JPS5833789B2 - Pulse amplifier for gate control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse amplifier, and more particularly to a pulse amplifier suitable for controlling the phase of an inductive load using a thyristor.

In an electric power equipment that controls the power to the load by interposing a conduction angle control element such as a thyristor between the power source and the load, if the load is an inductive load, the current with respect to voltage Since the phase of the thyristor is delayed, the gate pulse of the thyristor needs to be a wide pulse with a certain width.

Figure 1 is a circuit connection diagram of the power control device proposed earlier.
a is an AC power supply, 5CR1 and 5CR2 are antiparallel connected thyristors, L is an inductive load, and main thyristors 5CR1 and 5C.
The conduction angle of R2 is controlled to limit the power to the inductive load.

The part surrounded by the dotted line is the main thyristor 5CRI.

This is a wide pulse amplification device for controlling the conduction angle of 5CR2. Tr is a power transformer, 5CRs is an auxiliary thyristor (switching element), Tp is a wide pulse transformer consisting of one iron core, Pl, P2゜PS is the primary winding terminal, 8
1. S2. S3. S4 is a secondary winding terminal, D1 to D4 are diodes, R1 to R4 are resistors, and PS is a narrow pulse phase shift side device.

FIG. 2 is a diagram of voltage waveforms at various parts of the wide pulse amplification device shown in FIG. 1.

Ea is the power supply voltage, eg is the output of the narrow pulse phase shift control device, Es is the terminal voltage of the auxiliary thyristor 5CRs, Ep12
is the terminal voltage of the primary windings P1 to P2 of the wide pulse transformer Tp, Egl and Es2 are the main thyristor 5CR1, respectively.
This is the gate voltage of 5CR2.

In Fig. 1, if the output of the narrow pulse phase shift side device PS is fired every half cycle in synchronization with the power supply of the auxiliary thyristor 5CRs, when the power supply voltage Ea is positive, the primary of the wide pulse transformer Tp A diode D1 is connected to the windings P1 and P2.
A positive voltage is applied through the diode D2, and when the power supply voltage Ea is negative, a negative voltage is applied to the primary windings P3 to P2 of the wide pulse transformer 5Tp through the diode D2.

Then, the output voltage of the wide pulse transformer Tp is transferred to the main thyristors 5CRI and 5CR2 via diodes D3 and D4.
applied to the gate of

At this time, if the wide pulse transformer Tp is designed to integrate the required voltage over time, a wide gate pulse with a time width T can be obtained as shown in FIG.

This pulse amplifying device is very advantageous over conventional devices in that it can obtain desired wide pulses with an extremely simple configuration.

However, since positive and negative voltages are applied to the primary winding of the wide pulse transformer Tp consisting of one iron core, the gate pulse Eg1. It has been found that erroneous pulses of Egel and Ege2 shown in FIG. 2 are generated in Eg2, respectively.

This is due to the B-H characteristics of the iron core of the wide pulse transformer Tp. For example, when the squareness ratio of the iron core is 1 as shown in Figure 3, the power supply voltage changes from positive to negative or from negative to positive. Even if the power supply voltage becomes zero and the magnetomotive force H becomes zero in the process of changing to No false pulses occur.

However, in order to obtain the desired wide pulse width, it is necessary to use a transformer that does not easily saturate as the magnetomotive force H increases, so an iron core with a squareness ratio of 1 or less is used as shown in FIG.

In this case, when the power supply voltage becomes zero and the magnetomotive force H becomes zero,
The magnetic flux changes from the saturation magnetic flux ΦS to the residual magnetic flux Φm, inducing a voltage and generating an erroneous pulse Ege1. It generates Ege2.

This erroneous pulse may cause the main thyristor to malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pulse amplifying device for a gate system that eliminates the above-mentioned drawbacks and does not malfunction even when used in a power control device whose load is an inductive load.

The feature of this invention is that a clipper circuit is connected to the pulse amplifier for gate control as described above to remove the secondary output voltage below the expected value of the transformer. Alternatively, a resistor is connected in parallel with the secondary winding, or a constant voltage element is connected in series between the secondary winding and a control pole to be controlled.

The present invention will be explained below with reference to an embodiment shown in the drawings.

FIG. 5 is a circuit connection diagram showing an embodiment of the present invention, in which R5 is a resistor connected in parallel with the primary windings Pi, P2 and P3 of the wide pulse transformer Tp for removing erroneous pulses. , CI, R6 and C2, R7 are series circuits of a capacitor and a resistor, each connected in parallel to the secondary winding of the power transformer Tr.

Since the other parts are the same as those in FIG. 1, the same reference numerals are given and the explanation will be omitted.

FIG. 6 is a voltage waveform diagram of each part in FIG. 5, where Ea is the power supply voltage, eg is the narrow gate pulse of the auxiliary thyristor 5CRs,
Es is the terminal voltage of the auxiliary thyristor 5CRs, Ep12 is the terminal voltage of the primary windings P1 to P2 of the wide pulse transformer, and E
gl and Es2 are wide pulse voltages (voltages between terminals 01 and 1 and 02 and 2).

