Digital Control Strategy for Boost PFC Converter

• Main Author: PHAM PHU HIEU
• Other Authors: Huang-Jen Chiu
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/27729671064086308862

碩士 === 國立臺灣科技大學 === 電子工程系 === 103 === Power factor correction (PFC) shapes the input current to minimize the reactive power drawing from the mains. The use of PFC circuits is widely discussed and considered for most off-line power supplies. For high power applications, boost PFC converter operated in continuous conduction mode is usually employed and controlled by analog ICs such as UC3854. However, when the converter operates at lower power range, discontinuous conduction mode will appear during parts of line period, causing input current distortion. Moreover, the input EMI filter causes the significant displacement between input voltage and input current when the converter operates at high-line light-load condition. With functions integrated inside analog ICs, they cannot be adapted to various mode of operation of circuit, resulting in poor power factor (PF) and high total harmonic distortion (THD). In order to implement more complex control scheme to improve PF and THD, the advantages of digital control are exploited. With flexibility, decreased number of components, less sensitivity with change of noise, low cost and increased performance, the digital controller is an interesting topic to research and employ for boost PFC converter. In this thesis, the digital controller what employs the Sample Correction, Duty Ratio Feed Forward and EMI filter capacitance current injection algorithms is proposed to solve above problems. A 400W Boost PFC prototype is implemented to verify the feasibility of the proposed control algorithms. The experimental results show the PF and THD improvements in both CCM and DCM operations.