Switching mode system to supply pulse modulators in radar applications

The study of high-voltage isolated DC/DC converters used to supply pulse modulators is presented on this paper. The Full Bridge topology was selected, focusing in problems caused by parasitic capacitances in the circuit. This characteristic, which appears sharply in high voltage transformers and in inductors of output filter, is highly undesirable when the circuit is operated in switching mode. These capacitances are handled using a soft commutation technique, where their stored energy are returned to the primary source in the end of each switching cycle, trying to get a low size, high efficiency and low heat dissipation in the converter. Moreover, a charging regulator circuit is used to ensure good pulse stability and avoid typical problems in the pulse modulators use, such as the backswing effect. The pulse modulator used as load for this converter operates with a supply voltage of 1 kV, pulse repetition frequency (PRF) of 600 Hz and consumes 2.5 kW. The converter input is supplied by a 280 V unregulated DC bus.