FI61253C - COPYING INSTRUCTIONS AND COUPLING WITHOUT SPA STABILIZATION - Google Patents

Description

I ΓβΙ nn NOTICE OF PUBLICATION, Λ 0 c 7 MA [BJ (t1) UTLÄGGNINGSSKRIFT 61 25 3 c Patent granted 10 06 1982 * / [Α & Patent meddelat ^ τ ^ (51) Ky.ik.3 / i «.a.3 Η 02 Ρ 13/22 SUOMI-FINLAND (») Ptunttlhikamut - Pu« waiw5knlng 761068 (22) H »k * ml * ptlvi - Anattknlngadtg 09.0t.75 (23) Alkupllvl —Giltlghaodag 09.0t.75 (41) Tullut Julkisakil - Bllv offmtllg 11.10.75

Patent and Registration Office .... ... , . .....

_ '(44) Date of commencement and date of issue. -

Patent- och registerstyrelsen Aniökin Utlagd och utl.akrlftan publkarad 26.02.82 (32) (33) (31) Pyydetty etuoikeus - Bagird prlorltet 10. Ot. jb

Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 2 ^ 17628.1 (71) Siemens Aktiengesellschaft, Berlin / Munchen, DE; Wittelsbacherplatz 2, D-8000 Munchen 2, Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) (72) Heinz Ammon, Munchen, Rainer Dangschat, Landsham, Horst Grobecker,

Munich, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (7t) Berggren Oy Ab (5t) Switchgear for a mains switch with current limitation and voltage stabilization - Kopplingsanordning för en koppiingsnätdel med strömbegränstning och

The present invention relates to a switching device for a switching network part provided with current limiting and voltage stabilization and having an input for a rectified mains AC voltage and a self-oscillating blocking oscillator comprising a switching transistor, a transformer, a control circuit and a blocking circuit , wherein one winding of the transformer is a working winding in series with the input of the switching transistor load circuit and the second winding of the transformer is located in the switching transistor control circuit as a feedback winding, the control circuit further comprising a thyristor when the reference circuit connected to the ignition electrode and the voltage taken from the rectifier and rectified exceed the reference voltages the setpoint is inhibited by switching the transistor by switching on the thyristor, the blocking circuit further comprising a capacitor in series with the control circuit of the switching transistor, the ohmic resistance of the load current and the thyristor operating circuit and connected across the diode to the transformer

Such a switching device is already known and one of them is described, for example, in German application publication 2 160 659 ·

Another description can be found in "Funktechnik" 1971, No. 20, pages 782 and 784. It describes a circuit with a "self-oscillating blocking oscillator with a triggering switch-off". This triggering switch-off allows favorable switching conditions for the switching transistor. Without such a switch-off, the switching transistor, which would have been controlled exclusively via feedback, would only be "choked" due to the small base current. Switching off by means of a thyristor by short-circuiting the feedback coil not only gives a precise and clear switch-off event to the switching transistor, but also a good control possibility.

Through the ignition time of the thyristor, the output voltage of the blocking converter can be well controlled by means of a control circuit. By comparing the reference voltage describing the output voltage of the blocking oscillator with the stabilized reference voltage, which occurs simultaneously with the reference transistor acting as a control amplifier, the ignition moment of the thyristor can be influenced. In the known switching device, a reference voltage is applied via a voltage divider to the base of the reference transistor and across another voltage divider with a zener diode to the emitter of the transistor. The collector is connected to the ignition electrode of the thyristor. In addition, the transistor has an ohmic collector resistor to which the collector current generates a voltage. If this voltage exceeds the threshold, the thyristor is turned on. Thus, the flash point depends on the height of the blocking converter output voltage.

By switching off the switching transistor when the thyristor lights up and its output current can no longer rise, the output-output voltage of the blocking converter is stabilized.

