A typical electronic communication system, such as GPS receiver, unmanned aerial vehicle＇s （UAV＇s） data link, and radar, faces multi-dimensional and complicated electromagnetic interference in operating environmen...A typical electronic communication system, such as GPS receiver, unmanned aerial vehicle＇s （UAV＇s） data link, and radar, faces multi-dimensional and complicated electromagnetic interference in operating environment. To measure the anti- interference performance of the electronic communication system in the complicated electromagnetic interference environment, a method of multi-dimensional and complicated electromagnetic interference hardware-in-the-loop simulation in an anechoic room is proposed. It takes into account the characteristics of interference signals and the positional relationship among interference, the receiver and the transmitter of the electronic communication system. It uses the grey relational method and the angular domain mapping error correction method to control the relevant parameters, the microwave switch and so on, thus achieving the approximately actual mapping of the outdoor multi-dimensional and complicated electromagnetic interference in the anechoic room. To verify the effectiveness of this method, the multi-dimensional and complicated electromagnetic interference of the UAV＇s data link is simulated as an example. The results show that the degree of correlation between the calculated signal to interference ratio of the data link receiver in the actual scene and the measured signal to interference ratio of the data link receiver simulated with this method in the anechoic room is 0.968 1, proving that the method is effective for simulating the complicated electromagnetic interference.展开更多
针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导...针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导噪声模型。同时,还设计了一种串扰扼流圈以有效抑制因串扰引起的传导EMI噪声。实验结果表明,采用文中方法,某型商用车载导航和刷卡器能够通过GB 9254标准测试,噪声抑制效果分别可达44.8和29.28 dB V,从而验证了方法的有效性。展开更多
Developing lightweight and flexible thin films for electromagnetic interference(EMI)shielding is of great importance.Porous thin films of reduced graphene oxide containing SiC whiskers(SiC@RGO)for EMI shielding were p...Developing lightweight and flexible thin films for electromagnetic interference(EMI)shielding is of great importance.Porous thin films of reduced graphene oxide containing SiC whiskers(SiC@RGO)for EMI shielding were prepared by a two-step reduction of graphene oxide(GO),in which the two steps were chemical reduction by HI and the solid phase microwave irradiation.A significant increase of the film thickness from around 20 to 200μm was achieved due to the formation of a porous structure by gases released during the 3 s of solid phase microwave irradiation.The total shielding effectiveness(SET)and the reflective SE(SE_(R))of the SiC@RGO porous thin films depended on the GO/SiC mass ratio.The highest SET achieved was 35.6 dB while the SE_(R) was only 2.8 dB,when the GO/SiC mass ratio was 4∶1.The addition of SiC whiskers was critical for the multi-reflection,interfacial po-larization and dielectric attenuation of EM waves.A multilayer film with a gradient change of SE values was constructed using SiC@RGO porous films and multi-walled carbon nanotubes buckypapers.The highest SET of the multilayer films reached 75.1 dB with a SE_(R) of 2.7 dB for a film thickness of about 1.5 mm.These porous SiC@RGO thin films should find use in multilayer or sand-wich structures for EMI absorption in packaging or lining.展开更多
