A Highly Efficient Hybrid Devices-based MMC with a Novel Modulation Scheme Using Hardware-in- Loop System

The modular multilevel converter (MMC) is gaining popularity for medium voltage and high-power applications. With the advent of silicon carbide (SiC) devices, overall performance of the MMC can be enhanced. However, utilization of the SiC devices for the MMC lead to extremely high cost. Moreover, conduction losses of the converter may also increase due to the unipolar nature of the available SiC devices. To overcome these challenges, the hybrid MMC employing SiC MOSFETs and Si IGBTs based sub-modules (SMs) is proposed in this paper. In the proposed topology, each arm utilizes at least two SiC MOSFET half-bridge SMs, while the remaining SMs are Si IGBTs half-bridge configurations. This achieves reduction in the converter cost. Further, a novel control scheme is proposed to provide optimized utilization of the selected switching devices with enhanced efficiency. In this paper, a detailed analytical study is presented to investigate the performance of the proposed converter with the proposed control scheme. Finally, the real-time simulation results are presented using the OP AL-RT setup to highlight the performance of the proposed hybrid MMC with the proposed control scheme.