针对少子模块数的中压模块化多电平变换器(modular multilevel converter,MMC)装置损耗、成本等指标难以综合提升的问题,该文提出一种基于Si基绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)和 SiC 基金属氧化物半导体场效应晶体管(metal oxide semiconductor field effect transistor,MOSFET)混合的模块化多电平变换器,简称异质器件混合型模块化多电平变换器(heterogeneous device hybrid MMC,HDHMMC).HDHMMC 由全 Si IGBT 的低频模块和Si IGBT与SiC MOSFET混合的高频模块组成.针对此拓扑提出一种特定的高低频混合调制策略,充分发挥Si IGBT通态损耗低、SiC MOSFET开关损耗低的优势.此外,详细分析了高低频模块的能量波动机理,并针对高低频模块直流侧电容电压不稳定问题提出一种特定的稳压策略.仿真和实验结果验证了 HDHMMC拓扑及其调制、稳压策略的可行性.最后,将HDHMMC与现有MMC拓扑进行损耗与成本对比,证明所提拓扑可以更好地平衡成本、效率、功率密度等性能指标.
A High-performance and Low-cost Medium-voltage Heterogeneous Device Hybrid Modular Multilevel Converter and Its Control Strategy
Aiming at the problem that the loss,cost and other indexes of the existing medium voltage modular multilevel converter(modular multilevel converter,MMC)with a small number of submodules are difficult to be comprehensively improved,a hybrid modular multilevel converter based on Si insulated gate bipolar transistor(IGBT)and SiC metal oxide semiconductor field effect transistor(MOSFET)devices is proposed in this paper,referred to as heterogeneous device hybrid modular multilevel converter(heterogeneous device hybrid MMC,HDHMMC).The HDHMMC consists of a low-frequency module of all-Si IGBT devices and a high-frequency module of Si IGBT devices mixed with SiC MOSFET devices.A specific high-and low-frequency hybrid modulation strategy is proposed for this topology,which gives full play to the advantages of low conduction loss of Si IGBT and low switching loss of SiC MOSFET.In addition,the energy fluctuation mechanism of the high frequency modules and low frequency modules is analyzed in detail,and a specific voltage stabilization strategy is proposed for the DC side capacitor voltage instability of the high frequency modules and low frequency modules.The simulation and experimental results verify the feasibility of HDHMMC topology and its modulation and stabilization strategy.Finally,the loss and cost of HDHMMC are compared with the existing MMC,which proves that the proposed topology can better balance the cost,efficiency,power density and other performance indicators.
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