Steady-State Characterization of LLC-Based Single-Stage AC/DC Converter Based on Numerical Analysis
Steady-State Characterization of LLC-Based Single-Stage AC/DC Converter Based on Numerical Analysis
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DOI：
10.1109/tpel.2021.3058694
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发表时间：
2021-02
影响因子：
6.7
通讯作者：
Xiang Li;Liuniu Guo;Tianchen Lang;Daorong Lu;Khalil Alluhaybi;Haibing Hu
中科院分区：
文献类型：
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作者：
Xiang Li;Liuniu Guo;Tianchen Lang;Daorong Lu;Khalil Alluhaybi;Haibing Hu
基于llc的单级ac/dc变换器可以在全负载范围内实现零电压切换，为实现ac/dc功率转换的高效率、低成本和极度紧凑提供了非常有吸引力的解决方案。然而，在这种交直流转换中引入LLC谐振槽后，由于其复杂的谐振电路行为和时变的交流输入电压，使得准确分析变换器的稳态特性变得非常困难。虽然可以采用一阶谐波近似（FHA）、扩展FHA、多谐波近似等分析方法对该变换器进行分析，但无法得到准确的增益曲线，特别是当开关频率偏离谐振频率较远时。在这种情况下，针对交流输入时变和直流输出波动带来的困难，提出了数值分析方法。提出了一套描述谐振电路行为、功率守恒、电感电流和电容电压的方程。并给出了详细的数值分析过程。数值计算结果与PSIM模拟结果吻合较好。建立了1 kw 48v输出样机，验证了数值分析的有效性。
The LLC-based single-stage ac/dc converter can achieve zero voltage switching under full load range, which offers a very attractive solution to realize high efficiency, low cost, and extreme compactness of ac/dc power conversion. However, with the introduction of LLC resonant tank in this ac/dc conversion, it becomes very challenging to accurately analyze the steady-state characterization of the converter due to its complex resonant circuit behaviors and time-varying ac input voltage. Although some analysis methods, like first-order harmonics approximation (FHA), extended FHA, and multiharmonic approximation, etc., can be adopted to analyze this converter, they cannot obtain the accurate gain curves, especially when the switching frequency deviates far from the resonant frequency. In this situation, the numerical analysis method is offered to cope with the difficulties resulting from time-varying ac input and dc output fluctuation. A set of equations describing resonant circuit behaviors, power conservation, inductor current, and capacitor voltage are presented. Also, the numerical analysis procedure is given in detail. The numerical calculation results are found that they match with those results in PSIM simulation pretty well. A 1-kW 48-V output prototype is built to verify the effectiveness of the numerical analysis.