Design Of The Controller For LLC Resonant Converter

Since the 21 st century,the spurt of electronic information technology represented by wireless communication technology,cloud computing and cloud storage have driven the demand for high-end power supply systems in the industry.And there has been a trend of development characterized by miniaturization,high efficiency,low ripple,low electromagnetic interference,good dynamic characteristics and high reliability.Compared with the traditional linear regulated power supply,switching mode power supply gets lower loss and higher power density,so it has been investigated extensively and adopted in a variety of power supply.As a branch of many topologies in switching mode power supplies,LLC resonant converter has the characteristics of soft switching.Therefore,it has a built-in advantage in reducing switching losses as well as increasing power density,and then it's especially suitable for high frequency and high integration applications.This thesis mainly focus on the LLC resonant converter analog control,which derived from the operational amplifier,comparator and oscillator.Compared with digital control,it takes advantages of easier implementation and lower cost and is suitable for power adapter,liquid crystal display power supply,etc.In this thesis,first of all,a typical case analysis is conducted to define the matrices of the system designed.Then we compare the advantages and disadvantages of Flyback and LLC,and the topology selection is completed.Thirdly,the working procedure,transfer function and compensation method of LLC resonant converter are analyzed.The startup process,dead time calculation,light load control and various kinds of protection are discussed.Aiming at the shortage of traditional control method,we design the optimized strategy to improve the reliability of the controller.In this theses,CSMS 600V 0.8?m BCD process was chosen to simulate the designed system and accomplish the layout.The core functions such as soft-start,adaptive dead time regulation,dual-mode control,over current protection,phase protection,under voltage protection are verified.Analysis about applications with load and input voltage jump are also covered.The results shows that this design has the correct function and meets the expectation in the system matrices.