Design and application of variable frequency soft switching flyback converter

The use of switch mode power supplies has increased in the industry due to its high efficiency and low size. With the increase in circuit size and cost, the flyback converter has become indispensable for low power applications in switch mode power supplies. The transformer used in the flyback converter is smaller, provides isolation between input and output, and allows multiple outputs at different voltage levels, which has increased the popularity of this converter In this study, one of the switching power supply circuits, the Flyback converter uses the variable frequency switching method instead of the duty cycle change method which commonly used in pulse width modulation (PWM). Since there is no variable frequency PWM generator in the simulation program, a new variable frequency PWM generator is designed and used. In order to reduce the switching losses of the circuit, soft switching is applied by using zero current switching method. In addition, the voltage stress on the main switch caused by the leakage inductance of the transformer is suppressed. Simulation studies were performed in MATLAB/Simulink program and experimental studies were carried out in laboratory. Current and voltage values of input, output, main switch and transformer windings were measured for both simulation and experimental study. Simulation results and experimental results were compared. From the results, it was seen that the simulation study results and experimental study results were compatible and the proposed circuit was more usable at low output power.