DE1438588A1 - Controllable semiconductor valve arrangement - Google Patents

Description

Controllable semiconductor valve arrangement

Controllable converter arrangements with semiconductor valves for high voltage require the series connection of a relatively large number of controllable semiconductor valves. A steady one Distribution of the positive and negative reverse voltage to all As is known, valves of such a series circuit can be achieved by a voltage divider. Since here the valves are all open different potential, the control of each individual valve prepares, for example by means of a conventional grid transformer, significant difficulties; For each valve there is, among other things, a separate secondary winding of the grid transformer with a corresponding one Isolation required. Such a grid transformer would be used because of its large spread for the transmission of pulses steep planks, for example square pulses, unsuitable.

Kin / Da

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809803/0354

PA 60 / 146ο

These difficulties are largely avoided with the invention.

Accordingly, the invention relates to a controllable semiconductor valve arrangement for high voltage with a series connection of several valves, each of which has a member of an ohmic or a capacitive ohmic Voltage divider is connected in parallel. Such an arrangement is improved according to the invention in such a way that when used of such controllable semiconductor valves, which like current gates by means of a control voltage via a special control electrode are ignitable, in series with the controllable semiconductor valves, a non-controlled valve polarized in the flow direction of these valves it is arranged that, furthermore, only one controllable valve of the series connection, to which an auxiliary valve polarized in the blocking direction of the valve is connected in parallel, is connected to a special control voltage source of the usual type, and that the control electrodes of the other controllable valves with the tapping points of a capacitive " Control voltage divider, which controls the entire series connection of the valves bridged, connected in the same sequence.

Such a semiconductor valve arrangement can be controlled in this way be that only one valve from the particular control voltage source, preferably from a control set, is ignited and the rest Valves one after the other through potential shift in the control circuit be ignited. With the capacitive voltage divider, the control electrodes are not connected to the control voltage source controllable valves held at such a potential with respect to their cathode that no ignition current can flow. The power fair are thus "blocked. By the ignition of the Äinge ·· closed power gates, the potential distribution to the control

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electrodes of the other valves changed so that an ignition current flows through which all series-connected power gates are permeable be made.

The mode of operation of the control is to be explained in more detail with the aid of the drawing. A circuit example of a controllable Halb. Ladder valve assembly according to the invention is shown in FIG. Fig. 2 shows an advantageous further embodiment.

Pig. 1 shows a semiconductor valve arrangement which, for example a part of a converter with a series connection of pnpn four-layer semiconductor valves can be, with a series connection of controllable semiconductor valves 2 to 5 and a non-controllable valve 6, which is for example a semiconductor rectifier can be. With the four-layer semi-conductor valves used the outer η-layer is the cathode, the outer p-layer the anode and the middle p-layer the control electrode. In parallel to the valves 2 to 6 there is a resistor 8 to 12 as a voltage divider arranged. The arrangement of these parallel resistors,

• which are referred to as main voltage dividers in the following text is, causes an even distribution of the reverse voltage on the individual valves 2 to 6. The control electrode 2c of the valve 2 is over a pre-forest level 1? and a tax transfer

ί ger 18 with a control set 19 * · which supplies the ignition pulses for the '.; ■■ valve 2, connected. Parallel to the Valve 2 is also an auxiliary valve 7 which is polarized in the blocking direction of this valve. The cathode 2a of the valve 2, which has zero potential, is connected to the control electrode deq valves j5 via a capacitor 13.

Between the control electrode of the valve * 3 and that of the

BATH ORIGINAL

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Valve .Λ is a capacitor 14c The control electrode of the valve 4 is connected in the same way via a capacitor 15 to the control electrode of the valve 5 _o between the anode of the. img-a controlled valve 6 and the control electrode of the valve 5 is a capacitor 16-connected *. The capacitors lj? ₅ 1 ¹ ^ and 15 have equal Cape & intensity ₅ of the capacitor has lö half the capacity of these capacitors' The .Arrangement the capacitors \ J> to 16 to "in the following text as Steuerspannwigs divider foezeiehns-t be," The capacitors of Etsuerspannungsteilers and the resistance of the main circuit divider is dimensioned in such a way that the voltage of the control electrodes of the valves jS to -__ ■. gsgeiV.'cer its cathode is negative ₀ In the case of negative energy saving on the entire series circuit, the auxiliary valve 7 'prevents a voltage dropping resistor 8 and the entire reverse voltage is distributed over d: lj resistors 9 to 12 ;; "Mimmt, for example, -100 V as Augenbllcksvjert the negative barrier voltage on the gesaraten series circuit of _a so has the cathode of the valve." because dee valve, the zero potential, the cathode dec valve ^ the Fotential -2 ^V 3 V and the cathode of valve 5 has a potential of -50 V "The valve '( has no influence on the potentials of the control electrodes of valves 3 to 5. The voltage on the control electrode! -' is advantageous according to the capacities. The control electrode of valve 3 has a potential of -20 V, the control electrode of valve 4 has -hO V, the control electrode of valve 5 has -όΟ V and the remaining voltage of -hO V drops by capacitor 16 corresponding to half the capacity trode negative compared to the cathode in valves 3 to 5. As long as valve 2 is not ignited, if the blocking voltage is positive across the entire series circuit, valve 6 distributes the blocking voltage.

