| Title |
A Study of the Three Port NPC based DAB Converter for the Bipolar DC Grid |
| Authors |
Hyeok-Jin Yun ; Myoungho Kim ; Ju-Won Baek ; Ju-Yong Kim ; Hee-Je Kim |
| DOI |
https://doi.org/10.6113/TKPE/2017.22.4.336 |
| Keywords |
SST(Solid State Transformer) ; DAB(Dual Active Bridge) ; 3-Port ; 3-winding transformer ; Current sharing controller |
| Abstract |
This paper presents the three-port DC-DC converter modeling and controller design procedure, which is part of the solid-state transformer (SST) to interface medium voltage AC grid to bipolar DC distribution network. Due to the high primary side DC link voltage, the proposed converter employs the three-level neutral point clamped (NPC) topology at the primary side and 2-two level half bridge circuits for each DC distribution network. For the proposed converter particular structure, this paper conducts modeling the three winding transformer and the power transfer between each port. A decoupling method is adopted to simplify the power transfer model. The voltage controller design procedure is presented.
In addition, the output current sharing controller is employed for current balancing between the parallel-connected secondary output ports. The proposed circuit and controller performance are verified by experimental results using a 30 kW prototype SST system. |