中文摘要：

特定谐波消除脉宽调制（SHEPWM）方法具有功率器件开关损耗低、输出电压质量高、有效消除低次谐波等优点,在三电平逆变器的控制中得到广泛应用.这里在分析三电平SHEPWM方法原理的基础上,采用多目标粒子群优化（MOPSO）算法求解三电平SHEPWM开关角,将非线性方程组的求解转化为对特定目标的优化,无需给定开关角初始值;分析了该方法的谐波特性,包括未消除谐波幅值的变化规律和总谐波畸变率（THD）的变化规律.仿真和实验结果验证了理论分析的正确性,SHEPWM方法达到了消除特定低次谐波的目的.

英文摘要：

Selected harmonic elimination pulse width modulation （SHEPWM） method features in low switching loss of power devices,high quality of output voltage,and effective elimination of low-order harmonics.It is widely used in three-level inverter.The principle of three-level SHEPWM method is analyzed ,based on which switching angles are calculated by means of multi-object particle swarm optimization （MOPSO）.This method can transform solve of nonlinear equation set into optimization of specific objective, and doesn＇t have to give initial value of switching angles.Harmonic characteristics of this method are analyzed, including variation patterns of amplitude of existing harmonics and total harmonic distortion（ THD）.Simulation and experimental results verify the validity of theoretical analysis, and demonstrate that three-level SHEPWM method realizes the objective of eliminating specific low-order harmonics.