DE2753844C2 - Extinguishing device for a DC voltage regulator - Google Patents

Description

The invention relates to an extinguishing device according to the preamble of claim 1.

Such a quenching device is for the main thyristors of a positively commutated converter from DE-OS 15 63 257 known. The transformer windings each form a main thyristor, des it is assigned a quenching thyristor and the associated diode has its own coupling transformer. These Quenching circuit means especially when used with DC voltage controllers for the small and medium-sized Power range a not inconsiderable effort if a variable DC voltage with the possibility the energy direction reversal is to be generated.

The invention is based on the problem of reducing the expenditure for an extinguishing device of the initially mentioned specified type to decrease.

This object is achieved according to the invention by the in claim 1 characterized feature solved.

The allocation of all windings to a single coupling transformer reduces the construction costs and the space requirement when using the extinguishing device with DC choppers with lower power is portable.

In the event that energy cannot be fed back into the constant voltage source and by igniting a limiting thyristor, this energy is converted into heat in an ohmic resistance is implemented, in a further development of the invention is an extinguishing device according to the characterizing part of the claim 2 provided. For this purpose, it is actually from the DE publication »Technische Mitteilungen AEG-TeIefunken« 58 (1968), No. 3, page 159, known, by means of a series circuit, an erasable thyristor and A resistor parallel to the voltage source converts the energy into heat that cannot be fed back into this source to convert.

In the following, the invention will be explained in more detail with reference to the drawing figure for an embodiment will.

The figure shows the circuit diagram of a DC voltage controller for two-quadrant operation with current reversal, which is connected to a source of constant voltage Ud \ between the poles + and - It generates a variable DC voltage Uoi, which is behind a smoothing choke / 1 on a capacitor Ar 3 can be tapped

The main circuit has a main thyristor η 81 with an associated free-wheeling diode η 83 and a main thyristor η 82 with an associated free-wheeling diode η 84.

The quenching circuit is formed by a quenching capacitor Ar5, two quenching thyristors n91, / i92, two diodes λ 93, π 94 and two backup capacitors k 1, k 2 of the same size, which are large compared to the quenching capacitor Ar 5, each in series with the diodes π 93, π 94 and the quenching thyristors η 91, η 92 windings ί3 to / 6 of a coupling transformer. Two windings fl and t2 of the transformer are also connected in series with the main thyristors π 81 and π 82. The direction of the winding of all windings of the coupling transformer is indicated by an adjacent point.

To convert energy that cannot be fed back into the source of constant voltage in the heat, an ohmic resistor rl is provided, which is in series with a limiting thyristor π 85 and a further winding 17 of the coupling transformer.

If the capacitor Ar 3 is to be charged via the smoothing choke / 1, the main thyristor π 81 is ignited until the desired voltage is reached.The main thyristor is then extinguished with the polarity of the quenching capacitor Ar5 shown in brackets by igniting the quenching thyristor π 92. This applies the voltage of the capacitors Ar 2 plus Ar5 to the winding / 6 of the coupling transformer in series with the quenching thyristor η 92 Ht. This voltage, in absolute value ■ 1.5 Uo \ now lies on all windings of the coupling transformer and thus also across the winding 1 1 in series with the main thyristor π81. The driving voltage U _D \ is thus opposed to the transformer voltage 13 · Ud ι, so that 04 · Ud ι is applied as a negative reverse voltage to the main thyristor π 81 to be extinguished.

The quenching capacitor Ar 5 is now charged, and the quenching capacitor Ar 5 would like to be charged to a higher value, driven by the energy absorbed by the winding ί 6. To prevent this, the demagnetization circuits with the diodes η 93 and π 94 and the support capacitors Ar 1 and Ar 2 are provided. The oscillating current commutates when the voltage is reached

t /, 6

t / _D ,

into the windings i3 and r4 in series with the diodes η 93 and η 94 and can then flow back into the backup capacitors k \ and Jt 2.

If the voltage at the capacitor k 3 is again too low, the main thyristor π 81 is triggered again. The main thyristor π 81 is now extinguished by triggering the extinguishing thyristor η 91. As a result, the voltage of the capacitors ArI plus ArS is applied to the winding 15 lying in series with the extinguishing thyristor η 91, so that the main thyristor π 81 is extinguished again

and the ringing of the extinguishing capacitor Jt 5 takes place analogously to the previously described process.

If the voltage on the capacitor A'3 is too high, the main thyristor π 82 is triggered; the capacitor k3 is discharged. Depending on the polarity of the quenching capacitor k 5, when the nominal voltage of the capacitor / V3 is reached, one of the quenching thyristors η 91 or π 92 is ignited, whereby the winding i2 of the coupling transformer, which is in series with the main thyristor / j82, applies negative voltage, so that the current from the main thyristor π 82 in the freewheeling diode, π 83 commutates and thus flows back to the source of constant voltage.

If this source cannot absorb energy.

the limiting thyristor η 85 is ignited and the energy in the ohmic resistance r 1 is converted into heat. If the limiting thyristor π 85 is to be extinguished, this can in turn be done by igniting one of the two extinguishing thyristors ff 91 or η 92 (depending on the polarity of the extinguishing capacitor k 5).

In summary, it can be said that regardless of the polarity of the quenching capacitor k 5, one of the three thyristors π 81, π 82 or π 85

ίο can be deleted without the need for additional charge reversals, the triggering of the individual thyristors η 81, π 82, π 85, π 91, π 92 in each case in a suitable manner and at the correct point in time.

1 sheet of drawings

Claims (2)

Patent claims: 1. Quenching device for the main thyristors of a DC voltage regulator for two-quadrant operation with current reversal, which generates a voltage of variable magnitude from a constant voltage, a quenching capacitor, one of which is connected between two quenching thyristors connected in series between the positive and the negative pole of the source of constant voltage and the other surface of which is connected between two diodes connected in series between the negative and the positive pole of the constant voltage source, a backup capacitor being parallel to each diode and a coupling transformer winding being arranged in series with each main thyristor, each quenching thyristor and each diode and the sense of winding of all windings in relation to the direction of the anode-cathode paths of the diodes or thyristors is the same, characterized in that all coupling transformer windings (ti -16) form a single coupling transformer. 2. Extinguishing device according to claim 1, characterized in that a limiting thyristor (n 85) between the plus and minus pole of the constant voltage source, which is preceded by an ohmic resistor (r \) , also in series with another, the same winding sense having winding (t 7) of the coupling transformer is connected.