DE1079747B - Circuit arrangement for converting and amplifying ignition pulses for grid-controlled vapor or gas discharge paths - Google Patents

Description

To the generation. of ignition pulses for grid-controlled Vapor or gas discharge paths are saturation chokes and thyratrons as switching amplifiers known. Since the control circuit for a converter vessel must be constructed so that between Grid and cathode a deionization current can flow when using this switching amplifier In general, an impact resistance is provided parallel to the grid-cathode path, in which a considerable Part of the applied impulse power "is lost. ■ ... .-.

Furthermore, there are circuit arrangements containing transistors known for grid control of converters. When using transistors in Ignition pulse amplifiers, a transformer output is required that has the necessary voltage level of the Ignition pulse guaranteed, as previously commercially available transistors only switch relatively small voltages can. In addition, in order to be able to switch the highest possible power with a transistor, the circuit arrangement should be made in such a way that the maximum voltage between the emitter and the base is as close as possible cannot be greater than the battery voltage between the collector and emitter. About that In addition, the switching time during which the transistor is in an operating state of high losses be as short as possible. With the fulfillment of this requirement one comes at the same time to the wish after that the leading edge of the ignition pulse should be as steep as possible.

To convert the waveform of pulses or to generate pulses are also already Trigger circuits have been used. This results in particularly simple options for the latter Circuit structure, if in a known manner in each case a transistor amplifier stage with a transformer Feedback is provided.

The invention now relates to a circuit arrangement for converting and amplifying Ignition pulses for grid-controlled vapor or gas discharge paths using a transistor amplifier with "transformer output. The characteristic is that in per se known Way, the transistor is arranged in a flip-flop with transformer feedback and that after triggering by a trigger pulse the duration of the ignition pulse by the magnetic Properties of the core of the transformer and the dimensioning of the feedback branch is determined. The new circuit arrangement enables, in particular, narrow pulses to a desired one To stretch width.

The invention is to be explained with reference to the figures described below, which show the circuit arrangement for reshaping
and amplification of ignition pulses
for grid-controlled vapor or gas discharge lines

ίο applicant:

LICENTIA Patent-Verwaltungs-G.m.b.H., Frankfurt / M., Theodor-Stern-Kai 1

Dipl.-Ing. Wolfgang Reichelt, Berlin-Steglitz,
has been named as the inventor "'

Represent the principle of the circuit arrangement and FIG. 2 shows an advantageous further development of the feedback branch contains. With regard to the other switching elements, FIGS. 1 and 2 are the same.

In the figures, a narrow trigger pulse, which can be influenced in its phase position relative to the anode voltage of the converter vessel p2 to be ignited in a phase swivel stage (not shown), is fed to the input terminals α and b of an ignition pulse amplifier, which sistör / Ί the pnp-Tra.n. Includes collector voltage source ul and the output transformer ti. The collector current of the transistor pl flows through the primary winding ill of the transformer ti. The voltage to be fed back is taken from a secondary winding 1 13 and acts on the amplifier input via the valve η 2. 1 from the secondary winding 12 of the ignition pulse on the serving for grid current limiting resistor is r 2 and the grid bias M2 of the grid-cathode distance supplied to the converter vessel p2.

The ignition pulse amplifier is shown single-phase in the selected exemplary embodiment of the invention. In the case of multi-phase circuits which are used for grid control of multi-phase converters, the corresponding number of the single-phase circuits shown is connected together in such a way that they have the collector voltage source ul in common. The emitters of the transistors are thus at a common potential, which is particularly favorable for the connection of the control pre-stage.

909 770/345

1 07S747

The mode of operation of the proposed circuit arrangement is as follows: If a small voltage (negative at α , positive b ) is applied to the input, a small current can flow through the transistor p1. Since the grid-cathode path of the converter vessel pl is not yet conductive, the transformer ti in the collector circuit of the transistor is not loaded. The entire voltage of the voltage source ItI is therefore already at the transformer ti with a very small collector current. At the same time, a voltage is then applied via the feedback winding between the emitter and base of the transistor, which fully opens it. The transistor remains in this state until the integral of the voltage across the transformer over time has reached a value at which the iron core is magnetized to such an extent that it is in a flat area of the magnetization curve. The saturation in turn has the consequence that the feedback voltage is no longer sufficient to keep the transistor open. It tilts back to its original state.

