No description available.

With the advent of wide bandgap (WBG) semiconductor devices, the electromagnetic interference (EMI) emissions are more pronounced due to high slew rates in the form of high dv/dt and high di/dt at higher switching frequencies compared to the traditional silicon technology. To comply with the stringent conducted emission requirements, EMI filters are adopted to attenuate the high frequency common mode (CM) and differential mode (DM) noise through the propagation path. However, self and mutual parasitic components are known to degrade the EMI filter performance. While parasitic cancellation techniques have been discussed at length in prior literature, most of them have focused mainly on single phase applications. As such this work focuses on extending the preexisting concepts to three-phase systems. Novel component placement, winding strategy as well as shielding and grounding techniques were developed to desensitize the influence of the parasitic effects on a three-phase multi-stage filter. The effectiveness of the three-phase filter structure employing the proposed methodologies has been validated via noise measurements at the line impedance stabilization network (LISN) in a 15kW rated motor drive system. Consequently, general design guidelines have been formulated for filter topologies with different inductor and capacitor form-factors. / Master of Science / The adoption of wide bandgap (WBG) semiconductor devices, such as Silicon Carbide (SiC) or Gallium Nitride (GaN) transistors, improves the power density with higher slew rates and switching frequencies compared to the traditional Silicon technology. However, the high switching speeds and high frequencies have generated higher electromagnetic interference (EMI) noise in the surroundings. To comply with the conducted emission requirements at the grid terminal, EMI filter is mandatory to attenuate the high frequency EMI noise that flows into grid. However, near field and the effect of parasitic components are known to degrade the filter performance at the higher end of frequency spectrum where the limit lines are typically stringent. While parasitic cancellation techniques have been discussed at length in prior literature, most of them has focused mainly on single phase applications. Therefore, this thesis aims to extend the pre-existing concepts to compensate the mutual and self-parasitic coupling components in a three-phase multi-stage filter. In this regard, novel component placement, winding strategy as well as shielding and grounding techniques were developed to compensate for the parasitic effects in a three- phase multi-stage filter. The effectiveness of the three-phase filter structure employing the proposed methodologies has been validated in a 15kW rated motor drive system. Consequently, general design guidelines have been formulated for filter design with minimal parasitic effects.

La CEM (Compatibilité ElectroMagnétique) est de plus en plus importante dans la conception des systèmes électroniques et plus particulièrement dans le domaine automobile. En effet, avec la densification de l’électronique dans les véhicules, les problèmes liés à la CEM sont de plus en plus fréquents. Ainsi, afin de limiter ces interférences électromagnétiques, des filtres correctement dimensionnés et implémentés doivent être utilisés. Chaque filtre est dimensionné en tenant compte de l’environnement dans lequel il va être introduit. Cependant, de nombreux facteurs peuvent altérer ses performances, tel que le routage, la structure mécanique ou bien les couplages internes au filtre, entre les composants eux-mêmes. Cette thèse traite de l’étude de l’influence des couplages inter-composants sur les performances d’un filtre pour la CEM. En effet, les méthodes existantes sont basées uniquement sur des simulations électromagnétiques 3D qui sont couteuses en terme de temps et requiert également un trop grand nombre d’informations sur les composants (propriétés géométriques, des matériaux etc.). Ainsi, une méthode uniquement basée sur des calculs analytiques et exploitations de mesures a été développée. Cette méthode simplifiée est très efficace car elle permet la prédiction des performances d’un filtre, quelle que soit sa topologie et quelle que soit sa structure. Cette méthode a été validée via de nombreux cas d’applications de filtres implémentés sur des systèmes d’électronique de puissance du domaine automobile. Finalement, cette méthode a été capitalisée au travers d’un outil pour le design et la prédiction des performances de filtre pour la CEM en tenant compte de la proximité des composants. / EMC (ElectroMagnetic Compatibility) is increasingly important in electronic and electrical systems and more particularly in the automotive domain. Actually, there are more and more power electronics equipments in a vehicle and, therefore, EMC issues are more recurrent. In order to limit EMI (ElectroMagnetic Interferences), well designed filters are needed. Each filter is designed corresponding to a system and the required attenuation. However, different parameters can have influence on the filter performances, such as the layout, the mechanical structure or the inter-components coupling of the filter. Therefore, the thesis work is based on the study of the filter performance considering inter-components coupling. Some methods exist on that topic bu are generally based on 3D electromagnetic simulation, which is time-consuming and requires a lot of information on components (geometrical properties, material properties etc.). Therefore, our work is based on a methodology only based on analytical calculation and measurements. That simplified methodology is very accurate because it can predict a filter performance, whatever the filter topology, whatever the structure. That method was validated under several application cases on power electronics systems for automotive domain. Finally, the whole methodology has been accrued in a tool for filter design that can predict a filter attenuation by considering the components proximity.