In addition to the above, the moment of ignition also depends on the voltage generated by the load current of the switching transistor in the ohmic resistor flowing through it. If this load current exceeds a predetermined value, the thyristor will also be ignited. The ignition moment is thus determined by both the magnitude of the load current of the switching transistor and the output voltage of the blocking oscillator. The principle of control of the output voltage depends on the premature switching off of the switching transistor and, in addition to the control, it provides protection of the switching transistor against excessive output current.

3 61253 In order to implement both mechanisms for triggering the ignition of a thyristor, it has already been proposed (German patent application P 23 36 110.6) that the ohmic resistor flowing through the load current of the switching transistor be connected between the switching transistor emitter and the thyristor cathode, In this case, both resistors will be in series between the ignition electrode of the thyristor and the cathode, whereby the voltages generated in them, which must trigger the ignition of the thyristor, have the same polarity and thus add up for ignition. In this case, the two tripping torques, the overcurrent output voltage of the switching transistor or the overload load current, are independent of each other. It is further proposed that an anti-ignition bias voltage be applied to the ignition circuit of the thyristor. This extra bias voltage is taken from the blocking transformer transformer, stabilized, and applied with opposite polarity to the collector resistor of the reference transistor. In this case, the ignition of the thyristor is only possible if the voltage triggering the ignition exceeds this blocking voltage.

In a known switching arrangement, the blocking circuit consists of a capacitor arranged in the control circuit of the switching transistor, which is supplied via a diode from a transformer. At the moment the thyristor is turned on, this capacitor is in the control circuit of the switching transistor and reliably prevents this.

It is an object of the present invention to improve the control conditions of a known switching arrangement. However, in order to fulfill this purpose, the total equipment of the switching technology must be kept as small as possible.

In order to solve said task, the switching device according to the invention of the above-mentioned type is mainly characterized in that the feedback winding operates not only to provide feedback simultaneously both to supply a capacitor in the switching transistor control circuit which is affected by the voltage from the comparator and the voltage generated by the ohmic resistor flowing through the load current until the ignition voltage of the thyristor is reached.

11 61253

The switching device according to the invention has the advantage that a single winding of the converter fulfills three functions: It generates a blocking voltage for the switching transistor, a feedback voltage and a bias voltage against the ignition of the thyristor in the ignition circuit of the thyristor. In order for the mains component with the blocking converter to function properly in the event of a short circuit as well as at idle, it is important that the three voltages are in a certain ratio to each other. According to the prior art and previous proposals, these voltages are taken from two or three different windings, respectively, and therefore they are not exactly in the same proportion to the output voltage of the blocking oscillator. By generating these three voltages according to the invention by means of a single transformer winding, a narrow tolerance of the three voltages with respect to each other and to the output voltage of the blocking converter is ensured.

With reference to the embodiment of the switching device according to the invention shown in the accompanying drawing, the invention will be described in more detail below.

5 f '25 3 npn type switching transistor 1 is connected in its collector to the connection of the working winding 2 of the transformer 3. The second terminal of this working winding 2 is connected to the input terminal 4. The emitter of the switching transistor 1 is connected to the terminal of the winding 5 of the transformer 3 and has a potential which is hereinafter referred to as the reference potential. The second connection of the winding 5 leads through a diode 6 to a capacitor 7, the second connection of which is at the reference potential. The transformer 3 further has a winding 8 as a feedback winding, the first end of which is connected to the base of the switching transistor 1. The other end leads to the reference potential via the parallel connection formed by the capacitor 9 and the two resistor diodes 10 and 11 and the ohmic resistor 12 connected in series therewith. In addition to this, the second connection of the feedback winding 8 leads through the diode 13 to the anode of the thyristor 14 and via the series connection consisting of this diode 13 and the capacitor 15 to the base of the switching transistor 1. The cathode of the thyristor 14 is connected to the input terminal 16 and to the reference potential via an ohmic resistor 17. The ignition electrode of the thyristor 14 is connected to the output of a voltage divider formed by two ohmic resistors 18 and 19, which leads from the reference potential via the diode 20 to the first terminal of the feedback winding 8. In addition, a capacitor 21 is connected in parallel with the voltage divider 18, 19.

