Small-Signal Modeling and Analysis of Peak Current-Mode Buck-Boost LED Driver

• Main Authors: Chia-ChunLee, 李嘉峻
• Other Authors: Ray-Lee Lin
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/95891708160251676432

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 99 === This thesis presents the modeling of the peak current-mode buck-boost light-emitting-diodes (LEDs) driver in the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM), respectively. In order to analyze system characteristics, the equivalent circuits can be constructed with the pulse-width modulation (PWM) switch cells and the current-mode control schemes, to derive the system transfer functions, including control-to-output current gain, line-to-output current gain and output impedance. The derivation of the system transfer functions for the CCM and the DCM buck-boost LED driver, the system characteristic analysis and the compensator design are developed by Mathcad? to compare with the SIMPLIS? simulations. In order to precisely curve-fit the V-I characteristic curve of the LEDs, the exponential function of the V-I characteristic can be expressed by Taylor series. The DC and the small-signal equivalent circuit models of the LEDs have been constructed to describe the V-I characteristic of the LEDs. In order to realize the temperature effect on the LEDs model, the exponential function for describing the characteristics of the LEDs is used to analyze the relationship between the ambient temperature and the LEDs V-I curve. Finally the derived CCM and DCM system transfer functions are validated with the SIMPLIS? simulation and experimental results.