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

Common mode (CM) electromagnetic interference (EMI) can compromise electronics systems, interfere with communication systems, and degrade mechanical systems. Multiple inverters can also generate excessive CM EMI that often exceeds individual inverter EMI standards. Due to their weight, volume, cost, and suboptimal performance, active and passive filters and chokes are inefficient as EMI mitigation options. By utilizing frequency modulation (FM) or spread spectrum frequency modulation (SSFM), EMI energy is dispersed. In spite of not requiring expensive, bulky, and heavy filters, these techniques produce significant ripples in output voltages and currents. This dissertation uses enhanced sinusoidal frequency modulation to reduce CM EMI output, bridging the gap between existing EMI solutions: 1) To reduce performance degradation, a state-of-the-art FM topology with duty cycle correction is proposed. Due to large output voltage and current ripples, FM techniques have limited bandwidth and utilization. Duty cycle correction allows for a wider FM bandwidth with better EMI attenuation while minimizing output ripple performance tradeoffs. 2) CM EMI accumulation is a growing concern in power converter networks. Even if each converter complies with EMI regulations, multiple converters may produce CM EMI that exceeds EMI standards in parallel operation. A novel algorithm is proposed to suppress CM EMI in a large-scale network using SFMCW frequency indexing. The algorithm minimizes aggregate EMI by minimizing switching frequency overlap among converters. 3) CM EMI noise in complex systems presents a critical challenge. Since standalone converters are rarely affected by CM EMI phases, they were usually overlooked in most studies until recently. CM currents generated by multiple converters can be added or subtracted based on phase differences. The CM currents in large systems with multiple inverters are distributed randomly, resulting in multiple peaks and nulls. In order to reduce network EMI, a sinusoidal FM technique with phase shift is proposed to attenuate CM EMI on multiple parallel inverters. This method overcomes conventional methods' critical disadvantages, including the need for accurate component characterization and modeling, and reducing CM EMI without additional passive components.

No description available.

According to the regulation announced by Bureau of Standard, Metrology & Inspection (BSMI) of Ministry of Economic Affairs (MOEA), lamp fixtures must follow safety and electromagnetic compatibility (EMC) standards. However, the self-ballasted fluorescent lamps in the fixture should only be approved by the safety test but not regulated by EMC standard. Obviously, fixtures without light bulbs do not generate any electromagnetic noise. Electromagnetic interference (EMI) comes from the fluorescent light bulb embedded with an electronic ballast which included an inverter with high-frequency switching. A variety of tests demonstrate evidently that a fixture with different self-ballasted compact fluorescent lamps may possibly violate the EMC standard, revealing the absurdity of the regulation. In fact, self-ballasted fluorescent lamps use mostly self-excited electronic ballasts. The operating frequencies for this kind of electronic ballasts can not be precisely controlled due to the influence of many factors. They are not operated at a specified frequency but in a frequency range. This means that the generated EMI spectrum is hardly predicted, especially when a fixture is fitted by light bulbs from several manufacturers. This research inducts the worst cases from numerous measurements on a fixture with 1 piece to 8 pieces of light bulbs, and then attempts to design an EMI filter for all cases. As a result, a lamp fixture with the filter at the line input terminal can suppress the EMI. As long as the consumer buys the lamp fixture which are installed with the EMI filter together with any bulb in use, EMI noise can comply with standard limits.

In this thesis, an alternative solution for designing power line conductive electromagnetic interference (EMI) filter by using the consecutive orthogonal array method is proposed. The circuit parameters of EMI filters to be determined are assigned as the control variables in the orthogonal arrays, and the average effects corresponding to each control variable are calculated from the measured results. In accordance with the inferential rules, the average effects are used as the observational indices to adjust the levels of the control variables of the subsequent orthogonal array. Through manipulating consecutive orthogonal arrays step by step, the applicable ranges of circuit parameters are approached with desired output performances. Finally, the component values of EMI filters with minimum size can be found. The design procedure and the inferential rules are described by illustrative examples for a single-stage high-power-factor converter.

