Research And Design On Control Strategy Of Three-phase Three-wire VIENNA Rectifier

With the rapid development of power electronic technology,rectifier,as an important component of power electronic equipment,is widely used in the fields of variable speed drive,uninterruptible power supply,renewable energy conversion,multi-electric/all-electric aircraft,electric vehicles,electrified railways,surface warships and so on.However,the non-linear characteristics of traditional uncontrolled rectifier circuit itself pollute the power grid more and more seriously,so various rectifiers with power factor correction function emerge as the times require.Three-phase VIENNA rectifier has many advantages,such as low switching stress,fewer devices,low total harmonic content,and no bridge-arm direct connection,and it is one of the most widely used topologies.Firstly,the basic working principle of three-phase VIENNA circuit is analyzed step by step from single-phase structure.the three-level control algorithm based on SVPWM strategy is deeply studied,the division principle of each sector,the combination rule of basic space vectors and the working time are analyzed and deduced,the theoretical calculation formula is given,and the control method of DC side neutral point potential balance is discussed.Secondly,aiming at the problem of current zero-crossing distortion in three-phase VIENNA rectifier,the essential reasons are analyzed,and two improved control algorithms based on SVPWM are proposed,which effectively solve the problem of current zero-crossing distortion.The advantages and disadvantages of the two improved control algorithms are compared and analyzed,and the optimal design principle is given.Subsequently,in order to improve the dynamic response of output voltage of three-phase VIENNA rectifier at DC side,i.e.load dynamic response ability,combining with the dynamic response law of output voltage when the load jumps under the traditional double-loop control strategy,the inherent causes and influencing factors are analyzed in depth.A load feedforward control strategy is proposed.The basic form of feedforward function is deduced and analyzed in detail,the specific detection algorithm of load jump is designed.The results show that this method can effectively solve the problem of slow dynamic response of output voltage.Finally,based on the platform of matlab/simulink,the above control methods are simulated separately,and an engineering prototype of 1 kW three-phase VIENNA rectifier is designed,and the design schemes of software and hardware are given.The relationship between current ripple and inductance of three-phase VIENNA rectifier based on three-level SVPWM control strategy is analyzed emphatically,which provides theoretical basis for inductance design.The validity and correctness of the above control methods are verified by experiments.