Research On Three Phase Cascade High-frequency Link Matrix Rectifier

High-frequency link matrix rectifier(HFLMR)is a new type of converter developed on the basis of the traditional matrix converter.It saves the DC energy storage link in the traditional isolated AC-DC converter,which makes the system small,light,low cost,low noise and high reliability.It also succeeding the sine input of matrix converter and the power cause.The advantages of number adjustable and so on.It has good application prospects in such fields as new energy generation and high voltage transmission,but with the development of China's power industry,it is difficult to meet the application requirements of high voltage and high-power situations by the limitation of the technical level of traditional power devices by HFLMR.Therefore,the development of multiple HFLMR topology under high voltage and high-power applications is of great significance to the development of China's power industry.In order to improve the power and voltage level of HFLMR,this paper proposes a three-phase Cascaded High Frequency link Matrix Rectifier(line-voltage-cascade high-frequency link matrix rectifier,LVC-HFLMR)topology using the idea of multiple power converters.This topology is inheriting HFLMR without DC energy storage link,compact structure and small volume.With the advantages of good input characteristics,the power and voltage level of the system can be effectively improved by cascading line voltage,and it can be directly connected to the three-phase system,saving the number of switch devices and reducing the cost.Then,the operation characteristics of the topology are analyzed and deduced.At the same time,in view of the need of higher voltage level,the scalability of topology is analyzed.In theory,the topology can be cascaded indefinitely.The higher the number of cascades,the higher the voltage level.The LVC-HFLMR based on the 12 sector division of bipolar current space vector modulation strategy is described in detail,an improved modulation strategy without increasing the number of modules to improve the system voltage level is proposed.The double closed loop control system of the system is designed.On the basis of the bipolar current space vector modulation,the various modulation strategies of RMC are introduced.In view of the problems existing in the synchronous commutation action of each module of LVC-HFLMR,an improved LVC-HFLMR one-step commutation method is proposed,and a load opening of a module is solved through a direct passage of a group of open circuit modules.The problem of path is solved by using one way switch sequential conduction method to solve the transient interphase short-circuit problem when the working state is switched to zero vector.Finally,the LVC-HFLMR simulation model is built in MATLAB,and the correctness of the proposed topology and commutation strategy is verified by simulation.