Active Magnetizing Current Splitting ZVS Modulation of a 7 kV/400 V DC Transformer
Active Magnetizing Current Splitting ZVS Modulation of a 7 kV/400 V DC Transformer
复制标题
DOI：
10.1109/tpel.2019.2918622
复制
发表时间：
2020-02
影响因子：
6.7
通讯作者：
T. Guillod;D. Rothmund;J. Kolar
中科院分区：
文献类型：
--
作者：
T. Guillod;D. Rothmund;J. Kolar
LLC串联谐振转换器(SRC)是最常用的电流隔离式DC-DC转换器之一，因为当其工作在(或低于)谐振频率时，它提供零电压开关(ZVS)，降低均方根电流，并紧密耦合输入和输出电压，因此充当DC变压器(DCX)而不需要闭环电压控制。因此，这种拓扑结构对于大功率中压至低压固态变压器(SST)的DC-DC变换级具有特别重要的意义。本文首先强调了无源整流和同步整流的局限性(例如，振荡、电流失真、与负载相关的电压传输比)，用于采用大输出电容的半导体电桥。然后，分析了一种基于金属氧化物半导体场效应晶体管(MOSFET)桥的励磁电流分离ZVS(MCS-ZVS)调制方案，该方案允许一次侧和二次侧之间的励磁电流有源分担。结果表明，ZVS机构的作用相当于一个控制器，允许变流器的鲁棒开环运行。所提出的调制方案具有与负载无关的电压传输比、两个电桥的零电压与负载无关以及准正弦电流。最后，对基于SIC MOSFET的DC-DC转换器进行了实验验证，该DC-DC转换器的功率为${\Text{25}}$kW AC-DC SST，其工作频率为${\Text{48}}$kHZ，介于${\Text{7}}$V和${\Text{400}}$V之间，效率为${\Text{99.0}}{\%}$。
The LLC series resonant converter (SRC) is one of the most popular galvanically isolated dc–dc converters since it provides zero voltage switching (ZVS), reduces rms currents, and tightly couples the input and output voltages, when it is operated at (or below) the resonance frequency, and, therefore, acts as a dc transformer (DCX) without requiring closed-loop voltage control. Hence, this topology is of particular importance for the dc–dc converter stage of high power medium voltage to low voltage solid-state transformers (SSTs). This paper first highlights the limitations of passive and synchronous rectification (e.g., oscillations, current distortion, load-dependent voltage transfer ratio) for bridges employing semiconductors with large output capacitances. Afterward, a magnetizing current splitting ZVS (MCS-ZVS) modulation scheme, which allows an active sharing of the magnetizing current between the primary side and secondary side metal oxide semiconductor field effect transistor (mosfet)-based bridges, is analyzed. It is shown that the ZVS mechanism is acting equivalent to a controller, allowing for a robust open-loop operation of the converter. The proposed modulation scheme features a load-independent voltage transfer ratio, load-independent ZVS for both bridges, and quasi-sinusoidal currents. Finally, the phase shift modulation scheme is experimentally verified for the SiC mosfet-based dc–dc converter of a ${\text{25}}$ kW ac–dc SST, which operates at ${\text{48}}$ kHz between a ${\text{7}}$ kV and a ${\text{400}}$ V dc bus with an efficiency of ${\text{99.0}}{\%}$.