Analysis and Development of a Bidirectional Three-Phase Hybrid Rectifier for DC Microgrids With Distributed Energy Resources

This work presents the analysis and development of a bidirectional three-phase hybrid rectifier (BTHR) for application in direct current (DC) microgrids connected to the utility grid. The voltage regulation technique, called series dc-bus voltage compensation (SDCVC), allows the design of an active front-end converter with high power density. The decentralized control strategy ensures low harmonic distortion of current in the utility grid in both operating modes (rectification and regeneration), in addition to providing dc-bus voltage compensation against power flow dynamics related to renewable energy sources (RESs). The operating principle, the control strategy, and the design criteria used for determining the transfer function of the proposed BTHR-SDCVC for DC microgrid (DCMC), as well as the design of the dc-bus voltage controller, are presented. To validate the theoretical analysis, a 1-kW prototype was implemented and evaluated at the laboratory. A steady-state analysis demonstrates that high efficiency, high power factor, and low harmonic distortion of current are achieved. Finally, a transient analysis was performed and demonstrated that the stability of the dc-bus voltage with and without the insertion of RES into the DCMG can be assured by deploying the proposed solution.