the circuit 12.

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 of the signal lines 9-1 to 9-4 determined by the stopping angle, and also turns on the signal line 10. Turn on.

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 has a cycle of, for example, 50 microseconds and an on/off ratio of 1.
This is a repetitive pulse signal.

Since the signal on the signal line 10 is on, the AND gates 11-1 to 11-4 are controlled by the signal on the signal line 13, and the signal is passed through the drive circuit 12 to the drive line 8-1.
An intermittent drive current flows only through one line 8-4.

In this state, the average current flowing through one drive line of the pulse motor is reduced compared to the drive current during rotation,
Even if the same wire is continuously energized in this state, the temperature rise is suppressed within a low range that does not cause burnout.

However, in this control state, if a condition occurs such as the signal line 13 being continuously held in the OFF signal state due to some kind of failure, the drive current will continue to flow through one wire of the pulse motor. , the amount of heat generated will be greater than during normal stop control, and if such a energized state 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, but in the past, there was no easy way to directly detect this condition, so burnout could occur. It was used with the danger of

[Means for solving problems]

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

It has a timer section 5 as a pulse signal generating means, a counter 20, and a microprocessor 1 as a control means, and the timer section 5 controls the energization time rate of the excitation current for stopping the pulse motor.
A counter 20 generates a pulse signal of a predetermined period, subtracts a set value set by the microprocessor 1 for each pulse signal, and when the count value as a result of the subtraction reaches a predetermined value, a predetermined power supply is activated. Cut signal 2
2, the microprocessor 1 sets the predetermined setting value longer than the period in the counter 20 at each predetermined period, and determines whether the counted value of the counter 20 has been subtracted from the predetermined value by a predetermined value or more after the period. The configuration is configured to initiate predetermined error handling upon detecting that there is no such error.

[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 receives input via a signal line 21.
For example, it is configured to count down from a set value using a pulse signal on the signal line 13.

This set value is selected so that the microprocessor 1 counts down to, for example, "0" in a slightly longer time than the period at which the counter 20 is checked.

The microprocessor 1 periodically registers the counter 20.
If the count value is decreased by a predetermined amount from the set value, it is assumed that the pulse signal 13 is generated normally, and the counter 20 is reset.

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.

Further, the counter 20 detects that the count value becomes 0, for example, by counting down, and sends a power cutoff signal to the signal line 22. That is, if the microprocessor 1 continues to not perform resetting, a power cutoff signal is generated and the power is forcibly cut off.

By using the above monitoring method, abnormalities in the weak excitation state can be detected early and appropriate processing can be carried out.Also, even if the monitoring cannot be processed normally due to a runaway of the microprocessor, the power supply can be forcibly interrupted. By cutting, it is possible to minimize the occurrence of accidents such as motor burnout.

〔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 composed of a counting circuit that decrements a set value to "0" by a pulse signal input from a signal line 21, and turns off the signal line 22 when the value reaches "0" due to the subtraction. .

The signal on the signal line 22 blocks the signal on the signal line 3 as shown in the figure to cut off the power to the pulse motor,
It also generates an interrupt signal to the microprocessor 1 that cannot be masked.

These are the microprocessor 1 described below.
This is effective as a protection measure in case the monitoring operation is not executed properly.

As mentioned above, the value set in the counter 20 by the microprocessor 1 is determined by the value set in the counter 20 by the pulse signal from the signal line 21 when the pulse signal is normally generated repeatedly on the signal line 13.
, and the counter 20 is decremented.

For example, if the microprocessor 1 is set to generate an interrupt from the timer unit 5 every 4 milliseconds as described above, the timer 20 will have a timer 20 that is set to "0" every 6 milliseconds. Set the count value to be subtracted.

In this manner, the microprocessor 1 reads the count value of the counter 20 at an interrupt every 4 milliseconds. If the count value has decreased from the initial set value, it is assumed that a normal pulse signal is being output to the signal line 13, and the same count value as the previous time is sent to the counter 2.
Set it to 0 and restart monitoring again.

If the count value read from the counter 20 is
If the value has not decreased from the set value, signal line 13
Since this is an abnormal state, for example, a continuous ON or OFF signal is output, the microprocessor 1 immediately starts error processing.

In error handling, microprocessor 1
By resetting at least register 2 and register 7, the drive power of the pulse motor is cut off.

If the microprocessor 1 stops or runs out of control after performing pulse motor stop control and does not perform the monitoring process for the counter 20,
Since the counter 20 is not reset when 4 milliseconds have elapsed, the count value reaches "0" when, for example, 6 milliseconds have elapsed. Therefore, signal line 2 indicating this state
If counter 2 is used to generate a non-maskable interrupt signal for microprocessor 1 and to turn off the power, as described above, counter 20 can also be used to monitor 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 the pulse motor drive control It has a significant industrial effect of improving reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is a block diagram of an example of a conventional configuration. In the figure, 1 is a microprocessor, 2, 7
is a register, 4 is a pulse motor, 5 is a timer section,
8-1 to 8-4 are drive lines, and 20 is a counter.

Claims (1)

[Claims] 1. A pulse signal generating means 5, a counter 20, and a control means 1, wherein the pulse signal generating means 5 is configured to control the energization time rate of the excitation current for stopping the pulse motor. , generates a pulse signal of a predetermined period, the counter 20 decrements the set value set by the control means 1 for each pulse signal, and when the count value as a result of the subtraction reaches a predetermined value, The control means 1 sets the predetermined setting value longer than the period in the counter every predetermined period, and after the period, the count value of the counter changes from the predetermined value to the predetermined value. 1. A pulse motor drive monitoring method, characterized in that the method is configured to start predetermined error processing by detecting that the number has not been reduced.