JP2614292B2 - Induction motor speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention controls the rotation speed of a motor by increasing or decreasing the resistance value of a liquid resistor connected to the secondary side of a wound induction motor. The present invention relates to an induction motor speed control device.

(Prior Art) Generally, as a speed control device of a large-capacity wound-type induction motor, there are a secondary resistance variable system and a cervius system.

The Servius method can regenerate the electric power generated on the secondary side of the motor to the power source, which is advantageous in terms of energy saving.However, for equipment that is not always operated such as a motor used for rainwater drainage pumps, However, it is disadvantageous in terms of equipment cost. In this case, speed control is often performed by a variable secondary resistance method, and the secondary resistor used here has a large capacity and a continuously variable resistance value. Liquid opponents are commonly employed.

FIG. 3 shows a general system diagram of the drainage flow rate control using a liquid resistor. The present value PV of the drainage flow rate is detected by the flow rate detector F and compared with the target flow rate SV by the flow rate control device 2. The output of the pump driving motor 10 is calculated by increasing or decreasing the resistance value of a liquid resistor LRH, which is a secondary resistance, as an operation amount MV.
Control the speed of the car.

FIG. 4 shows a conventional example of a speed control device for an induction motor using a liquid resistor.

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

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

When the electrode 14 is lowered in the liquid resistor, the resistance between the electrodes is reduced and the secondary resistance is reduced, and when the electrode 14 is raised, the resistance between the electrodes is increased and the secondary resistance is increased. The speed of the induction motor 10 is controlled.

FIG. 5 shows an example of a control circuit of a small motor for raising the electrode of the liquid resistor. The small motor 11 of the liquid resistor LRH is operated in two roles.

The first role is the operation as a starting resistor, which is performed using the contacts a ₁₁ and b ₂₁ in FIG.

That is, the operation relay 52X for the main motor is turned on, the main motor 10 is started, the start is completed, and the limit switch 33M is turned on.
Until N, the forward rotation coil F of the motor 11 is continuously turned on through the contacts a ₁₁ and b ₂₁ , the motor 11 rotates forward, the electrode descends at a constant speed, and the secondary resistance decreases at a constant rate. I will do it.

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 number of revolutions,
The second role, that is, the rotation speed control of the main motor, is performed.

That is, when the operation relay 52X of the main motor 10 is ON, the rotation speed is equal to or higher than a certain speed, that is, when the start completion limit switch 33M is ON, the increase command or the decrease command which is the operation amount of the flow control device 2 is small. Turn on / off the forward / reverse command coils FX and RX of the motor 11 and raise and lower the electrodes of the liquid resistor LRH, thereby increasing or decreasing the secondary resistance. Is performed.

(Problems to be Solved by the Invention) The above-described conventional speed control device for an induction motor 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.

That is, since the moving speed of the electrode is also fixed at the time of speed control at the same time as at the time of starting, there is a problem that the control response when the target flow rate is changed is delayed, and also when the adjustment loop control is created by the adjustment device. In addition to considering the response delay of the rotation speed, increase and decrease the secondary resistor to convert the manipulated variable MV into the ON time pulse width of the increase / decrease command of the secondary resistance.
It is necessary to consider the relationship between the reduced time width and the amount of change in the number of revolutions, and there is a problem that it takes time to create an adjustment loop control system.

The present invention has been made in consideration of such problems as the response delay of the rotation speed and the conversion of the operation amount, and is a rational liquid that improves the response of the rotation speed and does not require the conversion of the operation amount. It is an object of the present invention to provide a speed control device for an induction motor using a resistor.

[Configuration of the invention]

(Means and Actions for Solving the Problems) The present invention uses an AC servomotor instead of a conventional small motor for position control of a liquid resistor, and performs high-speed position control of the liquid resistor by using a main motor. The speed control device of an induction motor that improves the response of the rotation speed control of the motor, thereby enabling it to be effectively applied to the control loop control such as a flow control device. Motor, and by using it in combination with a servo controller, the number of rotations and the 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. I have.

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

In FIG. 1, a rotation speed control device 1 includes a flow control device 2
To control the servomotor 3 for the liquid resistor LRH by inputting a rotational speed manipulated variable MV for the main motor 10 and an operation signal 52 from the motor control device 5. A conversion controller 1a for converting the operation amount MV into a movement amount and a movement speed of the liquid resistor, and a servo controller 1b for controlling the servomotor 3 according to the position movement amount and the movement speed from the conversion controller 1a are configured.

With the rotation speed control device 1 having such a configuration, at the time of starting the main motor, the electrode of the liquid resistor is moved to the start completion position at a moving speed of the liquid resistor such that the starting current of the main motor falls within a certain range, During the rotation speed control by the next target flow rate control, the electrode of the liquid resistor is moved at a high speed, and the rotation speed of the main motor is controlled with a quick response corresponding to the rotation speed operation amount MV of the flow rate adjusting 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 one-axis servo controller used in the normal FA field, and the movement amount (the number of rotations of the servo motor) and the movement speed (the rotation speed of the servo motor) are represented by digital signals. It is a device that can control the servo motor at the target speed with the input target amount at the target speed, and when the movement of the target amount is completed, output a trigger of movement completion with a digital signal and control the position at the specified response speed. .

