JPS5937733A - Circuit for firing series connection thyristors - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light-controlled semiconductor switch, each equipped with an ignition device having an energy storage device.

Such an ignition circuit is "Siemens-Zeits
ch-r i f t” Volume 52 (1968),
No. 3, pages 146-149. The light-controlled ignition method solves the problem of the isolation between the common control device and the ignition devices of the individual thyristors. The energy required for ignition is obtained from the protective parallel circuit of the individual thyristors. However, in this case care must be taken that the protective parallel circuit actually supplies sufficient energy for ignition of the thyristor. However, this cannot always be fulfilled, so that various constraints must be borne in mind when extracting the ignition energy from the thyristor-protected parallel circuit. Since the energy storage capacitor must first be charged, it is possible, for example, to switch on the cyrisk only after lQms or iooms have elapsed after the power has been switched on. Therefore, the protection parallel circuit of Cyrisk cannot be designed optimally for the purpose of protection, but also consideration must be given to securing the necessary ignition energy. Since the ignition energy is limited, only short ignition pulses of about 20 ms are obtained. anode,
Since the voltage between the cathodes must be at least 50 to 100 V, restrictions on the control range must also be accepted. Furthermore, there are usage conditions or operating conditions in which the voltage applied to series-connected thyristors may remain zero for a long time, such as in power factor improvement capacitor equipment, frequency converters, and braking operation of DC choppers for electric railways. exist. If the voltage applied to the series-connected cyrisks is too low,
Energy extraction as described above does not cover the entire range of applications, since it is no longer possible to extract energy from the protective parallel circuit.

The object of the invention is to configure an ignition circuit as mentioned in the introduction in such a way that the available ignition energy is independent of the voltage applied to the silisk.

This purpose is achieved according to the invention by providing n isolation transformers;
The primary winding of the first isolation transformer is connected to the AC power supply, the primary windings of the other isolation transformers are each connected to the secondary winding of the preceding isolation transformer, and each of the secondary windings of the isolation transformer is The winding is achieved by connecting the energy storage of the associated ignition device via a rectifier.

According to this circuit, the required ignition energy is supplied from the alternating current power supply via a deadlock transformer and is therefore independent of the voltage applied to the silisk. Such an ignition circuit is therefore applicable to all use and operating conditions. The principle of light ignition with easy potential separation remains the same.
Retained.

Since the isolation transformers are connected in cascade with each other, the isolation voltage of the individual isolation transformers need only correspond to the blocking voltage of the individual thyristors, rather than the total voltage across the series-connected thyristors.

A conventional ignition pulse transformer can therefore be used.

It is advantageous to connect a matching capacitor in parallel to each secondary winding. Thereby, the voltage distribution of each isolation transformer can be adjusted. In order to be able to use the same ignition voltage for all sirisks, the capacitance of the matching capacitor is selected using a known transfer function for the leakage inductance of the isolation transformer, and all secondary windings of the isolation transformer are It is advantageous for the voltages to be equal.

The terminals of each secondary winding are connected via a resistor to the AC input of the associated rectifying bridge circuit, and a capacitor as an energy storage can be connected to the outlet of the bridge (7). This resistance is determined by the magnitude of the required ignition current of the associated scissor. Due to the relatively high resistance, the thyristor is decoupled from the capacitance of the ignition circuit.

A primary winding of another isolation transformer can be connected to the secondary winding of the nth isolation transformer, and a capacitor is connected to the secondary winding. In that case, it is advantageous to connect a light-emitting diode to the secondary winding of the further isolation transformer, which light-emitting diode is coupled to the acknowledgment device via an optical fiber. This confirmation device makes it possible to ascertain whether all ignition devices are supplied with ignition energy.

The AC power supply may include a series circuit of a reverse conducting thyristor and an inductance connected to the DC power supply, in which case the series circuit of the primary winding of the first isolation transformer and the oscillating circuit capacitor is parallel to the reverse conducting thyristor. It is connected to the.

With this circuit, a high frequency AC voltage of, for example, 10 kHz is generated from a DC power supply, and this AC voltage can be transmitted by a relatively small isolation transformer.

