DE3149029A1 - METHOD FOR IGNITING AT LEAST ONE CONTROLLABLE SEMICONDUCTOR VALVE FOR AN AC SWITCHING DEVICE AND CIRCUIT ARRANGEMENT FOR IMPLEMENTING THE METHOD - Google Patents

Description

3U9029

BRQWN, BOVEBI & CIE AKTIENGESELLSCHAFT Mannheim December 7th, 1981

Mp.no. 694/81 ZPT / PH-Ft / Ht

A process for the ignition of at least one controllable Halbleiterventile3 for an alternating s trornscha xtp; et up instrument on and circuit arrangement for performing de s Ve rfahrens

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The invention relates to a method according to the supervisory] handle of claim 1 and a circuit arrangement

ί to carry out the procedure »

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The wear and tear on the contact and extinguishing system of exchangeable

: current switching devices with high switching frequency in heavy

i load operation can be achieved through the use of so-called hybrid

■ switches are significantly reduced «, Here the 30 load current is transferred to a secondary switch after opening the main contacts

: commutated away and there by built-in semiconductor valves switched off in its zero crossing. When using controllable valves in the bypass of the mechanical Switching point there is a requirement for an ignition die-35 these valves immediately after the start of the contact piece

■ opening to take over the load current zn and the effects of the switching arcs that develop on a

- .; Reduce the minimum.

Mp.no. 694/81 2T

In a previously known method DE-OS 31 32 338 is the electrical effect of the switching arc is used for the ignition process, which occurs when a voltage drop occurs arises between the contact pieces involved. After the load current has been switched off further control of the semiconductor valve must be prevented in order to continue to interrupt the load circuit to keep. When using a double break system, this can be done according to the in the DE-OS 31 32 338 specified method take place in that the control current of the connecting the two contact points Contact bridge is removed, which is potential-free after switching off.

On the other hand, should the hybrid switching concept be at a single interruption point Use, for example, to create the second interruption point of a. Double break system, as in DE-OS 31 37 321, already for the production of the electrical isolation of the circuit To use, the control circuit of the controllable semiconductor valve must be used to avoid re-ignition can also be electrically interrupted by the voltage returning to the interruption system.

The object of the invention is to provide a method of the type mentioned at the outset, in which an influencing of the Control current is effected in the simplest possible way without the use of additional auxiliary switches.

A further object of the invention is to create a circuit arrangement for carrying out the method.

According to the invention, this object is achieved in that the connection of the control current to the at least

-No. 69M / 81 VS-

a controllable semiconductor valve for its ignition by one of the current flow through the contact point generated measurement signal is controlled.

A circuit arrangement for performing this method, in which the at least one controllable semiconductor.

valve is connected in parallel to the contact point is characterized according to the invention in that in series a measuring device is connected to the contact point, the measuring signal of which can be fed to a switching device, which switches the control current through to the at least one controllable semiconductor valve.

There is the possibility of the load current, i. H. the Current flowing through the contact point to control the switching device for switching through the control current to use for the controllable semiconductor valve for its ignition, or to use external impulses with which the switching device can be controlled "Such" external "impulses can for example be electronically actuatable switches are generated, for example so-called tip switches. But it would have to » except for the contact point, all other switching contacts that may be in the load circuit must be closed.

Further advantageous embodiments of the invention are to be found in the further subclaims.

Based on the drawing, in which some embodiments of the invention are shown, the invention and further advantageous improvements and further advantages are explained and described in more detail.

Mp.no. 694/81

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It shows:

Figure 1 is a schematic diagram of an inventive trained hybrid switch,

Figure 2 shows another version of an inventive Hybrid switch similar to that of Figure 1 and

FIG. 3 shows a specific circuit arrangement for implementation of the principle shown in Figure 2

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Mp -.- No : 69 * 5/81

The main circuit of a trained device according to the invention Hybrid switch is located between two terminals 1 and 2. Between the two terminals 1 and 2 is located a contact point 3, which can be actuated in the usual way, d. h "from a switch-off position to a Switch-on position and vice versa can be brought.

The switching arc that occurs when the contact point 3 is opened under current is generated by commutating the load current I to a controllable semiconductor valve ¹ J connected in parallel to the contact point 3, which acts as a triac

-J _{5 is} formed, comrauted and deleted at the zero crossing. Instead of a triac, an anti-parallel thyristor pair could also be used the controllable semiconductor valve H flowing current is detected. The current measuring point or current measuring device 5 is connected to a switching device which is connected in the control circuit for the controllable semiconductor valve.

2g circuit there is a control power source 6. By means of of the Mefösignales generated by the current measuring device 5 when a current flows through the contact point, the switching device is controlled in the forward direction, so that a control current generated by the control current source 6 for the controllable semiconductor valve 4 on this is switched through. When a load current flows through the current measuring device 5, it generates load. current is the measurement signal that controls the switching device, so that the controllable semiconductor valve is ignited will. If a switching arc occurs at the contact point, it will turn on due to the higher resistance the contact point the load current commutates to the controllable semiconductor valve and there in its next

Mp.no. 69V81 & - $> -

Zero crossing interrupted. Another current flow in The following half-waves can no longer start because the switching device is due to the missing measurement signal Is blocked. The arrangement according to FIG. 1 is thus in principle both for deleting switch-off and suitable for starting arcs.

