Analysis and design of a current-fed push-pull parallel-resonant converter for cooker magnetrons

Abstract

This paper presents the analysis and design of a current-fed push-pull parallel-resonant (CFPP-PR) converter for cooker magnetrons. The CFPP-PR converter is fabricated with a buck converter, a push-pull parallel-resonant inverter and a full-wave voltage doubler. The front-end buck converter synchronously operated with the following push-pull resonant circuit is a controllable dc current source. The CFPP-PR converter operated at resonant frequency exhibits zero-voltage switching and the push-pull switches only conduct buck inductor current. The magnetizing inductance of transformer resonates with equivalent parallel capacitance. The resultant resonant voltage is boosted with the turn ratio of transformer. The voltage doubler reduces the voltage stress of transformer windings. To demonstrate the analysis and design, a CFPP-PR converter with integrated circuit UC3872 is built and tested. Simulation and experiment results meet the predictions.