Study And Design On Three-Phase Four-Wire VIENNA Rectifier

Electric Vehicles(EVs)have attached a lot of interesting all over the world for energy sav-ing and environment protection.The main challenges for EVs are long charging time and lim-ited driving range.High-power DC fast charging systems become a hot research topic in recent years.In this paper,for high power EVs DC fast charging system application,the design and control method for three-phase four-wire Vienna rectifier is studied.Because the neutral point is introduced,three-phase four-wire Vienna rectifier can be de-coupled into three single-phase three-level PFC converters.The control strategy is similar to that of a conventional single phase boost PFC converter,and it also needs a voltage balancing con-trol for the DC bus voltage.The small signal model for these control loops is firstly derived in this paper.The ripple current through the output capacitors in Vienna rectifiers determines the output capacitance selection and the thermal performance.The conventional methods,like estimation or simulation,usually suffer from poor accuracy or high complexity.In this paper,based on the analysis of t the operation principle of a three-phase four-wire Vienna rectifier,a simple expres-sion for the DC-link capacitor RMS current calculation is derived,which can be directly used for DC-link capacitor design of Vienna rectifiers.Finally,a 40kW three-phase four-wire Vienna rectifier is designed and built.The design steps,including parameter calculation,loss analysis,loop compensation and DSP configuration,are presented in details.In order to improve the control performance,a feedforward current con-trol is introduced to the current loop.The digital simulation and experimented results are pre-sented to verify the theoretical analysis.