JPH02155493A - Speed controller for induction motor - Google Patents

Abstract

PURPOSE:To improve the response of the number of revolution while eliminating the need for the conversion of a manipulated variable by using an AC servomotor for controlling the position of a liquid rheostat and controlling the position of the liquid rheostat at high speed. CONSTITUTION:A conversion controller 1a decides a movement completion signal from a servo controller 1b, and divides the ON of the operation signal 52 of a main motor 10 when movement is completed. When the operation signal 52 of the main motor 10 is turned ON and the motor reaches a start-completion position, the manipulated variable of the number of revolution from a flow controller 2 is read, converted into the movement of an electrode 14, and set as the next movement. Revolution at high speed is set to the speed of travel of the electrode 14, and output to the servo controller 1b and the position of the electrode 14 is controlled. Accordingly, an induction motor can follow up to the manipulated variable of the number of revolution of the main motor from the flow controller at high speed.

Description

[Detailed description of the invention] [Objective of the invention] (Industrial application field) The present invention controls the rotational speed of the motor by increasing or decreasing the resistance value of a liquid resistor connected to the secondary side of a wound induction motor. This invention relates to a speed control device for an induction motor.

(Prior Art) In general, there are two types of speed control devices for large-capacity wound induction motors: a variable secondary resistance system and a Cerbius system.

The Servius method is advantageous in terms of energy conservation because it can regenerate the power generated on the secondary side of the motor into the power source, but it is not suitable for equipment that is not constantly operated, such as motors used in rainwater drainage pumps. , which is disadvantageous in terms of equipment cost, and in this case speed control is often performed using a variable secondary resistance method. Liquid resistors are commonly employed.

Figure 3 shows a general system diagram of drainage flow rate control using a liquid resistor. The current value of the drainage flow rate Pv is detected by the flow rate detector F, and the target flow rate S is determined by the flow rate regulator 2. Comparative calculations are performed, and the output thereof is used as a manipulated variable MV to increase or decrease the resistance value of the liquid resistor LRH, which is a secondary resistance, thereby controlling the speed of the pump driving electric motor 10.

An example of a conventional speed control device for an induction motor using a liquid resistor is shown in FIG.

In FIG. 4, the secondary current of the wound induction motor 10 is taken out by a slip ring 13 and supplied to an electrode 14 of a liquid resistor LRH.

The electrode 14 is driven by being connected to a small motor 11 through a gear 12 or the like, and moves up and down within the tank of the liquid resistor LRH.

Lowering the electrode 14 within the liquid resistor decreases the resistance between the electrodes, decreasing the secondary resistance, and raising the electrode 14 increases the resistance between the electrodes, increasing the secondary resistance, thereby The speed of induction motor 10 is controlled.

FIG. 5 shows an example of a control circuit for a small motor that raises and lowers the electrodes of a liquid resistor, and the small motor 11 of the liquid resistor LRH is operated in two roles.

The first role is to act as a starting resistor.

This is done using the contact point a>xt bz□ in FIG.

That is, the operation relay 52X for the main electric motor is turned ON, the main electric motor filO is started, and the contacts a and 1 are held until the start is completed and the limit switch 33M is turned ON. Through b2□, the forward rotation coil F of the motor 11 is turned on continuously, the motor 11 rotates forward, the electrodes descend at a constant speed, and the secondary resistance decreases at a constant rate.

The electrode moving speed is a speed determined to keep the starting current of the main motor 10 within a certain range, and the electrode always moves up and down at this moving speed.

When the main motor 10 is controlled to start and reaches a certain rotation speed,
The second role is to control the rotation speed of the main motor.

That is, when the operating relay 52X of the main motor 10 is ON and the rotation speed is above a certain speed, that is, when the start completion limit switch 33M is ON, the increase command or decrease command, which is the manipulated variable of the flow rate adjustment device 2, is small. Set the coils FX and RX for commanding forward or backward rotation of the motor 11 to 0N10FF.
L, Raise and lower the electrode of liquid resistor LRH,
This increases or decreases the secondary resistance, and the rotation speed of the main motor 5 is controlled by the flow rate adjustment device 2.

