Design & Implementation of LLC Resonant Converter

Recent advances in modern power semiconductor device technology have led to high utilization of PWM power converters in a wide number of applications such as high Voltage DC power supply, HVDC power transmission, induction heating, electronic lamp ballast etc. In PWM converter the power switches are switched at high frequency to reduce size of transformer and overall size, weight and cost. An attractive alternative for it is to replace the power switch by a “Resonant Switch” in which switching is done at zero voltage/zero current and this can be achieved by forcing voltage and current to pass through zero crossing by creating LC resonant circuit called resonant pulse converter. So switching losses are decreased and efficiency is improved which are mainly depending on the choice of switching frequency for the converter. The aim is to design a Resonant Converter capable of operating at high frequencies to achieve high power density and better performance for medium/high power DC power supply. To make the DC power supply smaller, a high frequency switching resonant converter should be adopted. As at lower switching frequencies and without use of resonant converter the switching losses (turn on and turn off losses) are significant part of power losses, which reduce the efficiency and increase the size of the converter.The proposed Resonant Converter is developed for high frequency and input DC is stepped down by resonant action. The switching losses are minimized and efficiency is improved as compared to conventional methods. It employs a control scheme to regulate its output voltage. The control scheme has been chosen by comparing different control methods. Finally the simulation of whole system has been done by PSIM software.