The Power Supply System Research And Design Basic On PFC And LLC

Power adapter is the power supply conversion device for electronic equipment,its main function is to convert AC power to DC power which can be directly used by electronic devices.Power adapter is common used for cell phones and laptops,and more equipment of power supply is built into the product system,although not seen by users,but the function is the same.Various kinds of electronic equipment emerge endlessly in recent decades,the quality of power supply equipment is also unevenness.Many traditional power equipment inherent in the problem of low efficiency of low power factor and power supply,not only caused great waste of power,but also made great influence on the long-term reliability of electronic equipment.With the development of the power electronic semiconductor technology,especially for the active power factor correction technology and LLC resonant converter technology got great development.This thesis makes the best of these two technologies' development,the critical conduction control method combined with series resonance Boost type LLC technology,developed a 400 W power adapter with high power factor,high efficiency,high power density and high reliability,meantime it meets the requirement of medical electronic equipment products.This power supply can work worldwide,stable output voltage 24 V.Its main difficulty is under the limited space,achieve high efficiency,and to meet the strict requirements of the latest medical safety standard mainly about EMC and ESD.Based on PFC and LLC,research and choose the right solution,designing and producing the samples for testing and debugging,improve the design,and finally achieve the mass production.Main work content is as follows: 1.Through the analysis of the traditional PFC technology,understand its disadvantages.Study and research of active PFC common topology structure and control mode,aiming at different PFC topologies and control theory analysis,compare the advantages and disadvantages of all kinds of topology and control method,to seek for the design of PFC scheme.2.By analyzing the structure of series resonant LLC technology,detailed study under different working frequency series LLC,working mode and waveform,further study of the influence to series resonance circuit DC gain caused by the relationship of angular frequency,magnetic inductance and the resonant inductor.3.Select NCP1612 as the main chip of Boost type PFC scheme,select L6599 as the control chip of series resonance LLC circuit scheme,take most advantages of the function of the control chips,the relevant circuit parameters and peripheral device is calculated,choose the right components,design of main power circuit and related auxiliary circuit.4.Testing and debugging on the samples,mainly for ripple,efficiency,protect circuit,acoustic,loop gain test,ESD protection ability,EMI and other key indicators for testing and debugging.Implements improvements on test methods for electrostatic protection and improvement of the EMI problems put forward effective solutions.Finally makes it suitable for medical electronic equipment power supply system based on PFC and LLC stable performance and safe use of the product.The design has successfully passed the medical safety agency certification,and implement mass production.