Research Of An Interleave Power Factor Correction Circuit And Its Digital Control

As a new solution for distributed generation,micro-grid system can improve energy utilization effectively,meet the demands of distributed load and increase economic benefits.The concept of micro-grid system is also accepted by people gradually,along with the emergence of related applications.As the preferred solution of AC/DC part in micro-grid system,power factor correction(PFC)has been widely researched and applied.In the application of micro-grid system,PFC device needs to meet some requirements,such as flexible control,well cooperation with other device and so on.It's hard to meet all the requirements if only employing analog solution in the PFC device.With the development of digital control technology,digital power can provide a better solution and a higher performance,while avoiding the disadvantages of analog control,which includes high-cost upgrade maintenance and component parameter errors.For medium-power applications,this dissertation focuses on the research of digital control to interleave PFC.Switching principle of interleave PFC is analyzed and discussed in the very beginning.Then small-signal model and power transfer functions of interleave PFC are acquired based on the average state space method.Similarities and differences between single phase and interleave PFC are compared at the same time.The modeling analysis is verified by PSIM at last.Based on the analysis above,two control methods(traditional multiplier control and new one-cycle control)are introduced in the following chapters.The block diagram of closed-loop control and the formulas of compensator are given,and some improvements for synchronous sampling of digital implementation are also promoted in this dissertation.Finally,simulation shows that both control methods are feasible.In order to implement the digital control method,1kW interleave boost PFC hardware platform,using TMS320F28069 as the main digital controller,is designed and developed.Meanwhile the selection and design details of key components are also discussed.Due to space limitations,this dissertation only introduces the implementation of digital one-cycle control.Some control details,such as simplified digital calculation and synchronous sampling are analyzed deeply in the following chapters.At the same time,the main control flowchart and parameters in practice are shown at last.A good control effect is achieved by debugging and testing the hardware platform in the end.By comparing the waveforms between experiment and simulation,a conclusion can be drawn that interleave boost PFC with digital one-cycle control can achieve a good performance the same as analog control,such as high power factor,high precision and high quality control effect.