JPH0715355Y2 - Stationary Leonard device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a static Leonard device, and more particularly to a field control device.

B. Outline of the Invention The present invention is a static Leonard device having a field weakening control system that keeps the armature voltage constant by controlling the minimum limiter value of the voltage control amplifier according to the speed setting value. The speed control can be performed for a negative load in the weakened control state.

C. Conventional technology The static type Leonard device controls the speed by the armature voltage (constant torque) control of the DC motor up to the base speed, and the field weakening (constant output) control in the range exceeding the base speed. Increase the variable speed range with.

FIG. 2 shows a control block diagram of the thyristor-Leonard device. The DC motor 1 controls its armature voltage by the phase control of the thyristor converter 2, and this phase control is performed by the automatic speed control device 5 by comparing the set value of the speed setter 3 and the detected value of the speed detector 4. Be seen.

The current control of the field winding 1A of the DC motor 1 is performed by the speed setter 3
A current command is obtained from the polygonal line amplifier 6 which has a predetermined polygonal line characteristic and reduces the output in the region where the set value of (1) exceeds the base speed, and the output current control of the thyristor converter 8 is performed by the automatic current control amplifier 7 based on this command.

D. Problem to be Solved by the Invention In the conventional static type Leonard device, the relationship between the field current and the speed is determined by the characteristics of the polygonal line amplifier 6 for field control, and in order to obtain the desired characteristic for this polygonal line amplifier 6. There is a problem that the arithmetic circuit configuration is complicated. In addition, the DC motor 1
Each time the field characteristics of the above-mentioned change, the characteristics of the broken line amplifier 6 need to be changed, so that there is a problem that the versatility is inferior, such as time-consuming design and adjustment.

As one that does not require the broken line amplifier described above, there is one that obtains a field current command by a voltage control amplifier with a limiter that keeps the terminal voltage of the DC motor constant.

However, in this method, field control is performed to keep the terminal voltage of the electric motor constant, so in controlling an electric motor that has a load such as a crane, a negative load such as unwinding of luggage, etc. If a method to control the field current weakly (single command method) is used, the terminal voltage will try to rise when the lowering rotation speed rises due to disturbance, and as a result of limiting this voltage rise to a constant value on the field side, The magnetic current is reduced and the torque (field x proportional to armature current) is reduced.

Depending on the decrease in the torque, the lowering speed of the load cannot be reduced, that is, the speed control function is lost.

It is an object of the present invention to provide a static Leonard device that can have a speed control function even for a negative load while eliminating a broken line amplifier.

E. Means and Actions for Solving the Problem In order to achieve the above object, the present invention provides a speed control system for controlling an armature voltage of a motor based on a speed setting value and a speed detection value of a DC motor, and the electric motor. In a static Leonard device with a field weakening control system that controls the field current of the electric motor by a voltage control amplifier by comparing the child voltage and the set voltage, the minimum value of the voltage control amplifier is set in accordance with the speed set value. It has a limiter circuit to control, and in the field weakening control state, it limits the minimum value of the voltage control amplifier according to the speed setting value, and prevents the field current from becoming too small by this restriction to ensure the speed control function. .

G. Embodiment FIG. 1 is a control block diagram showing an embodiment of the present invention, and those having the same functions as those in FIG. FIG. 1 is configured in a field control system for making the armature voltage constant by the voltage control amplifier 10. That is, the field current command is obtained at the output of the voltage control amplifier 10 by comparing the set value of the voltage setter 11 and the armature voltage.

Here, in the present embodiment, the limiter circuit of the voltage control amplifier 10 is provided with the buffer 12 for extracting the set value of the speed setter 3,
The output voltage of the buffer 12 controls the limiter value of the limiter circuit.

With such a configuration, the minimum value output of the voltage control amplifier 10 is controlled by the setting value of the speed setter 3, and the minimum output of the voltage control amplifier 10 is limited by lowering the speed setting value of the speed setter 3. It limits the minimum current value of the magnetic winding and limits the maximum speed in field weakening control.

Therefore, for example, even when the crane is in the unwinding state with a negative load and is in the field weakening control region, deceleration control can be obtained by lowering the speed setting value. Then, in the normal field weakening control, the limitation by the speed setting value is limited only by the limiter value of the voltage control amplifier 10, and it is possible to obtain the same controllability as the conventional one by giving a margin to this limiter value. In addition, the broken line amplifier 6 is not required, and the field control system is simplified and versatile.

Although the embodiment is shown for the case of a thyristor-Leonard device, the present invention is applied to a static-type Leonard device having a field control system and has the same effect.

H. Effect of the Invention As described above, according to the present invention, the minimum value of the voltage control amplifier is limited by the speed setting value, so the speed can be limited by the speed setting value and deceleration with a negative load is possible. . Since the armature voltage constant control system is adopted, the field control system can be simplified and the field characteristics of the motor are hardly affected, and a highly versatile control device can be realized.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention, and FIG.
The figure is a conventional control block diagram. 1 ... DC motor, 3 ... speed setting device, 10 ... voltage control amplifier, 11 ... voltage setting device, 12 ... buffer.

Claims (1)

[Scope of utility model registration request] 1. A field current of a motor by a speed control system for controlling an armature voltage of the motor by a speed setting value and a speed detection value of the DC motor, and a voltage control amplifier for comparing the armature voltage and the setting voltage. A static Leonard device including a field weakening control system for controlling a static Leonard device, comprising: a limiter circuit for limiting the minimum value of the voltage control amplifier according to the speed set value.