以Si C-MOSFET和Si-IGBT器件混合型三电平有源中点钳位3L-ANPC(three-level active neutral point clamped)变流器拓扑为研究对象,对3种脉宽调制方式下的共模电磁干扰CM EMI(common-mode electromagnetic interference)特性进行研究。...以Si C-MOSFET和Si-IGBT器件混合型三电平有源中点钳位3L-ANPC(three-level active neutral point clamped)变流器拓扑为研究对象,对3种脉宽调制方式下的共模电磁干扰CM EMI(common-mode electromagnetic interference)特性进行研究。首先介绍了3L-ANPC变流器拓扑结构中Si C-MOSFET和Si-IGBT器件的2种组合模式及3种调制方式,然后对3L-ANPC变流器拓扑共模噪声传输机理进行分析,基于分析建立了包含寄生参数和噪声源的EMI模型,并推导出每种调制方式下传导路径的阻抗表达式,得到了共模传导路径阻抗特性曲线。最终通过实验验证了3种调制方式下器件混合型3L-ANPC变流器拓扑共模噪声的分析结论。展开更多
宽禁带WBG(wide band gap)半导体电力电子器件由于其开关频率高、开关速度快、寄生参数大等特点从噪声源头引发了越来越严峻的电磁干扰问题。然而,传统的噪声源研究主要集中在30 MHz传导频段以内,如何评估噪声源在30~300 MHz较高频率范...宽禁带WBG(wide band gap)半导体电力电子器件由于其开关频率高、开关速度快、寄生参数大等特点从噪声源头引发了越来越严峻的电磁干扰问题。然而,传统的噪声源研究主要集中在30 MHz传导频段以内,如何评估噪声源在30~300 MHz较高频率范围内的辐射频段产生的影响仍存在不确定性,因此提出1种改进的WBG器件电磁干扰分析模型,与传统的非对称梯形波电磁干扰模型相比,首次详细考虑了WBG器件的结电容和跨导体的非线性特性,评估了非线性参数对辐射频段噪声的影响,并进一步提出该模型在辐射频段噪声源抑制中的应用。仿真结果验证了所提计算方法的准确性,基于SiC器件的硬件测试结果与理论分析相吻合。展开更多
针对三电平中点钳位型NPC(neutral point clamped)变换器开关频率提高导致变换器电流纹波与电磁干扰噪声增大的问题,提出1种基于电流纹波预测的变开关频率调制策略,以降低三电平NPC变换器电流纹波、谐波噪声及电磁干扰噪声。根据电流纹...针对三电平中点钳位型NPC(neutral point clamped)变换器开关频率提高导致变换器电流纹波与电磁干扰噪声增大的问题,提出1种基于电流纹波预测的变开关频率调制策略,以降低三电平NPC变换器电流纹波、谐波噪声及电磁干扰噪声。根据电流纹波的要求计算出开关周期与采样周期并合成最新的开关周期,形成反馈,从而实现变频调制。使随机周期分布在期望周期的周围,从而使变换器的谐波噪声和电磁噪声更加均匀地分布在较宽的频段上,以达到减少变换器电磁噪声的目的,并改善输出电感上的电流纹波。相关仿真及实验结果表明,相较于传统的调制策略,所提调制策略共模噪声降低了约20 dB/μV,差模噪声降低了约10 dB/μV,其输出电感电流纹波幅值也有相应的减少。展开更多
基金supported by the National Natural Science Foundation of China(61571368)the certain Ministry Foundation(2014607B006)
文摘A typical electronic communication system, such as GPS receiver, unmanned aerial vehicle＇s （UAV＇s） data link, and radar, faces multi-dimensional and complicated electromagnetic interference in operating environment. To measure the anti- interference performance of the electronic communication system in the complicated electromagnetic interference environment, a method of multi-dimensional and complicated electromagnetic interference hardware-in-the-loop simulation in an anechoic room is proposed. It takes into account the characteristics of interference signals and the positional relationship among interference, the receiver and the transmitter of the electronic communication system. It uses the grey relational method and the angular domain mapping error correction method to control the relevant parameters, the microwave switch and so on, thus achieving the approximately actual mapping of the outdoor multi-dimensional and complicated electromagnetic interference in the anechoic room. To verify the effectiveness of this method, the multi-dimensional and complicated electromagnetic interference of the UAV＇s data link is simulated as an example. The results show that the degree of correlation between the calculated signal to interference ratio of the data link receiver in the actual scene and the measured signal to interference ratio of the data link receiver simulated with this method in the anechoic room is 0.968 1, proving that the method is effective for simulating the complicated electromagnetic interference.
