JPS5951233B2 - Reversible thyristor Leonard control device that performs constant output control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reversible thyristor Leonard control device that performs constant output control.

For example, when crane motors, winch motors, etc. are subjected to Leonard control, there is a requirement to effectively use the full range of power control (output car constant control) to improve work efficiency, especially during lowering (regeneration area, i.e., under negative load). is increasing.

An object of the present invention is to provide a reversible thyristor Leonard control device that satisfies this requirement at low cost. Hereinafter, the structure and operation of the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a connection diagram showing an embodiment of the reversible thyristor Leonard control device according to the present invention. In the figure, DM is the armature of a DC motor, F is the field winding of the same motor, SCRF, S
CRH is a thyristor for the main circuit, respectively for forward and reverse rotation, CT is a current transformer for main circuit current detection, R is a resistor for armature voltage detection, and SCR is a thyristor CT for field control. 55 is a current transformer for detecting field current, and 55 is a speed setting device.
FG is a normal ramp function device, A and ~A' are respective amplifiers, LE is a forward/reverse logic switch, TDF, TDH, TD
are thyristors SCRF, SCRH, and SCR, respectively.
ignition device, D is a rectifier. Further, SV is an armature voltage limiter setting device, which is provided to prevent runaway by increasing the field current when the armature voltage rises above this setting device. LE. is a field weakening logic circuit, and the field current of the motor is basically controlled according to the output signal of this circuit. In other words, when the motor is speed-controlled by armature voltage control (i.e., torque-constant control), a constant rated field current command signal is always output, and when the motor is speed-controlled by field current control. (In other words, when constant output control is performed), the weak field current command according to the set speed set on the speed setter SS (that is, the rated field current is increased to the field current value determined according to the set speed). The field current value is gradually weakened from this value).

In addition, the changeover switches S1 and S2 are configured to output signals for turning S1 on and S2 off only during negative load operation (for example, when the cargo handling equipment is being lowered) and during output-constant control operation. SF is a field strengthening point setter, which is used as an upper limiter for the armature current, and is set to, for example, the rated armature current value, and when the armature current exceeds this set value, the field current is strengthened and the armature This is provided to suppress the increase in child current. FG2 is a part inserted according to the present invention, and is a ramp function device. This ramp function device decreases with a normal time constant (approximately 2 to 3 seconds) when the field current command decreases (at the time of field weakening command), and when the field current command increases (at the time of field weakening command). For example, 230 when the field is weakened.
It has a characteristic that it increases with a time constant (for example, 100 seconds) that is about 50 times as large. SL, S2 is a ramp function device FG2 during power control in the regeneration area.
The switching switch J■■ is used to switch the insertion of the field weakening logic circuit LE2 according to the output signal of the field weakening logic circuit LE2. FIG. 2 shows an example of speed-load torque characteristics when controlled by the reversible thyristor Leonard control device of FIG. 1. The operation when operating with the characteristics shown in FIG. 2 in the circuit configuration shown in FIG. First, set the field strengthening point setter F to 100% (
(rated) armature current value and armature voltage limiter setter SV to 120% armature voltage value.

Also, set the speed setter SS to 200% speed. In this state, we will first explain the operation when hoisting. First, although not shown, when the controller is turned to the winding side, the forward/reverse logic switch LE is activated.
The output of the amplifier A2 is switched to the forward rotation ignition device TDF side by l, and the armature voltage is applied by the forward rotation thyristor SCRF, and is gradually increased from O to 100% armature voltage value. Here, on the other hand, the current in the field winding F is such that the armature voltage signal fed back by the armature voltage detector R is 1.
Since it is less than 00% armature voltage value, field weakening logic circuit LE2 detects this and outputs a 100% (rated) field current value command signal, which is a strong field, and contacts S2 and amplifier A4.
, ignition device TD, and controls the field thyristor SCR to keep the rated field current flowing.

Therefore, up to the 100% winding speed shown in Figure 2,
The speed of armature DM increases from speed 0. That is, in this operating section (speed 0 to 100%), the engine is operated with constant torque by armature voltage control. next,
After the armature voltage reaches 100% (rated) voltage, the armature voltage is kept constant at 100%, and the field weakening logic circuit LE2 detects this, and furthermore, the setting position of the speed setting device SS is changed. It is detected that the speed setting value is higher than 100% speed (in this example, it is set to 200%), and from the 100% (rated) field current command, which is a strong field,
A field current command is output to gradually weaken the field, and the field current is decreased until it reaches a field current value corresponding to 200% speed.

