Research on control strategy of three-phase VIENNA rectifier
In order to reduce the current distortion rate of the AC side of the three-phase VIENNA rectifier and to suppress the potential fluctuation of the midpoint of the capacitor on the DC side,this paper proposes to ap-ply the control method of passive control and zero-sequence component injection to the three-phase VIENNA rectifier.Firstly,based on the mathematical model of the VIENNA rectifier in the three-phase stationary coordi-nate system,the equations of state of the voltages and currents with respect to the power switches in the syn-chronous rotating coordinate system are obtained after a coordinate transformation.Then the Euler-Lagrange mathematical model based on the three-phase VIENNA rectifier is established by the passive control theory,and the voltage modulation equation of the passive controller is derived analytically.At the same time,a mid-point potential balance control module for injecting zero-sequence components into the modulating wave is de-signed.Finally,the proposed control strategy is verified and analyzed by building a simulation model.Simula-tion results show that the control strategy proposed in this paper results in a more balanced capacitor voltage midpoint potential for the three-phase VIENNA rectifier compared to the conventional control,the input current exhibits a lower distortion rate,and the system is achieved to operate reliably at unit power factor.