Analysis, design and implementation of a three-phase AC to DC converter using single-phase isolated CUK rectifier modules with small DC bus capacitor

The paper presents an implementation and control of a high power-factor and fast dynamic transient response of the modular three-phase ac to dc converter using three CUK rectifier modules with a small dc bus capacitor. The methodology aims at finding the small dc bus capacitor which meets the desired system performance, with power balance control technique. Modeling a modular three-phase rectifier system is considered as the first step in the optimal sizing procedure. In this paper, mathematical average small-signal model for characterizing modular three-phase rectifier is proposed. Design of an analog controller for a small dc bus capacitor based modular three-phase rectifier is presented. The controller senses the parameters of the proposed system, and makes decisions about reject load and input voltage disturbances. The second step consists in minimize the sizing of the dc bus capacitor according to the transient response of dc bus output voltage and the delivered energy of capacitor concepts. Considering various types and capacities of dc bus capacitor, which can meet the desired system performance, are obtained by changing the type and size of the dc bus capacitors. The proposed system with the dc bus capacitor 470 muF gives the optimal choice. A 750W laboratory prototype with 470 muF is implemented and tested to verify the feasibility of the proposed system. The experimental results show that the proposed system, meet the desired system performance. Therefore the system choice plays an important role in cost reduction.