(Problems to be Solved by the Invention) The above-mentioned conventional induction motor speed control device using a liquid resistor has the following problems when used for constant flow rate control of a pump as shown in Fig. 3, for example. There is.

In other words, since the moving speed of the electrode is fixed at the same speed as when starting, there is a problem that the control response is delayed when the target flow rate is changed, and when creating a regulating loop control with a regulating device. In addition to taking into account the response delay of the rotation speed, in order to convert the manipulated variable MV into the ON time pulse width of the secondary resistance increase/decrease command, the time width of the increase/decrease of the secondary resistor is calculated. There is a problem in that the relationship between the rotation speed and the amount of change in the rotation speed must be taken into consideration, and it takes time and effort to create the adjustment loop control system.

The present invention was made in consideration of such problems such as the delay in the response of the rotation speed and the conversion of the manipulated variable. The object of the present invention is to provide a speed control device for an induction motor using a resistor.

[Structure of the invention]

(Means and effects for solving the problem) The present invention uses an AC servo motor instead of a conventional small motor to control the position of a liquid resistor, and by controlling the position of the liquid resistor at high speed, the main electric motor This is an induction motor speed control device that improves the responsiveness of the rotation speed control of the AC servo motor, thereby making it effectively applicable to regulation loop control such as flow rate control devices. It may be a control motor, and when used in combination with a servo controller, the number of rotations and rotation speed of the AC servo motor can be freely controlled according to the target position movement amount and movement speed given to the servo controller. ing.

(Example) An embodiment of the present invention is shown in FIG.

In FIG. 1, the one-rotation speed control device 1 inputs the rotation speed operation amount MV from the flow rate adjustment device 2 to the main motor 10 and the operation signal 52 from the motor control device 5 into a liquid resistor L.
It controls the servo motor 3 for RH, and includes a conversion controller 1a that converts the rotational speed manipulated variable MV into the movement amount and movement speed of the liquid resistor according to preprogrammed control contents, and a position movement from the conversion controller 1a. A servo controller lb is configured to control the servo motor 3 according to the amount and moving speed.

With the rotation speed control device 1 having such a configuration, when starting the main motor, the electrode of the liquid resistor is moved to the starting completion position at a moving speed of the liquid resistor such that the starting current of the main motor falls within a certain range, When controlling the rotation speed using the next target flow rate control, the liquid resistor f! ! By moving the pole, the rotation speed of the main motor is controlled with quick response in response to the rotation speed manipulated variable MV of the flow control device.

FIG. 2 is a flowchart showing the operation of the rotation speed control device according to the present invention.

Here, the servo controller 1b may be a general 1-axis servo controller used in the normal FA field, and the amount of movement (the number of rotations of the servo motor) and the movement speed (the rotation speed of the servo motor) are determined by digital signals. A device that controls the servo motor at the target speed according to the input target amount, outputs a movement completion trigger using a digital signal when the target amount of movement is completed, and can control the position at the specified response speed. be.

In FIG. 2, the conversion controller 1a determines the movement completion signal from the servo controller 1b in step (3),
If the movement is completed, it means that the movement of the electrode in the control cycle of the turn has been completed, and in step (2) it is determined whether the driving signal 52 of the main motor is turned on.

52 is OFF, in order to move the resistor to the upper limit, it is determined in step ① whether the resistor upper limit position limit switch signal is ON or not, and ONL is executed.

If not, set the movement amount to -4 in step (A) to move it 4 rotations in the upper limit direction at speed 2, and set Q to the movement speed in step ■, and move to the current position in step 0. Amount - Add stones.

Here 4. Q is a constant related to the response speed of position control, and the larger Q is, the faster the response speed is.

Next, in step (2), the amount of movement and the speed of movement are output to the servo controller to control the position of the electrode.

Since the servo movement completion is OFF while the servo motor is moving, wait until the servo movement is completed in step (D).

In addition, when the resistance reaches the upper limit in step ■ and the upper limit switch signal turns ON, step (8)
Set the moving amount and moving speed to 0 in (2), and set the current position to O in step (10).

By repeating steps ω to (10) above, the electrode is moved to the upper limit position (resistance upper limit) when the main motor is turned OFF, that is, when the main motor is stopped, and a standby state is entered.

