Design Of A Transition Mode APFC Controller Based On BCD Process

With the development of the power electronic technology, harmonic noise created by various electric equipment becomes more and more serious. In order to increase the efficiency of switch power system, the research and application of Power Factor Correction (PFC) become the focus of the power electronic. The power factor (PF) of which the selecting PFC method is on the basis, is the most important parameter of excellent power supply. The active PFC (APFC) which is the main method of PFC, not only has higher PF and lower total harmonic distortion (THD), but also has wide input range. The boost circuit is usually used in APFC. In view of the focus of the power electronic, a transition mode APFC controller is designed.Firstly, this paper summerizes the current situation and development of PFC. Secondly, the topology circuit of PFC and the method of application is introduced. According to the chip's application and the requirement of parameters, after analysing and comparing the features, the transition mode (TM) APFC with the type of current controlled is adopted. On the above basis, a APFC controller XD2656 is presented. According to its principle, the chip's structure is designed, and then the simulation and the test of its submodules and typical application circuit is accomplished. In order to make the chip have lower starting consumption and become more reliable, an under voltage lock out circuit and an over voltage protection circuit are designed. Furthermore, for improving the PF and decreasing the THD, a multiplier with minimum THD is included in the chip.The chip in this paper is based on 0.4μm 40V BCD process and simulated by Hspice and Cadence software. The PCB of the chip's typical application is also designed for test. According to the results of simulation and test, XD2656 can correct PF in boost APFC circuit, and it has higher PF and lower THD. The circuit's function and parameters meet the design specification.