Objective. To study whether an electrosurgery device interferes with the operation of a low-power spread-spectrum wireless network adapter. Methods. Nonrandomized, unblinded trials with controls, conducted in the corridor of our institution's operating suite using two portable computers equipped with RoamAbout omnidirectional 250 mW spread-spectrum 928 MHz wireless network adapters. To simulate high power electrosurgery interference, a 100-watt continuous electrocoagulation arc was maintained five feet from the receiving adapter, while device reported signal to noise values were measured at 150 feet and 400 feet distance between the wireless-networked computers. At 150 feet range, and with continuous 100-watt electrocoagulation arc five feet from one computer, error-corrected local area net throughput was measured by sending and receiving a large file multiple times. Results. The reported signal to noise (N = 50) decreased with electrocoagulation from 36.42 ± 3.47 (control) to 31.85 ± 3.64 (electrocoagulation) (p < 0.001) at 400 feet inter-adapter distance, and from 64.53 ± 1.43 (control) to 60.12 ± 3.77 (electrocoagulation) (p < 0.001) at 150 feet inter-adapter distance. There was no statistically significant change in network throughput (average 93 kbyte/ second) at 150 feet inter-adapter distance, either transmitting or receiving during continuous 100 Watt electrocoagulation arc. Conclusions. The manufacturer indicates "acceptable" performance will be obtained with signal to noise values as low as 20. In view of this, while electrocoagulation affects this spread spectrum network adapter, the effects are small even at 400 feet. At a distance of 150 feet, no discernible effect on network communications was found, suggesting that if other obstructions are minimal, within a wide range on one floor of an operating suite, network communications may be maintained using the technology of this wireless spread spectrum network adapter. The impact of such adapters on cardiac pacemakers should be studied. Wireless spread spectrum network adapters are an attractive technology for mobile computer communications in the operating room.

This dissertation presents the systematic analysis and the critical assessment of the AC side soft-switching inverters in electric vehicle (EV) applications. Although numerous soft-switching inverter techniques were claimed to improve the inverter performance, compared with the conventional hard-switching inverter, there is the lack of comprehensive investigations of analyzing and evaluating the performance of soft-switching inverters. Starting with an efficiency comparison of a variety of the soft-switching inverters using analytical calculation, the dissertation first reveals the effects of the auxiliary circuit's operation and control on the loss reduction. Three types of soft-switching inverters realizing the zero-voltage-transition (ZVT) or zero-current-transition (ZCT) operation are identified to achieve high efficiency operation. Then one hard-switching inverter and the chosen soft-switching inverters are designed and implemented with the 55 kW power rating for the small duty EV application. The experimental evaluations on the dynamometer provide the accurate description of the performance of the soft-switching inverters in terms of the loss reductions, the electromagnetic interference (EMI) noise, the total harmonic distortion (THD) and the control complexity. An analysis of the harmonic distortion caused by short pulses is presented and a space vector modulation scheme is proposed to alleviate the effect. To effectively analyze the soft-switching inverters' performance, a simulation based electrical modeling methodology is developed. Not only it extends the EMI noise analysis to the higher frequency region, but also predicts the stress and the switching losses accurately. Three major modeling tasks are accomplished. First, to address the issues of complicated existing scheme, a new parameter extraction scheme is proposed to establish the physics-based IGBT model. Second, the impedance based measurement method is developed to derive the internal parasitic parameters of the half-bridge modules. Third, the finite element analysis software is used to develop the model for the laminated bus bar including the coupling effects of different phases. Experimental results from the single-leg operation and the three-phase inverter operation verify the effectiveness of the presented systematic electrical modeling approach. With the analytical tools verified by the testing results, the performance analysis is further extended to different power ratings and different bus voltage designs. / Ph. D.

