Abstract
Switching mode power supply (SMPS) has been dominant in the power supply systems such that it has replaced traditional linear power supplies in the past mainly because it has been known for high efficiency, small package, and low weight. However, high speed switching devices would produce high current ripples at input that deteriorate the power factor. Therefore, the improvement on the power factor of SMPS is prominent and important. Today, most countries in the world have enforced appropriate laws and standards for regulating the power factor of SMPS so that SMPS manufacturers would have to comply accordingly.According to the literatures, there are some methods developed for improving the power factor of electrical systems. More recently, a handful of power IC manufacturers have designed power factor correction (PFC) circuits and made it into a commodity such that electronic engineers can master the design clearly. In this thesis, a most available PFC IC has been chosen for studying the operational principles and details. SPICE simulation program has been employed for establishing the circuit model and simulating the PFC functions. The simulated results of PFC circuits could be used for verifying the operational details. Finally, evaluations and conclusions are made for potential applications in the future.