Research On The Technology To Reduce The Losses Of The Flyback Converter

The flyback converter was initially applied in automobile ignition coil. Nowadays, theflyback converter is widely used in the field of Consumer Electronics. However, the flybackconverter featured lower working efficiency. To ameliorate this problem, some researchersdevoted their efforts to reduce the loss of the flyback converter.After the state of the art on the technology to reduce the flyback converter’s loss isintroduced, the effect on the duty ratio of switch tube and the duty ratio of output rectifier tosix kinds of losses in the flyback converter, which include switch loss and conduction loss ofswitch tube, loss of input filter capacitor, winding loss of transformer, conduction loss ofoutput rectifier and, loss of output filter capacitor, is analyzed. From theoretical perspective, itconcluded as follows:(1) When the duty radio of switch tube is increasing, the off-loss ofswitch tube has the rule of first descended then rose. However, all losses of the input show therule of descended and the reduced rate is decreasing.(2) When the duty radio of outputrectifier is increasing, all losses of the output and the off-loss of switch tube show the rule ofdescended and the reduced rate is decreasing.Three groups of simulation experiments are designed to validate the theoretical analysis:(1) The conduction duty ratio of output rectifier is fixed, the duty ratio of switch tube is onlychanged;(2) The duty ratio of switch tube is fixed, The conduction duty ratio of outputrectifier is only changed;(3) The conduction duty ratio of output rectifier and the duty ratio ofswitch tube are changed at a fixed intervals. In addition, a real circuit was designed andimplemented to verify theoretical results. Based on the experimental results above mentioned,a conclusion can be drawn that the efficiency of the flyback converter is the highest if the dutyratio of switch tube is set to around0.45and the duty ratio output rectifier is set to around0.55. The theoretical analysis is demonstrated by the simulation results.