| 摘要 |
The invention concerns an interference-control circuit for switching power supplies suitable for use in the operation of both discharge and incandescent lamps. The interference-control circuit has at least one controlled auxiliary supply (ZW, F) plus a control circuit (TR1). The auxiliairy supply/supplies (ZW, F) generate controlled compensation signals which are inverted with respect to the interference signals caused by the fast switching transistors (T1, T2). The auxiliairy supply (ZW, F) is connected either parallel to the source of interference and capacitively to the environment or in series with the source of interference and galvanically into the supply leads. In the first case, the auxiliairy supply preferably includes, near the switch (T1, T2), a metal surface (F) whose potential variations are inverted with respect to those of the source of interference essentially round the junction point (M) between the switching transistors (T1, T2) e g. by means of the transformer (TR1). In the second case, the auxiliairy supplies are preferably formed by two secondary coils of a transformer. The primary coil is controlled by the potential changes in the source of interference and induces in the leads of the secondary coil an opposite phase common-mode compensation signal. Optionally, the interference-suppression circuit can be designed as a closed control circuit, the common-mode interference current in the leads being used as the regulating variable.
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