The aim of this semestral project was to propose the measuring system for measuring three-phase EMI filters in symmetrical, asymmetrical and non-symmetrical mode according to information from supplier of the filters. The major part of this project was focused on measuring the frequency dependence of the insertion loss of three-phase EMI filters in impedance systems 50?/50?, 0,1?/100 ? and 100?/0,1?. It was determined that results approximately agree with specifications in datasheets.

No description available.

The multi-conductor lossy transmission-line model and finite element simulation tool are used to analyze the high-frequency attenuator and the DM transmission-line EMI filter. The insertion gain, transfer gain, current distribution, and input impedance of the filter under a nominal design are discussed. In order to apply the transmission-line EMI filter to power electronics systems, the performance of the filter under different dimensions, material properties, and source and load impedances must be known. The influences of twelve parameters of the DM transmission-line EMI filter on the cut-off frequency, the roll-off slope, and other characteristics of the insertion gain and transfer gain curves are investigated. The most influential parameters are identified. The current sharing between the copper and nickel conductors under different parameters are investigated. The performance of the transmission-line EMI filter under different source and load impedances is also explored. The measurement setups of the DM transmission-line EMI filter using a network analyzer have been discussed. The network analyzer has a common-ground problem that influences the measured results of the high-frequency attenuator. However, the common-ground problem has a negligible influence on the measured results of the DM transmission-line EMI filter. The connectors and copper strips between the connectors and the filter introduce parasitic inductance to the measurement setup. Both simulated and measured results show that transfer gain curve is very sensitive to the parasitic inductance. However, the insertion gain curve is not sensitive to the parasitic inductance. There are two major methods to reduce the parasitic inductance of the measurement setup: using small connectors and applying a four-terminal measurement setup. The transfer gain curves of three measurement setups are compared: the two-terminal measurement setup with BNC connectors, the two-terminal measurement setup with Sub Miniature version B (SMB) connectors, and the four-terminal measurement setup with SMB connectors. The four-terminal measurement setup with SMB connectors is the most accurate one and is applied for all the transfer gain measurements in this dissertation. This dissertation also focuses on exploring ways to improve the performance of the DM transmission-line EMI filter. Several improved structures of the DM transmission-line EMI filter are investigated. The filter structure without insulation layer can greatly reduce the thickness of the filter without changing its performance. The meander structure can increase the total length of the filter without taking up too much space and results in the cut-off frequency being shifted lower and achieving more attenuation. A prototype of the two-dielectric-layer filter structure is built and measured. The measurement result confirms that a multi-dielectric-layer structure is an effective way to achieve a lower cut-off frequency and more attenuation. This dissertation proposes a broadband DM EMI filter combining the advantages of the discrete reflective LC EMI filter and the transmission-line EMI filter. Two DM absorptive transmission-line EMI filters take the place of the two DM capacitors in the discrete reflective LC EMI filter. The measured insertion gain of the prototype has a large roll-off slope at low frequencies and large attenuation at high frequencies. The dependence of the broadband DM EMI filter on source and load impedances is also investigated. Larger load (source) impedance gives more attenuation no matter it is resistive, inductive or capacitive. The broadband DM EMI filter always has more high-frequency attenuation than the discrete reflective LC EMI filter under different load (source) impedances. / Ph. D.

