JPS596596B2 - speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved speed control device for controlling the speed of a wound induction motor based on the secondary voltage of the wound induction motor.

From the beginning, when controlling the speed of a load connected to a wound induction motor, it is possible to directly control the secondary voltage of the wound induction motor without installing a speed generator, etc., in order to simplify the configuration of the control device and reduce the cost. The motor is removed, the operating speed is determined from this, and the wound induction motor is controlled so that it continues to operate at the target operating speed. Examples of such devices are shown in FIGS. 1, 2, and 3. The one shown in the figure is a combination of a wound induction motor 1 and an eddy current brake 2 for controlling the hoisting and lowering of a crane. To explain this in detail, the primary side of the wound induction motor 1 is connected to the main power source 3, and the secondary side is connected to the external resistor 4. A thyristor bridge 9 5 is connected between the eddy current brake 2 and the operating power source 6, and controls the excitation power supplied to the eddy current brake 2.

7 is an operating speed command means 9 for issuing a command signal Er for instructing the operating speed of the wound induction motor 1; a rectifier 9 that rectifies the AC voltage of the rectifier 9, a stabilization circuit 10 that adjusts the DC voltage of the rectifier 9 to a constant value, a voltage divider 11 that appropriately divides the DC output of the stabilization circuit 10, and a voltage from the voltage divider 11. It is composed of a speed setting device 12 that generates a command signal Er based on.

13 is a speed detection means for detecting a speed signal Ef corresponding to the operating speed of the wound induction motor 1, and includes a transformer 14 that receives the secondary voltage of the wound induction motor 1 and a rectifier 15 that rectifies the secondary voltage. .

16 is a comparator which inputs the command signal Er and the speed signal Ef and compares the two; when the command signal Er is larger than the speed signal Ef, the deceleration command signal Ed is reversed, and when the speed signal Ef is larger than the command signal Ev, the comparator issues a speed increase command signal Eu.

A phase control circuit 17 receives the output signal of the comparator 16 and adjusts the firing angle of the thyristor bridge 5.

That is, when this phase control circuit 17 receives a deceleration command signal Ed from the comparator 16, it issues a braking control signal Ea to widen the conduction angle of the thyristor bridge 5, and when it receives a speed increase command signal Eu, it issues a braking control signal Ea to widen the conduction angle of the thyristor bridge 5. It receives the braking control signal Ea so as to narrow the conduction angle. This thyristor bridge 5 and phase control circuit 17 supply exciting power Q! to the eddy current brake 2! ! :Constitutes a brake control means 18 that controls and adjusts the braking force. Next, the operation of the speed control device configured as described above will be explained.

First, when hoisting the crane at high speed, the external resistor 4 is short-circuited or adjusted to a small value.
The torque curve of the wound induction motor 1 at this time is shown by a in FIG. 2. When the crane continues to lower the load, it is necessary to control the operating speed of the wound induction motor 1 to an appropriate value while applying an appropriate brake torque to prevent the lowered load from falling. . First, an external resistor 4 is connected to this, and the eddy current brake 2 is excited. FIG. 2 shows a torque curve b of the wound induction motor 1 at this time, and a brake torque curve e when the eddy current brake is most strongly excited. That is, as shown in FIG. 3, the value of the command signal Er is set to the value taken when the speed signal Ef, which is generated based on the secondary voltage that decreases as the operating speed V increases, is at the target operating speed V. If V is adjusted by the speed setting device 12, the wound induction motor 1 is always operated at a constant operating speed V. For example, if the lowering speed decreases because the load being suspended becomes lighter when lowering the crane, the speed signal Ef becomes higher than the command signal Er. Then, the comparator 16 receives this signal and issues a speed increase command Eu to weaken the braking force of the eddy current brake 2 and increase the operating speed, thereby correcting the operating speed of the wound induction motor 1. Conversely, when the hoisting speed of the crane increases due to reasons such as the weight of the suspended load becoming heavier, the comparator 16 receives this signal and issues a deceleration command Ed to increase the braking force of the eddy current brake 2 and reduce the operating speed. The operating speed of the linear induction motor 1 is corrected. In this way, even if the weight of the suspended load changes, by controlling the excitation power Q of the eddy current brake 2, the load can always be lowered at a constant speed. However, such a speed control device has a drawback that the operating speed also changes when the power supply voltage fluctuates.

