Modelling and Analysis of an LLC Series Resonant Converter

• Main Authors: Pei-jung Lin, 林沛蓉
• Other Authors: Yu-Kang Lo
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/25122516691681194871

碩士 === 國立臺灣科技大學 === 電子工程系 === 96 === This thesis focuses on derivation and analysis of a LLC series resonant converter model by a 240W single-output and a 340W double-output half-bridge series resonant converter. First of all, the basic operating principle of series resonant converters is discussed in detail. Besides the significant parameters, such as resonant capacitors and inductors, turn ratio and magnetizing inductance, the on-state resistance of MOSFETs, the leakage inductors in the secondary side of the transformers, stray capacitors, line loss and ground plane are considered in the LLC equivalent model. Furthermore, the remaining loss of the secondary side is approximated as a parallel capacitor in the resonant tank. Thus, the output voltage is obtained by MATHCAD with above parameters. According to previous experiments, a revised LLC equivalent model is presented in the thesis. By doing simulation with the revised model, the frequency response of the output voltage gain can be shown in a chart with better accuracy and the operation frequency of converters is clearly predicted. In addition, in the case of verifying this model, a single-output and a double-output LLC-type resonant converter are implemented as following specifications: 12V/20A for the former and 12V/20A and 5V/20A for the latter with 400V input voltage. The deviation between the real output voltage and the simulated one is reduced from 35.0% to 3%. To sum up, the revised LLC equivalent model is proposed and improved with less deviation and much convenience in the LLC SRC convertor design.