Digital Control Of Power Factor Correction Converters Using A Single Sensor

Traditional diode rectifier results in a lot of input current harmonics, which brings harmonics distortion to the mains. In order to limit the input current harmonics, many countries have established some rules to force the implemention for some limitation standards. Active power factor correction (APFC) technology can achieve high power factor and low harmonic distortion (THD), and become a hotspot of research in power electronics field. Due to the high power consuming characteristic of the next generation processors, the regulation requirement for power converter systems becomes more and more demanding in industry. Since it has the advantages of good programmability, flexibility and reliability, digital control system has the potential to achieve high performance control of switching-mode power supply (SMPS). Nowadays it is popular to use digital control in power supply design. Based on average current mode, the paper introduces the design and implementation of a fully digital controlled single-phase boost power factor corrector. The control-loop circuit is realized using digital control and the power factor corrector can tend to unity power factor, lower current harmonics and high transfer efficiency.This paper focuses on the study of the digital control algorithm to improve the transient response characteristics of switching converter. Based on the traditional double PI-loop control, the output voltage sample-and-hold algorithm is introduced into the voltage control loop which filters voltage ripple of the output voltage feedback signal and improves the load response speed of the converter. A novel input voltage feed-forward control algorithm with correcting the reference initial phase angle is proposed, which reduces the computation process, improves the input voltage response speed and eliminates zero-crossing distorted phenomenon and DCM mode of the PFC converter.Based on the theory analysis results, design of the boost converter main circuit parameters, the digital control system software has also been performed. The software system consist of main program and interrupt subprogram, which contained some modules to realize independent functions, such as initialization module, PI algorithm module, soft-start algorithm module and duty cycle saturation module, etc. Under connection of the main program, these modules realize an integrated system. It is easier to do some management and upgrade when the program at the end of this dissertation. Assembly language and C language is using to programming in order to achieve the best use of the DSP chip software and hardware resources. All design thoughts and theoretical are verified by emulation and experiment.