To explain this simply, when the wound induction motor 1 is operating at the target operating speed v, for example, when the power supply voltage of the main power supply 3 increases, the secondary voltage of the wound induction motor 1 also increases, and the speed increases. The signal Ef becomes higher than the command signal Er. Therefore, the relationship is as if the wound induction motor 1 were decelerated, and the comparator 13 receives the speed increase command signal Eu.
emits. As a result, the wound induction motor 1 continues to operate at an operating speed faster than the target operating speed v.
Conversely, if the power supply voltage of the main power supply 3 decreases, the speed signal Ef
Is it smaller than the command signal Er? 9, the relationship is as if the wound induction motor 1 had increased its speed. Then comparator 16
issues a deceleration command signal Ed, which intensifies the excitation of the eddy current brake 2, causing the wound induction motor 1 to reach the target operating speed V. The driver also starts driving at a slow speed. As described above, in the conventional speed control device, the operating speed of the wound induction motor 1 fluctuates due to fluctuations in the power supply voltage of the main power source 3, and the operating speed cannot be kept constant. In addition, the main power supply 3
It is also conceivable to incorporate a tap-switching transformer or other constant voltage circuit into the motor to automatically adjust the power supply voltage so that even if the voltage on the input side fluctuates, the voltage applied to the wound induction motor 1 does not fluctuate. However, this would not only make the device complicated but also expensive. SUMMARY OF THE INVENTION Therefore, the present invention provides a speed control device that has an extremely simple configuration and is capable of continuing operation at a preset target operating speed even when the power supply voltage fluctuates.

In other words, in the present invention, even if the secondary voltage changes due to the influence of power supply voltage fluctuations, the value of the command signal also changes relatively at the same rate as the change in the secondary voltage, thereby eliminating the influence of power supply voltage fluctuations. In order to prevent a deceleration command signal or a speed increase command signal from being generated in response to the received command signal, the operating speed command means for obtaining the command signal to be applied to the comparator is provided on the primary side of the wound induction motor, and the primary input voltage of this is taken into the primary side of the wound induction motor. It is connected.

One embodiment of the crane hoisting and hoisting control is shown in FIG. 4 below.

That is, as shown in the figure, the operating speed command means 19 for obtaining the command signal Er that changes according to the change in the primary input voltage of the wound induction motor 1 is connected to the main power source 3 connected to the primary side of the wound induction motor 1. A transformer 8 connected to the main power supply 3, a rectifier 9 for extracting a voltage signal according to the power supply voltage of the main power supply 3, a voltage divider 11 for dividing the DC voltage from the rectifier 9 into an appropriate value without going through a stabilization circuit, The speed setting device 12 generates a command signal Er based on this divided voltage. This voltage divider 11 adjusts the divided voltage applied to the speed setting device 12, and generates a speed signal Ey due to fluctuations in the power supply voltage.
This is to make the changes in the command signal Er coincide with the changes in the command signal Er.
The rest of the configuration is completely the same as the conventional example explained in FIG. 1, so the explanation will be omitted. Next, the operation of the device configured as described above will be explained.

Now, when the wound induction motor 1 is operating at a preset operating speed v, even if the secondary voltage changes due to fluctuations in the power supply voltage and the speed signal Ef changes, the command signal is sent at the same rate. Since Er also changes, no extra speed increase command signal EU or deceleration command signal Ed is generated from the comparator 16, and the operating speed of the wound induction motor 1 is always maintained at the predetermined operating speed v. Furthermore, in the embodiment shown in FIG. 4, the eddy current brake 2 was used as the brake; however,
In addition, conventionally known electromagnetic brakes, hydraulic servo brakes, etc. that can generate brake torque can be used.

Next, the embodiment shown in FIG. 5 will be described.

