JPS5814715Y2 - Electric motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor control device using a chopper circuit, and particularly to a motor control device used in a device that performs plugging, such as a driving motor.

A conventionally known configuration will be explained with reference to FIG.

1 is a DC power supply, and 2 is a DC motor, which is composed of a field winding 21 and an armature 22.

3 is a chopper circuit such as a thyristor, which is controlled by a control circuit that issues on/off commands, and a detection circuit 32 that detects the plugging state of the motor 2.

4 and 5 are field electromagnetic switches, and 61 and 62 are diodes.

The configuration shown in Fig. 1 first consists of the field electromagnetic switch 4 (
or 5) is turned on, and then the chopper circuit 3 is turned on and off by a control signal from the control circuit 31, and a load current commensurate with the average voltage flows through the armature 2.

At this time, a load current flows through the chopper circuit 3 while the chopper circuit 3 is on, and a flywheel current flows through the diode 61 during the off period.

Now, when the electric motor 2 is rotating, turn off the electromagnetic switch 4 (or 5), turn on the electromagnetic switch 5 (or 4), switch the connection polarity of the field winding 21, and turn the chopper circuit 3 on and off. Since the armature 22 rotates due to inertia, electromotive force is generated in the eleven directions shown in the figure.

The detection circuit 32 that detects the plugging state is activated by this electromotive force, and controls the control signal from the control circuit 31 to reduce the output of the chopper circuit 3.

On the other hand, since the electromotive force of the armature 22 is short-circuited through the diode 62, almost all of the inertial energy possessed by the rotating armature 22 is dissipated by the armature 22.

Therefore, if the motor has a high rotational speed or a large inertia, a very large current flows through the armature 22 in order to obtain the specified braking force, and the difference between the current flowing through the field winding 21 becomes too large and the electric motor Child reaction becomes severe.

Therefore, there was a drawback that the sparks from the brush were large and the brush wear became severe.

In order to solve the above-mentioned drawbacks, the present invention detects the plugging operation and activates the electromagnetic switch to short-circuit the motor and braking resistor, suppressing the armature current and reducing the chopper circuit accordingly. The output is increased to increase the field current, which reduces the armature reaction and
The object of the present invention is to obtain a motor control device that can reduce the generation of sparks from brushes when obtaining the same braking, and can also omit a diode that flows the generated current of the armature across the plugging.

In FIG. 2, which describes one embodiment of the present invention apparatus with reference to the drawings, parts having the same or equivalent functions as those in FIG.

7 is an electromagnetic switch having a normally closed terminal B, a normally open terminal A, and a common terminal C; 8 is a braking resistor connected between the normally closed terminal B and the common terminal C of the electromagnetic switch 7.

In a normal control state, the electromagnetic switch 7 is not excited and the normally closed terminal B and the common terminal C are closed.

Then, the excitation switch 4 (or 5) is turned on and the control circuit 31
The chopper circuit 3 is turned on and off by the control signal to control the average voltage to the motor 2.

At this time, the flywheel current of the motor 2 flows through the diode 61 while the chopper circuit 3 is off.

Furthermore, since the braking resistor 8 is short-circuited by the electromagnetic switch 7, it does not affect the operation under normal control conditions.

Furthermore, since the detection circuit 32 does not operate unless the armature 2 is in the plugging state, this also does not affect the operation.

Next, while the electric motor 2 is rotating in this state, when the electromagnetic switch 4 (or 5) is turned off and 5 (or 4) is kept on and an on/off control signal is applied from the control circuit 31 to the chopper circuit 3, the field The excitation polarity of the winding 21 is reversed, and an electromotive force of the polarity shown is generated in the winding of the armature 22 rotating due to inertia, resulting in a so-called plugging operation state.

The plugging operation detection circuit 32 is activated by the electromotive force generated in the winding of the armature 22 in the direction shown in the figure to excite the electromagnetic switching device 7, and the normally open terminal A and the common terminal C are closed.

At the same time, the control signal from the control circuit 31 to the chopper circuit 3 is controlled to control the output of the chopper circuit 3 to an optimum value.

Therefore, at this time, the load on the chopper circuit 3 is only the field winding 21 of the motor 2, and the diode 61 again works as a flywheel circuit for the field winding 21 of the motor 2.

Further, the electromotive force generated by the armature 22 is consumed inside the armature 22 and the braking resistor 8.

Therefore, the current in the windings of armature 22 is limited by these impedances.

Note that the short circuit path is formed between the armature 22, the control resistor 8, and the contacts A and C of the electromagnetic switch 7.

In addition, the operation of the electromagnetic switch 7 can be done by connecting the braking resistor 8 to both ends of the armature 22 during the plugging operation, and by controlling the power supplied to the field winding 21 by the chopper circuit 3. Furthermore, since it is sufficient if the braking resistor 8 is short-circuited during normal operation, the excitation to the excitation coil of the electromagnetic switching device 7 is reversed so that it is normally energized and braking is performed with the normally open contact. The resistor 8 may be shorted.

As mentioned above, in the present invention, the braking resistor is connected to the armature winding only during plugging operation to limit the armature winding current, and during normal operation the braking resistor is short-circuited, so during plugging operation limits the current flowing through the armature winding and increases the current in the field winding by that amount, which reduces armature reaction in the armature and prevents deterioration due to brush sparks and abnormal heat generation in the armature winding. It has an excellent effect of disappearing.

Furthermore, there is no need for a large diode that conventionally short-circuited the electromotive force generated in the armature winding during plugging and caused a large current to flow, which also has the advantage of being inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram of a conventional motor control device, and FIG. 2 is an electrical wiring diagram showing an embodiment of the device of the present invention. 2...DC motor, 3...Chopper circuit, 4, 5...Electromagnetic switch for field, 7...
...Electromagnetic switch, 8...Braking resistor, 21...
... Field winding, 22 ... Armature, 31 ...
...Control circuit, 32...Detection circuit, 61.
...Flywheel diode.

Claims (1)

[Scope of utility model registration request] a DC motor having a field winding connected in series with an armature, a chopper circuit that controls the speed of the DC motor, and a detection circuit that detects a plugging operation of the DC motor;
a control circuit that receives the output of the detection circuit and controls the chopper circuit; a field electromagnetic switch that reverses the current flowing through the field winding; and a field electromagnetic switch that is controlled by the detection circuit and controls the armature during plugging operation an electromagnetic switching device that short-circuits to form a short-circuit path and interposing a braking resistor in the short-circuiting path; and connected in parallel to the field winding, the armature, the braking resistor, and the electromagnetic switching device. During the OFF period of the chopper circuit, the flywheel current of the DC motor flows, and during the plugging operation, the flywheel current is connected in parallel to the field winding by the contacts of the electromagnetic switch, and is connected in series to the chopper circuit. A motor control device characterized by comprising a flywheel diode.