JPH01255498A - Speed controller for variable-speed induction motor - Google Patents

Abstract

PURPOSE:To permit the rotational frequency of an induction motor to reach a desired rotational frequency earlier, by working the regulating motor of a stator rotationally-moving device in modes different according to the degree of a difference between the desired rotational frequency and actual rotational frequency. CONSTITUTION:By working a stator rotationally-moving device 20, between stators 12A, 12B, a periphery-directional rotationally-moving difference is generated. According to this generation, a phase difference between secondary voltage amounts induced to the different section of a rotor conductor is changed, and a speed is controlled. By a speed controller 50, according to a difference between the output of a rotational frequency detector 30 and that of a rotational frequency setting device 34, a regulating motor 15 is controlled continuously or at a high speed when the absolute value of the difference is large, and is controlled intermittently or at a low speed when the absolute value of the difference is small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a speed control device for a variable speed induction motor, and more particularly, to a speed control device for a variable speed induction motor, and more particularly, to This invention relates to a speed control device for a so-called multi-stator variable speed induction motor, which has a device and is capable of arbitrarily changing the rotational speed and generated torque of a rotor by operating the stator rotation device. It is.

[Conventional technology]

A single rotor having two rotor cores spaced apart from each other on the same rotation axis, two sets of stators installed around each rotor core facing each other, and both stators. an electric rotating device that rotates at least one of the stators at a desired angle in the circumferential direction; the rotating device is operated to create a relative angle between both stators based on a command from the speed control device; Variable speed induction motors are known that can control speed over a wide range by changing the phase of the secondary voltage generated in each of the rotor cores, and therefore the magnitude of the composite secondary voltage. The conventional speed control device of variable speed induction motor is
Regardless of the size of the difference between the set target rotation speed and the actual rotation speed at that point, the electric stator rotation device always rotates at a constant speed so that both rotation speeds match and reach the target rotation. It was configured to run until a number was obtained. Therefore, when changing the speed of the induction motor during operation,
Alternatively, when starting the engine after setting the target rotation speed in advance, there are the following problems.

[Problem to be solved by the invention]

In other words, if the operating speed of the electric stator rotation device is set relatively fast in advance, the speed change control is performed from the actual rotation speed to the target rotation speed, with the target rotation speed as the center. In this case, there is a problem in that the rotational speed during the gear change once passes through the target rotational speed and goes too far in the opposite direction, and the so-called hunting phenomenon tends to occur, in which the speed control in the opposite direction has to be repeated several times.

On the other hand, if the operating speed of the stator rotation device is set relatively low in advance, the hunting phenomenon does not occur, but on the other hand, the problem range where speed control is difficult becomes wider and the target rotation speed is lowered. It is difficult to reach the target rotation speed accurately, and when the difference between the target rotation speed and the actual rotation speed is large, or when starting with a certain target rotation speed set in advance, it takes time to reach the target rotation speed. There were problems such as it taking too much time.

Therefore, the present invention has been made in view of such problems of the prior art, and its purpose is to:
Provided is a speed control device that can quickly reach the target rotation speed even when the difference between the target rotation speed and the actual rotation speed is large, can effectively prevent hunting phenomenon, and has a narrow dead area where speed control is impossible. An object of the present invention is to provide a speed control device.

[Means for solving problems]

In order to achieve the above object, the speed control device according to the present invention compares the target rotation speed set by the rotation speed setting device with the actual rotation speed detected by the rotation speed detector, and makes sure that the two match. In a speed control device that stops the operation of the stator rotation device when the target rotation speed is obtained, based on the absolute value of the difference between the target rotation speed and the detected rotation speed, when the absolute value is large, the rotation device is stopped. It is equipped with a circuit that controls the operation of the rotating device continuously or at a high operating speed, and when the absolute value is small, the operation of the rotating device is controlled intermittently or at a slow operating speed.

[Effect]

The operation of the speed control device for a variable speed induction motor according to the present invention constructed as described above is as follows.

In the speed control device according to the present invention, when the difference between the target rotation speed set by the rotation speed setting device and the actual rotation speed detected by the rotation speed detector is large, the speed control device reaches the target rotation speed from the actual detected rotation speed. By operating the stator rotation device continuously or at high speed up to an intermediate stage, and by operating it intermittently or at low speed from a stage approaching the target rotation speed, or gradually as the target rotation speed is approached. By slowing down the rotational speed, the target rotational speed can be reached quickly overall and without causing any hunting phenomenon.

〔Example〕

Examples will be described below with reference to the drawings.

First, with reference to FIG. 1, the configuration of a variable speed induction motor 1 to which a speed control device according to the present invention is applied will be schematically explained.

Rotor cores 2A and 2B are fixed on the rotor shaft 3 of the rotor 2 with a fixed interval therebetween. rotor core 2A,
A non-magnetic core portion 2C is provided between 2B. A plurality of rotor conductors 4 are installed in a cage shape on the rotor cores 2A and 2B in communication between their outer ends, and both ends are connected to each other by short-circuit rings 5 and 6. Short circuited. The rotor conductors 4 are mutually connected (resistance short-circuited) by the resistance material R at the non-magnetic core portion 2C. The rotor 2 configured in one direction in this way has bearings 7, 7 at both ends thereof.
By being pivotally supported by the electric motor frame 10, it becomes rotatable within the electric motor frame 10.