Next, when the main motor operation 52 is turned on from this state,
This is determined in step ■, and since the current position is below the starting completion position (m rotations) in step (11), the travel amount is set to 4 rotations in step (12), and the travel speed is set to Q in step ■. Set the revolutions/second and output to the servo controller at step ■, and these steps ■,■
, (11), (12) and 0,0. By repeating step (2), the electrode moves. Here, the constant m is the number of rotations of the servo motor from the electrode upper limit position to the starting completion position.

Furthermore, since the motor moves at a low moving speed of Q rotations/second to the starting completion position, the starting current can be suppressed within a certain range.

When the starting completion position is reached, in step (13), the rotational speed control IMV from the flow regulating device is read, converted into the amount of movement of the electrode, and set as the next amount of movement.

Next, in step (14), set the moving speed of the electrode to high-speed rotation (revolutions/sec), and then step 0. In (2), the signal is output to the servo controller and the electrode position is controlled. By setting the constant t to a larger value than the starting constant ℃, the servo motor can move the position at high speed.
The response of the rotation speed control of the main motor can also be made faster.

Below are the steps above ■, ■, (11), (13),
(14).

By repeating steps 0 and 2, it becomes possible to follow the rotational speed manipulated variable MV of the main motor from the flow rate adjustment device at high speed.

In addition, in step (13), the rotational speed manipulated variable MV is converted into a movement amount by the value directly outputted by the control loop control calculation of the flow rate regulator. There is no need to convert and then output the pulse width, which simplifies the creation of regulation loop control.

(Effects of the Invention) As explained above, according to the present invention, in the speed control device for an induction motor that controls the rotational speed of the motor by changing the secondary resistance of the induction motor by moving the electrode of the liquid resistor, A small motor that moves the electrode of the resistor and its control circuit use an AC servo motor, servo controller, and conversion controller, and when starting the motor, it controls the rotation speed as a starting resistor that suppresses the starting current within a certain range. As well as reducing secondary resistance at slow speeds,
After the electric motor has started, the characteristics of the servo motor are utilized to move it at high speed to the target secondary resistance position.
It becomes possible to follow the rotational speed manipulated variable from a flow rate adjustment device or the like at high speed, and the responsiveness of regulation loop control of the flow rate adjustment device or the like can be improved.

Furthermore, conventionally, the rotation speed operation amount from the adjustment device is controlled by a 0N10FF signal for forward or reverse rotation of a small motor to move the electrode by the rotation speed operation amount.
It was necessary to control the moving time of the electrode, that is, the time for forward or reverse rotation of the motor in terms of the time width of the 10FF signal, which was extremely troublesome in creating the adjustment loop control, but according to the present invention, The signal given to the rotation speed control device can be directly the manipulated variable of the rotation speed, that is, the result calculated by the adjustment loop control, so it has the advantage of being extremely easy to create the adjustment loop control system. .

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the speed control device for an induction motor according to the present invention, Fig. 2 is a flowchart showing the functions and operations of the present invention, and Fig. 3 is a rotation of a drainage pump using a liquid resistor. A system diagram showing an example of flow rate adjustment by numerical control,
FIG. 4 is a system diagram showing an example of a conventional speed control device using a liquid resistor, and FIG. 5 is a circuit diagram showing an example of the rotation speed control device in FIG. 1.4... Rotation speed control device 1a... Conversion controller 1b... Servo controller 2... Flow rate adjustment device 3... Servo motor 5... Motor control device 0... Main motor l... Small motor 2...Gear 3...Slip ring 4...Electrode 4a...Upper limit switch 4b...Start completion position limit switch L RH...
・Liquid resistor F...flow rate detector P...pump 52...main motor contactor (8733) Attorney Yoshiaki Inomata (and 1 other person)

Claims (1)

[Claims] In an induction motor speed control device, a liquid resistor is connected to the secondary side of a wound induction motor, and its electrodes are raised and lowered to increase and decrease resistance, thereby starting and speed controlling the induction motor. A speed control device for an induction motor, characterized in that a servo motor is used as the electric motor for raising and lowering an electrode, and a servo controller is provided that rotates the servo motor at a low speed when starting the induction motor and at a high speed when controlling the speed.