开关电源中印刷电路板寄生参数对传导电磁干扰影响的研究

PARASITIC PARAMETERS OF CIRCUIT TRACES AND THEIR EFFECTS ON CONDUCTED EMI IN SWITCHING POWER SUPPLY

研究了开关电源中印刷电路板寄生参数及功率器件瞬态特性产生的传导电磁干扰现象。针对半桥型DC/DC变换器电路拓扑,使用Cadence软件中的SpecctraQuest工具提取了印刷电路板上主要印制线的寄生参数,通过噪声等效电路模型的仿真计算,表明高频情况下印刷电路板寄生参数对传导电磁干扰有较大的影响。最后,对两台原理样机(仅 印刷电路板布线不同)的工作波形进行了实验测试,实验结果表明功率器件开通和关断瞬间形成的电压和电流突变而造成的高频振荡现象与电路杂散参数有关。最后,对两台原理样机(仅印刷电路板布线不同)的工作波形进行了实验测试,实验结果表明功率器件开通和关断瞬间形成的电压和电流突变而造成的高频振荡现象与电路杂散参数有关,说明在不改变原理电路的条件下,通过合理设计印刷电路板布线可以有效提高开关电源的EMC性能。

Conducting Electromagnetic Interference (EMI) in switching power supplies caused by parasitic parameters and transient characteristic of power electronic elements is studied in this paper. Traditionally, the EMI in switching power supplies is dealt with cut-and-try approaches. Here, an improvement of the approach has been made to minimize the cut-and-try design process. The main parasitic parameters (resistance,inductance,and capacitance) of printed circuit board (PCB) are characterized by using the software tool Cadence and the simulation results reveal that the conducting EMI is effected by parasitic parameters heavily. Finally, two half-bridge DC/DC converter prototypes that are different only in traces distribution are completed and tested. The experimental results show that high-frequency oscillation caused by transient voltage and current is related with the parasitic parameters and prove that the analysis approach is better for EMC predictions of switching converters.