Stators 12A and 12B are arranged in parallel on the inner wall surface of the machine frame 10, facing each outer peripheral surface of the rotor cores 2A and 2B. In the illustrated embodiment, the stator 12B is a fixed stator fixed to the inner wall surface of the machine frame 10, but the stator 12A is equipped with a reversibly rotatable adjustment motor 15 and gears 16, 17 (gears 16, 17). 17
is configured to be able to rotate relative to the fixed stator 12B by an electric stator rotation device W20 whose main component is . Note that a configuration may be adopted in which a relative rotation difference is caused by rotating both the stators 12A and 12B in the circumferential direction at different speeds. By operating the stator rotation device 20, specifically, by rotating the adjusting motor 15, an example of which is shown in FIG. 2, by an arbitrary amount in either the forward or reverse direction, the stator 12A , 12B, a rotational difference in the circumferential direction occurs. Accordingly, the phase difference between the secondary voltages induced in different parts of the rotor conductor corresponding to each stator 12A, 12B of the rotor, and therefore the magnitude of the composite secondary voltage changes, and speed control is performed. It turns out. In addition, stator winding 13A wound around each stator 12A, 12B,
The power source 13B may be connected either in series or in parallel.

FIG. 2 t shows a connection method in which a three-phase induction motor is used as the adjusting motor 15 of the stator rotation device 20, and the motor is connected to a power source for single-phase operation and is capable of reversible rotation. Relay switch RLI is closed during speed change control and is opened when the rotational speed of induction motor 1 reaches target rotational speed L7. The switches RL2 and RL3 determine the rotation direction of the adjusting motor 15, and one of the switches is selectively closed during speed change operation. The capacitor indicated by the symbol C is a phase advancing capacitor for generating a rotating magnetic field in a single-phase connection.2) Next, for controlling the operation of the adjusting motor 15 of the stator rotation device 20 configured as described above. An embodiment of the speed control device 50 of the present invention will be described with reference to the block diagram shown in FIG. In the figure, numeral 30 is a rotation speed detector composed of a tacho generator or the like that detects the actual rotation speed of the induction motor, and 32 is a rotation speed detector that converts the output of the rotation speed detector 30 into an electric format. 34 is a rotation speed setter that outputs a voltage corresponding to the target rotation speed, and 36 is a converter that receives DC input voltage from the converter 32 and the rotation speed setting device 34. This is a differential amplifier that outputs 4 differential values.The output of the differential amplifier 36 is sent to a polarity detector 38 to determine the rotation direction of the adjustment motor 15, and an absolute value that amplifies the absolute value of the differential value. The output of the absolute value amplifier 40 is sent to the comparator 42 in which the dead band width adjustment value is set as the absolute value by the regulator 41. and the voltage
It is input to a pulse converter 48. Voltage/pulse converter 4
8 converts the input voltage into a pulse signal based on the output signal from the evening/f timing signal generator 46 and outputs the pulse signal. If it is connected to the adjustment motor 15 or the race isochi RLI,
Ratio 1? Opening/closing is controlled based on the output of the iQ device 42. Pulse output from voltage/pulse converter 48 &;t: 'y
:, 'Toge 1□ 50 a.

50b is input to each - direction input. Ant game 5
0a other input 4. : is the output from the polarity detector 38,
Also, the other hand of the AND gate 50b (the polarity detector 3
Since the output from 8 is input through the inverter 52, the output beam racer RL2 from the voltage/pulse converter 48 selectively controls the opening and closing of RL and 3.

Next, the operation of the above embodiment will be explained. induction motor 1
is operating at the rotational speed set by the rotational speed setting device 34, the two input voltages input to the differential amplifier 36 are equal, so the differential amplifier 36 outputs an output, the absolute value amplifier 40. The voltage input to comparator 42 via is also zero. As a result, comparator 42 outputs relay switch RLI
is not closed and the adjustment motor 15 is not rotated.

On the contrary, if a new target rotation speed different from the actual rotation speed is set by the rotation speed setting device 34 while the induction motor 1 is in operation, the differential amplifier 36 Outputs the differential value of the input voltage. The polarity of this differential value, that is, whether the adjustment motor 15 should be rotated forward or reverse is determined by a polarity detector 38.

