应用于三相PWM逆变器的EMI滤波器元件不对称度研究

Investigation of the Asymmetry of EMI Filter Components Applied to Three-phase PWM Inverter

三相电磁干扰滤波器的性能会由于差、共模噪声的转换而降低,文中揭示脉宽调制(pulse width modulation,PWM)逆变器中因滤波元件参数不对称而引起的噪声转换机理。通过分别对不平衡电容和电感开展噪声转换的行为模型研究,并结合PWM策略的差、共模谐波分布规律研究,提出评估差、共模噪声转换程度的方法。此外,以常见的LC滤波拓扑为例进行分析与实验验证,结合商用滤波元件公差参数开展讨论与选型建议,发现在LC滤波拓扑中电容的公差参数相较于电感而言更为敏感,实验结果验证了所提理论分析的正确性。

The performance of a three-phase electromagnetic interference(EMI) filter will be degraded due to noise mode conversions. This paper revealed the noise conversion mechanism caused by the asymmetry of the filter components in the pulse width modulation(PWM) inverter.Moreover, through the study of the noise conversion behavior model of unbalanced capacitors and inductors, combined with the study of the difference mode and common mode harmonic distribution of PWM, this paper proposed a method to evaluate the degree of noise conversions, and took the LC filter topology as an example for analysis and experimental verification. Based on the commercial filter components tolerance parameters, this paper proposed the selection suggestions. It can be found that the tolerances of the capacitors in the LC filter are more sensitive than the inductors.The experimental results fit the analysis very well.