基于IGBT的Buck电路共模EMI特性研究

针对IGBT的高du/dt给电力电子装置带来的严重共模电磁干扰(common-mode electromagnetic interfer-ence,CM EMI)问题,深入分析了Buck电路的CM EMI,首先提出了Buck电路的共模电流等效电路,分析了噪声源频谱及其与输入电压、开关频率、开关速度等运行参量间的关系。为弥补理论分析的不足,以实验手段研究了采用IGBT的Buck电路的输入电压、开关频率、负载电流、占空比、驱动电阻等参量对共模EMI的影响。研究表明:共模EMI与占空比无关而与输入电压和开关频率成正比关系。驱动电阻和负载电流均影响开关速度,因而对共模EMI也有影响,其中负载电流的影响与开关器件的开关特性有很大关系。

Common-Mode EMI Behavior of an IGBT Buck Converter

The common-mode electromagnetic interference(CM EMI) of Buck converters is analyzed in detail in or-der to get the relationship between the CM EMI and key operation parameters.A CM equivalent circuit of the con-verter is proposed,and the relationship between spectrum of the CM noise source and operation parameters such as input voltage,switching frequency,switching speed are analyzed.To verify and supplement the theoretical analysis,experiments are carried out on an IGBT Buck converter to test the actual influences of input voltage,switching fre-quency,duty ratio,load current and driving resistance on the CM EMI.The results indicate that CM EMI is not af-fected by the duty ratio and it is proportional to the input voltage and switching frequency.Both the load current and gate drive resistance can influence the CM EMI since they can change the switching speed.The influence of load cur-rent is closely related to characteristics of switching devices.