DE1538739A1 - Thyristor circuit - Google Patents

Description

Dr.-lng. Wilhelm Beichel - _lflQ . Frankfurt / Mcrin-1 ⁴ ■ Parkilrafl 13

Brush Electrical Engineering Company, Ltd., Loughborough, Engl.

Thyristor maintenance

The invention relates to a thyristor circuit * under "thyristors" are to be understood here controllable rectifiers whose (rectifier property between

two main connections is controllable., For this purpose, they are provided with a third connection, the control connection or "gate", via which or they can be controlled by a pulse in the lead the state when the rectifier path between the main connections is forward biased ο As long as this so-called "ignition pulse" is not supplied , these thyristors remain non-conductive or blocked, regardless of the polarity of the voltage applied to the synchronous resistor. As is known, these components are often used in AC power supply units to control or regulate the output power of the Hetsgerä- tes . For this, the current flow will represent Thyristo ren by shifting the ignition timing during a half-cycle is controlled AC supply voltage * The construction. element is then automatically blocked in the adjacent half-cell of opposite polarity.

The control of a DC supply voltage can not be carried out easily, however, because the component,

once it has been brought into the conductive state,

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remains conductive until special measures are taken »Firstly, one of the best-known measures is the Use of a capacitively matched resonance output circuit that forms a reverse voltage, and secondly the use of an additional switch component, to interrupt the thyristor current or the thyristor short-circuiting, resonance circuits are known to have the Disadvantage that it is difficult to ensure that the capacitor is always properly charged before the blocking time is, and if the mean value of the output variable is to be controlled by the repetition frequency of the ignition pulses of the thyristor is changed, the frequency of the DC output pulses and the frequency an alternating current appearing somewhere in the circuit (or several different frequencies) influence each other. These difficulties can be overcome by using a switch component, however this would result in additional costs and complications ο

The object of the invention is thus to provide a thyristor circuit which is simple and cheap and which does not have the disadvantages mentioned. The circuit is intended in particular to control the mean value of a direct current in a choke coil can be used as an intermediate stage of an alternating power control with the help of a single thyristor »

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BADORiQiNAL

According to the invention, a circuit is created which contains a thyristor in series with a choke coil on an alternating current source old compared to the time constant of the circuit of short pericdene duration and a second current source in series bit , which is connected in parallel to the choke coil in such a way that the thyristor is connected during a part each wave of the AC voltage is biased to the choke coil in the reverse direction while it is forward biased during the remaining portion of each shaft and can be controlled in the conductive state.

Although the circuit should be primarily epeiat overall DC, d. throat. Second current source of a direct current source should be used, the circuit according to the invention also works satisfactorily if an alternating current source is used as the second current source and the two alternating current sources are synchronized. The two current sources are then expediently in antiphase.

The invention will now also be described with reference to the accompanying illustrations of exemplary embodiments, wherein all details and features for solving the task that emerge from the description and the illustrations can contribute within the meaning of the invention and included in the application with the will * nr patenting became,

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Figure 1 is the circuit diagram of a basic version of the Invention,

Figure 2 ie an oscillation IGT Ever run asur explanation and

the figures 3-7 are circuit diagrams of other Aueführungen "

In the embodiment shown in figure 1 embodiment are a diode D1 and a choke coil L in series source to an AC 10 "from which a terminal is grounded, schematieoh represented as Battery" A DC power source 12, and a thyristor T connected in series to the choke coil L, The output voltage of the current source 12 is less than the peak voltage of the current source 10,

First eel the circuit with the diode D1 and the inductor L, which in addition to their inductance also have an effective resistance R has considered the mean of this Direct current flowing in the circuit depends not only on the value of the effective resistance R, but also on the size of the time constant L / R compared to the period of the output voltage The alternating current source starts a current in the half-wave of the alternating current source Choke coil to flow, -the due to the inductance of the The choke coil continues to flow into the next half-wave until that of the choke coil is fed from the power source Counter-voltage makes the current to zero - The current

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can not rise to a higher value than that which results during the first half-wave and which depends on L / R. When a high direct current initially flows through the choke coil »the diode remains conductive until the current has dropped to zero and appears as long as it does also the AC voltage on the choke coil _? (However, there is always a small residual voltage, which is equal to the forward voltage drop of the diode D1) »(

Now only the effect of the direct current source 12 and the thyristor

In FIG. 2, the sinusoidal alternating supply voltage is shown in dashed lines, the constant direct voltage and (as a strong line) the voltage at the choke coil L. The thyristor T is shown at time t. ignited »The thyristor can be ignited at any point in time within the time period S as long as the alternating potential is lower than the direct potential. At the end of this interval, the current stops flowing from the direct current source 12 into the inductor L, and the Thyristor T is blocked again. ₀ As long as the output voltage of the Weohselstroraquelle is more positive than the output voltage of the direct current source, the diode D1 is conductive

If the thyristor is not ignited by a control circuit 14 that is connected to its control terminal * 6 is, the current flows in circuit D1, I so on, as

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if the thyristor T and the direct current source 12 were not present, and the direct current assumes its smallest value determined by the ratio L / R. The mean value of the direct current can be increased by triggering the thyristor. The mean value of the current increases when the ignition point t _{1 is} advanced in the time period S.

