Stability Analysis of a Drain Feedback Flyback Converter Based on DCM under PFM Peak Current Mode

Aiming at the problem that the primary side feedback flyback converter has auxiliary winding and high cost, based on the primary side feedback and peak current control scheme, a flyback converter model based on switch drain feedback is proposed. Compared with the primary side feedback flyback converter, the drain feedback flyback converter can reduce the auxiliary winding of the transformer, reduce the cost, and has high stability. Firstly, the theoretical analysis of the drain feedback flyback converter model is carried out, and a high-precision drain sampling method is proposed. Secondly, based on the switching network model method, the small signal modeling and compensation design of the drain-pole feedback flyback converter operating under discontinuous conduction mode(DCM) pulse frequency modulation(PFM) are carried out. Then the model is built by Matlab/Simulink to verify its correctness. Finally, an experimental platform is built to verify. The results show that the proposed model of drain feedback flyback converter is feasible.