Research And Improvement Of Cross-regulation Rate Of Multi-output Flyback Switching Power Supply

With the development of the Internet of things,our electronic devices are becoming more and more informationalized,intelligent and complicated.Since different systems and modules require different levels of power supply,multiple power sources are required to power the system in an iot device.The multi-output isolated switching power supply only needs to add one high-frequency transformer winding,rectifier diode at the back stage and LC filter circuit for each additional output circuit.In this way,the cost and volume of the multi-output power supply system can be rapidly reduced.In this paper,the problem of multi-output cross-adjustment rate is studied deeply.(1)the distribution principle of secondary current at flyback time and full cycle is analyzed,and the influencing factors of cross-regulation rate of multi-output flyback switching power supply are found out.(2)the primary leakage inductance and diode on-lead voltage drop of the transformer are simulated and analyzed,and it is pointed out that the non-ideal characteristics of the transformer leakage inductance and diode are the main reasons affecting the cross-regulation rate.(3)the output rectifier diode with a smaller change in the voltage drop of the forward guide and the method of appropriately increasing the turn ratio of the secondary winding are adopted to effectively improve the cross-regulation rate of the multi-output flyback type.Improve cross regulation of several measures for verification,in this paper,the design and construction of a 30 v3 a 12 v1 a / 5 v1 a three output flyback switching power supply,first adopted in transformer winding arrangement stacked winding design,on the number of turns calculation using the precise winding reduction design,at the same time in the output rectifier diode on the choice of selection is to the change of the pressure drop less schottky diode,and combining the stack output,the weighted voltage feedback control and increase the false passive improvement scheme of load,for multiple output flyback switching power supply has carried on the comprehensive improvement.Finally,the cross-adjustment rate and other performance parameters of the system are tested.The cross-adjustment rate of the passive improvement scheme system in this paper is 6.3%(30V3A),4.3%(12V1A)and 10%(5V1A),respectively.