Research On Interleaved Parallel PFC Converters Based On Digital Average Current Control

The requirement of electric energy is higher and higher with the development of power electronic technology.The use of a large number of power electronic equipments in the power system brings serious harmonic pollution.APFC is a very effective measure to reduce the harmonic pollution and improve the utilization of electric energy.Therefore,the APFC has become a hot research topic in the field of power electronics.The market demand for high power PFC converter is increased with the development of electric power equipment level is more and more big.Due to the limitation of the technology,the traditional PFC Boost converter can not meet the requirements of high power applications.The interleaved technique is introduced into the PFC circuit,which reduce effectively reduce the current stress of the switches and the input current ripple,especially suitable for application in high power field.So,this paper will be staggered parallel Boost PFC converter as the specific research object.With the emergence of a large number of high speed digital control chips,digital control technology has been developed rapidly,PFC circuit using digital control technology is the main direction of future development.In this paper,the digital average current technique is used to control the interleaved PFC circuit,and the double loop control strategy is adopted.The current loop is used as the same phase of input current and output current.And the duty cycle feed-forward control is introduced in the current loop to ensure the input resistance is resistive input.The digital trap and voltage feed-forward control are added in the voltage loop to improve the stability and dynamic performance of the system.Analysis of the working principle of one cycle control and one cycle control technology in the PFC circuit,and the average current control are compared,concluded that the single cycle control response speed,eliminating the average current control in the multiplier,but the average current control is more robust.In order to solve the problem of unequal current in parallel circuit,the two control schemes are improved and simulated.The simulation results show that the improved average current control and the improved single period control circuit can solve the problem of parallel branch current.