Parallelling three-phase AC to DC converter using CUK rectifier modules based on power balance control technique

The analysis and design of a paralleling three-phase ac to dc converter using CUK rectifier modules for DC Distributed Power System (DPS) applications are presented. The proposed control technique is used to obtain the three-inductor current compensators and to improve the dynamic response of the rectifier without affecting its steady-state performance and also to minimize total harmonic distortion (THD_i) in the source current. As a result, the output voltage of the converter can withstand the variations of the dc load current and input voltage. The control method is employed in the voltage feedback loop. The implementation of this control circuit uses only analog circuitry. The experimental prototype has been built with a DC output voltage -48 V and output power 1.5 kW. Each converter operates in Continuous Conduction Mode together with hysteresis current control. The experimental results indicate that such scheme is effective and offers the good dynamic transient response. The results obtained are: power factor higher than 0.99 and THD_i less than 3%. The system offers 88% efficiency and provides good inductor current sharing among the converter modules. The simulation and experimental results are presented to verify the feasibility of the control strategy.