JPS582160Y2 - speed control circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in detecting an abnormality in the speed control system of a DC motor.

In a speed control system that feeds back the output of a speed generator directly connected to a DC motor and controls the rotational speed of the DC motor according to the deviation between this and a speed reference signal of the DC motor, the above-mentioned If a disconnection failure occurs in the speed generator or its wiring, the feedback signal from the speed generator becomes zero, causing the DC motor to run out of control.

Therefore, in order to prevent this runaway, conventional speed control circuits are provided with various runaway detection and prevention circuits.

FIG. 1 is a block diagram showing an example of a conventional speed control circuit equipped with this type of runaway prevention circuit, in which 1 is a DC motor, 2 is a SIRISK device that serves as a power source for this DC motor, and 3
is a speed generator directly connected to the DC motor 1; 4 is a setting device for setting a speed reference signal of the DC motor 1; 5 is a setting device that compares the speed reference signal of this setting device with the speed signal of the speed generator 3; A speed controller that generates a control signal according to these deviations, 6 an ignition circuit that controls ignition of the thyrisk device 2 according to the control signal of this speed controller, 7 transforms the alternating current flowing into the thyrisk device 2 8 is an armature voltage detector that detects the armature voltage of the DC motor 1; 9 is an armature voltage detector that detects the output of this armature voltage detector and the speed generator 3;
10 is an abnormality signal sending circuit that sends out an abnormality signal when the comparison value of this voltage comparison circuit exceeds a certain value.

Note that the voltage comparison circuit 9 and the abnormal signal sending circuit 10 constitute a runaway prevention circuit 11.

That is, the speed controller 5 inputs the speed reference signal of the DC motor 1 supplied from the setting device 4 and the speed signal corresponding to the actual speed of the DC motor 1 supplied from the speed generator 3, and calculates the difference between them. A corresponding control signal is sent to the ignition circuit 6.

The ignition circuit 6 controls the ignition of the silisk device 2 based on the control signal supplied from the speed controller 5, and controls the armature voltage of the DC motor 1, that is, the rotational speed of the DC motor.

That is, the actual speed of the DC motor 1 is fed back, compared with the speed reference signal of the setting device 4, and controlled so that the actual speed corresponds to the speed reference signal.

The current transformer 7 transforms an alternating current proportional to the armature current of the direct current motor 1 flowing into the sirisk device 2 and supplies it to the speed controller 5 to compensate for the current.

Now, in such a control system, if a disconnection occurs in the speed generator 3 or the line connecting the speed generator 3 and the speed controller 5, the speed controller 5 will change the speed reference signal of the setting device 4 and In order to output the deviation from the speed signal of the speed generator 3, an abnormally increased control signal is supplied to the ignition circuit 6, and as a result, the DC motor 1 runs out of control.

The runaway prevention circuit 11 is provided to prevent this, and this will be explained below.

That is, the voltage comparison circuit 9 compares the armature voltage detected by the armature voltage detector 8 and the speed signal of the speed generator 3,
These deviations are output to the abnormal signal sending circuit 10.

The rotational speed N of the DC motor is, however, E is the armature voltage Φ, which has a constant relationship with the magnetic flux, but in speed control in the region below the base speed, Φ is kept constant and the armature voltage E is changed. Speed control is then performed.

Since speed control in this region has the advantage of being able to perform constant torque control, speed control is often performed only in this region.

Therefore, in this region, NoCE occurs, and if the output of the armature voltage detector 8 and the output of the speed generator 3 are made equal during normal operation, the voltage comparator circuit 9 can be connected to the speed generator 3 or the speed generator 3. When a break occurs in the line connecting the speed controller 5, the output of the speed generator 3 becomes zero.
Generates output.

An abnormality signal sending circuit 10 uses the output of this voltage comparison circuit 9.
operates and sends a stop command or a warning signal to the DC motor 1.

In this way, runaway of the DC motor 1 can be prevented.

However, since the conventional device is configured as described above, it has the disadvantage of requiring an armature voltage detector 8 to detect the armature voltage, and also has the disadvantage that the ignition circuit 6 and the cyrisk device 2 may be abnormal. Even if it were occurring, there was a drawback that it could not be detected.

This invention was made in view of the above-mentioned drawbacks, and by focusing on the fact that the speed controller 5 outputs a control signal according to the armature voltage, the control signal of the speed controller 5 is prevented from running out of control. The aim is to eliminate the above-mentioned drawback by guiding the light to the circuit 11.

FIG. 2 is a block diagram showing an embodiment of this invention, and the same parts as in FIG. 1 are given the same reference numerals.

2 differs from FIG. 1 in that the armature voltage detector 8 is omitted and that the control signal output from the speed controller 5 is guided to the runaway prevention circuit 11.

That is, the ignition circuit 6 controls the ignition of the thyrisk device 2 based on the control signal of the speed controller 5, thereby starting the DC motor 1.
Since the armature voltage of the DC motor 1 is controlled, the control signal of the speed controller 5 and the armature voltage of the DC motor 1 are in a proportional relationship.

Therefore, if the control signal of the speed controller 5 and the speed signal of the speed generator 3 are made equal during normal operation, the voltage comparison circuit 9 can control the speed generator 3 or the speed generator 3 and the speed controller 5. When a disconnection occurs in the connecting line, the output of the speed generator 3 becomes zero, so an output is generated.

Then, the abnormality signal sending circuit 10 is activated by the output of the voltage comparison circuit 9, and in order to send out a stop command or a warning signal to the DC motor 1, the DC motor 10 is
can be prevented from running out of control.

In addition, since the control signal output from the speed controller 5 and the speed signal of the speed generator 3 are compared, if some abnormality occurs in the ignition circuit 6 or the silisk device 2, the direct current is determined based on the control signal. Even if the armature voltage of the electric motor 1 becomes uncontrollable, this can be detected immediately.

As described above, according to this invention, abnormalities in the speed control system are detected by comparing the control signal output from the speed controller and the speed signal of the speed generator that feeds back the actual rotational speed of the DC motor. This makes it possible to eliminate the need for an armature voltage detector, prevent the DC motor from running out of control, and detect abnormalities in the ignition circuit and silisk device.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a speed control circuit of a conventional DC motor, and Fig. 2 is a block diagram showing an embodiment of this invention, in which 1 is a DC motor, 2 is a thyrisk device, and 3 is a speed generator. 5 is a speed controller, 6 is an ignition circuit, and 9 is a voltage comparison circuit. The same symbols in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A speed generator that generates a speed signal according to the rotational speed of a DC motor whose speed is controlled within the base speed region, and a speed generator that compares the speed reference signal of the DC motor with the speed signal of the speed generator, and calculates the difference between them. a speed controller that controls the armature voltage of the DC motor with a corresponding control signal; a comparison circuit that compares the control signal of this speed controller with the speed signal of the speed generator and outputs a deviation signal; A speed control circuit characterized by comprising an abnormality signal sending circuit that emits an abnormality signal based on the output of the comparison circuit.