A collector of a pnp-type reference transistor 23 is further connected to the distribution point of the ohmic voltage divider 18, 19 via an ohmic resistor 22. The base of the transistor is at the output of an ohmic voltage divider, which voltage divider is connected in parallel with the capacitor 7 and consists of three series-connected ohmic resistors 24, 25 and 26, the middle ohmic resistor 25 being implemented as an adjustable ohmic voltage divider. In parallel with the capacitor 7, there is also a series connection formed by the zener diode 27 and the ohmic resistor 28, whereby the ohmic resistor 28 is between the emitter and the reference potential of the reference transistor 23. A capacitor 29 is connected between the base of the reference transistor 23 and the emitter.

The second input terminal 30 is connected to the base of the switching transistor 1 via a series connection formed by a diode 31 together with a capacitor 32 and an ohmic resistor 33. In addition, there is an ohmic resistor 34 between the connection point of the diode 31 and the capacitor 32 and the input terminal 16.

6 61253

Furthermore, a capacitor 35 is connected in parallel with the ohmic resistor 17. · Between the collector of the switching transistor 1 and the reference voltage, there is a series connection formed by three capacitors 36, 37 and 38 together with the ohmic resistor 39.

The transformer 3 further has an output winding 40, one side of which is connected to the body and has four outputs. These outputs in each case lead to one of the four output terminals 45-48 via their own diode 41-44, the output terminals 45-48 being connected to the housing in each case by one of the four capacitors 49-52. An ohmic resistor 64 is further connected in parallel with the capacitor 49.

The connection arrangement described so far is surrounded by a broken line and forms a network part implemented as a module, with input terminals 4, 6 and 30 and output terminals 45-48.

Connected to the input terminals 4 and 16 is the output of a rectifier bridge 65 of four diodes and a parallel rectifier capacitor 66, an ohmic resistor 53 and a capacitor 54. The input terminals of the rectifier bridge 65 are each connected via a choke 55 to both terminals of the AC voltage 57. There is a fuse 58 between the second terminal of the mains AC power supply 57 and the choke 55. In addition, the mains connections of both chokes 55 and 56 are connected to each other via a capacitor 59 and their other two connections are connected to each other via a capacitor 60. In parallel with the capacitor 60, there is a series connection formed by two capacitors 61 and 62, whereby their connection point is connected to the body potential. The second AC terminal of the rectifier bridge 65 is connected to the input terminal 30. There is an ohmic resistor 63 between the second AC terminal and the choke 56.

The load circuit of the switching transistor 1 now consists of a series connection comprising a working winding 2, a collector emitter circuit, an ohmic resistor 17 and a direct current input with both input terminals 4 and 16. The actual control circuit consists of a series connection of a feedback winding 8.

7 61253

The control circuit including the reference transistor 23 receives a reference voltage from the winding 5, which is rectified via the diode 6 across the capacitor 7. This reference voltage is applied through a voltage divider 24, 25 and 26 to the base of the reference transistor 23 and is compared to the reference voltage generated by the zener diode 27. The collector current of the reference transistor 23 resulting from this comparison passes through the ohmic resistor 18.

In addition, this ohmic resistor 18 has a division ratio of the voltage divider 18, 19 corresponding to a part of the voltage of the capacitor 21. This capacitor 21 receives its voltage via a diode 20 and a feedback winding 8.

The blocking circuit consists of a feedback winding 8, a diode 13 and a capacitor 15. This capacitor 15 forms a supply voltage source for the thyristor 14 and when the thyristor 14 is conductive it locks the control circuit between the base and the emitter in the switching transistor 1.

