单相电力变换器交流侧与直流侧之间的瞬时功率不平衡，均会将交流侧含有的二倍工频脉动功率和无功功率辐射到直流侧形成二倍工频纹波和高次谐波电流，对单相变换器的安全、稳定和可靠运行带来巨大的威胁。DC-Link电解电容常被用于单相变换器中消除直流侧谐波，实现功率解耦。然而，谐波电流流过电容等效串联电阻时会产生热，对系统效率及稳定可靠性造成严重影响，故DC-Link电容可靠性问题已经成为了制约单相电力变换器发展的一大因素。消除DC-Link电解电容提高单相变换器可靠性的功率解耦技术已成为学术界的研究热点和工业界的热门话题。

    本文通过建立单相变换器数学模型，揭示二倍脉动功率和无功功率的产生机理和传播途径。针对具有差分电路结构特征的单相变换器，提出一种无需添加任何额外元器件的基于差分电容波形控制的功率解耦技术，通过控制交流侧两支串联差分电容电压产生交流侧所需要的二倍脉动功率和无功功率。该方法能够将二倍脉动功率和无功功率在交流侧进行就地补偿，缩短了功率流通路径，具有效率高、成本低和可靠性高等优势。在此基础上，本文对电容参数进行了优化设计，从变换器成本和效率的角度优化交流侧两支电容的容值，确定了对称结构实现变换器元器件电流应力最小，效率较高的电容配置方式。

    其次，对于不具有差分结构特征的单相变换器，本文在基于差分电容波形控制方法的基础上，从拓扑结构的角度出发构造交流侧串联电容结构的有源功率解耦模块，并通过理论分析推导出能够产生脉动功率且不包含直流分量的电压波形控制函数，提出一种基于功率解耦模块的功率解耦技术。该方法能够在不改变原单相变换器结构和控制策略的基础上，以模块的形式并联在交直流侧端口上实现功率解耦，消除DC-Link电解电容。相比包含直流分量的解耦方法，波形函数中不包含直流分量的解耦方法能够减小环流，提高变换器的工作效率；充分利用交流电容的正负半周，提高变换器中元器件的利用率，降低成本。

    本文在Simulink中建立了差分变换器，基于功率解耦模块的H桥变换器的仿真模型并搭建实验平台，通过对比分析验证了所提出基于差分电容波形控制的功率解耦技术和基于功率解耦模块的功率解耦技术的正确性和可行性。

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