JPS63268493A - Current control device of thyristor motor - Google Patents

Abstract

PURPOSE:To obtain constant current built-up characteristic, by letting the output voltage of a power converter on power source side in building up the current be the sum value of preset voltage and DC load counterelectromotive force. CONSTITUTION:In starting current interrupting action let the input of a firing angle control circuit 6 be at a semi-fixed potential source Vs. At the same time, let a signal (a) be '1', so that a switch 7a is driven and the integrator output of a PI regulator 5 is held. At this time, the integrator output corresponds to the counter electromotive force E of a DC load 2. A thyristor rectifier 1 outputs negative voltage equivalent to the semi-fixed potential source Vs to reduce the current Ic to zero. When the current Ic=0 is discovered by a signal e, the output of the firing angle control circuit 6 is denoted by semifixed potential source Vp+counter electromotive force E after a predetermined time to increase the current Ic. When the current Ic is discovered immediately before the arrival at the set point Ir by a signal +, the input of the firing angle control circuit 6 is connected to the PI regulator 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current control device for a thyristor motor.

[Conventional technology]

Figure 6 shows this type of current control device (
Patent Application No. 62-571 2 et seq. is also simply referred to as the proposed device. ), FIG. 4 is a waveform diagram of each part for explaining its operation, and FIG. 5 is an explanatory diagram for explaining the function of the firing angle control circuit.

In FIG. 6, the motor-side power converter and the motor are collectively shown as a DC load 2. Main circuit DC current ■. is detected by the DC current detector B, and compared with the set value I by the adder 4a, and the difference I, -Ic is input to the PI regulator 5 via the switch 7a. The switch 7a is for holding the output of the precision device 5 of the PIvI 4 moderator 5, and when the signal a is set to '1'' as shown in FIG. , is input to the V/α circuit 6 via the switch 7b.The switches 7b+7c, 7d input the input of the V/α circuit 6 to PIP
This is to be connected to the A node 5 or the semi-fixed voltage source Vs+Vp depending on the case, as shown in FIG. 4(d).

The switch is turned "ON" by setting the signals S, c, and d to "1" as shown in (e) and (f). Note that vs.

VP is for fixing the input of the 776 circuit when the current falls and rises.

As shown in FIG. 5(a), the V/α circuit 6 receives the input voltage V
The thyristor firing angle is controlled to an angle α corresponding to PI.

FIG. 5(b) shows an example of the U-phase ignition pulse. In addition, VP
The relationship between I and α may be linear (solid line in FIG. 5(a)) or nonlinear (broken line in FIG. 5(a)). 77
The outputs of the six circuits 6 are each connected to the gate of the thyristor rectifier 1, and the OR gate circuit 10 inputs the OR of the gate ON signal to the sequence circuit 9 as a signal g. When the signal g is 61" as shown in FIG. 4, the gate signal is input to one of the thyristors. The auxiliary setting value r' is the current value.

This is to know that the value is just before reaching the set value, and is notified to the sequence circuit 9 as a signal f by the adder 4b and the comparator 8a. The signal f is the fourth
As shown in the figure (H), IC>Ir' becomes 1"1". Comparator 8b receives current I. The sequence circuit 9 is notified that the value has become zero as a signal e. signal e is f
As shown in Figure s4 (G), it becomes '1' when IC=0.

The sequence circuit 9 controls the sequence for starting the thyristor motor with intermittent current.

Now, in such a configuration, at time t1 shown in FIG.
Intermittent current operation shall be started at .

That is, the input of the 776 circuit is connected to Vs, and at the same time, the signal a is set to '°·1# to drive the switch 7a to hold the integrator output of the PI regulator. At this time, Ic=I
If sufficient time has passed since , then the integrator output corresponds to the back electromotive force E of the DC load 2. The thyristor rectifier 1 outputs a negative voltage corresponding to Vs, and the current flow increases. is reduced to zero (point 12 in Figure 4). ■. = 0 from the signal e, the input of the 776 circuit becomes V after a certain period of time.
By connecting to P and making the thyristor rectifier 1 output a positive voltage equivalent to Vp, T-current operation is performed. (t3 in Figure 4)
point). When it is learned from the signal f that Ic is about to reach I, the input of the 776 circuit is connected to the PIFIMI node (point 14 in FIG. 4). The PI controller is held at a value equivalent to the DC load back electromotive force E, and after firing once at the firing angle corresponding to this (point t5 in Figure 4), switch 7a is driven to release the bold. Then perform the normal PI system.

In this way, by appropriately setting r' and Vp, it is possible to quickly cause the current IC to reach the set value, and to immediately transition to a steady state without overshoot. This method is particularly effective when the inductance component of the DC load is large.

[Problem that the invention seeks to solve]

However, such a method has the following problems. Figure 6 shows the equivalent circuit of a DC load.

The back electromotive force E constantly changes depending on the field current rotation speed of the motor or the operating state of the motor-side power converter. ■／α
Nonlinear compensation of the thyristor rectifier by the circuit (α = c
os CVpx) ), the entire main circuit can be expressed as an equivalent circuit as shown in FIG. Here, the current rise period during intermittent current operation (13 to 13 in Figure 4)
14), the initial value of the current is . = 0, and in the circuit shown in Fig. 7, V = VpI-E.
Since VPI=VP is constant, it can be expressed as V=Vp-E. Here, if Vp)E, it can be considered that v=vP and the same current waveform can always be obtained, but if E is of a size that cannot be ignored, the waveform will differ depending on the direction of E.