809803/0354. _n “BAD üAoüwal. _{Kln / Da}

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voltage on the main voltage divider to resistors 8 to 11. With an instantaneous value of the positive reverse voltage of, for example, +100 V, the following potential distribution results at the cathodes: valve j5 +25 V, valve 4 + 5OV, valve 5 +75 V; at the control electrodes: valve 3 +20 V, valve 4 +40 V, valve 5 +60 V. Thus, through valves 6 and 7, the potential distribution on the main voltage divider is dependent on the reverse voltage that occurs, the direction of which in the case of the controlled converter several times within one period can change, so influenced that the voltage of the control electrode of the valves 3 to 5 is always negative with respect to their cathode and the valves remain locked. If a control pulse is given to the valve 2 via the control transmitter 18 during a positive reverse voltage on the series circuit from the control set 19, this is ignited and the potential of the anode 2b drops to zero. This means that the potential of the control electrode of the valve is positive compared to its cathode, which is now at zero potential. This potential shift causes a discharge of the con-

capacitor 13 via the control electrode of valve 3> and this valve also becomes permeable. The voltage drop at valve 3 is thus zero and the same process is repeated with the Valve 4, which is ignited by the discharge current of the capacitor 14, as well as with the valve b. Thus it is almost simultaneously with the ignition of valve 2, the entire row of semiconductor valves ignited.

In Fig. 2, the control of a high voltage direct current motor by means of a converter which contains a semiconductor valve arrangement ^x according to the invention is illustrated. The converter is made from a three-phase network with phases R, S and T via a trans-

p- _ Kin / dassAD

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transformer with the primary winding 20 and the secondary winding 21 ■ fed. In each phase, the converter contains a series connection of, for example, 10 current gates with a permissible reverse voltage of 400 volts each. The arrangement of the current gates with the wiring elements is the same in every phase; the circuit was therefore only shown in phase R. With the semiconductor valves 23 to 32, of which only valves 23, 24, 25 and .31 ^; and 32 are drawn is a. Non-controllable semiconductor valve 33 connected in series. Each valve is connected in parallel as the main voltage divider. one of the resistors 34 to 44 and one of the capacitors 4 "5 to 55 are connected in parallel. The capacitors 56 to 65 of the control voltage divider can advantageously each be connected in parallel with an ohmic resistor 6? to 76. Between the control electrode and the cathode of the controllable semiconductor valves; 24 to 32; an ohmic resistor 78 to 86. Furthermore, the control electrodes of the valves 24 to 32 are preceded by a diode 87 to 95, which is polarized in the flow direction of the control current Resistance arranged at the cathode, the occurrence of an undesirable negative voltage; the control electrode opposite its cathode. The size of the resistors 78 to 86 is advantageously chosen to be small compared to the blocking resistance of the diodes 87 to 95. In connection with a four-layer semiconductor valve for approx. 10 A and a maximum blocking capacity of approx ... 500 V could, for example, be a resistor nd of approx. 100 ohms can be used. At the same time, these resistances prevent the positive blocking capability of the current gates from falling; with increasing temperature. In parallel with the entire series circuit, an ohmic resistor 96 can advantageously be connected in series with ■ ■ - ■>', r Kin / Da;

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a capacitance 97 are arranged, which prevents the occurrence of ignition oscillations when igniting the semiconductor valves. The controllable valve 2j5 is an auxiliary valve polarized in the reverse direction of this valve 98 connected in parallel. If during positive anode voltage from the control set 100 a control pulse, whose phase position e.g. by means of a control potentiometer 101 can be changed via a control transformer 102 and a series resistor 105 to the valve 23 given, this valve is ignited. This will increase the potential • its anode zero. Due to the associated shift in potential At the cathode of the other valves, all of the valves that are controlled are one after the other Valves of the series connection are ignited, as has already been shown with reference to FIG. 1. This will make the entire row of valves permeable and a current flows in phase R. In the same way the current in phase S can be controlled by a pulse via the control transmitter 105 and the series resistor 106 on a controllable valve of the Phase S are given and thus the series connection of the valves in the phase S can be made permeable. The process is repeated in the same way for phase T. The series connection of the semiconductor valves is protected in each phase by an upstream fuse 22. The direct current flows over a smoothing choke 108 the switch 109 and through the armature 111 of the motor, which has a Winding 112 is externally excited.

4 claims
2 figures

BATH

Kin / Da 809803/035 4

Claims (1)

ρ ν / ν ν Claims | . ; Controllable semiconductor valve arrangement for high voltage with a series connection of several valves, each of which has a member of an ohmic or a capacitive-ohmic voltage divider connected in parallel, characterized in that, when using such controllable semiconductor valves which, like current gates by means of a control "voltage on a particular control electrode ignitable are, 1st arranged a poled in the flow direction of the valves uncontrolled valve in series with the controllable semiconductor valves is that of the series circuit of only one controllable valve, to which a reverse bias of the _valve; special poled auxiliary valve is connected in parallel to a Control voltage sources of the usual type is connected, and that the control electrodes of the other controllable valves are connected in the same sequence to the taps of a capacitive control voltage divider, which bridges the entire series connection of the valves. . Semiconductor arrangement according to Claim i, characterized in that between of the control electrode and the cathode of each of the remaining controllable Valves a resistor is arranged. . Semiconductor arrangement according to claim l _f . characterized in that between the taps of the expensive voltage plate and the associated control electrodes; an auxiliary valve polarized in the direction of flow of the control current is arranged in each case - _ ■ _. , Semiconductor arrangement according to claim 1, characterized ^ that to each capacitance of the control voltage divider has a parallel resistor is switched /: - ■ - "": '