A New Hybrid Modular Multilevel Rectifier as MVac–LVdc Active Front-End Converter for Fast Charging Stations and Data Centers
A New Hybrid Modular Multilevel Rectifier as MVac–LVdc Active Front-End Converter for Fast Charging Stations and Data Centers
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DOI：
10.1109/tpel.2023.3283469
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发表时间：
2023-09
影响因子：
6.7
通讯作者：
Jian Liu;J. Motwani;R. Burgos;Zhiding Zhou;D. Dong
中科院分区：
文献类型：
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作者：
Jian Liu;J. Motwani;R. Burgos;Zhiding Zhou;D. Dong
随着电动汽车快速充电站和数据中心中直流储能和负载的电力需求持续增长，电力输送基础设施面临着安装体积庞大、重量沉重且响应缓慢的工频电力Transformer（LFT）的挑战。这些变压器需要将馈线电压从中压（MV）交流电网服务降压到低压（LV）交流，然后是LVac-LVdc整流器。这种方法导致设备占用空间大、导体铜使用量大以及效率较低。因此，人们越来越有兴趣探索从MVac到LVdc的直接接口，而无需LFT。本文提出了一种新的解决方案，称为MVac-LVdc混合模块化多电平整流器（HMMR）。HMMR可用作集中式降压有源前端转换器，通过减少DC/DC后端隔离转换器的数量实现向LVdc的供电。与采用模块化多电平变换器（MMC）作为MVac接口解决方案相比，HMMR可节省40%的子模块数量，降低22%的损耗，显著减少37%的占地面积，有效提高功率密度，降低建设成本。此外，建议HMMR有可能在单位和非单位功率因数模式下运行，使其能够提供电网支持功能。HMMR的性能进行了评估，并与全桥MMC的情况下，13.8千伏交流到6千伏直流。仿真结果验证了该变换器的可行性。最后，一个缩小的1.4 kV HMMR原型开发，以验证所提出的转换器的有效性。
As the power demands from dc energy-storage and loads continue to grow in electric vehicle fast charging stations and data centers, the power delivery infrastructure faces challenges with the installation of bulky, heavy, and slow responsive line-frequency power transformer (LFT). These transformers are required to step-down the feeder voltage from medium-voltage (MV) ac grid-service to low-voltage (LV) ac, followed by LVac–LVdc rectifiers. This approach results in a large equipment footprint, heavy conductor copper usage, and lower efficiency. Consequently, there is increasing interest in exploring direct interface from MVac to LVdc without the need for LFT. This article proposed a new solution called MVac–LVdc hybrid modular multilevel rectifier (HMMR). The HMMR serves as a centralized step-down active front-end converter, enabling power delivery to LVdc with a reduced number of dc/dc back-end isolated converters. Compared to the modular multilevel converter (MMC) used as the MVac interface solution, the proposed HMMR could save the submodule number by 40%, reduce losses by 22%, and significantly reduce the footprint area by 37%, effectively increasing the power density and reducing the construction cost. Moreover, the proposed HMMR has the potential to operate in both unity and nonunity power factor modes, allowing it to provide the grid-support functionality. The performance of HMMR is evaluated and compared with full-bridge MMC in the case of 13.8 kV ac to 6 kV dc. The feasibility of the proposed converter is verified by the simulation results with the same specifications. Finally, a scale-down 1.4 kV HMMR prototype is developed to validate the effectiveness of the proposed converter.