Analysis and design of dual switch flyback

CAO Xinzhi1， WANG Lujun2
（1College of Electrical & Electronic Engineering, Zhejiang Institute of Mechanical & Electrical Engineering，
Hangzhou 310053, China；2College of Electrical  Engineering,  Zhejiang University，Hangzhou 310007, China）

Abstract： Aiming at too much voltage stress on the main switch and voltage spikes from transformer air gap leakage inductance when switching off ， experimental study on the topology and operation principle of dual switch flyback were carried out The energy transfer model of dual switch flyback in DCM was built, and the result was revealed that the transformer turns ratio impacts magnetic reset time of the primary leakage inductance which has influence on maximum duty cycle and energy returned The design formulas on the main parameters of the dual switch flyback was deduced With the design formulas， a 30 W dual switch flyback in DCM was designed The Saber simulation was established， to research the operating current in main switches The results indicate that the transformer turns ratio is appropriate and energy feedback is weakened Some calculated results are verified by the experimental data， which shows they are reasonable The design formulas can be used as a design tool to develop more efficient dual switch flyback
Key words： dual switch flyback；auxiliary power；energy transfer；Saber simulation