Modular multilevel converter (MMC) has a wide application prospect in medium voltage equipment, and its efficiency improvement and cost reduction have attracted much attention. Therefore, a novel hybrid MMC (NHMMC) topology is proposed from the perspective of modulation improvement and rational utilization of power devices in this paper. Each bridge arm of NHMMC is composed of the low-frequency half-bridge submodules (LF-HSMs) and a three-phase coupled high-frequency module (TPC-HFM) in series. LF-HSM is composed of Si IGBT devices, while TPC-HFM is composed of Si IGBT and SiC MOSFET devices together. Further, a frequency doubling hybrid modulation strategy is proposed for this topology. It gives full play to the advantages of low conduction loss of Si IGBT and low switching loss of SiC MOSFET while ensuring high output waveform quality. In addition, the energy fluctuation mechanism and operating status of TPC-HFM are analyzed in detail. Moreover, a specific voltage balancing strategy is proposed for TPC-HFM. Simulation and experimental results verify the feasibility of the topology, modulation and voltage balancing strategy. Finally, a comprehensive comparison of loss and cost between NHMMC and the existing topologies proves that the proposed topology can better balance performance indexes such as cost and efficiency.

中文翻译：

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一种具有三相耦合高频模块的新型混合模块化多电平转换器，用于多指标优化


模块化多电平变流器（MMC）在中压设备中具有广阔的应用前景，其效率提升和成本降低备受关注。因此，本文从调制改进和功率器件合理利用的角度提出了一种新型混合MMC（NHMMC）拓扑。 NHMMC的每个桥臂由低频半桥子模块（LF-HSM）和三相耦合高频模块（TPC-HFM）串联组成。 LF-HSM由Si IGBT器件组成，而TPC-HFM由Si IGBT和SiC MOSFET器件共同组成。此外，针对该拓扑提出了倍频混合调制策略。在保证高输出波形质量的同时，充分发挥了Si IGBT低导通损耗和SiC MOSFET低开关损耗的优势。此外，还详细分析了TPC-HFM的能量波动机制和运行状态。此外，还为TPC-HFM提出了一种特定的电压平衡策略。仿真和实验结果验证了该拓扑、调制和电压平衡策略的可行性。最后，对NHMMC与现有拓扑的损耗和成本进行综合比较，证明所提出的拓扑能够更好地平衡成本和效率等性能指标。