Therefore, as shown in FIG. 2, when the load torque is 50% or less, the speed of the armature DM increases to 200% speed. In other words, this driving section (speed 100
~200%) will be operated with constant power by field current control. However, if the load torque exceeds 50%, the required output of the load will exceed the rated output of the motor at a certain speed between 100 and 200% speed, so use it within the range shown in Figure 2. . For this reason,
Current transformer CTl for armature current detection, field strengthening point setter S
When the armature current exceeds 100% (rated) current, the circuit consisting of F and amplifier A3 increases the field current, suppresses the speed increase, and operates below the rated armature current. ing. That is, the armature current feedback signal from the current transformer CTl is 1, which is the setting value of the field strengthening point setter SF.
When the current value becomes larger than 00%, the amplifier A3 outputs a field current signal proportional to the difference, and the output is added to the output of the field weakening logic circuit LE2 to become a field current command. Therefore, the motor is operated within a range of less than the rated output of the motor. Here, amplifier A3 is used that outputs only when the input signal is positive (feedback current > set current), so when armature current is below the rated current, it does not output and LE2 The field current is determined only by the output of . The circuit consisting of the armature voltage detector R, the armature voltage limiter setting device SV, and the amplifier A5 is not particularly relevant to the present invention, but since it is shown in FIG. 1, the operation will be explained as follows. The armature voltage feedback signal from the armature voltage limiter setter SV is set at 120
Amplifier A when the armature voltage is less than %. does not output any output, but when the feedback signal exceeds the set value, the amplifier A5 outputs an output proportional to the difference, which is the field weakening logic circuit LE. The field current is added to the output of the motor to increase the field current and prevent the speed from escaping. Therefore, this part (R
, SV, A5) function as an armature voltage limiter. Next, the operation during lowering will be explained.

Each setting device, field strengthening point setting device SF, speed setting device SS, and armature voltage limiter setting device SV, is operated at the set value at the time of winding. First, when the controller (not shown) is turned to the lowering side, the amplifier A is activated by the forward/reverse logic switch LE.

The output is switched to the reverse ignition device TDH side, the armature voltage is applied by the reverse thyristor SCRH, and the armature voltage value is gradually increased from 0 to 100%. On the other hand, since the armature voltage signal fed back by the armature voltage detector R is less than 100% of the armature voltage value, the current in the field winding F is applied to the field weakening logic circuit LE. detects this and outputs a 100% (rated) field current value command signal, which is a strong field, and contacts S. , amplifier A, and ignition device TD, the field thyristor SCR is controlled to keep the rated field current flowing. Therefore, the speed of the armature DM increases from speed 0 to the 100% lowering speed shown in FIG. 2, as in the case of winding up. In other words, this driving section (speed 0 to 100
%) will be operated with constant torque due to armature voltage, same as when hoisting. Then the armature voltage is 1
After reaching 00% (rated) voltage, the armature voltage becomes 1
00% voltage is kept constant.

On the other hand, the field weakening logic circuit LL detects this, and furthermore, the setting value of the speed setting device SS is set to a speed setting value of 100% or more (
In this embodiment, it is set to 200%), and the changeover switches S,,S are activated. Switch, S, On, S. OFF, a ramp function device FG is inserted into the field command circuit, and a field current command that gradually weakens the field from the 100% (rated) field current command, which is a strong field, is output, and the speed is set to 200% speed. Decrease the field current until the field current value corresponds to . Therefore, as shown in FIG. 2, when the load torque is 50% or less, the speed of the armature DM increases to 200% speed. That is, in this operation section (speed 100-200%), the power is constantly operated by field current control.