Because of the switching action, power electronics converters are potentially large EMI noise sources to nearby equipment. EMI filters are necessary to ensure electromagnetic compatibility. Conventional discrete EMI filters usually consist of a large number of components, with different shapes, sizes and form factors. The manufacturing of these components requires different processing and packaging technologies, of which many include labor-intensive processing steps. In addition, due to the parasitics of discrete components, high-frequency attenuation of the filter is reduced and the effective filter frequency range is limited. As a result, discrete EMI filters are usually bulky, high profile, and have poor high-frequency performance. With an aim to solving these issues, this study explores the integration of EMI filters. The goal is to achieve a smaller size, lower profile, better performance and reduced fabrication time and cost via structural, functional and processing integration. The key technology for EMI filter integration is planar electromagnetic integration, which has been a topic of research over the last few years. Most of the previous applications of this technology for switch mode power supplies (SMPSs) were focused on the integration of high frequency power passive electromagnetic components, such as HF transformers, resonant/choke inductors and resonant/blocking capacitors. Almost no work has been done on the subject of EMI filter integration. Since the major function of EMI filters is to attenuate, instead of propagate, energy at the switching frequency and its harmonics, the required technology and design objectives are very different from those of other components. High-frequency modeling of the integrated structure becomes more essential since the high-frequency performance becomes the major concern. New technology and a new model need to be developed for EMI filter integration. To bridge this gap between existing technologies and what is necessary for EMI filter integration, this dissertation addresses technologies and modeling of integrated EMI filters. Suitable integration technologies are developed, which include reducing the equivalent series inductance (ESL) and equivalent parallel capacitance (EPC), and increasing, instead of reducing, the high frequency losses. Using the multi-conductor lossy transmission-line theory, a new frequency domain model of integrated LC structure is developed and verified by experimental results. Through detailed electromagnetic analysis, the equations to calculate the required model parameters are derived. With the developed frequency domain and electromagnetic model, the characteristic of integrated LC modules can be predicted using geometry and material data. With the knowledge obtained from preliminary experimental study of two integrated EMI filter prototypes, a technology is developed to cancel structural winding capacitance of filter inductors. This can be realized by simply embedding a thin conductive shield layer between the inductor windings. With the resultant equivalent circuit and structural winding capacitance model, optimal design of the shield layer is achieved so that EPC can be almost completely cancelled. Applying this technology, an improved integrated EMI filter with a much simpler structure, a much smaller size and profile, and much better HF performance is designed, constructed and verified by experiment. The completed parametric and sensitivity study shows that this is potentially a very suitable technology for mass production. The integrated RF EMI filter is studied, as well. Its frequency domain model is developed based on multi-conductor lossy transmission-line theory. With the model parameters extracted from the finite element analysis (FEA) tool and the characterized material properties, the predicted filter characteristic complies very well with that of the actual measurement. This model and modeling methodology are successfully extended to study the RF CM&DM EMI filter structure, which has not been done before. To model more complicated structures, and to study the interaction between the RF EMI filter and its peripheral circuitry, a PSpice model with frequency dependent parameters is given. Combining the structural winding capacitance cancellation and the integrated RF CM&DM EMI filter technologies, a new integrated EMI filter structure is proposed. The calculation results show that it has the merits of the two employed technologies, hence it will have the best overall performance. / Ph. D.

Around 19% of global power consumption and around 3% of global oil demand is attributable to lighting. After the first incandescent lamp was invented in 1879, more and more energy efficient lighting devices, such as gas discharge lamps, and light-emitting diodes (LED), have been developed during the last century. It is estimated that over 38% of future global lighting energy demand could be avoided by the use of more efficient lamps and ballasts [1]. High intensity discharge (HID) lamps, one category of gas discharge lamp, have been widely used in both commercial and residential lighting applications due to their merits of high efficacy, long life, compact size and good color rendition [2-4]. However, HID lamps require a well-designed ballast to stabilize the negative VI characteristics. A so-called ignitor is also needed to provide high voltage to initiate the gas discharge. Stringent input harmonic current limits, such as the IEC 61000-3-2 Class C standard, are set for lighting applications. It is well-known that high-frequency electronic ballasts can greatly save energy, improve lamp performance, and reduce the ballast size and weight compared with the conventional magnetic ballast. However, a unique phenomenon called acoustic resonance could occur in HID lamps under high-frequency operation. A low-frequency square wave current driving scheme has proved to be the only effective method to avoid acoustic resonance in HID lamps. A typical electronic HID ballast consist of three stages: power factor correction (PFC), DC/DC power regulation and low-frequency DC/AC inverter. The ignitor is usually integrated in the inverter stage. The three-stage structure results in a large size and high cost, which unfortunately offsets the merit of the HID lamp, especially in low-wattage applications. In order to make HID lamps more attractive in low-wattage and indoor applications, it is critical to reduce the size, weight and cost of HID ballasts. This dissertation is aimed at developing a compact HID with an ultra-compact ballast installed inside the lamp fixture. It is a similar concept to the compact fluorescent lamp (CFL), but it is much more challenging than the CFL. Two steps are explored to achieve high power density of the HID ballast. The first step is to improve the system structure and circuit topology. Instead of a three-stage structure, a two-stage structure is proposed, which consists of a single-stage power factor correction (SSPFC) AC/DC front-end and an unregulated DC/AC inverter/ignitor stage. An SSPFC AC/DC converter is proposed as the front-end. A DCM non-isolated flyback PFC semi-stage and a DCM buck-boost DC/DC semi-stage share the semiconductor switch, driver and PWM controller, so that the component count and cost can be reduced. The proposed SSPFC AC/DC front-end converter can achieve a high power factor, low THD, low bulk capacitor voltage, and the desired power regulation with a simple control circuit. Because the number of high-frequency switches is reduced compared to that of state-of-the-art two-stage HID ballast topologies, the switching frequency can be increased without sacrificing high efficiency, so the passive component size can be reduced. The power density of the whole ballast is increased using this two-stage structure. It results in a 2.5 times power density (6 W/in3) improvement compared to the commercial product (2.4 W/in3). The power density of the converter in discrete fashion usually suffers as a result of poor three-dimensional (3D) volume utilization due to a large component count and the different form factor of different components. In the second step, integration and packaging technologies are explored to further increase the power density. A 3D passive integrated HID ballast is proposed in this dissertation. All power passive components are designed in planar shape with a uniform form factor to fully utilize the three-dimensional space. In addition, electromagnetic integration technologies are applied to achieve structural, functional and processing integration to reduce component volume and labor cost. System partitioning, integration and packaging strategies, and implementation of major power passive integration, including an integrated EMI filter, and an integrated ignitor, will be discussed in the dissertation. The proposed integrated ballast is projected to double the power density of the discrete implementation. By installing the HID ballast inside the lamp fixture, the ambient temperature for the ballast will be much higher than the conventional separately installed ballast, and combined with a reduced size, the thermal condition for the integrated ballast will be much more severe. A thermal simulation model of the integrated ballast is built in the IDEAS simulation tool, and appropriate thermal management methods are investigated using the IDEAS simulation model. Experimental verification of various thermal management methods is provided. Based on the thermal management study, a new integrated ballast with improved thermal design is proposed. / Ph. D.