For example, FIG. 8 shows a current waveform when E changes in a control system that is adjusted to have an optimal waveform when E=EO. This means that if the magnitude of the back electromotive force E cannot be ignored, the current waveform will change depending on the change in E, as shown in Figure 8 (a), (),), making it impossible to adjust the control system. There will be problems.

Therefore, in the current intermittent starting operation of a thyristor motor, the present invention makes it possible to always obtain the same current rising waveform regardless of changes in the DC back electromotive force appearing at the DC terminal of the motor-side power converter, and to obtain a good current start-up waveform. The purpose is to enable control.

[Means for solving problems]

a first setting means for setting the input of the firing angle regulator to a first value represented by the sum of a preset value and a DC load back electromotive force equivalent value; and an integrator output of the PI regulator and firing. a second setting means for setting the input of the angle adjuster to a second value corresponding to the DC load back electromotive force; and a second setting means for setting the input of the angle adjuster to a second value corresponding to the DC load back electromotive force; When the converter output current is increased from zero to its set point in order to start intermittent current starting of the thyristor motor, the firing angle regulator input is set to the first one.
, and at the point when the current value exceeds the current supplementary set value, fix the integrator output of the PI regulator and the input of the firing angle regulator to the second value, Once the ignition operation is performed at the ignition angle corresponding to the second value, the PI regulator is brought into normal operation.

[Effect]

At the time of current rise in intermittent current starting operation of the thyristor motor, the preset voltage Vp and the counter electromotive force E
A voltage vp+E represented by the sum of the voltage vp+E is outputted to the power converter on the power source side. By doing so, the influence of the back electromotive force E is canceled out, the same current waveform is always obtained, and the control performance is improved.

[Embodiments of the invention]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining its operation.

The difference from the proposed device shown in FIG. 3 is that an adder 4C is added. With this adder 4C, as shown in FIG.
When trying to increase the current from zero as shown in b), the input of the V/α circuit is set to the sum of Vp and the value E equivalent to the back electromotive force of the DC load, that is, fi VPI = VP + E. do. Therefore, in the equal circuit of Fig. 7, V=VP,
-E=VP, the back electromotive force E is canceled. In this way, constant current rise characteristics can be obtained under any back electromotive force by adjusting Vp and / to be optimal under the condition of back electromotive force E=O.

＼ [Effects of the Invention] According to the present invention, the output voltage of the power supply side power converter at the time of current rise is set as an adder of the preset Vp and the DC load back electromotive force E, thereby reducing the back electromotive force E. This provides the advantage that constant current rise characteristics can be obtained under any back electromotive force.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of this invention, and FIG.
Figure 6 is a configuration diagram showing the proposed device, Figure 4 is a waveform diagram of each part to explain its operation, and Figure 5 shows the function of the firing angle control circuit. An explanatory diagram for explaining, Fig. 6 is a circuit diagram showing an equal number of DC load circuits, Fig. 7 is a circuit diagram showing an equal number of circuits of the entire main circuit, and Fig. 8 is a circuit diagram showing an equal number of circuits of the entire main circuit. FIG. 3 is a waveform diagram showing an example of a change in a current waveform when the current waveform changes. Code explanation 1...Thyristor rectifier, 2...DC load, 3...DC current detector, 4 a * 4
b B 4 c... Adder, 5...
PI regulator, 6... Firing angle control circuit, 7., 7
b, 7., 7d...Switch, "l, X
,,. °°゛Comparator, 9...Sequence circuit,
10...OR gate circuit, Vs, Vp...Semi-fixed voltage source. Agent Patent Attorney Akio Namiki Agent Patent Attorney Kiyoshi Matsuzaki Figure 2C Figure 4■. t1 t2 t3 t4 t5 Fig. 5 (b) U o l: I, C, Hiro pulse 1 Fig. 6 Ae tuplet (E: back electromotive force) Fig. 7 R Fig. 8

Claims (1)

[Claims] 1) In order to drive a thyristor motor through a power converter having a large reactor between a converter and an inverter, a proportional-integral regulator ( In a current control device for a thyristor motor, the input to the firing angle regulator is inputted to a firing angle regulator, and the output thereof is input to a firing angle regulator to adjust the firing angle of the converter to control the current. a first setting means for setting the integrator output of the PI regulator and the input of the firing angle regulator to a first value represented by the sum of the set value and a DC load back electromotive force equivalent value; The second value is set to a second value corresponding to the back electromotive force.
and a detection means for detecting that the converter output current exceeds a preset current supplementary setting value (<current setting value), and the converter output current is set to start intermittent current starting of the thyristor motor. When increasing the current from zero to the set value, set the firing angle regulator input to the first value to increase the current, and when the current value exceeds the supplementary current set value, the PI After fixing the integrator output of the regulator and the input of the firing angle regulator to the second value, and once performing the firing operation at the firing angle corresponding to the second value, the PI regulator A current control device for a thyristor motor, characterized in that the current control device shifts the current to normal operation. 2) In the current control device for a thyristor motor according to claim 1, the value immediately before the current intermittent operation is stored by the means for storing the integrator output of the PI regulator, and this value is stored in the second A current control device for a thyristor motor, characterized in that it is used as a value of . 3) In the current control device for a thyristor motor according to claim 1, the means for storing the PI regulator output stores a value immediately before the current intermittent operation, and uses this as the second value. A current control device for a thyristor motor.