改善随机调制抑制EMI性能的研究  

Research on improvement of EMI suppression performance of random modulation

作　　者：张鑫 王斌[1] 李达 陈赟[1] ZHANG Xin;WANG Bin;LI Da;CHEN Yun(School of Information Science and Engineering,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]武汉科技大学信息科学与工程学院,湖北武汉430081

出　　处：《现代电子技术》2020年第11期140-143,147,共5页Modern Electronics Technique

基　　金：湖北省过程控制与先进装备制造协同创新中心项目(HX2016A1005);2018国家级和省级大学生创新创业训练项目(201810488064)。

摘　　要：随机PWM调制技术可有效解决电力系统中的电磁干扰(EMI)问题,被广泛应用于控制开关频率达到10 kHz及以上的高频开关器件中,然而,在相对较低开关频率下(如2 kHz),随机调制技术抑制EMI效果并不理想,甚至会使输出信号发生畸变。通过对随机调制扩频原理与随机开关函数及其傅里叶变换的研究,分析了低频下输出信号发生畸变的原因,结合输出信号滤波电路的传递函数,对LC参数值进行合理调整。结果表明,在相对低频下应用随机调制会增加输出信号的低频谐波,适当调整LC参数可更好地解决谐波问题,使随机调制具有更宽的开关频率应用范围,改善其抑制EMI的性能,并且随着开关频率的逐渐增大,随机调制抑制EMI的效果越来越好。The random PWM modulation technology can effectively deal with electromagnetic interference(EMI) in the power system. Therefore,it is widely used in high-frequency switching devices with switching frequency up to 10 kHz and above. However,at relatively low switching frequency(e. g. 2 kHz),the effect of EMI suppression by random modulation technology is not ideal,and distortion may even occur to the output signal.,The reason of output signal distortion at low frequency is analyzed on the basis of the research of random modulation spread spectrum principle,random switching function and Fourier transform. In combination with the transfer function of output signal filtering circuit,the parameters of LC are adjusted reasonably. The results show that the application of random modulation at relatively low frequencies will increase the lowfrequency harmonics of the output signal,and proper adjustment of the parameters of LC can better deal with the harmonic problem and the random modulation can be applied at a wider range of switching frequency,which improves EMI suppression performance of random modulation. In addition,with the increase of switching frequency,the effect of EMI suppression by random modulation is getting better.

关 键 词：随机调制性能改善 EMI抑制 随机调制扩频原理 随机开关函数 傅里叶变换 LC参数调整 

分 类 号：TN76-34[电子电信—电路与系统] TM571.2[电气工程—电器]