Microwave heating power supply operating in a high power-factor mode

Abstract

The performance of a switched-mode magnetron power supply is considered in which a rectified, non-filtered mains voltage is applied to the converter input. The system features output voltage boosting at the input voltage zero crossings, and provides high power-factor operation. A closed-form expression for the system gain is obtained with and without active input current shaping. The analytical results show that the system tends to linearize the inherently nonlinear magnetron characteristic, and that a complete linearization could be achieved by frequency modulation within the mains period. The optimum converter component values are identified and the results are verified experimentally.