JPS59123489A - Drive device for motor - Google Patents

Abstract

PURPOSE:To simplify the structure of a plurality of motor and to reduce the cost of the motor by sequentially intermittently driving a plurality of motors by an inverter. CONSTITUTION:When a switching timing circuit 4 instructs a start of a motor 21, a switch 1 is shifted to a motor 21 side, a switch 2 is shifted to a voltage regulator 31 and a current regulator 41 side, and the motor 21 is started. A rotating speed detector 3 informs the fact that the motor 21 reaches the normal rotating speed to a switching timing circuit 41, and shifts the switches 1, 2 to a motor 22 side. The motor 22 is started similarly to the motor 21. In the meantime, the motor 21 which has already reached the normal rotation continues rotating by inertia. After the motors 21, 22 reach the respective normal rotating speeds, the switching timing circuit is driven at the prescribed time interval, power is sequentially supplied to the motors, thereby maintaining the normal rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for an electric motor that is directly connected to a rotating body such as a Turbo Molecule 2 pump and operates it at ultra high speed.

1 to 2X10' like a general busy turbo molecular bong
0 x 10' rpm An ultra-high speed motor that is directly connected to a high-speed rotating body of 8 degrees without using a mechanical speed-up mechanism such as a gear train (a high-frequency electric motor has a simple rotor structure and a non-contact rotor). Three-phase squirrel-cage induction motors and Hall motors that can introduce driving power are used.The drive circuit for these types of motors uses an adjustable frequency power supply that takes advantage of the fact that the rotational speed of the induction motor is proportional to the frequency of the power supply. However, transistor inverters are often used in ultra-high-speed motors with an output of several kilowatts or less as described above.

However, when several electric motors* are driven in parallel with this type of power supply, it is especially difficult to control the speed up until the steady rotation speed is reached, such as during startup, so one inverter must be used for one electric motor. It was like that.

In order to increase the speed of two or more electric motors with one inverter, a method has been proposed in which the rotation speed detector is duplicated and divided into one for controlling the steady rotation speed and one for speed increase measurement, but this method is Measuring rotational speed over a wide range with the same accuracy is convenient for monitoring the parallel starting of multiple motors, but
Since the inverter capacity needs to be increased according to the number of motors, the price of the inverter is rather high.

In particular, recently, electric motors with speeds of several tens of thousands of rpm have been put into practical use for use directly in internal grinding machines, milling machines, spinning machines, etc., which are even faster than the turbo molecular pumps.
In these applications, starting and stopping are more frequent than in the above-mentioned turbo molecular bombs, and load fluctuations are severe, so the difficulty of speed increase control in the above-mentioned parallel drive cannot be ignored.

This invention has gone beyond the above, and when multiple ultra-high-speed motors are driven by power from an inverter, during the start-up speed increase, each motor is increased in speed until it reaches a steady rotation speed, and the motors are started one after another. Then, after all the motors reach a steady rotation speed, by sequentially controlling the switching at regular intervals, it is possible to control the inverter capacity for one motor with the maximum capacity. The present invention provides a drive device N that can perform stable rotational speed control in exactly the same way as when using a separate inverter.

In other words, only one motor is always connected to the power supply inverter both when starting up and speeding up and when operating at a steady rotation speed, so an inverter with the same capacity as conventional equipment can be used, and at the same time when starting up and speeding up, only one motor is connected to the power supply inverter. It detects changes in the DC power supplied to the accompanying inverter and performs closed-loop control of the input DC voltage to the inverter, and during steady rotation, monitors the rotational speed of the motor, which is controlled by the inverter's oscillation frequency, at regular intervals. By doing.

An inverter with the capacity of one motor can drive several motors at the same time.

Next, embodiments of the present invention will be described. In Figure 1, 1
is electric with inverter 5! 21, 22 etc. connection switch, 2 is the DC of the inverter 5? lf source 7 pressure regulator 6, each voltage regulator 31.32, etc. and each current regulator 41.4
3 is a rotation speed detector for the electric motors 21, 22, etc., and 4 is a switching timing circuit that commands the switching time M of the switching devices 1 and 2.