Since the absolute value of the differential value is amplified by the absolute value amplifier 40 and input to the comparator 42, the comparator 42 is connected to the adjustment motor 15.
Relay switch RLI is closed to activate the . The differential value amplified by the absolute value amplifier 40 is applied to the voltage/pulse converter 48 after voltage adjustment is performed based on the set value of the proportional constant regulator 44 . Voltage/pulse converter 48
outputs pulses with different pulse intervals or duty ratios to the AND gates 50a and 50b based on the signal from the timing signal generator 46, depending on the magnitude of the input voltage applied via the proportional constant adjuster 44. anime game
) 50a and 50b are turned on based on the signal from the polarity detector 38, and accordingly, the pulse from the voltage/pulse converter 48 is applied to the relay switch RL2 or RL3.
Selectively close one of the switches. If the difference between the rotation speed set by the rotation speed setting device 34 and the actual rotation speed detected by the rotation speed detector 30 is large, the differential amplifier 3
6° absolute value amplifier 40. The voltage input to the voltage/pulse converter 48 via the proportional constant adjuster 44 also increases,
The pulse that will be output from now on will have a higher frequency or a larger duty ratio in proportion to the input voltage value, so
The regulating motor 15 will be operated almost continuously. On the other hand, if the difference between the rotation speed set by the rotation speed setting device 34 and the actual rotation speed detected by the rotation speed detector 30 is small, the voltage input to the voltage/pulse converter 48 is also small. Since the pulses to be outputted have a lower frequency or a smaller duty ratio in proportion to the input voltage value, the adjusting motor 15 is operated almost intermittently or intermittently.

Furthermore, even within the range of intermittent operation, if the difference between the rotation speed set by the rotation speed setting device 34 and the actual rotation speed detected by the rotation speed detector 30 becomes smaller, the degree of intermittent operation can be reduced. In some cases, the speed controllability may be further improved by making the adjustment motor larger, that is, by shortening the time during which electricity is applied to the adjustment motor.

In the above embodiment, the adjustment electric motor 1 of the stator rotation device 20
In Section 5, we explained the case where a three-phase induction motor was used and operated in a single phase, but the adjustment motor is of course not limited to this, and DC motors with higher performance in terms of response speed, etc., fine motors, etc. It goes without saying that stepping motors, servo motors, etc., which are capable of rotary operation and have higher performance than DC motors, can be selected depending on the purpose of speed control of the induction motor, the required precision, etc.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces effects as described below.

For the purpose of speed change control of the induction motor, the adjustment motor of the stator rotation device is operated in different ways depending on the magnitude of the absolute value of the difference between the target rotation speed and the actual rotation speed. This allows the rotation speed of the induction motor to quickly reach the target rotation speed.

The adjustment motor of the stator rotation device is operated at low speed or intermittently when the induction motor approaches the target rotation speed, so hunting phenomenon is less likely to occur than with conventional speed control devices, and the dead band width is It also becomes narrower.

When an induction motor is used as an adjustment motor for a stator rotation device, the cost is lower than when a variable speed motor such as a DC motor or a stepping motor is used.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a variable speed induction motor to which the speed control device according to the present invention is applied, Fig. 2 is a wiring diagram of a motor for adjusting a stator rotation device, and Fig. 3 is a speed control device according to the present invention. FIG. 2 is a block diagram showing one embodiment of the present invention. In the figure, 2...rotor, 2A, 2B... rotor core,
2C...Nonmagnetic core part, 3...Rotor shaft, 4
... Rotor conductor, 5, 6 ... Short circuit ring, 7 ... Bearing, 10 ... Machine frame, 12A ... Rotating stator, 1
2B... Fixed stator, 13A, 13B... Stator winding, 15... Adjustment motor, 16.17...
Gear, 30... Rotation speed detector, 32... Converter,
34... Rotation speed setting device, 36... Differential amplifier,
38...Polarity detector, 40-...Absolute value amplifier,
42... Comparator, 44... Proportionality constant adjuster,
46...Timing signal generator, 48...Voltage/
Pulse converter, 50a, 50b = AND gate, 5
2...Inverter, RLI, RL2. RL3
...Relay switch. Patent applicant Satake Seisakusho Co., Ltd. July 9, 1988 1. Display of the case 1988 Patent Application No. 082366 2) Title of the invention Speed control device for variable speed induction motor 3, person making the amendment Relationship with the case Patent applicant f! +0312
53-3111 June 8, 1988 (Shipped on June 28, 1988) 5. Subject to amendment

Claims (3)

[Claims] (1) a single rotor having two rotor cores spaced apart from each other on the same rotational axis, and two stators disposed around each rotor core to face each other; In a variable speed induction motor equipped with an electric stator rotation device that rotates at least one of the two stators to generate a relative rotation difference between the two stators, the rotation Speed control is performed based on a comparison between the target rotation speed set by the speed setting device and the actual rotation speed detected by the rotation speed detector, and when the target rotation speed is obtained when the two match, the stator A speed control device that stops operation of a rotation device, the speed control device controlling the stator rotation device in different ways depending on the magnitude of the absolute value of the difference between the target rotation speed and the detected rotation speed. A speed control device for a variable speed induction motor, comprising a drive circuit for operating a variable speed induction motor. (2) The speed control device according to claim (1), wherein the drive circuit controls the operating speed of the rotation device when the absolute value of the difference between the target rotation speed and the detected rotation speed is large. A speed control device characterized by controlling speed quickly and slowing down when the absolute value is small. (3) The speed control device according to claim (1), wherein the drive circuit operates the rotation device when the absolute value of the difference between the target rotation speed and the detected rotation speed is large. A speed control device characterized by controlling continuously and intermittently when the absolute value is small.