This paper presents a novel converterconcept of the off-board electric vehicle (EV) charging, which is based on an unfolding rectification approach where the three-phase Vienna rectifier-based unfolder (VRU) is followed by two identical isolated current-source converter (CSC) modules in input-series output-parallel configuration. The VRU operates at low frequency and thus features negligible switching losses, while the CSCs are responsible for the synthesis of the high-quality sinusoidal grid current waveforms and output voltage regulation. The proposed configuration features two time-varying soft DC-links, thus no bulky electrolytic capacitors are required. Input inductors of the CSCs limit the input current ripple, eliminating the need for separate grid filter inductors. Another notable advantage lies in the simplicity of the control system. Each CSC operates at a fixed frequency and provides the required current wave-shaping using only a single independent control variable, while no high-frequency synchronization between the two modules is required. The proposed configuration features a modular structure and was verified with a scaled 5 kW experimental prototype based on two identical 2.5 kW dc-dc modules and a common unfolding stage. During the experiments, the system provided power factor above 0.97 and THD below 5%. At rated power, the maximal efficiency of 94.8% was obtained.

中文翻译：

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适用于电动汽车充电应用的准单级三相无滤波器转换器


本文提出了一种新颖的非车载电动汽车 (EV) 充电转换器概念，该概念基于展开式整流方法，其中基于三相维也纳整流器的展开器 (VRU) 后接两个相同的隔离电流源转换器 ( CSC）模块采用输入串联输出并联配置。 VRU 在低频下运行，因此开关损耗可以忽略不计，而 CSC 负责合成高质量正弦电网电流波形和输出电压调节。所提出的配置具有两个时变软直流链路，因此不需要笨重的电解电容器。 CSC 的输入电感器限制输入电流纹波，无需单独的栅极滤波电感器。另一个显着的优点在于控制系统的简单性。每个 CSC 以固定频率运行，仅使用单个独立控制变量即可提供所需的电流波形整形，而两个模块之间不需要高频同步。所提出的配置采用模块化结构，并通过基于两个相同的 2.5 kW DC-DC 模块和通用展开级的按比例缩放的 5 kW 实验原型进行了验证。实验过程中，系统功率因数高于0.97，THD低于5%。在额定功率下，获得了94.8%的最大效率。