Distributed Digital Control of Modular-Based Solid-State Transformer Using DSP+FPGA

This paper proposes a distributed digital control architecture of a modular-based solid-state transformer (SST) using a digital signal processor (DSP) and a field-programmable gate array (FPGA). In particular, the three-stage SST based on a modular structure is the topology of most interest because of its superior controllability. In order to make the modular-based SST, the digital implementation is inevitable to achieve higher performances, improved reliability, and an easy development. In addition, the modular-based SST requires enough capacity for implementing complex control algorithms, multiple interfaces, and a large number of internal variables. In this paper, a digital control platform for the modular-based SST is built using a floating-point DSP and an FPGA that operate cooperatively. As a result, the main control algorithms are performed by the DSP, and the simple logical processes are implemented in the FPGA to synthesize the suitable gating signals and control external devices, respectively. The proposed implementation method enables high-switching-frequency operation, multitasking, and flexible design for the modular-based SST. Experimental results are presented to verify the practical feasibility of the proposed technique for the modular-based SST.