Modelling and control of VIENNA rectifier a single phase approach

Input harmonic and power factor (PF) regulations necessitate the use of front end active PF correction (APFC) circuit for power electronic converters. In recent times, the VIENNA rectifier has become a popular choice for three-phase APFC applications. The converter is a fifth-order system and results in a highly complex model. This calls for a complex control design procedure and involves enormous computation requiring the use of a high end digital signal processor (DSP). This can be simplified if the order of system is reduced. In this study, it is proposed to decouple and analyse the converter as three independent single phase units operating in parallel with current mode control, thereby reducing the order to two, simplifying the analysis and control design. The transfer function of the proposed small-signal model is derived and its Bode plot is drawn. A high bandwidth inner average current controller and a low bandwidth outer voltage controller are designed to obtain a 60° phase margin. With the proposed design, a 10 kW prototype VIENNA rectifier is developed with a low cost analogue integrated circuit (IC) and validated. The results obtained prove the accuracy of the proposed model and effectiveness of the control. Single phase operation is also made feasible with the proposed technique.