文摘针对复杂电子系统产生的传导EMI噪声,该文分别利用电偶极子模型、电路分析方法和散射参数方法提出了3种传导EMI噪声理论模型及其等效电路,包括因串扰引起的传导噪声模型,因接地不良引起的传导噪声模型,以及因PCB线缆阻抗失配引起的传导噪声模型。同时,还设计了一种串扰扼流圈以有效抑制因串扰引起的传导EMI噪声。实验结果表明,采用文中方法,某型商用车载导航和刷卡器能够通过GB 9254标准测试,噪声抑制效果分别可达44.8和29.28 dB V,从而验证了方法的有效性。
文摘Developing lightweight and flexible thin films for electromagnetic interference(EMI)shielding is of great importance.Porous thin films of reduced graphene oxide containing SiC whiskers(SiC@RGO)for EMI shielding were prepared by a two-step reduction of graphene oxide(GO),in which the two steps were chemical reduction by HI and the solid phase microwave irradiation.A significant increase of the film thickness from around 20 to 200μm was achieved due to the formation of a porous structure by gases released during the 3 s of solid phase microwave irradiation.The total shielding effectiveness(SET)and the reflective SE(SE_(R))of the SiC@RGO porous thin films depended on the GO/SiC mass ratio.The highest SET achieved was 35.6 dB while the SE_(R) was only 2.8 dB,when the GO/SiC mass ratio was 4∶1.The addition of SiC whiskers was critical for the multi-reflection,interfacial po-larization and dielectric attenuation of EM waves.A multilayer film with a gradient change of SE values was constructed using SiC@RGO porous films and multi-walled carbon nanotubes buckypapers.The highest SET of the multilayer films reached 75.1 dB with a SE_(R) of 2.7 dB for a film thickness of about 1.5 mm.These porous SiC@RGO thin films should find use in multilayer or sand-wich structures for EMI absorption in packaging or lining.
文摘以Si C-MOSFET和Si-IGBT器件混合型三电平有源中点钳位3L-ANPC(three-level active neutral point clamped)变流器拓扑为研究对象,对3种脉宽调制方式下的共模电磁干扰CM EMI(common-mode electromagnetic interference)特性进行研究。首先介绍了3L-ANPC变流器拓扑结构中Si C-MOSFET和Si-IGBT器件的2种组合模式及3种调制方式,然后对3L-ANPC变流器拓扑共模噪声传输机理进行分析,基于分析建立了包含寄生参数和噪声源的EMI模型,并推导出每种调制方式下传导路径的阻抗表达式,得到了共模传导路径阻抗特性曲线。最终通过实验验证了3种调制方式下器件混合型3L-ANPC变流器拓扑共模噪声的分析结论。
文摘宽禁带WBG(wide band gap)半导体电力电子器件由于其开关频率高、开关速度快、寄生参数大等特点从噪声源头引发了越来越严峻的电磁干扰问题。然而,传统的噪声源研究主要集中在30 MHz传导频段以内,如何评估噪声源在30~300 MHz较高频率范围内的辐射频段产生的影响仍存在不确定性,因此提出1种改进的WBG器件电磁干扰分析模型,与传统的非对称梯形波电磁干扰模型相比,首次详细考虑了WBG器件的结电容和跨导体的非线性特性,评估了非线性参数对辐射频段噪声的影响,并进一步提出该模型在辐射频段噪声源抑制中的应用。仿真结果验证了所提计算方法的准确性,基于SiC器件的硬件测试结果与理论分析相吻合。
文摘针对三电平中点钳位型NPC(neutral point clamped)变换器开关频率提高导致变换器电流纹波与电磁干扰噪声增大的问题,提出1种基于电流纹波预测的变开关频率调制策略,以降低三电平NPC变换器电流纹波、谐波噪声及电磁干扰噪声。根据电流纹波的要求计算出开关周期与采样周期并合成最新的开关周期,形成反馈,从而实现变频调制。使随机周期分布在期望周期的周围,从而使变换器的谐波噪声和电磁噪声更加均匀地分布在较宽的频段上,以达到减少变换器电磁噪声的目的,并改善输出电感上的电流纹波。相关仿真及实验结果表明,相较于传统的调制策略,所提调制策略共模噪声降低了约20 dB/μV,差模噪声降低了约10 dB/μV,其输出电感电流纹波幅值也有相应的减少。
