Research On Three-phase Single-stage Isolated Sepic Rectifier And Control

In order to overcome the distortion of the input current in the power electronic device,the power factor correction technology has been used in large quantities.Most rectified equipment consists of two levels,and the pre-stage performs power factor correction,and the post-level implementation isolation and output voltage control.This method requires a large number of devices,which is complicated,and the reliability is low.This article has been detailed in the Sepic rectifier,and the Sepic circuit has the advantages of easy to achieve single-stage isolation,which is received more and more attention.First,the Sepic rectifier in continuous and intermittent mode was modally analyzed,and the circuit stress analysis and comparison,circuit continuous mode decision condition calculation,isolation Sepic topology analysis,and RCD clamp circuit analysis.The Sepic rectifier of the continuous conductive mode without the output inductive topology is selected,the circuit stress is low,and the volume weight and cost are reduced.Secondly,the voltage current double closed loop control method based on the Sepic rectifier is designed,and the voltage current loop controller is designed,and the system stability of different circuit parameters is simulated in the frequency domain and time domain,respectively.The simulation results show that the system can achieve adjustment of power factor correction and output voltage through voltage current double closed loop control.In different load conditions,the system can remain stable.In addition,a single-cycle control strategy based on the Sepic rectifier is proposed.The single-cycle control core control equation is established.It has a small signal model to design a voltage loop controller,and a system of different circuit parameters in frequency domain and time domain,respectively.Stability is simulated,the simulation results indicate that the system can achieve adjustment of power factor correction and output voltage through a single voltage ring.Finally,in order to verify the correctness of theoretical analysis,the design and device selection of system main circuits,overcurrent protection circuits and drive circuits are designed,and 1500 W Sepic rectifier experiment platform is built.The experimental results show that this converter can well realize the input current following the input voltage through the two control methods,the power factor is high,and the THD is small,which verifies the correctness of the theoretical analysis and the rationality of the parameter design,and at the same time proves this The feasibility and superiority of the scheme for three-phase power factor correction under medium and small power.