High efficiency start-up control of magnetron filament for MWO applications

Nowadays, the white goods consumer market is very aggressive concerning energy saving, reliability and cost. In microwave ovens applications one of the most delicate part is the magnetron, in particular during start up. Usually, in Microwave oven using inverter, an expensive and complicated circuit is required, especially for proper start up. This paper proposes a novel start up control strategy for LLC converters for microwave applications aiming at high reliability and lower cost. This method takes advantage of the parasitic elements of a standard step up LLC converter in order to facilitate the heating of the magnetron cathode, thus allowing a faster and more reliable start up. The experimental results on a 1.5 kW LLC prototype confirm the method viability.