针对传统AC-AC变换器在大容量变换领域中存在的开关管电压应力高、谐波干扰严重等问题,提出了一种新型的高频隔离式半桥三电平AC-AC直接变换器.深入分析了该变换器的高频开关工作过程,对变换器的6种工作模式进行了详细阐述.经过对输出滤波器前端电压进行傅里叶分析,发现频谱结构得到改善,谐波成分减少.为能快速响应输入及输出电压的变化,采用基于电压瞬时值反馈的SPWM控制策略.仿真分析和实验结果说明变换器具有改善输出波形质量、抑制谐波干扰的作用,三电平开关单元的电压应力为两电平的一半,适用于高压大功率变换场合.%As the traditional AC-AC converter has high voltage stresses and harmonic interferences,a kind of high-frequency isolated half-bridge three-level AC-AC direct converter is proposed. The process of its high-frequency switching operation is analyzed and its six working modes are explained. The front voltage of output filter is studied by Fourier analysis, which demonstrates that the frequency structure is improved and the harmonics are decreased. The transient voltage feedback SPWM control is applied to rapidly respond to the change of input and output voltages. Simulative and experimental results show that the proposed converter can improve the output waveform quality and suppress the harmonic interference. Its voltage stress is half of that of two-level converter, suitable for the high-voltage large-power conversion.
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