In an ignition circuit for multiple thyristor columns each consisting of n thyristors connected in series, a power isolation transformer is provided for each thyristor column, and its secondary winding is the first insulator for the associated thyristor column. Advantageously, it is connected to the primary winding of the transformer. The primary windings of all power supply isolation transformers are then connected in series to the AC power supply. The ignition circuits of all the Cyrisk columns can thereby be fed from a common AC power supply.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a series circuit of Th□ to Thn. A protection circuit in the form of RC□ to RCn is connected in parallel to each of the risks Th□ to Th. The gate of the thyristor Th or Thn is connected to the ignition device EA□ via a light-sensitive transistor T□ or Tn, respectively.
or EAn. The cathodes of the thyristors Th□ to Thn are connected directly to the ignition devices FliA to EAn, respectively, by light-controlled transistors T□.
to Tn are controlled via light guides L□ to Ln.

In order to transmit the necessary ignition energy to the thyristors Th□ to Thn, the primary winding of the isolation transformer U1 is connected to an alternating current power source W, which will be explained further below. The primary winding of the insulation transformer U2 is connected to the secondary winding of the insulation transformer U□, and in this way, n insulation transformer stands or sails are connected one after another. Individual isolation transformer stand or convex. Further, ignition devices EA□ to EAn having the same specifications are connected to the secondary windings of the respective secondary windings. Ignition device EA□
The construction of EAn will be explained below with reference to the ignition device EA. In the ignition device EA, the secondary winding of the isolation transformer Un is bridged by a matching capacitor C1, which adjusts the voltage of the individual isolation transformer O or the unit, as will be explained later. can be adjusted. Furthermore, the terminals of the secondary winding of the isolation transformer Un are connected to the AC input terminals of a set of rectifying bridges Bn via resistors Rna and Rnb. The DC output terminal of the rectifier bridge Bn is bridged by a capacitor CBn, which acts as an energy storage, and a light control transistor T. The gate of the associated thyristor Th and its cathode are directly connected via the thyristor Th.

The secondary winding of the isolation transformer Un is yet another isolation transformer U. +
1, and another matching capacitor C1□ is connected in parallel to its secondary winding.

Furthermore, a light emitting diode D is arranged between one terminal of the secondary winding and a tap terminal of the secondary winding, and is optically coupled to the optical fiber Ln+□.

In these ignition circuits, each capacitor CB□ is charged via the two resistors R1a, R1b or R18°Rnb and the associated rectifier bridge Bn. For example, capacitor CBn is connected to AC power supply W or resistors Rna, Rnb.
and 0, which is charged via the rectifying bridge Bn, is used to fire the thyristor Thn, which is fired when the transistor Tn is made conductive by a light pulse via the optical fiber Ln.

Light emitting diode D connects AC power supply W and isolation transformer U
Or U. can be monitored. As long as all isolation transformers U or Un+□ are healthy! A voltage is applied to the diode D to cause it to emit light, and a signal is sent to a monitoring unit (not shown) via the optical fiber Ln+1.

On the other hand, if the AC power supply W, one of the isolation transformers U□ to Un, or one of the connecting conductors between them fails, no voltage is applied to the light emitting diode and a failure alarm is issued.

The voltages applied to the individual ignition devices EA□ to EA can be determined from the equivalent circuit diagram in FIG. The circuit of FIG. 1 now has in its lateral branches the reduced leakage inductance L', to L/ of the isolation transformer, and at the same time the reduced secondary winding resistance +1, R'1 to R'n+1. It is shown as a circuit network lined up. Between the two inductances L', the longitudinal branch of the network has a reduced capacitance C' to the series resistor R1a, R1b to RnapRnb, and a reduced resistance value R', a, b to R'. na,
b exists. The voltage in the device based on the network is Karl
Written by KiSpfm511er, “Einf'Lhru
ngin die theoretische Ele
ktrotechnik I+ 7th edition, 1962, 3
It can be calculated using the formula described on pages 87 to 388 and pages 354 to 359. In this case, the calculation of the properties of the network reduces to the calculation of the conductors.

