直流电网挂接单个三相逆变器的差模传导干扰

Research on Differential Mode Conducted EMI in DC Power Supply with a Three Phase Inverter

为研究挂接单个三相逆变器的直流电网的差模传导干扰,分析了干扰源和耦合路径并建立了差模传导干扰的频域等效电路,在10 kHz^30 MHz频率范围内分析了实验测得的相关器件参数。结果表明计算得到的差模传导干扰频谱和实测频谱一致,证明提出的差模传导干扰频域等效电路及其分析的正确性。研究阻性和感性负载变化下的差模传导干扰所得结论在实测和计算下基本一致。

This paper researches differential mode conducted electromagnetic interference （DM EMI） in DC power supply with a three-phase inverter. The DM EMI excitation source generated by power electronic switches and coupling paths is analyzed. Based on experimental and theoretical analysis, the conducted EMI of DC power supply with a typical inverter （DC/AC） is studied systematically. The study shows that the bigger conducted EMI are presented at the integral times of its PWM controlling frequency and the conducted EMI decreases with the increase of frequency. A new DM EMI frequency-domain equivalent circuit is established in the frequency bandwidth of 10 kHz-30 MHz. By the experiment, the parameters of component in this circuit is obtained and the DM EMI between 10 kHz to 30MHz is studied. Compared the calculated DM EMI spectra in 10-150 kHz, 0. 15-1 MHz and 1-30 MHz with those obtained in experiment, the established model is validity. Furthermore, the rule of DM EMI with the change of the resistance and inductance loads is researched. The study shows that it changes with resistance loads and does not change with inductance loads basically. Under the condition of resistance load, the DM EMI boosts up with the load drop, especially in low frequency bandwidth. In high frequency bandwidth, the effect of change of the resistance load on the DM EMI is diminished, the change of the DM EMI is not obvious. When the inductance load changes, the DM EMI does not change obviously because of the capacitance. The conclusion is agreement with the analysis of EMI mechanism and coupling paths.