共查询到17条相似文献,搜索用时 171 毫秒
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混沌频率调制降低开关电源传导EMI的研究 总被引:2,自引:0,他引:2
利用混沌频率调制技术从噪声产生源头上降低了开关电源传导电磁干扰。将蔡氏电路产生的混沌信号加入脉宽调制芯片,实现了混沌频率调制技术,使开关频率随混沌信号随机变化。简单分析了混沌频率调制降低EMI噪声的原理,并试制了一台混沌频率调制反激变换器电源样机。给出了开关管电流信号的频谱以及传导干扰测试的结果。实验结果表明,该技术能有效降低开关谐波峰值,使开关电源易于通过EMI测试,因此极具应用前景。 相似文献
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DC-DC开关变换器中混沌映射的不变分布求解及其应用 总被引:2,自引:0,他引:2
开关电源中存在的混沌现象可以用来提高电磁兼容(EMC),通过量化其混沌映射的不变分布可达到控制开关变换器电磁干扰(EMI)的目的.该文用简单的映射,描述了DC-DC开关变换器的混沌运行.并在此基础上,利用特征向量法对其混沌映射的不变分布进行了求解.仿真结果通过与混沌映射图和其分岔图的比较证明了该算法在求解DC-DC变换器混沌映射不变分布时的正确性.进而利用不变分布对系统输入、输出量的功率频谱密度、平均开关频率进行了估计,仿真和实验结果证明了估计的正确性.同时不变分布也为混沌电路的参数设计提供了有效途径. 相似文献
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DC-DC boost变换器是开关变换器中最常用、最基本的电路,其丰富的非线性行为为研究混沌现象提供了便利。该文以Boost变换器为研究对象,分别就参数控制和外加混沌信号控制两种行为进行仿真和实验研究。参数控制演示了Boost变换器由单周期通向混沌运行的演化过程;外加混沌信号控制时,为了得到较好的输出特性,该文加入了电流负反馈,实验基于DSP数字控制,分别研究了变频混沌控制与变幅混沌控制两种情况。以上实验结果都证明了混沌控制对于降低DC-DC开关变换器EMI十分有效。 相似文献
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开关变换器混沌PWM抑制EMI的机理和实验研究 总被引:1,自引:0,他引:1
在分析定频、周期扩频和混沌PWM频谱分布基础上,深入探讨了开关变换器混沌PWM抑制EMI的机理和特点。由此在1台AC-DC反激式变换器上进行了详尽的实验研究。分别进行的定频、周期扩频和混沌PWM实验结果表明,EMI的频谱分布取决于 PWM频谱分布,其中混沌PWM抑制EMI效果最好,虽然开关变换器输出电压的纹波频率随混沌扩频信号改变,但峰峰值基本不变。稳定性和效率测试显示,混沌PWM下开关变换器运行稳定,效率变化不大。该文较好地弥补了现有混沌PWM抑制EMI实验研究的不足。 相似文献
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利用频率调制技术从噪声产生源头上降低了开关电源传导电磁干扰.分析了频率调制降低EMI噪声的原理,并试制了一台周期频率调制反激变换器电源样机.比较了不同周期调制信号情况下开关管电流信号的频谱以及传导干扰测试的结果.实验结果表明,两种调制信号均能有效降低开关谐波峰值,但是三角波调制信号的扩频效果优于正弦波调制信号. 相似文献
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High frequency power semiconductor switches in power converters generate common-mode and differential-mode conduction noise in addition to radiated noise and cross-talk. Compliance with existing EMI standards is expected of switch mode power converters after fabrication. This article discusses a methodology to mitigate conducted noise effectively at the point of its origin using switching frequency modulation. The switching frequency modulation of DC-DC converters results in redistribution of harmonic energy and consequent suppression of peaks in the switching frequency harmonic components. This phenomenon is clearly visible in the experimental results. Therefore it is evident that the size of the EMI filter can be reduced significantly with the suppression of peaks of switching frequency harmonic components by spreading the spectrum appropriately as described in this article. Moreover, the switching frequency modulation can reduce radiated interference as it lowers the peaks of the harmonic components in current carrying conductors 相似文献
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Smart grid is an upgrade of the existing electricity infrastructure in which integration of non conventional energy sources are an integral part. This leads to the introduction of harmonics and increased switching losses in the system. Thus there is a need of loss less switching techniques for smart grid applications. Switched mode power supplies (SMPSs) are being extensively used in most power processes [1]. Developments were carried out centered on hard switched converters, where switching frequency is limited to 10 s of kHz [2]. The uses of soft switching techniques, [3], [4], [5], [6] zero voltage switching (ZVS) or zero current switching (ZCS), is an attempt to substantially reduce the switching losses and hence attain high efficiency at increased switching frequency. The soft-switching topologies belong to families namely resonant load converters [3], resonant switch converters [2], [4], resonant transition converters [5], [6], and most recently active clamped PWM converters [7], [8], [9]. The active clamp topology adds an active clamp network, consisting of a small auxiliary switch in series with a capacitance plus the associated drive circuitry to the traditional hard switch converters. The proposed paper basically deals with the design, modeling and simulation of a ZVS–PWM active clamp/reset forward converter having features like zero switching power losses, constant frequency and PWM operation, Soft-switching for all devices and Low voltage stresses on active devices due to clamping action. 相似文献
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电力电子变换器是频域内典型的单输入多输出系统,当输入某一频率的扰动信号时,变换器各状态变量既包含扰动频率分量,也包含与扰动相关的边带频率成分。在包含多个电力电子变换器的分布式供电系统中,一个变换器的开关纹波为另一个变换器的扰动,这种相互作用在某些情况下可能会导致母线电压差频振荡从而影响系统电能质量。然而,传统小信号模型以单个变换器的分析和设计为背景提出,主要用于描述变换器的低频特性。由于这些模型忽略了开关变换器的很多固有特性,因此不能准确地分析上述变换器之间在开关频率附近的相互作用。为此,提出了一种新的矩阵小信号模型并以Buck变换器为例进行了详细的说明。该模型可以准确地描述变换器的单输入多输出特性,并解释分布式供电系统中电力电子变换器相互作用导致的母线电压差频振荡现象。对比结果表明,传统的平均小信号模型和多频率小信号模型都是所提出的矩阵模型在不同情况下的近似。仿真和实验结果证明了所提模型的准确性和有效性。 相似文献