Therefore, at startup, the switching timing circuit 4 first switches the electric motor 2.
1, switch 1 is switched to the motor 21 side, and switch 2 is switched to the voltage regulator 31 and current regulator 41 sides. Therefore, the electric motor 21 generates three-phase phase difference generation timing in the timing generation circuit 11 based on the reference frequency oscillated by the oscillator 12 as before, controls the base drive circuit 10 at that timing, and controls the six power outputs in the inverter 5. It is activated by controlling the high frequency oscillation of the inverter 5 by sequentially driving the bases A and A6 of the transistors. The rotation speed detector 3 monitors the speed increase of the electric motor 21 and ultimately notifies the switching timing circuit 4 that the electric motor 21 has reached a steady rotation speed, and switches the switching devices 1 and 2 to the motor 22 side. Make the switch. The electric motor 22 is started in exactly the same manner as the electric motor 21, but in the meantime, the other electric motors, which have already reached a steady rotation speed, continue to rotate due to inertia. As described above, after all the motors 21, 22, etc. reach their respective steady rotation speeds, the switching timing circuit 4 is driven at regular time intervals, and power is sequentially supplied to each motor to maintain steady rotation.

As described above, speed-up control at startup is performed by adjusting the power supplied from the DC power supply 6 of the inverter 5 to the voltage regulator 31 by detecting the DC voltage 9 and the DC current 8 by the shunt resistor 7, using the reference oscillation number of the oscillator 12 as the target value. The measurement and control using the current regulator 41 etc. is the same as before.
The role of the rotation speed detector 3 is mainly monitoring rather than controlling, and the control is limited to instructing the switching timing circuit 4 to switch the timing of the electric motor or the like.

In the above embodiment, an example was shown in which two motors with the same rating are driven by one inverter, but the ratings of the motors driven at one time do not necessarily have to be the same, but in this case, the voltage The regulator 31, etc., the current regulator 41, etc. must be separated into a plurality of independent parts as divided by dotted lines in FIG. 1, and must be switched as the corresponding electric motor is switched.

It is sufficient to use a timer to set the fixed time interval after the steady rotation speed has been reached, but the rotation detector 3 is not necessarily required in this case. If particularly necessary, it is also possible to detect the rotational speed of a motor to which no power is being supplied, and to set it based on the degree of decrease in the rotational speed. Furthermore, the inverter referred to in this invention also includes a power source for driving a Hall motor.

As detailed above, the present invention is a system in which when multiple electric motors are driven in parallel, one inverter corresponding to the maximum capacity among them is used to sequentially and intermittently drive the multiple electric motors. In the belt, the inverter, which is the power source, and any one electric motor are always coupled and driven, and it is possible to safely drive multiple electric motors at high speed with a relatively small-capacity inverter. In addition, in order to maintain the steady rotation speed of other electric motors that are not driven by an inverter, the drive electric motor A steady rotation speed can be maintained stably without being affected by transient phenomena that occur when switching.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention. 1... Motor switch 2... Voltage/current regulator switch 3... Rotation speed detector 4... Switching timing circuit 5... Inverter 6... DC power supply and voltage regulator 8. ...DC current 9...DC voltage

Claims (1)

[Claims] a switching device that sequentially supplies power from an inverter to a plurality of motors; and a switching device that sequentially connects and switches the DC power supply of the inverter to a voltage regulator and a current regulator corresponding to each motor in synchronization with the switching device. The motor is equipped with a rotation speed detector that detects the rotation speed of the electric motor, and a switching timing circuit that commands switching timing of the two switching devices according to the output signal of this detector, and corresponds to speed increase during startup. A driving device for an electric motor, which is configured such that a switching timing is commanded and the rotational speed is controlled by switching at regular intervals during steady operation.