This example shows a stationary cerbium device that controls the operating speed of the wound induction motor 1 by returning power generated on the secondary side of the wound induction motor 1 to the primary side. That is, 20 is a rectifier connected to the secondary side of the wound induction motor 1, and 21 is a rectifier 20 connected via a DC reactor.
22 is a transformer for matching the AC output of the inverter 21 with the voltage of the return destination, 23 is an ignition control circuit for the inverter 21, which changes the output frequency of the inverter 21 to the power supply frequency. This is to synchronize with the power source and adjust the amount of returned power that is returned to the power source through the inverter 21. Stationary Calbius device 2 as a power return means configured in this way
4 works to reduce the amount of power returned to the power source when receiving the speed increase command signal Eu from the comparator 16, and to increase the amount of power returned to the power source when receiving the deceleration command signal Ed.
To explain further, when receiving the speed increase command signal Eu, the ignition control circuit 23 issues a return amount control signal Eb to advance the conduction angle of the inverter 21, and also issues a deceleration command signal Ed.
When the return amount control signal Eb is received, a return amount control signal Eb is generated so as to delay the conduction angle of the inverter 21. In this way, the electric power generated on the secondary side of the wound induction motor 1 can be returned to the power source side without wasting it. Next, Figure 6,
The embodiment shown in FIGS. 7 and 8 will be described.

These embodiments each include a secondary resistor means 25, such as a secondary chopper device, a secondary resistor with short-circuiting means or a thyristor device providing ignition control, and a comparator 16.
When receiving the speed increase command signal Eu, the wound induction motor 1
It works to lower the resistance on the secondary side of the wound induction motor 1, and conversely to increase the resistance on the secondary side of the wound induction motor 1 when receiving the deceleration command signal Ed. That is, in FIG. 6, 26 is a thyristor bridge constituting, for example, a secondary chopper device, and a rectifier 20 connected to the secondary side of the wound induction motor 1.
By turning the DC output on and off, the resistance value on the secondary side is changed. To explain a little more, when the short-circuit control circuit 27 receives the speed increase command signal Eu, it emits the resistance value control signal Ec to widen the conduction period of the thyristor bridge 26, and when it receives the deceleration command signal Ed, it emits the resistance value control signal Ec. The conduction period of the thyristor bridge 26 is narrowed. The resistance value control signal Ec is generated so as to increase the resistance value. In addition, as shown in FIG. 7, an external resistor 4 connected to the secondary side of the wound induction motor 1 as a secondary resistor equipped with a short-circuiting means is sequentially connected to a contact group 28.
The resistance value on the secondary side is adjusted by short-circuiting.

That is, when the contact group leg circuit 29 receives the speed increase command signal Eu from the comparator 16, it issues the resistance value control signal Ec to close the contact group 28, and when it receives the deceleration command signal Ed, it issues the resistance value control signal Ec to close the contact group 28. A resistance value control signal Ec is generated to open the resistor. ? Furthermore, the one shown in FIG. 8 is a thyristor device that performs ignition control by connecting a thyristor bridge 30 to the secondary side of the wound induction motor 1 and adjusting the conduction period of this thyristor bridge 30. This is an example of varying the resistance value of the lift. That is, when the ignition control circuit 31ij receives the speed increase command signal Eu from the comparator 16, it issues the resistance value control signal Ec to extend the conduction period of the thyristor bridge 30, and conversely, when it receives the deceleration command signal Ed. A resistance value control signal Ec is generated to narrow the conduction period of the thyristor bridge 30. In this way, by controlling the resistance value on the secondary side of the wound induction motor 1 as shown in FIGS. 6, 7, and 8, the operating speed of the wound induction motor 1 can be freely adjusted. You can walk around. Is it clear from the above explanation? In this way, the present invention utilizes the secondary voltage of the wound induction motor to determine its operating speed, and adjusts speed control means such as a brake, a stationary Servius device, and a secondary resistance device to reduce the speed of the wound induction motor. In controlling the operating speed of an electric motor, a command signal for instructing the operating speed is generated based on the primary side artificial voltage of the wound induction motor.

