Study On VIENNA Rectifier

With the widespread utilization of power electronic devices in various fields, the problem of harmonic pollution to the grid is becoming serious. Therefore how to improve the power factor of electronic devices, especially the rectifier equipments, and reduce the current Total Harmonic Distortion (THD) has become a serious problem to be solved urgently. VIENNA rectifier is one kind of three-level Boost type neutral point clamped structure rectifiers, and it has great research value and broad application prospect because of its high power factor, few switches, and low switch stress.Firstly, this thesis introduced the working principle of VIENNA rectifier. Then the main circuit parameters design methods are studied, and the design principles and constraints of the key parameters are given.Furthermore, the mathematical models of VIENNA rectifier in static coordinate system and two-phase rotating coordinate system were studied. According to the mathematical model in two-phase rotating coordinate system, the control method based on conventional three-level space vector pulse width modulation (SVPWM) was studied, and the flow chart of control algorithm was given.Because of the need for complex judgments of current sector in the application of traditional SVPWM control strategy of VIENNA rectifier, a sector judgment method with reference voltage auxiliary was proposed in this thesis through the analysis of relationship of the vectors in the AC side under the condition of unit power factor. The modulation process of this method was analyzed in detail, and a simulation model was built to verify the effectiveness of the proposed control strategy.At last, the complete design parameters, control system structure, and software flow chart of experimental prototype were given in this thesis. The experimental platform was established, and then the system experiments of the prototype were done. The results of system experiments were analyzed, and the results showed that the proposed control strategy was feasible and effective.