The switch mode converters included thyristors concept of zero current switching (ZCS) and zero voltage switching (ZVS) resonant converters Prior to the accessibility to controllable switches with appropriate voltage and managing capability that is present. Each thyristor such a converter needed a commutation that is present, which consisted of an LC resonant circuit plus an thyristor that is auxiliary diode ,which switched the main thyristor down by forcing the present through it to go to zero. Due to the complexity and losings that are significant the commutation circuits, thyristors was indeed changed by controllable switches, as their power control capability enhanced. A need certainly to increase frequencies being switching to lessen EMI led ro dependence on controllable switches. The switching frequencies come in the megahertz range or even tens of megahertz. Realistically ,the switching frequencies could be increased to high values as long as the issue of switch stresses ,switching losings even though the EMI from the switch mode converters is overcome.