Working conditions of a converter installation with electromagnetic compatibility

Resumo

This paper outlines the effect of the switching frequency and the conducting relative duration of a power switch in an impulse convertor on the level of conductive emission by a feed circuit in a frequency range of from 0.15 to 30 MHz. Expansion was performed of the rectangular impulse at frequencies of 50 and 100 kHz in the Fourier series in an LTSpice simulated system. The results of this research allow us to determine the ability to reduce the level of the conductive emission using a lower switching frequency of the power switch. These results are confirmed by full-scale experiments. These experiments are based on imitation of the output block of the impulse convertor. Means of measurement were used that are restricted by GOST (State Standard) to large-scale experiments. It is shown that (1) it is necessary to choose the switching frequency, not only using gross geometry minimization of the device, skin effect, and magnetization reversal of the coil and transformer core, but taking into account of allowable emission level as well, and (2) it is necessary (in the case of nominal power) to provide an open state relative impulse duration close to 50% in the switching PWM convertor.