Pigur 3 shows a practical application of the circuit according to the invention for voltage regulation an alternating current generator 17, its field winding 18 from a direct current exciter 20, which takes the place of the one shown in FIG Current source 12 occupies, is fed .. The control circuit 14 speaks in the usual way to the amplitude in this way the output voltage of the generator 17 that they the Shifts the ignition time t * of the thyristor in such a way that this amplitude maintains a predetermined value =

The advantages of this circuit are that, firstly only a single thyristor is used so that control maintenance is easy and, second, when the alternator is shorted, the DC exciter supplies enough field current to clear the short. If an AC power source is used to generate the Field current would be used, the voltage would collapse and only a small current from the alternator to be delivered.,

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At the times tg (Figure 2), in which the diode Dt and the thyristor T are disabled, the armature is of 01tiehetromerregere 20 with them in series., A small (not dissolved IGT s) mn of the AC power source 10 lying condenser ^ prevents This is because the waveform of the output voltage of the Wecheeletron generator is distorted by commutation currents ο

4 shows a Dreiphasenechaltung is illustrated, wherein the DC voltage wipe Oleichrichtung by the voltage "" wei phases L ₁ and L ₂ is obtained by means of two DiodenD2 and 2) 3, while the third phase L3 supplies the AC voltage. The inductor L is here the field winding dee Wecheelstromgenerators 17 »der.die provides three phase voltages, although a Gleiohstromer- could be arranged brisk or a brushless alternating-current exciter between the inductor L and the field winding of Wechseletronigeneretora. The feed alternating voltage for the diode D1 and / or the?) Iodes D2, D3 could also be supplied by a permanent magnet exciter, which is arranged on the same wall as the alternator, instead of the alternator itself - as shown - _c

Figure 5 shows a symmetrical DreiphaβenseheItung in which all three phases (30) to form the dc supply voltage of the thyristor T are full-wave rectified by diodes D4 _n The Food ewe cha e! Voltage for the diode D1.

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is tapped at the secondary winding of a step-up transformer 22, that of two of the three phases fed usit! gur achieve the desired ratio »Between the alternating current amplitude and the direct voltage is used*

Figure 6 shows a single-phase circuit with a bridge rectifier 24, for generating the DC supply voltage for the thyristor T and also with a high-transformer end Trans forma tor 22 gur supplying the diode 1) 1 "

Finally, FIG. 7 shows a single-phase circuit that is fed by fineo transformer 26. The transformer has a secondary winding provided with a tap, the lower half of which feeds an alternating voltage to the diode Di and the upper half of which feeds a phase-shifted voltage to the thyristor T. During the half-waves in which the potential of the anode of the thyristor is positive compared to that of the anode of the Mod® 'is, the thyristor can be ignited

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Claims (2)

Expectations Circuit with a single in series with a power source, specially a direct current source, lying thyristor with one connected to the control connection of the thyristor, the ignition control point of the thyristor controlling circuit and with a circuit to determine the locking time dee thyristor, characterized in that the last-mentioned circuit is a choke coil (L) in series with a diode (Dt) and an alternating current source (10) and that the thyristor (T) and the current source (12) mentioned first are connected in series and this series connection is parallel to the choke coil, 2. Circuit according to claim 1, characterized by a common one «or Mehrphasenwechselaelotromversorgungssohaltung, an alternating current source for generating a single-phase alternating current signal from a or several phase voltages of the Wecimel power supply connection forming device (22) and by a rectifier circuit forming the current source named zuerefe (D2, D3 or D4 or 24) to form a DC signal from one or more of these phase tensions * 3 »Circuit according to claim 2, dad v. rchgek e η η ζ eich η et that the device [22) is a high-transforming transformer, BATH ORIGINAL 009813/0043 4 ·. Circuit according to the eleventh or more of claims 1-3 »d © & VL '£ ο h. marked that the Droßaalapule (L) is the field winding of an alternating 8tro © gsneffat © i? B (17) is ₉ from the »tin control signal for the Stsuer & naGhIuIS (16) & thyristor (5) in a manner known per se (14 ) is derived » ^; 5 "Circuit according to one or more of claims 1-3" characterized in that the series circuit consisting of choke coil (L) and thyristor (T) is parallel "to a Sieichstrom exciter (20) or a burden-free Weohselatromerreger, which is also parallel aur? Eldwicklimg (18) an AC generator. (17), from which a control signal for the Steueransohluß (16) of the thyristor (T) is derived in a manner known per se (H). 6 _a circuit according to claim 4 or 5 _S characterized in that the common alternating current supply circuit is the alternating current generator (17) or an exciter driven together with the alternating current generator, 7 »Circuit according to claim 1, characterized in that the current source mentioned first is an alternating current source (26) which is synchronized with the first-mentioned alternating current source, 0998 13/0043 BADORiQiNAL Of phase 8 "circuit according to claim 1, dadurchg βίε en ηβ β i t without that the Ausgangespannungen the two Change servicekit trofflquellen 180 ° SAD ORIGINAL 009813/0043