This works systematically presents various strategies to reduce both differential mode (DM) and common mode (CM) noise using a passive filter in a dc-fed motor drive. Following a standard approach a baseline filter is first designed to be used as reference to understand and compare the available filter topologies. Furthermore, it is used to analyze the grounding scheme of EMI filter and more specifically provide guidelines to ground single or multi stages filter. Finally, the baseline filter is investigated to recognize the possible solutions to minimize the size of the whole filter. It turns out that the CM choke and DM capacitors are the two main downsides to achieve a small EMI filter. Therefore, ideas are proposed to improve the CM choke by using other type of material such as nano crystalline core, different winding technique and new integrated method. A material comparison study is made between the common ferrite core and the nano crystalline core. Its advantages (high permeability and saturation flux density) and drawback (huge permeability drop) are analyzed thought multitudes of small and large signals tests. A novel integrated filter structure is addressed that maximizes the window area of the ferrite core and increases its leakage inductance by integrating both CM and DM inductances on the same core. Small- and large-signal experiments are conducted to verify the validity of the structure showing an effective size reduction and a good improvement at low and high frequencies. To conclude, a final filter version is proposed that reduce the volume of the baseline filter by three improve the performances in power tests. / Master of Science

No description available.

A method and apparatus are presented for generating suppressed carrier digital clock signals. These clock signals have the advantage of being broad band in nature and thus exhibiting lower power spectral density. Structures or systems utilizing such clock signals would be less likely to create electromagnetic noise of sufficient intensity to interfere with radio frequency systems and services. The apparatus requires only digital logic devices, rather than the analog devices required for frequency- or phase-modulated spread spectrum clock generators. The method provides the opportunity to synchronously demodulate the clock, thus restoring the original narrow band clock signal where required. The apparatus was implemented in a programmable gate array using 20 MHz and 33.33 MHz fundamental clocks. Measurements of the resulting electronic spectra and clock jitter are reported. / Graduation date: 1999

Conducted Electromagnetic Interference (EMI) is a major cause of concern in switchmode power supplies (SMPS) which commonly use standard pulsewidth modulation (PWM). In this thesis, Sigma-Delta (����) modulation is proposed as an alternative switching technique to reduce conducted EMI from SMPS. The result of using ���� modulation is a spread in the spectrum of the conducted emissions so that large concentrations of power at discrete frequencies are avoided. Experimental time-domain waveforms and spectra of the switching function from first-order and second-order ���� modulators are presented to prove the viability of the scheme in EMI mitigation. These modulators are then applied to an off-the-shelf computer power supply and experimental results using FCC-specified methods show a reduction of roughly 5-10dB in EMI emissions over standard PWM modulators. / Graduation date: 1999

The suitable frequency range of electromagnetic interference (EMI) filters is always limited by the parasitic inductances and capacitances of components. The main object in this research is to develop design rules for lowering parasitic effects due to parasitic inductance of capacitor by using three coupled inductors. In this thesis, the properties and equivalent circuit of three coupled inductors are discussed first. It is found that two negative series inductances can be simultaneously obtained at two ports when the parameters of three coupled inductors are appropriately selected. These two negative inductances can be used to lower parasitic effect of capacitors. In other words, the EMI filter performance can be effectively improved by using this technology. Furthermore, method to completely reduce parasitic inductances is derived. The common mode insertion loss of this design is able to achieve at the rate of -60 dB/decade at high-frequency. For differential mode the insertion loss is even higher to the rate of -100 dB/decade.

In This Thesis , We primarily introduce some results with suppression of ground bounce noise in high-speed PCB by the formal researchers and summarize their advantages and weaknesses .In the next section .we explain why the EBG (Electromagnetic Band Gap ) design structure is from PBG (Photonic Band Gap ) concept in optical research field and that its principle can suppress GBN . We also summarize their advantages and weaknesses .In the following part, we define five parameters of EBG design structure to find the optimal solution by HFSS simulation method .The optimal solution can enlarge the bandwidth of suppression of GBN to 5.40GHz.We prove the accuracy of HFSS simulation method by actual measurement . When the EBG basic cell gradually compact from n=9.their characteristics are according to 1.central frequency towards high frequency 2.bandwidth of suppression of GBN is more broadband 3. forbiddance band depth becomes wider. Finally we oppose some new EBG design structures to solve some problems of old EBG design structure .These new EBG design structures can enhance signal integrity (SI) and law frequency response. Include three items 1.Meander design structure 2. Buddha design structure 3. Budder design structure .We also prove the accuracy of HFSS simulation method by actual measurement.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 66-67). Also available via the Internet.

Thesis (Ph.D.)--Hong Kong Polytechnic University, 2007. / Adviser: Yaping Du. Includes bibliographical references.

Thesis (M.S.)--Ohio University, November, 2004. / Includes bibliographical references (p. 76-77)