Power Factor Corrector Design and Electromagnetic InterferencePrevention for 300 Watts Forward Switching Power Supply

• Main Authors: Yuan-Sz Wang, 王思淵
• Other Authors: YUAN KANG
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/28363909594355777590

碩士 === 中原大學 === 機械工程研究所 === 95 === The fast developments of high-level computers and operating machine platforms have promoted the demands for switch-mode power supplies with high energy density and efficiency recently. However, the problem due to the harmonic current in the circuit and different load phase would not only affect the stability of the switch-mode power circuits but also deteriorate the power factor with more energy losses. Thus, how to improve the power factor of switch-mode power supplies has been the common goal in the industry. This report is focused on the design and implementation of a power factor corrector (PFC). Various types of PFC topologies and several control schemes are also discussed. The set-up converter by the average current mode control with a constant switching frequency is proposed. The main objective is to reduce the input current harmonics and to increase the power factor to approaching one. At last, a 300W Forward PFC prototype is manufactured based on the ML4800 control IC to be the test board. The experimental results confirm the validity and feasibility of the adopted scheme. The PF value can be higher than 0.95 when it operated in fully loading. In addition, this report presents the steps for solving the conducted EMI problems for switching power supply. A second-order passive filter is put in front of the switch power supply circuit to indicate the EMI element’s functions for different source of noise. The result would be a reference for the EMI test in the further.