Droop-based Current Control Method in Autonomous Distributed Modular Power Conversion System

This paper proposes a decoupling control method among autonomous distributed modular power modules for an Universal Smart Power Module (USPM) concept. In this concept, the power conversion systems are configured as the Power Electronics Building Block (PEBB) to realize the simplification of the power electronics design. The original point of USPM is that each power module operates independently because a high-speed power electronics controller is implemented on each power module. The power modules of PEBB are typically configured by the main power circuits with gate controllers. Therefore, the controller is designed specifically according to various applications although the advantages of PEBB are high flexibility and user-friendly. USPM enhances these advantages in comparison with the PEBB. The USPM systems establish a decoupling method among each USPM because USPM does not share the physical information among the other USPMs. In addition, USPM is utilized in the multi-series and parallel connection to increase the voltage and current rating of the power system according to the applications. In this paper, a droop-based current control for series connection USPM is proposed in order to stabilize the current control of each USPM. Furthermore, the design criteria of the droop control are revealed. The experimental result with series-connected USPMs demonstrate that the proposed method avoided the overmodulation due to interference of the current controllers of each USPM. In addition, the current deviation in the experiment was coincident with the current deviation in design with an error of 3.17%.