However, if the load torque exceeds 50% in this case, the
Since the required output of the load exceeds the rated output of the motor at a certain speed between ~200% speed and above, it is used within the range shown in Figure 2. For this reason, the current transformer CT for armature current detection,
, field strengthening point setter SF, amplifier A. , the field current is increased when the armature current exceeds 100% (rated) current, the speed increase is suppressed, and the armature is operated at less than the rated armature current. That is, the armature current feedback signal of the current transformer CT beam is transmitted to the field strengthening point setter S.
When the current value becomes larger than the 100% current value, which is the set value of F, the field current signal proportional to the difference is sent to amplifier A. Output from
Its output is the field weakening logic circuit LE. is added to the output of , and becomes the field current command. Therefore, the motor is operated within a range of less than the rated output of the motor. FIG. 3 is a time chart for explaining the operation during lowering. The electric motor is started at point S in FIG. 3, and as described above, the voltage is controlled and the motor moves from point S to point A, where the speed increases to 100%. All operations during this time are the same as those during winding. When point A is reached, the field weakening logic circuit LE is activated. The switch S1 is turned on by the switching signal from S. Turns off and ramp function FG. Insert LE. The field current command from is subtracted according to the value of the speed setter SS. Ko de A
The reason for inserting the ramp function only after this point, that is, during field control during lowering, is first. During lowering, the motor torque is in the opposite direction to the direction in which the load is falling, so there is little danger even if the field is reduced somewhat suddenly.However, when controlling the field during lowering, the speed increases in the direction in which the load is falling. , Moreover, since the constant torque of the electric motor is not guaranteed as in voltage control,
This is because it is safer to gradually reduce the field using a ramp function, and to prevent the problem at point B in Figure 3, which will be described below. In other words, if the field current is gradually reduced from 100% with the armature voltage constant at 100% from point A in Figure 3, the armature current will gradually increase as shown in Figure 3A, and at point B. 100% (rated) armature current is reached. As shown by the dotted line in Fig. 3A, the armature current exceeds 100% ('-
．． When the armature current attempts to increase, the output is output from the amplifier A3, and the field current increases as shown by the dotted line at point B in Figure 3, preventing further speed increase. Restrict. However, this causes a problem that the armature current escapes. This is because, during unwinding, the motor is driven by a load, that is, works as a generator, and the armature current also coincides with the output direction of the generator. Therefore, when the armature current transiently exceeds 100% and the field current is strengthened, the electromotive force as a generator increases transiently. As a result, the armature current increases further, and when the armature current increases, the field current increases further,
Eventually, the armature current will escape. This problem does not occur during hoisting because the motor works as an electric motor, and even when lowering, it does not occur during voltage control (between points S and A in Figure 3) and during field control (between points A and B in Figure 3). (between) does not occur because the field is not strengthened. Therefore, in order to eliminate this problem, a ramp function device FG2 is inserted and the time constant when the field is strengthened is set to the normal time when the field is weakened. This transient problem is solved by setting a time constant (for example, 100 seconds) that is about 20 to 50 times larger than the constant (for example, 2 to 3 seconds). In conventional devices, as a means to prevent such problems, the magnitude of the armature current is stored in analog memory or digital memory, the current feedback circuit is temporarily cut off, and the value in the memory is used as the current setting in the field. After controlling the magnetic current and reaching a speed corresponding to the field current, the current feedback circuit is memorized as a closed circuit again, then shut off, and the same control is repeated many times in a sampling manner using the memorized value as the set value. However, the present invention has the excellent effects of eliminating the need for memory circuits and sampling circuits, reducing costs, and enabling continuous automatic control. It is something.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram showing an embodiment of the reversible thyristor Leonard control device according to the present invention, Fig. 2 is a speed-load torque characteristic diagram when controlled by the device shown in Fig. 1, and Fig. 3 is a time diagram for explaining the operation. In the chart, A indicates the armature current, C indicates the armature voltage, and C indicates the field current.

Claims (1)

[Claims] 1 In a reversible thyristor Leonard control device that performs constant output control in an operating range where a negative load acts, the feedback signal of the motor's armature (DM) current is compared with the setting signal of the field strengthening point setter (SF), and the feedback signal is Signal - An amplifier (A_
3), the output signal is output as a constant rated field current command signal when not performing constant output control, and as a weak field current command signal according to the set speed when performing constant output control. Compare again with the output signal of the field weakening logic circuit (LE_2), and use the sum signal of the output signal of the amplifier (A_3) + the output signal of the field weakening logic circuit (LE_2) as the field (F) current command of the motor. At the same time, only during constant output control with negative load, the above field (F) current command has a normal time constant when it decreases, and when it increases, it has a time constant of about 30 to 50 times that of decrease. A reversible thyristor Leonard control device that commands a field (F) current through a ramp function device (FG_2) that outputs a large time constant.