Effect of Transformer's Parameters on Harmonic Generation

Recently, switching power supplies are used in almost all electronic devices to convert and regulate the voltage amplitude. The only obstacle on using these devices is the production of high frequency harmonics that violates different standards such as (FCC, VDE, 461). In this paper the sources of various noises in switching power supplies will be introduced. Then, using appropriate model for high frequency transformers, a sample switching power supply will be simulated. In this simulation, the effect of transformer leakage inductance on current and voltage waveforms of the input and output switches, which are the main cause of common and differential mode noises and radiations, will be discussed and harmonically analyzed. Finally the experimental results are given to confirm the simulation conclusions.