DD261255A1 - ARRANGEMENT FOR GENERATING HIGH VOLTAGE - Google Patents

Abstract

The invention relates to an arrangement for generating high voltage, as it can be used, inter alia, for the operation of lasers, but also for television high voltage parts. The object is to design the pulse transformer of a flyback converter so as to make additions of known circuit variants in such a way that an open-circuit and short-circuit-proof high-voltage source having a power of up to a few 100 W is available. The object is achieved as follows: The pulse transformer used in a flyback converter circuit consists of a U-shaped ferrite core, which carries on both legs a high-voltage winding located a short distance from the core. This is designed as a "wild step winding" in individual chambers. The primary winding and the return winding are realized by coaxial cables in one layer winding. In the collector branch of the switching transistor, a series-connected circuit consisting of a diode and a Zener diode is connected in parallel with a resonable choke. Between high-voltage rectifier and load capacity, a circuit consisting of Umladeldrossel and capacity, inserted.

Description

Field of application of the invention

The invention relates to a transformer for generating high voltage in switching power supplies. Such high voltage transformers are used in power supplies for television receivers or z. B. also used to operate pulsed lasers.

Characteristic of the known state of the art

There are high-voltage transformers with U-shaped core for flyback converter circuits are known in which the windings for the primary side and the high-voltage secondary side are arranged side by side on a core leg (DE-PS 3328181) or one above the other (DE-OS 3347372). A disadvantage is the relatively large leakage flux caused by the geometry of the arrangement in both cases. It is also known, in the interest of a tighter coupling, primary winding and feedback winding directly to each other (DD-PS 225889). However, the relatively high parasitic capacitance between these windings is disadvantageous.

Object of the invention

The aim of the invention is to have a high voltage transformer for switching power supplies available, which has favorable operating characteristics and can be relatively easily produced.

Presentation of the essence of the invention

The invention has for its object to make the high voltage transformer of a switching power supply so that the ferrite core is a close coupling between the primary winding and high-voltage winding and between the primary winding and demagnetization with the least possible parasitic capacitance.

According to the invention the object is achieved by the following arrangement:

A U-shaped ferrite core F carries on its two legs over the entire leg length form-fitting to the core cross-section adapted bobbin Si and S ₂ , a low-capacitance accommodated in chambers high-voltage winding A21-E21 or A22-E22 at a small distance from the core and above a Layer winding with coaxial cable executed combination of primary winding An-E ₁₁ or A ₁₂ -E ₁₂ and demagnetization winding A ₃₁ -E ₃₁ or

A ₃₂ -E ₃₂ has. In this case, the coaxial jacket forms the primary winding and the inner conductor of the coaxial cable forms the demagnetization winding. The coaxial cable realizes a relatively small parasitic capacitance between the two windings.

The invention will be explained with reference to an embodiment:

embodiment

In the accompanying drawings show

Fig. 1: Schematic representation of the structure of the high voltage transformer Fig. 2: high voltage transformer in a flyback converter circuit.

In Fig. 1 a U-shaped ferrite core F with the air columns I ₁ and I _{2 are} identical, high-voltage resistant bobbin Si and S ₂ are mounted on two legs, which extend over the entire leg length and positively surround the core cross-section. These bobbins can be cast, for example, epoxy resin. At the bottom, the high-voltage winding A ₂₁ -E ₂ I or A ₂₂ -E _{22 has} low capacitance as a chamber winding. This high-voltage winding is expediently cast in insulating resin, wherein an insulating layer I is applied to ensure the dielectric strength against the primary winding. The primary winding A ₁₁ -E ₁₁ or A ₁₂ -E ₁₂ and the demagnetization winding A ₃₁ -E ₃₁ and A ₃₂ -E ₃₂ is realized by a thin coaxial cable, which is applied in layers over the entire leg length. The coaxial jacket forms the primary winding and the inner conductor of the coaxial cable forms the demagnetization winding.

Fig. 2 shows the use of a high voltage transformer in a flyback converter circuit. The primary winding A ₁₁ -Ei ₂ is located between the supply voltage + U ₈ and the collector of the emitter side grounded switching transistor T. Of the high voltage winding A ₂ iE ₂ 2 is a diode arrangement, indicated by the diode D ₁ , in the blocking phase of Transistor T, the capacitor C charged. The Entmagnetisierungswicklung A ₃₁ -E ₃₂ is clamped via the diode D ₂ to the supply voltage source + Ug, whereby the maximum reverse voltage amplitude at the collector of the transistor T limited and excess energy, eg. B. at idle the high voltage winding, is fed back.

Claims (2)

Hochspannungsstransformatorfür switch mode power supplies with LMörmigem ferrite core and chamber winding for the high voltage, characterized in that on both legs of the ferrite core over the entire leg length on positively matched to the core cross-section wound bodies, a high-voltage winding at a small distance from the core and overlying layered a winding of coaxial cable, wherein the Coaxial cable sheath forms the primary winding and the coaxial cable's inner conductor forms the demagnetization winding. For this 2 pages drawings