The valve nl then enables the demagnetizing current to flow in the transformer when the transistor is blocked after the pulse. The resistor RL, the amount of ^a 5 Abmagnetisierungs- determined voltage which is added to the ill collector voltage. The valve »2 prevents the trigger pulse from being short-circuited via the feedback winding.

The circuit described offers the following advantages:

1. The switching amplifiers with thyratrones or saturation chokes can only use an alternating voltage cut. The new circuit arrangement, however, delivers pulses of a certain length with almost constant height. So it only needs the pulse power required to ignite the vessel To be made available. Since there is also no impact resistance, there is a more favorable efficiency.

2. The resistance for the deionization current is less than in the new circuit arrangement in circuits with a surge resistance that takes the place of the secondary winding of the pulse transformer but would have a much higher resistance than the transformer winding.

3. The supercritical feedback achieves a very steep pulse edge. Through this the transistor power loss is kept very small. In addition, the slope is im In contrast to transistors switched by overdriving, independent of the shape of the control pulse.

4. The transistor can not be overloaded in the new circuit arrangement that the transferor due to the long duration of the tax

"impulse or excessively high supply voltage wl is saturated, since the pulse duration is determined by the saturation of the transformer itself. This means that the transformer and transistor can always be fully utilized ..., ■. \ '. f- ■■■ · ..: ':'

5. The power gain of a stage is due to ■ -., the supercritical feedback so great that a otherwise necessary additional amplifier stage not even with a low-power phase swivel stage necessary is. ; .. · ".".

6. To phase shift the impulse can Low-power swivel stages are used, which are more favorable when used in control loops have dynamic properties than larger swivel circles.

7. The trigger pulses can be very narrow.

In order to operate the transistor with a low residual current during the blocking period and thus to be able to select the colector voltage as high as possible, a voltage source u3 is inserted between the base and emitter according to FIG. 2 and the valve nl is bridged by the resistor r3. This voltage and the resistance are dimensioned in such a way that the residual collector current flows exclusively through the base and not through the emitter. In the case of multiphase circuits, voltage source «3 can also be common to all transistors.

Claims (5)

Patent claims: 1. Circuit arrangement for converting and amplifying ignition pulses for grid-controlled vapor or gas discharge paths using a transistor amplifier with transformer output, characterized in that in a known manner the transistor (pl) is arranged in a trigger circuit with transformer feedback and that after being triggered by a Trigger pulse the duration of the ignition pulse is determined by the magnetic properties of the core of the transformer (il) and the dimensioning of the feedback path. 2. Circuit arrangement according to claim 1, characterized in that the transformer (il), whose primary winding (ill) is traversed by the collector current, is provided with an additional secondary winding (il3) from which a voltage is tapped, which in the feedback sense on the Input (α, b) of the transistor amplifier acts. 3. Circuit arrangement according to claim 2, characterized in that the series connection of an ohmic resistor (rl) and a valve (nl) is arranged parallel to the primary winding (ill) of the transformer (il), the valve (nl) being polarized such that the collector current of the transistor (pl) does not flow through it. ■. 4. Circuit arrangement according to claim 1, characterized in that a valve (n 2) is arranged and polarized in such a way in the feedback branch that it prevents the short circuit of the trigger pulse via the feedback winding. 5. Circuit arrangement according to claim 4, there- • 'characterized in that the valve («2) in : Feedback branch a resistor (r3) in parallel is switched and that a voltage of such polarity is inserted in the feedback branch, "_: That the flow of the collector residual Strömes above" the ^1. Emitter (E) is prevented. '. . Publications taken into consideration:
German Auslegeschriften No. 1 003 362, 1000936; . British Patent No. 771,451. 1 sheet of drawings © 9M 7-70 / 3 + 5 4.60