In FIG. 2, the conversion controller 1a determines the movement completion signal from the servo controller 1b in step (1). If the movement is completed, the movement of the electrode in the previous control cycle has been completed. In), it is determined whether or not the operation signal 52 of the main motor is ON.

If 52 is OFF, it is determined in step (3) whether or not the resistance upper limit position limit switch signal is ON to move the resistance to the upper limit. In step (4), the amount of movement -k is set in order to move by k rotations, and step (5)
To set l to the moving speed, and add the moving amount -k to the current position in step (6).

Here, k and l are constants related to the response speed of the position control. The response speed increases as l increases.

Next, in step (7), the movement amount and the movement speed are output to the servo controller to perform electrode position control.

Since the completion of the servo movement is OFF while the servo motor is moving, the process waits in step (1) until the completion of the servo movement.

When the resistance reaches the upper limit in step (3) and the upper limit switch signal is turned on, the moving amount and the moving speed are set to 0 in steps (8) and (9), and the current position is set to 0 in step (10). I do.

By repeating the above steps (1) to (10), 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 established.

Next, when the operation 52 of the main motor is turned on from this state, this is determined in step (2). In step (11), the current position is equal to or less than the start completion position (m-th rotation), and step (12) is performed. In step (5), set the movement amount to k rotations, and in step (5), set the movement speed to 1 rotation / second, and in step (7), output to the servo controller, and in these steps (1), (2), (11), (12) and (5),
The electrodes move by repeating (6) and (7). Here, the constant m is the number of rotations of the servomotor from the electrode upper limit position to the start completion position.

Further, since the motor is moved at a low speed of 1 rotation / second to the start completion position, the starting current can be suppressed within a certain range.

When the start position is reached, in step (13), the rotational speed manipulated variable MV from the flow control device is read, converted into the electrode travel distance, and set as the next travel distance.

Next, in step (14), the moving speed of the electrode is set to high-speed rotation k rotations / sec. In steps (6) and (7), the output is output to the servo controller to control the electrode position. Here, by setting the constant k to a large value with respect to the constant 1 at the time of starting, the position of the servomotor can be set at a high speed, and the response of the rotation speed control of the main motor can be quickened.

The following steps (1), (2), (11), (1
By repeating 3), (14), (6), and (7), it becomes possible to follow the rotational speed operation amount MV of the main motor from the flow control device at high speed.

In step (13), the rotation number manipulated variable MV converts a value directly output by the control loop control calculation of the flow rate control device into a movement amount. There is no need to output the pulse width after conversion, which simplifies the creation of the control loop control.

〔The invention's effect〕

As described above, according to the present invention, in the speed control device of an induction motor that controls the rotation speed of the motor by changing the secondary resistance of the induction motor by moving the electrode of the liquid resistor, An AC servomotor, a servo controller, and a conversion controller are used for the small motor to be moved and its control circuit. While reducing the secondary resistance
After the start of the motor is completed, it is moved to the target secondary resistance position at high speed by utilizing the characteristics of the servo motor.
It becomes possible to follow the operation amount of the number of revolutions from the flow control device at a high speed, thereby improving the responsiveness of the control loop control of the flow control device and the like.

Further, conventionally, the rotation amount operation amount from the adjusting device is moved by the ON / OFF signal of the forward or reverse rotation of the small motor to move the electrode by the rotation amount operation amount. It is necessary to control the moving time of the electrode, that is, the time of forward rotation or reverse rotation of the motor in terms of the time width, which is very troublesome in creating an adjustment loop control. Since the signal given to the apparatus can be given as it is the operation amount of the rotation speed, that is, the result calculated by the adjustment loop control, there is an advantage that it is very easy to create an adjustment loop control system.

[Brief description of the drawings]

1 is a system diagram showing an embodiment of a speed control device for an induction motor according to the present invention, FIG. 2 is a flowchart showing functions and operations of the present invention, and FIG. 3 is a rotation of a drain pump using a liquid resistor. System diagram showing an example of flow rate adjustment by number 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 a rotation speed control device in FIG. 1,4 ... rotation speed controller 1a ... conversion controller 1b ... servo controller 2 ... flow rate controller 3 ... servo motor 5 ... motor controller 10 ... main motor 11 ... small motor 12 ... gear 13 Slip ring 14 Electrode 14a Upper limit switch 14b Start completion position limit switch LRH Liquid resistor F Flow detector P Pump 52 Main motor contactor

Claims (1)

(57) [Claims] 1. A speed control device for an induction motor for connecting a liquid resistor to the secondary side of a wound induction motor and raising and lowering its electrodes to increase or decrease the resistance, thereby starting and controlling the speed of the induction motor. A servo controller is used for the electrode lifting / lowering motor of the liquid resistor, and a servo controller is provided for rotating the servo motor at a low speed when the induction motor is started, and rotating the servo motor at a high speed during speed control. Speed control device for induction motor.