This dissertation is to focus on the development of modeling and simulation methodology to predict conductive electromagnetic interference (EMI) for high power converters. Conventionally, the EMI prediction relies on the Fast Fourier Transformation (FFT) method with the time-domain simulation result that requires long hours of simulation and a large amount of data. The proposed approach is to use the frequency-domain analysis technique that computes the EMI spectrum directly by decomposing noise sources and their propagation paths. This method not only largely reduces the computational effort, but also provides the insightful information about the critical components of the EMI generation and distribution. The study was first applied to a dc/dc chopper circuit by deriving the high frequency equivalent circuit model for differential mode (DM) and common mode (CM) EMIs. The noise source was modeled as the trapezoidal current and voltage pulses. The noise cut-off frequency was identified as a function of the rise time and fall time of the trapezoidal waves. The noise propagation path was modeled as lumped parasitic inductors and capacitors, and additional noise cut-off frequency was identified as the function of parasitic components. . Using the noise source and path models, the proposed method effectively predicts the EMI performance, and the results were verified with the hardware experiments. With the well-proven EMI prediction methodology with a dc/dc chopper, the method was then extended to the prediction of DM and CM EMIs of three-phase inverters under complex pulse width modulation (PWM) patterns. The inverter noise source requires the double Fourier integral technique because its switching cycle and the fundamental cycle are in two different time scales. The noise path requires parasitic parameter extraction through finite element analysis for complex-structured power bus bar and printed circuit layout. After inverter noise source and path are identified, the effects of different modulation schemes on EMI spectrum are evaluated through the proposed frequency-domain analysis technique and verified by hardware experiment. The results, again, demonstrate that the proposed frequency-domain analysis technique is valid and is considered a promising approach to effectively predicting the EMI spectrum up to tens of MHz range. / Ph. D.

In recent years, advancements in the field of wireless communication have led to more innovative consumer products at reduced cost. Over the next 2 to 5 years, short-range wireless devices such as Bluetooth and Wireless Local Area Networks (WLANs) are expected to become widespread throughout hospital environments for various applications. Consequently the medical community views wireless applications as ineludible and necessary. However, currently there exist regulations on the use of wireless devices in hospitals, and with the ever increasing wireless personal applications, there will be more unconscious wireless devices entering and operating in hospitals. It is feared that these wireless devices may cause electromagnetic interference that could alter the operation of medical equipment and negatively impact patient care. Additionally, unintentional electromagnetic radiation from medical equipment may have a detrimental effect on the quality of service (QoS) of these short-range wireless devices. Unfortunately, little is known about the impact of these short-range wireless devices on medical equipment and in turn the interference caused to these wireless devices by the hospital environment. The objective of this research was to design and develop an automated software reconfigurable measurement system (PRISM) to characterize the electromagnetic environment (EME) in hospitals. The portable measurement system has the flexibility to characterize a wide range of non-contiguous frequency bands and can be monitored from a remote location via the internet. In this work electromagnetic interference (EMI) measurements in the 2.4 GHz ISM band were performed in two hospitals. These measurements are considered to be very first effort to analyze the 2.4 GHz ISM band in hospitals. Though the recorded EMI levels were well within the immunity level recommended by the FDA, it can be expected that Bluetooth devices will undergo a throughput reduction in the presence of major interferers such as WLANs and microwave ovens. A Bluetooth throughput simulator using semi-analytic results was developed as part of this work. PRISM and the Bluetooth simulator were used to predict the throughput for six Bluetooth Asynchronous Connectionless (ACL) transmissions as a function of piconet size and interferer distance. / Master of Science

Exploring RF models for an integrated power electronics module (IPEM) is crucial to analyzing and predicting its EMI performance. This thesis deals with the parasitics extraction approach for an active IPEM in a frequency range of 1MHz through 30MHz. Based on the classic electromagnetic field theory, the calculating equations of DC and AC parameters for a 3D conducting structure are derived. The influence of skin effect and proximity effect on AC resistances and inductances is also investigated at high frequencies. To investigate RF models and EMI performance of the IPEM, a 1kW 1MHz series resonant DC-DC converter (SRC) is designed and fabricated in this work. For extracting the stray parameters of the built IPEM, two main software simulation tools ¡ª Maxwell Quick 3D Parameter Extractor (Maxwell Q3D) and Maxwell 3D Field Simulator (Maxwell 3D), prevailing electromagnetic simulation products from Ansoft Corporation, are introduced in this study. By trading off between the numerical accuracy and computational economy (CPU time and consumption of memory size), Maxwell Q3D is chosen in this work to extract the parameters for the full bridge IPEM structure. The step-by-step procedure of using Maxwell Q3D is presented from pre-processing the 3D IPEM structure to post-processing the solutions, and exporting equivalent circuit for PSpice simulations as well. RF modeling of power MOSFETs is briefly introduced. In order to verify extracted parameters, in-circuit impedance measurements for the IPEM using Agilent 4294A Impedance Analyzer together with Agilent 42941A probe are then followed. Measured results basically verify the extracted data, while the discrepancy between measured results and simulated results is also analyzed. / Master of Science