Due to poorly regulated performance of non-feedback branches and influence of cross between output branches of the traditional voltage-type PWM control which controlled multiplexed output switching power supply,the paper implemented the single input and three output voltage based on flyback converter,at the same time, adopted time-sharing multiplexing control method of voltage-type when controlled,so as to obtain stable and reliable three levels of voltage 5V,15V,24V.Which introduced the working principle of main power circuit and control circuit in detail,in addition,analyzed the AC small signal dynamic feature of the three kinds working conditions of the flyback converter when it worked in the DCM (Discontinuous Current Mode), thereby established open loop transfer function of the control object and carried simulation analysis.which showed that the low frequency band slope of 0dB/dec, can not achieve astatic; high frequency band slop of -20dB/dec, anti-interference ability is poor. Based on this, the paper added a single pole-single zero compensation network in the voltage control loop,as a result,low frequency slope up to -20dB/dec, high frequency slope up to-40dB/dec,output performance of this system was improved.Finally built a model of time-sharing multiplexing control multiple output switching power supply and carried simulation by matlab software and the result showed that the voltage type of time-sharing multiplexing control method can get stable and good regulated performance of three way output switching power supply.
