JPS605758Y2 - Drive device with synchronous motor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a drive device that starts a synchronous motor in a no-load state and accelerates the load via an air clutch after synchronous pull-in, and is particularly concerned with increasing the capacity of the synchronous motor. The present invention relates to a drive device using a synchronous motor that can shorten the load acceleration time without any problem.

For example, when driving a load such as a ball mill for cement or ore crushing with a motor, as shown in Figure 1,
After starting the electric motor 10 in a no-load state and performing synchronous retraction, air at a predetermined pressure is sent from the pressurized air supply device 11 to the air clutch 14 through the pressurized air pipe 13 provided through the hollow shaft 12, and the load 15 and synchronous motor 10
After connecting, the load 15 is accelerated.

In such a drive system, if the escape torque of the synchronous motor is small, the acceleration period of the load 15 becomes long, the wear of the air clutch 14 increases, the life of the air clutch 14 is shortened, and air is not rapidly supplied to the air clutch 14. In this case, the coupling force of the air clutch is too strong and the synchronous motor 10 loses synchronization, so a synchronous motor with an escape torque of about 200% is normally used.

However, since 150% of the escape torque is sufficient for torque fluctuations during operation, in conventional drive systems, the escape torque is large in order to shorten the load acceleration time and reduce wear on the air clutch 14. This is extremely uneconomical since a synchronous motor is used.

Therefore, an object of the present invention is to provide a drive device using a synchronous motor that can prevent the load acceleration time from increasing and extend the life of the air clutch even when using a synchronous motor with a smaller escape torque than conventional motors. .

An embodiment of the present invention will be described below with reference to FIG.

In the figure, a synchronous motor 10 energized from an AC power supply bus 21 through which a breaker 20 is connected is a synchronous motor 1o that drives a load 15 shown in FIG. be done.

The variable DC power supply 22 is composed of, for example, bridge-connected thyristor converters, and its AC power is supplied from an AC power supply bus 25 via a switch 23 and a transformer 24.

The output of the variable DC power supply 22 is controlled by a phase control device 26.

That is, by advancing the phase of the ignition pulse given from the phase control device 26, the output of the variable DC power supply 22 increases.

The field strengthening device 27 holds, for example, the contact 28A in a closed state for a predetermined period of time after the air clutch shown in FIG. 1 is operated (-).

When this contact 28A is closed, a signal is applied to the phase control device 26 from the bias bus 29, and this signal acts to increase the output of the variable DC power supply 22.

One end of each contact 14A1. 14A2 is a normally open contact of a relay (not shown) that closes when the air clutch 14 in FIG.
1 to the other control power supply bus 32.

The other end of the normally open contact 14A2 is connected to the normally closed contact 3 of the time-limited relay 31.
1B and the relay 28 through a series circuit of the control power supply bus 3.
Connect to 2.

The operation of the present invention having the above configuration will be explained below.

The synchronous motor 10 is started in a no-load state, and after synchronous pull-in, the air clutch 14 is operated to connect the synchronous motor 10 and the load 15.

If the air clutch 14 operates, the contacts 14A1 and 14A2
is closed, but the normally closed contact 31B of the time-limited relay 31 maintains the closed state for the time required.

Therefore, the relay 28 is energized for this time and its normally open/closed valve 28A is closed.

When the normally open/closed circuit 28A is closed, the variable DC power supply 22 is controlled by the phase control device 26 to increase its output, so that the field 101 of the synchronous motor 10 is strongly excited.

Since the field 101 of the synchronous motor 10 is strongly excited, the escape torque of the synchronous motor 10 increases, and the waist load 15 can be accelerated in a short time.

The time-limited relay 3 is activated at a time commensurate with the acceleration completion time of the load 15.
If 1 is set, the contact 28A will open after acceleration is completed, and the strong excitation of the synchronous motor 10 will be automatically canceled.

As explained above, even if the present invention uses a synchronous motor with low escape torque, the field is strengthened and excited only when accelerating the load, so the acceleration time of the load does not become long.
This makes it possible to extend the life of the air clutch and provide an economically superior drive device using a synchronous motor.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a drive device to which the present invention is applied, and FIG. 2 is a connection diagram showing an embodiment of the present invention. 10...Synchronous motor, 101...Synchronous motor field, 14...Air clutch, 15.
... Load, 20 ... Breaker, 21 ...
... AC power supply bus, 22 ... Variable DC power supply, 23 ... Switch, 24 ... Transformer,
25... AC power supply bus, 26... Phase control device, 27... Field strengthening device, 28...
...Relay, 29...Bias bus, 30.
... Control power bus, 31... Time-limited relay, 32... Control power bus.

Claims (1)

[Scope of utility model registration request] In a drive device in which a synchronous motor is started in a no-load state and the load is accelerated via an air clutch after synchronous pull-in, the escape torque of the synchronous motor is increased only for a predetermined period of time after the air clutch operates. A drive device using a synchronous motor, characterized in that a field strengthening device is provided to shorten the slip time of the air clutch.