Analysis And Design Of Full Bridge LLC Resonant Converter

With the advancement of power conversions technology,the demand for high power density,low profile and high power efficiency is also increased day by day.The DC-DC power conversion is one of the most important key to power supplies and energy-related application.Magnificent challenges are faced by the power performances of the DC-DC converter stage,which is not only the demand for high efficiency and density but also needs the ability to control over a wide variation range of input voltage and load condition.The conventional pulse width modulation(PWM)DC-DC converter can't obtain such a high efficiency because it distributed the power by controlling the duty cycle of the switching frequency.Woefully,hold-up time requirement is also a significant challenge for these topologies.Also,high switching loss bound these topologies to achieve high power density.For this purpose,three resonant topologies,series resonant converter(SRC),parallel resonant converter(PRC)and series-parallel resonant converter(SPRC)are inspected due to their renowned low switching loss.However,unluckily to design with hold-up time requirement,no one of them gives us better performance over PWM converter.To solve the limitations of the conventional converters,LLC resonant converter has been proposed.Which process the power in a sinusoidal form and the switching devices are softly commutated.Among different resonant topologies,the LLC resonant converter becomes very popular and valuable due to its wide gain range and achieving of ZVS for switches from full load to zero load condition.This thesis presents the analysis and optimal design of Full Bridge LLC resonant Converter.Firstly,the basic working principle or operation mode of Full Bridge LLC resonant converter are discussed such as operation above,at,and below the resonance frequency along with it's ZVS operation waveforms and circuit diagram.Next,a step by step design procedure of FB LLC resonant converter is given with a specific parameter values and then simulate the design through Saber software that wheather it fullfil our desirable requirements or not.Also the power losses in it were analyzed.This thesis also gives us information about the design procedure of transformer..At last the advantages of Full Bridge LLC resonant converter are outlined.From the simulation result,it is clearly seen that the design successfully achieves Zero Voltage Switching(ZVS)and Zero Current Switching and gives us very good efficiency with a very minimum(negligible)power loss.The peak efficiency was 94%,the average efficiency was 92.7%and the output voltage was 48V which is our desirable results.The results mainly meet the request of the thesis.