LLC Type Resonant Converters with Notch Filter
LLC resonant converters are adopted gradually due to high efficiency and high frequency operation capability. Several topologies have the similar characteristics as LLC, like CLL. However, to make practical use of these converters, there are still some issues to be solved. The purpose of over current protection is to limit the current stress in the system during over load or short circuit condition, also to limit the inrush current during start up when output voltage is zero so that the power converter can be protected from destructive damage under those conditions. Traditional resonant topologies are always band pass filters, like LLC, etc. Notch filter is a band stop filter, which can block selected frequency power. In order to overcome the start-up and short circuit protection issues, a notch filter is added to LLC type resonant topologies. These novel multi-element resonant converters can achieve natural inherent over load, startup and short output protection.