A multilevel inverter produces an output to approximate a desired sine wave. The closeness of the output waveform to the sine wave depends on the logic applied for switching angle calculation, resulting in different switching angle calculation methods. In this paper, various switching angle calculation methods are compared based on of the parameters quantifying the quality of the output waveform. The main focus of this work is on the study of convergence of the output waveform to a smooth waveform as number of levels increases theoretically. The convergence is analytically proved and validated numerically by computing up to 201 levels. Also, a parameter quantifying the deviation of the output waveform from the sine wave is defined, and its closed form expression is derived. This parameter is strongly correlated to and computationally less expensive than the total harmonic distortion. Hence, the deviation is proposed as a better measure of the quality of the output wave form. The convergence and the deviation of the output waveform are also used as the basis of the comparison of different switching angle calculation methods. These two give a better insight into the switching angle calculation methods. The analysis presented in this paper provides a good understanding of various switching angle computation methods and helps in choosing an appropriate method for a given application.

中文翻译：

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多电平逆变器开关角计算方法对比分析

多电平逆变器产生输出以接近所需的正弦波。输出波形与正弦波的接近程度取决于应用于开关角计算的逻辑，从而导致不同的开关角计算方法。在本文中，基于量化输出波形质量的参数，比较了各种开关角计算方法。这项工作的主要重点是研究输出波形在理论上随着电平数增加而收敛到平滑波形。通过计算多达 201 个级别，对收敛性进行了分析证明和数值验证。此外，还定义了量化输出波形与正弦波偏差的参数，并推导出其闭合形式表达式。该参数与总谐波失真密切相关并且计算成本低于总谐波失真。因此，建议将偏差作为输出波形质量的更好度量。输出波形的收敛性和偏差也作为不同开关角计算方法比较的依据。这两个可以更好地了解切换角计算方法。本文中的分析提供了对各种切换角计算方法的良好理解，并有助于为给定应用选择合适的方法。输出波形的收敛性和偏差也作为不同开关角计算方法比较的依据。这两个可以更好地了解切换角计算方法。本文中的分析提供了对各种切换角计算方法的良好理解，并有助于为给定应用选择合适的方法。输出波形的收敛性和偏差也作为不同开关角计算方法比较的依据。这两个可以更好地了解切换角计算方法。本文中的分析提供了对各种切换角计算方法的良好理解，并有助于为给定应用选择合适的方法。