Comprehensive analysis of power loss in the output diode of flyback switching converter operating in DCM and CCM

This paper analyzes the maximal power loss in the output diode of flyback switching converter operating in both continuous conducting mode (CCM) and discontinuous conducting mode (DCM). Comparing with the previous work, this paper extends the condition, under which the maximal power loss of the output diode occurs, from the CCM to the DCM. Three correlative tasks are included. Firstly, through an analytical analysis, the condition under which the maximal power is consumed by the output diode is obtained. Secondly, to verify the analytical analysis and acquire more accurate results, based on nonlinear finite element analysis, a detailed field-circuit indirect coupling model of flyback switching AC to DC converter is built, where several nonlinear factors such as the saturation of magnetic ferrite core, control delay and switching characteristic are included. Finally, the above analysis results are applied to control the maximal power loss in the output diode of flyback switching AC-DC converter to be an approximate minimum; this would improve the converter reliability and power efficiency.