Housekeeping and Auxiliary Quasi-Resonant Flyback Converter Design for a 350W Power Supply

Power supplies are evolving towards the future and are now moving towards the integration of digital control systems in their circuits. This research is in line with this development and is aimed to show what a digital system can do to protect a power supply. The purpose of this research is to design an auxiliary circuit that will power all auxiliary components and implement a housekeeping for protection against voltage and current abnormalities of the power supply. The auxiliary circuit uses a quasi-resonant flyback converter topology to improve the efficiency of the device while the housekeeping system uses a DSPIC as its core processor to make use of the different signals coming from the power supply. The DSPIC will control the turn-on and turn-off sequence as well as the different fault protections to properly power up and power down the whole system. The design achieved has inputs ranging from 300 to 450 Vdc with a regulated output of 12-volts ±4% and has achieved a phase margin of 47.37 degrees and a gain margin of 12.12dB. The housekeeping system was also successful in detecting and reacting against different faults.