The capacitor 21 is charged with such polarity that the corresponding voltage across the ohmic resistor 18 blocks the ignition circuit of the thyristor 14. In this case, this blocking voltage occurs over a series connection consisting of an ignition circuit and an ohmic resistor 17, through which the load current of the switching transistor 1 passes. The collector current of the reference transistor 23 passing through the resistor 18 generates a voltage opposite to the voltage from the capacitor 21. Also opposite is the voltage generated by the load current in the resistor 17. The ignition blocking bias voltage across the resistor 18 can thus be compensated both by a corresponding collector current of the reference transistor 23 - caused by too high output voltage of the transformer 3 - and by too high a load current that thyristor 14 is ignited. This happens if either the load current of the switching transistor 1 or the output voltage of the transformer 3 becomes too high.

The start-up circuit consists of an input terminal 30, a diode 31, a capacitor 32 and both ohmic resistors 33 and 34. The input terminal 30 is then connected to the mains AC voltage and pulses the diode 31 and the RC circuit 32,33 at the mains frequency to the base of the switching transistor 1.

8 61253

Input terminals 45-48 take DC voltages of different heights. According to the embodiment described above and shown in the drawing, the output side of the transformer 3 is completely separated from the mains. This disconnection can, of course, also be omitted if it is not required.

In normal use, the capacitor 15 is charged through the winding 8 and across the diode 13 to a voltage reduced by the diode output voltage. After the switching transistor 1 is locked, a reverse voltage is induced in the winding 8, which acts over the capacitor 15 with a lower opposite voltage, releasing the working circuit of the thyristor 14.

In the event of a short circuit in one of the outputs 45-48, the network part switches from normal operation to intermittent operation. In this use case, the continuous load pulse sequence is replaced by short pulses at the mains AC voltage frequency. At the same time, the collector voltage of the switching transistor 1 is greatly reduced, so as to ensure that the switching transistor 1 is not damaged even in the event of a short circuit. Also, the short-circuit currents of the outputs must not be higher than the currents allowed by the individual diodes in order to avoid damaging the diodes. These short-circuit currents in this operating mode are determined by the energy stored in the transformer 3.

When a short circuit occurs at the output, the peak current of the switching transistor 1 rises sharply. This causes the thyristor 14 to light up and the switching transistor 1 to turn off. The switching transistor 1 can become conductive again only when first the thyristor 14 is again released via the discharge of the capacitor 15 and on the other hand a starting pulse is given to the base of the switching transistor 1. In this way, the number of collector current pulses allocated to the transformer 3 per unit time is greatly reduced, so that the energy cannot reach the value which may be a danger to the output diodes 41-44. By means of a diode 31, both ohmic resistors 33 and 34 and a capacitor 32, pulses of about 5 ms are generated from the mains alternating voltage. Thus, the collector current pulses of the switching transistor 1 are only possible within this time interval of about 5 ms. These measures significantly reduce the short-circuit current. The effect of the holding current of the thyristor 14 is then only small. Thus, groups of pulses are generated from individual collector current pulses that follow each other 9 61253 at approximately 20 ms intervals.

Another special feature is the limitation of the collector peak current of the switching transistor 1 in the event of an overload at one of the outputs 45-48. The anti-ignition bias voltage at the ignition electrode of the thyristor 14 is obtained by means of a diode 20 in the inhibit phase of the blocking oscillator, i.e. this voltage is proportional to the output. At high overload, the output voltages decrease, which also reduces the blocking voltage of the 1 * 4 ignition circuit of the thyristor. In this case, the thyristor 14 ignites at lower collector peak currents and thus the output current decreases with overload.

In the case of idling, when the load leaves the outputs, the operating frequency of the network component rises sharply. If the minimum load is exceeded, the duration of the switching frequency period becomes less than the release time of the thyristor 14. In this case, the thyristor 14 remains lit for several cycles, so that the oscillation of the blocking oscillator ceases. The new oscillation can only start with the next start pulse.

Thus, pulse groups are also generated every 20 ms at idle. The ohmic resistor 64 forms a preload in idle mode and prevents an excessive rise in output voltages when the mains component is released from the load.

