DE2423034C3 - Circuit arrangement for impedance matching, in particular for a high-frequency voltage generator for induction heating systems - Google Patents

Description

The invention relates to a circuit arrangement for impedance matching, in particular for a voltage generator high frequency for induction heating systems, with an oscillator tube, a resonant circuit, beslehend from the inductor of the heating system and a capacitor battery connected to its terminals, as well as one of the resonant circuit with constant Voltage-supplying aperiodic transformer and a transformer for controlling the oscillator tube, the / between the grid and the resonant circuit is sounded.

Such a circuit arrangement for impedance matching is known from US ^{Pat. No. 3 r} > 71 b44. Here, an aperiodic transformer with a fixed transmission ratio is used, so that the external resonant circuit, which is formed by the inductor and a parallel capacitor bank, is fed with a constant output voltage via the 1 high frequency transmission cable. The transfer of the energy to the resonant circuit took place / was free of reactive current, but the commonly used transmission ratios / wipe '/ 4 and ι / κ cause output voltages on the aperiodic transformer in the order of magnitude of 100-2000 volts. The inductive consumer in the form of an inductor, which also forms the resonant circuit, must therefore have a relatively large inductance in the order of magnitude of /. B. I have μΗ and more. Accordingly, it is disadvantageous in this known circuit arrangement that no adaptation to an inductor with a few or even a single turn and thus a small inductance is possible.

DE-AS 12 74 724 describes a learner I low frequency generator, in which the over a high frequency transmission cable fed resonant circuit from a capacitor and a parallel-connected matching transformer ordered, the primary cable a Tap to adapt to the mixed secondary line Output voltage for the indicator connected on the secondary side. This is a disadvantage known generator that here the resonant circuit via the transmission cable with a substantial Blindstrniiüinicil is fed, which leads to considerable losses and a costly and expensive construction of the Generator conditional. In addition, the element between the inductor and capacitor of the resonant circuit is Switched matching transformer, through which the entire reactive current flows, is difficult to manufacture and expensive.

The invention is based on the object to the effect of the circuit arrangement described above to improve that an adaptation to inductors with few or even only one Winding becomes possible, with the oscillation circuit still being fed without a blind irony target.

The invention solves this problem by wiping the output of the aperiodic transformer and the resonant circuit switched via a high-frequency / transmission cable connected transmitter, with its output tier input of the transmitter to Grid control connected isl.

The fact that the hole frequency / transmission cable at the output of the I connected, additional transformers only from active current, but not from reactive current is flowed through, it is relatively easy to manufacture and also works with a high Efficiency.

Because the voltage which is fed back to the grid of the oscillator tube is secondary to this Transformer and thus removed from the resonant circuit, the generator continues to work under defined frequency ratios. The in and for itself / u small, back / recoupling tension is generated by a Step-up transformer back to the necessary size for the grid of the oscillator tube hoehtransformierl.

Further refinements of the invention emerge from the claims.

The invention is described in more detail below with reference to the circuit diagram shown in the drawing.

The generator essentially consists of an oscillator tube 1 which, via an aperiodic transformer 2 and a transmission cable 3 for hole frequencies / energy, feeds an inductive diode 4 with an inductive frequency voltage, which, together with a capacitor battery 5, forms the oscillating circuit of the generator. The winding 6 of an economy transformer lies between the output end of the cable 3 and the resonant circuit 4, 5. The ends of the winding 6 are each connected to the ends of the secondary winding of the aperiodic transformer 2. The connection 7 is connected to the capacitor bank 5. The anode 8 of the tube I is connected to a high voltage source HT via the primary winding of the aperiodic transformer 2 and its cathode is connected to ground. Your grid 10 is connected via one or more grid resistors 12, to which a decoupling capacitor 13 is connected in parallel, to the connection end of a winding 11 of an economy transformer for controlling the grid.

The transformation ratio of the saving transformer 11 can be the same as the saving transformer 6 ties be.

The other connection of the winding 11 is to ground occasional while her Abgreilansehliiß 14 with the Terminal 7 of the transmitter fi is connected. Ijne Such an arrangement prevents a reaction of the genera> rschwingu: igen aiii the practitioner f>.

The thus connected spar translonnaior β only becomes flowed through by pure active agent, whereby a regulation of the output voltage of the generator on any desired value is possible. so that he is at any inductor to be used can be adapted.

For example it is possible to adjust the output voltage of the generator to values in the order of magnitude of / .. H. 100 V / usenkcn. whereby he is also in Let use connection with inductors very low values.

The use of such a transformer also allows an exact adaptation of the generator to its load. Consequently, the number of condensers η 5 on one with the preconditions for the Plant can be reduced to a minimum.

In particular, it is possible. Low voltage

Use glow capacitors, their operating voltage is on the order of about 500 volts.

without capacitor battery !! hiutcreinanderschalien zu must, resulting in a simplification in assembly and thus a lowering of the position cosia results.

In addition, the costs of such an economy transformer are significantly below those of one Capacitor battery, as it is normally used for rendering the additional reactive power is required. the lack of adaptation of the generator to its load balance.

In the described embodiment Spar transformers are used, but normal transformers can of course also be used.

1 sheet of drawings

Claims (3)

Patent claims: I. Circuit arrangement for impedance matching, especially for a voltage generator higher Frequency for induction heating systems. with an oscillator tube, a resonant circuit, consisting of the inductor of the heating system and a capacitor battery connected to its terminals, and an aperiodic transformer that supplies the resonant circuit with constant voltage and a transformer for controlling the oscillator tube, the filter and the oscillating circuit is switched. marked by one / wipe the output of the aperiodic I I carrier (2) and the oscillating circuit (4, 5) switched, via a 1 lehfrequency transmission cable (3) connected transformer (6). with its output (7) the input (14) of the transformer (II) / urGitterieuerung is connected. 2. Arrangement according to claim I, characterized in that the primary winding of the aperiodic transformer (2) is connected between a 1 hole voltage source (HT) and the anode (8) of the oscillator tube (1). 3. Arrangement according to one of the preceding claims, characterized in that the transformer (6. 11) Spar translormalors are.