If the capacitance C1 to Cn is not selected correctly in relation to the leakage inductance L to Ln□, the individual resistance values appearing in the network, as well as the frequency of the supply voltage, the individual ignition devices EA□ to EA ,
The voltage applied to will generally vary. In FIG. 3, one possible variation of voltage along the network, here considered to be an approximately uniform conductor, is shown in dashed lines. Here, for example, the voltage of capacitor C1, ie, ignition device EA, is higher than that of capacitor C, ie, ignition device EA.

However, the already mentioned transfer function makes it possible to select the individual elements of the ignition circuit in relation to the frequency of the supply voltage in such a way that the voltages of all ignition devices are equal. The voltage UX of the ignition device in this case is shown by a solid line in FIG.

With the device described above, it is possible to supply the same ignition voltage to all the cylinders Th or Thn. This firing voltage is independent of the voltage applied to the thyristor, so that the thyristor can be placed in full-range control or sustained firing. Since both exist and can be monitored, fault diagnosis of the ignition circuit can be carried out without applying a high voltage, making the diagnosis extremely easy. When one end of the series-connected thyristors is grounded or when the AC power supply W has no potential, the isolation transformer U□ or U. 10□ is only designed for the blocking voltage of the thyrsks, and there is no need to design for the voltages applied to all the series thyrisks Th or Thn. Instead, a conventional ignition pulse transformer can be used. In addition, the isolation transformer □ or 0 has a sufficiently high reliability that according to the VDE standard, a protective fuse is not required.

The AC power supply W that supplies power to the ignition circuit EA or EAn is
It is necessary to provide an output voltage with as high a frequency as possible so that small isolation transformers can be used. However, on the other hand, the frequency cannot be increased indefinitely. In this case, the appropriate value for the ignition energy transmission frequency is IQk
It is said to be H2.

Such an AC voltage can be realized by an AC power supply W shown in FIG. Here, the DC power supply S is equipped with a reactor.
A series circuit consisting of the primary windings of the sv' isolation transformers Tr□ to Trm and the vibration capacitor Cs is connected. A reverse conduction thyristor Th is connected between the connection point between the reactor L5v and the negative winding of the isolation transformer T'r and the second terminal of the DC power supply.This reverse conduction thyristor Th is connected in antiparallel. It can be regarded as a combination of a connected thyristor Th5a and a diode Th8b, which are normally connected, that is, are always in a blocking state in one direction. The aforementioned isolation transformers U to Un+1 are connected in a chain to the secondary windings of the isolation transformers Tr□ to Trm, respectively.
The figure shows one set of chains. Such an AC power supply W can supply power to a plurality of series circuits of the thyristors Th.

The reverse conduction risk Th is applied at regular intervals with an alternating frequency determined by a clock oscillator, which is not shown here for the sake of simplicity.

At that time, the isolation transformer Tr□ or 71m9 leakage inductance forms an oscillation circuit together with the vibration capacitor C8,
This oscillator circuit is similarly designed to the desired output frequency. The prerequisite here is that the inductance of the reactor L8v is essentially larger than the sum of the leakage inductances of the isolation transformers Tr□ to Trm.

As a result, an alternating current voltage is generated in the secondary winding of the isolation transformer transistor or Trm, which alternating voltage can be used to supply energy to the ignition circuit of a plurality of series circuits of thyristors. If the thyristor arrangement is not grounded, the isolation transformer Tr□ or Trm must be designed for the potential of the first thyristor Th□. Since the first thyristor Th□ is always selected to have the lowest potential among all devices, the isolation transformers Tr□ to Trm are also designed to have the lowest device potential.

The exemplary embodiments of FIGS. 4 to 6 illustrate the assignment of the ignition device EA& to the thyristor of various conversion devices.

Figure 4 shows a set of rectifiers in a three-phase bridge connection, each bridge arm consisting of two series-connected thyristors Th□
to Th2.

Regarding the arrangement of the individual ignition devices EA□ to EA,
No. 10 Ignition device EA
It should also be noted that voltages higher than the blocking voltage of the individual thyristors Th should not occur between two pairs of adjacent ignition devices EA. Sodame No.1 ignition device EA
1.Thyristor Th□ at the ground potential of the bridge circuit
It is combined with Ignition device EA2 or E for the next stage or later
A4 is a thyristor Th2 to T connected in series.
Belongs to h4. The next ignition device EA5 is assigned to the thyristor Th5 of the next bridge arm, which is connected to the thyristor Th4.