In FIG. 2, the hybrid switch according to FIG. 1 is modified to the extent that the voltage drop across the switching arc at contact point 3 itself is used as the voltage source for generating the control current for the controllable semiconductor valve. For this purpose, the control circuit for the controllable semiconductor valve 4 is connected in parallel to the contact point. In this parallel branch there is a current limiter 8 in front of the switching device 7, which can be designed as a linear or non-linear resistor, for example. The control current for the controllable semiconductor ^{valve 1} J is taken from the load circuit via the current limiter 8 as soon as a voltage drop occurs at the contact point 3 due to a switching arc and, at the same time, the measurement signal that is generated by the current measuring device 5 indicating its presence of the load current I is signaled and the switching device 7 switches through. Then, when the switching device 7 is switched on or through, the controllable semiconductor valve 4 is ignited again.

With both arrangements there is the possibility of the electronic switching device in addition to the control can also be influenced externally by the current measuring device 5, so that while maintaining the hybrid switch design of the overall system, a purely electronic one Switching on and off, for example in inching mode, is enabled. For this, however, apart from the

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"" 3U9029

,-No. 691/81 ^

Contact point 3 all others possibly in the load circuit existing stop contact points must be closed »

The transfer function of the current measuring device 5 can Depending on the desired effect, binary (current-no current) or analog (dependence of the ignition on the level of the

• jO Stromes). Circuits or components with a high differential internal resistance are particularly suitable as current limiters 8 in order to achieve a ^{level of the control current that is beneficial to the controllable semiconductor valve 1} I, both when the driving voltage of the load current circuit is applied.

■ J5 ses as well as concerns of around an order of magnitude lower arc voltage of contact point 3 guarantee.

Figure 3 shows a erfindungsgeraäß designed, realized hybrid switch in which the principle shown in Figure 2 is used. Parallel to .the Contact point 3 are two thyristors 9 and 10 connected in anti-parallel, which thyristors 9 and 10 with the Terminals 1 and 2 are connected. An RC element 11, 12 is connected in parallel to the two thyristors 9 and 10, with which occurring overvoltages are dampened. In addition, there is one in front of the two thyristors Fuse 13 switched, which secures or protects the thyristors 9 and 10 from excessive load currents. Parallel to the gate-cathode paths of the thyristors 9 and 10, diodes IM or »15 are connected, which are known per se Way prevent excessive reverse voltage loading of these gate-cathode sections of the thyristors. The terminals 1 and 2 are also connected via the contact point 3, which is not shown For example, it can be formed by the first opening half of a double break system the circuit arrangement according to

Mp.no. 691/81

DE-OS 31 37 321 with the current measuring device designed as a current transformer 5. This current transformer, in the following also denoted by the reference number 5, is located immediately in front of the contact point and the two thyristors are parallel to the series connection of the contact point and the current measuring device. The secondary side of the current converter 5 is connected to a bridge rectifier, in parallel with the direct current output of the Bridge rectifier 16 is a Zener diode and a resistor 18 is connected in parallel to the Zener diode. By this load on the secondary side of the current transformer 5

-J ₅ with the Zener diode, the corresponding Zener voltage is established at the resistor 18, which in a known manner is practically independent of the instantaneous value of the primary current in the converter 5 as soon as this current differs from zero at all.

This voltage is applied to the gate-source control path a vertical MOS field effect transistor serving as a variable resistor 19, the simultaneous presence of a current flow in the current transformer 5 and a Voltage drop at the junction x 3 for source-drain voltages above a few volts one of the Gate-source voltage-dependent constant current into the control electrode for the respective load current polarity responsible thyristor 9 or 10 drives and this with it

3Q ignites. Since the field effect transistor 19 is only for currents one polarity works as a controllable resistor, this polarity is rectified by a bridge provided in a manner known per se. The resistor 18 ensures, among other things, that the gate-source voltage of the transistor 19 after the current flow has ended in the primary side of the current transformer 5 by discharging the gate-source capacitance quickly falls below a minimum value dependent on transistor 19,

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3U9029

Mp.no. 694/81 9 ^ -41-

whereby the transistor 19 locks safely. For the vertical MOS transistor 19 types are to be selected whose permissible drain-source voltage is definitely above the voltage peaks occurring in the load circuit.

Claims (1)

«Φ Mp ₈ no. 69'4 / 81. Expectations (Iy method for igniting at least one of at least one contact point of an AC switching device that draws a switching arc during a switching operation to extinguish the switching arc , thereby geken n draws t that the connection of the control current to the at least one controllable semiconductor valve for its ignition is controlled by a measurement signal generated by the current flow across the contact point. 2. Circuit arrangement for performing the method according to claim 1, wherein the at least one controllable semiconductor valve is connected in parallel to the contact point, characterized in that in series the contact point a measuring device (5) switched 3Q is, the measurement signal of a switching device (7) can be fed to the switches through the control current to the at least one controllable semiconductor valve ⁽¹ O. 3 ο circuit arrangement according to claim 2, characterized characterized in that an external voltage source (6) is provided which generates the control current. H. Circuit arrangement according to claim 2, characterized · · - 3Η9029 Mp.no. 694/81 characterized in that as a voltage source for generating the control current or the control voltage for the at least one semiconductor valve for the voltage drop of the switching arc drawn at the contact point (3) is used. 5. Circuit arrangement according to one of the preceding claims, characterized in that as a switching device a vertical MOS field effect transistor (19) is provided is. 6. Circuit arrangement according to one of the preceding claims, characterized in that the switching device (7) also has further, external, the connection of the Control current causing switching pulses can be supplied.