Research On Digital Control Technology For One Cycle Controlled Power Factor Correction

Switching-mode power supplies(SMPS) are serving as a bridge between power grid and consumer electronics. Moreover, being the first part of the SMPS, the power factor correction(PFC) circuit, plays a crucial role in restraining harmonic current from injecting power grid. Therefore, performance of the PFC circuit has direct impact on the security of power grid and the quality of electrical energy. Nowadays the modern SMPS technology is gaining momentum in its development towards high frequency,modularization and intellectualization. While,because of inherent limitations, the traditional analogue control system has restrained itself from meeting the trend of further research and the market. Therefore, based on the situation above, by researching the theory and structure fo the SMPS, a kind of one cycle controlled(OCC) Boost-APFC circuit and its digital control sysytem is designed in this thesis.This thesis introduces the theory of SMPS and PFC technology. By analyzing topological structure, control strategy and sampling algorithm, a parameter solution for PFC circuit is worked out. This thesis establishes a range of mathematic models for Boost convertor by simulation in PSpice、Simulink and SIMPLIS. The simulation result reflects that the transfer function formed by this thesis have a high integrating degree with the practical switching circuit.This thesis designes a double electric loop control system designed for Boost convertor. To optimize the stability and responding speed of the system, a frequency compensate for control loop is made. Then a PFC part based on the boost convertor is designed by using OCC scheme. With simulation and optimization in PSim, the final result shows that the PF value reaches above 99.7% and the THD value declines to 5%.For the charactor of the OCC strategy, a digital PI module and a digital sampling module are designed for DSP/ARM control system. By abandoning the traditional foreground-background embedded system, a multi-task process scheduling policy is designed based on the uC/OSII real-time operating system, and tests successfull on mini2440 development board with a core of ARM920 T.