Therefore, according to the present invention, it is possible to obtain a speed control device which has an extremely simple configuration and which is not affected by fluctuations in the power supply voltage and can always maintain stable control.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining the configuration of a conventional speed control device, Fig. 2 is a diagram with operating speed V on the horizontal axis and torque T on the vertical axis to explain the torque characteristics, and Fig. 3 4 is a diagram showing the operating speed V on the horizontal axis and the signal voltage E on the vertical axis to explain the relationship between the respective signals. FIG. Figure, Figure 5,
FIG. 6, FIG. 7, and FIG. 8 are block diagrams for explaining other embodiments. DESCRIPTION OF SYMBOLS 1... Wound induction motor, 2... Braking means (eddy current brake), 3... Main power supply, 4... Secondary resistor, 1
1... Voltage divider, 13... Speed detection means, 16...
Comparator, 18, 24, 25... Speed control means, 18.
...Brake control means, 19...Speed command means, 20,
21, 22, 23... Stationary Servius device, 20, 2
6, 27... Secondary chopper device, 24... Power return means, 25... Secondary resistance means, 28, 29, 4...
Secondary resistor equipped with short circuit means, 30, 31...Thyristor device for controlling ignition.

Claims (1)

[Scope of Claims] 1. A wound induction motor connected to a main power supply, a speed detection means for detecting a speed signal according to an operating speed from a secondary voltage of the wound induction motor, and a primary motor of the wound induction motor. speed command means for issuing a command signal for commanding the operating speed of the wound induction motor based on the divided voltage of a voltage divider into which the side input voltage is input; a comparison means that issues a deceleration command signal when the speed signal is greater than the command signal and, conversely, issues an increase command signal when the speed signal is greater than the command signal; speed control means for reducing the operating speed of the wound induction motor by means of a speed increase command signal, and conversely increasing the operating speed of the wound induction motor by means of a speed increase command signal. 2. A wound induction motor connected to a main power source, a braking means connected to the wound induction motor, a speed detection means for detecting a speed signal according to an operating speed from a secondary voltage of the wound induction motor, and the speed command means for issuing a command signal for commanding the operating speed of the wound induction motor based on a divided voltage of a voltage divider inputting the primary side input voltage of the wound induction motor; and comparing the command signal and the speed signal. Comparing means for issuing a deceleration command signal when the command signal is larger than the speed signal and, conversely, emitting a speed increase command signal when the speed signal is larger than the command signal; A speed control device comprising speed control means for generating a braking control signal for increasing the braking force of the braking means and, conversely, for weakening the braking force of the braking means in response to a speed increase command signal. 3. The speed control device according to claim 2, characterized in that the braking means includes an eddy current brake. 4. A wound induction motor connected to a main power source, a power return means connected between a secondary circuit of the wound induction motor and the main power source, and a speed corresponding to the operating speed based on the secondary voltage of the wound induction motor. speed detector means for detecting a signal; and speed command means for issuing a command signal for commanding the operating speed of the wound-rotor induction motor based on the divided voltage of a voltage divider into which the primary input voltage of the wound-rotor induction motor is input. and comparison means for comparing the command signal and the speed signal and issuing a deceleration command signal when the command signal is larger than the speed signal, and on the other hand, issuing a speed increase command signal when the speed signal is larger than the command signal. and a return amount control signal that increases the amount of power returned by the power return means to the main power source by the deceleration command signal of the comparison means, and conversely decreases the amount of power returned by the power return means to the main power source by the speed increase command signal. A speed control device comprising a speed control means that emits a speed control means. 5. A speed control device according to claim 4, characterized in that a stationary Servius device is used as the power return means. 6. Detecting a speed signal according to the operating speed from a wound-type induction motor connected to a main power source, a secondary resistance means connected to a secondary circuit of the wound-type induction motor, and a secondary voltage of the wound-type induction motor. a speed detection means; a speed command means for issuing a command signal for commanding the operating speed of the wound induction motor based on a divided voltage of a voltage divider into which the primary input voltage of the wound induction motor is input; and the command signal. and the speed signal, and when the command signal is larger than the speed signal, a deceleration command signal is issued; and when the speed signal is larger than the command signal, a speed increase command signal is issued; a speed control device for generating a resistance value control signal for increasing the resistance value of the secondary resistance means in response to a deceleration command signal and decreasing the resistance value of the secondary resistance means in response to a speed increase command signal. 7. A speed control device according to claim 6, characterized in that a secondary chopper device is used as the secondary resistance means. 8. The speed control device according to claim 6, characterized in that the secondary resistance means includes a secondary resistor provided with shorting means. 9. The speed control device according to claim 6, characterized in that the secondary resistance means includes a thyristor device that performs ignition control.