With the switching arrangement according to the invention, it is possible to provide a switching network part with current limitation and voltage stabilization both in both extreme cases, short-circuit and idling, as well as with overload. The switching technology required for this has been reduced to a minimum.

Claims (5)

10 61 253 A switching device for a switching network part provided with current limiting and voltage stabilization and having an input (4, 16) for a rectified mains AC voltage and a self-oscillating blocking oscillator comprising a switching transistor (1), a transformer (3), a control circuit and a blocking circuit 8, 13 »15), and which forms an alternating voltage from the rectified mains AC voltage, wherein one winding (2) of the transformer is in working winding in series with the input circuit of the switching transistor (1) and the other winding (8) of the transformer (3) is located in the control circuit of the switching transistor (1). the control circuit comprises a thyristor (14) whose operating circuit is parallel to the control circuit of the switching transistor (1) and a series connection formed by the ohmic resistor (17) flowing through the load current of the switching transistor, and includes a reference circuit (18, 22, 23, 24, 25) connected to the thyristor ignition electrode 26, 27, 28), and taken from the transformer (3) n and when the rectified voltage exceeds the reference value formed by the reference voltage, the switching transistor (1) is blocked by switching on the thyristor (14), the blocking circuit (8, 13, 15) further comprising a capacitor (15) in series with the current flowing through the switching transistor (1). (17) and a thyristor operating circuit and connected across the diode (13) to the transformer winding (8) through which it becomes charged and when the thyristor (14) lights up, latches the switching transistor (1), characterized in that the feedback winding (8) operates not only for simultaneously supplying both a capacitor (15) in the control circuit of the switching transistor (1) and a further capacitor (21) via the second diode (20), the voltage acting over this second capacitor (21) supplying a blocking bias voltage to the ignition circuit of the thyristor (14), which is affected by the voltage from the reference circuit and the loads the voltage generated by the ohmic resistor (17) flowing through the current until the ignition voltage of the thyristor (14) is reached. Switching device according to claim 1, the reference circuit of which comprises a reference transistor, characterized in that the blocking bias voltage of the ignition circuit of the thyristor (14) is present across the partial resistor (18) of the ohmic voltage divider (18, 19) connected to this bias voltage and 61253 the output current of the reference transistor (23) passes through the partial resistor (18) in such a direction that the voltage thus generated is opposite to the blocking bias voltage. Switching device according to Claim 2, characterized in that the partial resistor (18) is connected in parallel with the series circuit formed by the ignition circuit of the thyristor (14) and the ohmic resistor (17) flowing through the load current of the switching transistor (1). A coupling arrangement for a coupling state and a span stabilizer with a circuit breaker (4, 16) for a rectifying voltage and with a blocking oscillator, a single voltage transformer (3), a coupling transistor (1), och en spärrkoppling (8, 13, 15) samt av den likriktade nätväxelspänningen alstrar en växelspänning, varvid en lindning (2) pä transformatorn som ar-betslindning is kopplad i serieen ingengen account copplingstran-sistorns (1) belastningskrets och en annan 8. belastningsström genomflutet resistivt motständ (17), och en til tyristorns tändelektrod an-sluten jämförelsekoppling (18, 22, 23, 24, 25 , 26, 27, 28), as well as from a transformer (3), and with a spindle spreader with reference to the splice copying transistor (1), the genome of the splitter (14), colors sparged (8, 13, 15 ) in the case of a series of copying transistors (1) of a styrofoam, detached from a genomic flux motor (17) and a thyristor with an interconnected capacitor (15), a single overnight diode (13) and an alternating current transformer (8), as well as a thyristor tower (14) with a blocking copying transistor (1), which can be used as a transmission block (8), for the purpose of copying a signal circuit and an anode of a capacitor (15) and a copying transistor (1) above the diode (20), the variables of the capacitor (21)