FIG. 5 shows the arrangement of the ignition device for the high frequency generator. This generator is a thyristor Th connected to a DC power supply.
The first ignition device EA is placed at one pole of the DC power supply. It is connected to the cyrisk Th. The next ignition device EA2 is the first thyristor Th□
It belongs to the thyristor Th2 connected in the conducting direction.

Figure 6 shows a three-phase chopper, with each phase conductor having two thyristors Th or Th T connected in series.
4ゝ 1 Including anti-parallel connections of ``h'' to Th'4, ThII□ to Th''.
A pair of ignition devices EA is assigned to a phase-connected thyristor Th, so that an isolating transformer is connected to the individual thyristor Th.
It is only necessary to design for a blocking voltage of . However, since the thyristors Th'□ to Th/ and Th" and Th"i of the other phase conductors have different potentials, they cannot be supplied with power from the same isolation transformer network. Corresponding to FIG. 1, a separate isolating transformer is therefore provided for each line of the three-phase system, which
It is advantageous to supply an isolating transformer network of A, to EA/4, EA/; to EA%.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram of an embodiment of the present invention, Fig. 2 is an equivalent circuit diagram of Fig. 1, Fig. 3 is a diagram for explaining the voltage distribution of the ignition device, and Figs. 4 to 6. 2A and 2B are connection diagrams of different embodiments of the present invention, respectively. Th engineering ~ Th, ... Cyrisk, EA1
~EA n゛° curved ignition device, CB1~CBn...
・Capacitor (energy storage), U1~Un+
□・・・Isolation transformer, T□~Tn・・・Transistor, W・・・AC power supply.

Claims (1)

[Claims] ■) A ignition circuit of n series-connected thyristors in which each thyristor is provided with an ignition device having an energy accumulator, and the gate of the thyristor and the energy accumulator are connected via an optically controlled semiconductor switch. , n isolation transformers are provided, the primary winding of the first isolation transformer is connected to the AC power supply, and the primary winding of each other isolation transformer is connected to the secondary winding of the preceding isolation transformer. ignition circuit of series-connected thyristors, characterized in that each secondary winding of the isolating transformer is connected via a rectifier to the energy accumulator of the associated ignition device. 2. An ignition circuit for series-connected thyristors according to claim 1, characterized in that a matching capacitor is connected in parallel to each secondary winding. 3) In the ignition circuit according to claim 1 or 2, the capacitance of the matching capacitor is selected according to the transfer function with respect to the leakage inductance of the isolation transformer, and all secondary windings of the isolation transformer are An ignition circuit for series-connected cyrisks, characterized in that the voltages are made equal. 4) In the ignition circuit according to any one of claims 1 to 3, each terminal of each secondary winding is connected to an AC input terminal of an associated rectifier bridge via a resistor, An ignition circuit for series-connected cyrisks, characterized in that a capacitor is connected as an energy storage to the output end of a rectifier bridge. 5) In the ignition circuit according to any one of claims 1 to 4, the secondary winding of the n-th stage isolation transformer is connected to the primary winding of another isolation transformer. 6) In the ignition circuit according to claim 5, the ignition circuit of series-connected thyristors is characterized in that a capacitor is connected to the secondary winding of this separate insulating transformer. An ignition circuit for series-connected cyrisks, characterized in that a light-emitting diode is connected to the secondary winding of the device, and the light-emitting diode is coupled to an acknowledgment device via an optical fiber. 7) In the ignition circuit according to any one of claims 1 to 6, the AC power source includes a series circuit consisting of a reverse conduction silicate actuator connected to the DC power source, and the reverse conduction A ignition circuit for series-connected thyristors, characterized in that a series circuit consisting of a primary winding of a first isolation transformer and a vibration capacitor is connected in parallel to a thyristor. 8) The ignition circuit according to any one of claims 1 to 7, comprising a plurality of thyristors each having n thyristors connected in series, and a power isolation transformer for each thyristor. characterized in that the secondary winding is connected to the primary winding of the first isolation transformer for the associated silisk pole, and the primary windings of all the power isolation transformers are connected in series to the alternating current power supply. Ignition circuit of series connected thyristors 0