In FIG. 5, when the power supply voltage Ea is positive, the capacitor C1 is charged with current, and the auxiliary thyristor 5CRs
When igniting, the charge on capacitor C1 becomes C1-R1-D
1-P 1-P 2-8CR5R6-Cl and CI
-Ftl-DI-PIR5-P3-P2-8CRs-
When the power supply voltage is negative due to sudden discharge in the R6-CI path, the capacitor C2 is charged with current, and when the auxiliary thyristor 5CRs is fired, the charge in the capacitor C2 is changed to C2-R.
2-D2-P 3-P2-8CR5-R7C2 and C
2-R2-D2-P3-R5P1-P2-8CRs-R
A sudden discharge occurs in the path of 7-C2, and the voltage Ep12 of the negative windings P1 and P2 generates a large wide pulse-like voltage when the auxiliary thyristor 5CRs is fired, as shown in Fig. The pulse transformer is saturated and the voltage Ep12 becomes zero.

An erroneous pulse generated when the power supply voltage changes from positive to negative or from negative to positive becomes almost zero because it is divided by the resistor R5.

Here, if capacitor CLC2 and resistor R6R7 are not provided, and only resistor R5 for eliminating false pulses is connected, false pulses can be eliminated, but at the same time, the output voltages Egl and Eg2 will also become smaller, and the required voltage to fire the main thyristor will decrease. It takes longer to reach the voltage.

Therefore, as shown in Fig. 5, a series circuit of capacitor C1 and resistor R6 and a series circuit of capacitor C2 and resistor R7 are connected in parallel with the secondary winding of the power transformer, and when the auxiliary thyristor 5CRs is fired, By rapidly discharging the voltages of the capacitors C1 and C2 and generating a large narrow pulse at the rising edge of the pulse, the output voltage Eg1. Eg2 rises very quickly.

As described above, according to this actual case, it is possible to eliminate the erroneous pulses that have conventionally occurred and caused problems.

Furthermore, since the rise of the output pulse can be made very fast, a high-performance, highly reliable, and economical pulse amplification device for gate system (goods) can be obtained.

FIGS. 7 to 9 each show other embodiments.

Figure 7 shows resistors R7R8 for removing erroneous pulses connected to the secondary windings S1-s2, s3-S4 of the wide pulse transformer Tp.
are connected in parallel.

FIG. 8 shows a case where Zener diodes ZD1 and Zn2 are connected to the secondary side of the wide pulse transformer Tp, and erroneous pulses are voltage-divided therein.

In addition, in the actual case shown in Fig. 5, it is necessary that the current flowing through the auxiliary thyristor 5CRs becomes zero within the turn-off time of 5CRs, so if the current does not become zero within the turn-off time, the 9th Using two auxiliary thyristors 5CRs 1.5CRs 2 as shown in the figure,
A reverse voltage may be applied to these auxiliary thyristors to extinguish the arc.

In this case, resistors R5°R6 for eliminating false pulses are connected to the primary windings P1-P2. p3～P
Connect in parallel to 4.

[Brief explanation of drawings]

Figure 1 is a circuit connection diagram of the power control device and the previously proposed pulse amplifier, Figure 2 is a voltage waveform diagram of each part of the pulse amplifier shown in Figure 1, and Figure 3 is the B of the iron core with a squareness ratio of 1. -H characteristic diagram, Figure 4 is the B-H characteristic diagram of iron core with squareness ratio of 1 or less, Figure 5
The figure is a circuit connection diagram showing one embodiment of this invention, FIG. 6 is a voltage waveform diagram of each part of FIG. 5, and FIGS. 7 to 9 are circuit connection diagrams showing other embodiments of this invention. be. Ea... AC power supply, 5cRL2... Main thyristor, Tr... Power transformer, Tp...
... Wide pulse transformer, 5CRs ... Auxiliary thyristor (switching element), D1 to D4 ...
・Diode, R1-R8...Resistance, CI,
C2... Capacitor, PS... Multi-phase side equipment, ZDl, Zn2... Zener diode (constant voltage element).

Claims (1)

[Scope of Claims] 1. A power transformer that outputs a secondary voltage that changes positively and negatively, and a power transformer that outputs a secondary voltage that changes positively and negatively, and a phase side (
a primary winding consisting of a first winding to which the phase-controlled positive voltage is input and a second winding to which the negative voltage is input, and a voltage induced by the above voltage. a transformer having a secondary winding consisting of a first winding that outputs a voltage for a gate signal and a second winding that outputs a voltage induced by the negative voltage for a gate signal; 1. A pulse amplifying device for a gate system, characterized in that a resistor is connected in parallel with the first and second primary windings or the first and second secondary windings. 2. A power transformer that outputs a secondary voltage that changes positively and negatively, a switching element that controls the phase of the positive secondary voltage and negative secondary voltage, and a switching element that inputs the phase-controlled positive voltage. A primary winding consisting of a first winding and a second winding that inputs a negative voltage, and a first winding that outputs a voltage induced by the above voltage for gate control, and a second winding that a transformer having a secondary winding consisting of a second winding that outputs a voltage induced by the voltage for a gate signal, the transformer being in series with the first and second secondary windings, 1. A pulse amplification device for a gate system, characterized in that a constant voltage element is connected in a direction opposite to the generated voltage.