Design and Simulation of a New Isolated Feedback Circuit for Flyback Charging Circuit

摘要

The characteristics of the waveforms of the flyback charging process are analyzed. A connection between the Drain-to-Source voltage of the MOSFET and the output voltage of the energy-storing capacitor is found. An isolated feedback circuit which samples from the input side of the flyback charging circuit is presented. It can improve the characteristics of conventional feedback which samples from the output voltage across a resistive divider. Moreover, a filter circuit is added to the feedback circuit in order to minimize the influence of the transformer leakage inductance. Principles of choosing the circuit parameters are introduced. Simulation results are presented to show that by choosing appropriate parameters this feedback circuit is capable of controlling the charging circuit as well as solving the isolation problem.