基于共模电流频谱能量的共模干扰抑制研究

Common Mode Suppression Based on Common Mode Currenct Spectrum Energy

在电力电子装置中不存在两个互补对称共模噪声源时,可以采用外加补偿电路的有源并联共模电磁干扰抑制技术。分析了补偿电路与被补偿桥臂的PWM信号传输时间差对共模电磁干扰抑制效果的影响。分析了共模电流频谱最大值、频谱平均值和频谱能量3种评估指标的特点与计算,并仿真研究了它们与传输时间差之间的关系。说明了共模电流频谱能量是一个理想的快速评估共模电流大小的指标。采用DSP建立了数字化并联有源共模EMI抑制的单相半桥逆变器物理实验模型,实验结果表明了共模电流频谱能量评估的有源并联共模电磁干扰抑制技术的正确性和有效性。

An active compensatory common mode EMI suppression technique with an external compensating circuit can be used at the conditions without two complementary common mode noise sources.In active parallel compensatory common mode EMI suppression,whether PWM signals transmission delay of compensating circuit and main bridge are the same or not will impact the effect of common mode current suppression.The three evaluation indexes of maximal spectrum,average spectrum and common mode spectrum energy were proposed to express the common mode noise level.The computational complexity of three evaluation indexes,and the relationship between three evaluation indexes and the delay time difference of two PWM signals were studied.Common mode spectrum energy is a monodromy index and can be considered as a good evaluation index of the common mode current.An experimental bench of single-phase half-bridge converter consists of digitalized active EMI suppression system based on DSP2812.Experimental results show that the parallel active common mode EMI suppression method based on spectrum energy evaluation index can suppress the common mode current noise level effectively.