Harmonic Resonance Suppression Strategy Of Vienna Rectifier

With a significant improvement of the number of charging piles,the interaction between rectifiers of the charging piles and utility grid increases and should not be ignored.One issue is the backgourd harmonic propagation on the cables,which threatens the security of the charging piles.The harmonic resonance suppression strategy for front end Vienna rectifier is studied in this thesis.Firstly,the input impedance of the Vienna rectifier and the impedance characteristics of the transmission cable are analyzed in this thesis.Based on the basic operatioin principle,the mathematical model of the Vienna rectifier in the abc and dq coordinate frame is established,and the expression of the input impedance characteristics of the Vienna rectifier based on the dq dual closed-loop control scheme is investigated.With the mathematical model of the transmission cable,the impedance characteristics of the transmission cable and the amplification law of the background harmonic voltage along the line oscillation are analyzed according to the transmission line theory.Secondly,the influence of transmission cable on the harmonic of Vienna rectifier network side is analyzed,and the Harmonic Resonance Suppression Strategy of Vienna Rectifier(HRSS-VR)is proposed.Simulation results show that the proposed suppression strategy can not only reduce the output ripple of dc side voltage,but also improve the power quality of network side current and the voltage at PCC.Then,in order to further increase the power level of the EV charging module,the charging module with higher power often adopts the structure of two Vienna rectifiers connected in parallel,which will cause the loop current problem.The generation mechanism of zero-sequence circulating current is analyzed,and then the zero-sequence component closed-loop regulation control strategy is used to manage it.The influence of transmission cables on the parallel connection of two Vienna rectifiers is further considered,and a harmonic resonance suppression strategy is proposed for the parallel connection of two Vienna rectifiers.Finally,a hardware-in-the-loop experimental platform based on the Real Time Digital Simulation System(RTDS)is established and the effectiveness of the proposed suppression strategy is verified in this thesis.Where,the π-aggregate parameter equivalent circuit of the grid and transmission cable is simulated by the RTDS,while the three-phase Vienna rectifier is digitally controlled by the TMS320F28335 using the actual circuit.