| Microwave Power Module (MPM) is a high density compact microwave amplifier which includes a mini-traveling wave tube (TWT), a solid-state driver amplifier (SSA), and a high density electronic power conditioner (EPC). EPC is a comparatively complicated compact power supply with miniaturized property and high efficiency. In this thesis the general design idea of EPC, especially low voltage model power supply and control-protect circuit is introduced.Development of MPM, overseas EPC and domestic switching power supply are introduced. Theory about low power, low voltage switching power supply and selecting main components are mainly discussed. The operation characteristic of fly-back inverter is analyzed in detail and as a result, a TWT filament power supply is designed based on the current-mode Pulse Width Modulation integrated chip UC3842A. The planar transformer is used because of its has excellent comprehensive performance such as small volume, low leak inductance, low EMI radiation ,high current density and so on compared with traditional transformers. The soft switching technology especially zero current switching (ZCS) and zero voltage switching (ZVS) are studied with the aid of simulation software ORCAD10.5 aimed at the switching loss of MOSFET switching tube. Main factors which influence ZCS and ZVS are analyzed and the efficiency of ZVS power supply is improved significantly. An overall efficiency of 85% was achieved for the ZVS power supply and corresponding simulation efficiency is 90%.The design mothed of planar transformer with the aid of software Magnetics Designer and control-protect circuit are also introduced and their validity is tested by the experiments.The research has an important significance in improving the volume and efficiency of MPM, and the circuits can be used in other fields widely. The low power switching mode power supply especially the ZVS technology in fly-back inverter and MOSFET driving circuit deserve using for reference. |
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