JPS6233835B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a numerical control device for a synchronous motor that can control the drive and stop of the synchronous motor so that the motor stops after being driven to a desired set rotation amount. The frequency of the AC voltage, which is the drive power source for the electric motor, is converted into pulses as appropriate using a waveform shaping circuit that includes a half-wave rectifier, etc., and this number of pulses is compared with a preset value of the desired rotation amount, and then the set value is reached. The purpose of this invention is to control the AC power supply to the synchronous motor to be cut off at this stage, and the drawings show a preferred embodiment thereof.

FIG. 1 is a block diagram conceptually representing a numerical control device for a synchronous motor according to the present invention.
2 is a synchronous motor; 2 is a zero-volt switch circuit as a gate circuit that functions to supply and stop power to the motor 1; 3 is a pulse conversion circuit that pulses the AC power voltage applied to the synchronous motor 1; 4; 5 is a comparison circuit, and 5 is a setting device for inputting a setting value to the comparison circuit 4. Due to its characteristics, the synchronous motor 1 rotates in synchronization with the AC power frequency, and when disconnected from the power supply, it rotates rapidly. This effectively utilizes the property of stopping at .

FIG. 2 shows a specific circuit configuration diagram for this purpose.
The alternating current voltage is appropriately lowered by a transformer 6 and then subjected to half-wave rectification by a diode 7. A waveform shaping circuit 8 consisting of a Schmitt trigger circuit and the like in the latter stage converts the half-wave rectified voltage by the diode 7 into a number of pulses corresponding to the power supply frequency, and this pulse output is sequentially input to a counter 9 that performs a preset countdown operation. Then, a countdown is performed to be compared with a set value corresponding to the desired rotation amount set by the preset switch 11 as a setting device. 10 is a set switch for the preset down counter 9, which functions as a start switch for the synchronous motor 1. 12 is an OR circuit that operates in response to the output of the preset down counter 9; 13
is a zero-volt synchronous circuit installed at the next stage of the OR circuit 12, which gives a drive/stop signal to the triax 14, which is a switching element connected in series to the synchronous motor 1.

Now, when the set switch 10 is automatically pressed in relation to a device incorporated in this device or manually pressed, the preset down counter 9 starts and the zero volt synchronous circuit is turned on via the OR circuit 12. 13 acts to drive the triac 14 into conduction, so that the voltage of the AC power supply 15 is applied to the synchronous motor 1, causing it to rotate. When the motor rotates by the required amount of rotation, the preset down counter 9 cuts off the pulse output to the OR circuit 12 at the value set by the preset switch 11. to instantly stop the synchronous motor 1 and power supply 15.
It will be separated from the Therefore, synchronous motor 1
is rotated by a rotational amount regulated by a desired set value and then abruptly stopped, thus completing one cycle of numerically controlled operation of the synchronous motor. By automatically or manually operating the set switch 10 of the preset down counter 9, intermittent or continuous repeated numerical control in the above manner is possible, especially when the rotational speed of the synchronous motor 1 is low. As the stopping accuracy can be improved, it can be applied to this type of application to achieve a sufficient purpose.

Conventionally, in position control devices for various machine tools, etc., it has been common to use stepping motors to perform high-precision drive and stop control, and they are highly useful in today's various NC machines. There is. However, depending on the type of object to be controlled, for example, a structure similar to a stepping motor may be used, for example, where the desired purpose can be achieved as long as the accuracy is not so high and the accuracy is within an acceptable practical range. There are various fields such as low speed synchronous motors.

As is clear from the above description, the present invention includes a pulse conversion circuit that pulses the frequency of an AC voltage applied to a synchronous motor, and a comparison circuit that compares the pulse output of the pulse conversion circuit with a set value. A zero volt synchronous circuit is provided which provides a drive/stop signal to a control switch connected to a synchronous motor under the regulation of the output of this comparison circuit. Therefore, when applied to the field of low-speed synchronous motors where such relatively rough accuracy does not pose a practical problem, it is most suitable as a simple numerical control means that involves repeated driving and stopping operations. . In the present invention, the drive/stop signals to be given to the control switch connected to the synchronous motor are generated in the zero-volt synchronous circuit, which is regulated by the comparison circuit for numerical control. It exhibits various effects such as being able to easily improve accuracy and providing this at a low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram conceptually showing a numerical control device for a synchronous motor according to the present invention, and FIG. 2 is a specific circuit configuration diagram thereof. 1...Synchronous motor, 2...Gate circuit, 3...
Pulse conversion circuit, 4... Comparison circuit, 5... Setting device.

Claims (1)

[Claims] 1. It is equipped with a pulse conversion circuit that pulses the frequency of the alternating current voltage applied to the synchronous motor, and has a comparison circuit that compares the pulse output of the pulse conversion circuit with a set value, and synchronizes under the regulation of the output of this comparison circuit. A numerical control device for a synchronous motor, characterized in that it is equipped with a zero-volt synchronous circuit that provides a drive/stop signal to a control switch connected to the motor.