Design and Optimization of a Magnetron DC-DC Isolated Power Supply With High Efficiency

High-efficiency high voltage dc power supply is the core equipment for magnetron in the microwave industry. This article presents an input-parallel output-serial modular high isolated resonant converter for the magnetron. However, the high stray capacitance of the high isolation transformer brings some challenges, such as high turn-off current, longer dead time, increasing gain, and transformer optimization. A simplified model including the stray capacitances is built to deal with these problems, and the minimum turn-off current is derived after the detailed time-domain analysis. The appropriate deadtime and the maximum magnetic inductance needed for the proposed converter are obtained with the minimum turn-off current. Then, a 15 kW, 60 kV isolation multiple-windings output transformer is designed and optimized for the converter. The insulation design, core shape, losses, and parasitic parameters are calculated thoroughly. The Pareto optimization process optimizes the switching frequency and the transformer's turns to obtain higher efficiency and a more stable gain. The finite element method and time-domain simulation verified the optimized design results. Finally, a 0.8/2.5 kV, 15 kW all-SiC dc-dc converter module is developed to validate the proposed design. The results indicate that the module efficiency is as high as 98.6%.