Filters with active tuning for switched-mode converters

In this thesis Switched-Mode Power Converters basic?s, output voltage ripples are analyzed and control feedback loop between the resonant filter network and switching circuit is provided by using Phase Locked Loop (PLL). There are more effective ripples on Switching-Mode Power converters according to linear converters. The ripples can be reduced by adjusting low pass filter cut off frequency below the fundamental harmonic ripple. But this state may not provide exact attenuation. In this thesis resonant filters are designed as additional to the low pass filter. If the switching frequency is selected equal with resonant frequency an important attenuation is provided at fundamental harmonic frequency. To provide an effective attenuation resonant filter network must be stay on resonance frequency. The operating conditions or component tolerances sometimes cause the missing attenuation of resonant filter. In this study the feedbacks control is designed by Phase Locked Loop to avoid this state. With the feedback loop the switching frequency is controlled as a resonance frequency and continuous ripple attenuation is provided. In this thesis, resonant networks models, Switched Mode Buck Converters and PLL control loop for switching circuit are simulated by using MATLAB and B2 Spice. This study shows the necessity and importance of PLL circuit. If the switching frequency changes from resonance frequency, output voltage ripples amplitude increasing rapidly. Keywords: Switched Mode Power Converters, Resonant filter, Phase Luck Loop, Resonator.