Power factor correction (PFC) converter is a species of switching mode power supply (SMPS) which is widely used in offline frond-end converter for the distributed power systems to reduce the grid harmonic distortion. With the fast development of information technology and multi-media systems, high frequency PFC power supplies for servers, desktops, laptops and flat-panel TVs, etc. are required for more efficient power delivery within limited spaces. Therefore the critical conduction mode (CRM) PFC converter has been becoming more and more popular for these information technology applications due to its advantages in inherent zero-voltage soft switching (ZVS) and negligible diode reverse recovery. With the emerging of the high voltage GaN devices, the goal of achieving soft switching for high frequency PFC converters is the top priority and the trend of adopting the CRM PFC converter is becoming clearer. However, there is the stringent electromagnetic interference (EMI) regulation worldwide. For the CRM PFC converter, there are several challenges on meeting the EMI standards. First, for the CRM PFC converter, the switching frequency is variable during the half line cycle and has very wide range dependent on the AC line RMS voltage and the load, which makes it unlike the traditional constant-frequency PFC converter and therefore the knowledge and experience of the EMI characteristics for the traditional constant-frequency PFC converter cannot be directly applied to the CRM PFC converter. Second, for the CRM PFC converter, the switching frequency is also dependent on the inductance of the boost inductor. It means the EMI spectrum of the CRM PFC converter is tightly related the boost inductor selection during the design of the PFC power stage. Therefore, unlike the traditional constant-frequency PFC converter, the selection of the boost inductor is also part of the EMI filter design process and EMI filter optimization should begin at the same time when the power stage design starts. Third, since the EMI filter optimization needs to begin before the proto-type of the CRM PFC converter is completed, the traditional EMI-measurement based EMI filter design will become much more complex and time-consuming if it is applied to the CRM PFC converter. Therefore, a new methodology must be developed to evaluate the EMI performance of the CRM PFC converter, help to simplify the process of the EMI filter design and achieve the EMI filter optimization. To overcome these challenges, a novel mathematical analysis method for variable frequency PFC converter is thus proposed in this dissertation. Based on the mathematical analysis, the quasi-peak EMI noise, which is specifically required in most EMI regulation standards, is investigated and accurately predicted for the first time. A complete approximate model is derived to predict the quasi-peak DM EMI noise for the CRM PFC converter. Experiments are carried out to verify the validity of the prediction. Based on the DM EMI noise prediction, worst case analysis is carried out and the worst DM EMI noise case for all the input line and load conditions can be found to avoid the overdesign of the EMI filter. Based on the discovered worst case, criteria to ease the DM EMI filter design procedure of the CRM boost PFC are given for different boost inductor selection. Optimized design procedure of the EMI filter for the front-end converter is then discussed. Experiments are carried out to verify the validity of the whole methodology. / Ph. D.

The effectiveness of an EMI filter is closely related to the impedance of the noise source. Due to the time-varying nature of the noise source impedance of an offline power supply, the measurement of it cannot be done using conventional impedance measuring methods. Two new methods, the insertion loss method and the signal injection method, are proposed to perform such a measurement. The insertion loss method utilizes the EMI emission as a signal source and derives the source impedance by measuring the emission attenuation caused by an inserted impedance. The signal injection method injects a signal to the power supply and measures the response. The insertion loss method is verified experimentally both for common mode and differential mode, The signal injection method for common mode source impedance measurement is experimentally verified. That for differential mode source impedance measurement requires a faster equipment and is not fully verified. An EMI filter is usually characterized in the manufacturer’s catalog by its attenuation in a standard system (50Ω source impedance and 50Ω load impedance). The effectiveness of the filter in a practical system may significantly deviate from the manufacturer’s data. To provide the users with practically useful information, a scheme to characterize the EMI filter, the impedance matrix approach is proposed. This approach takes parasitic effect into consideration and the parameters can be measured relatively easily. The approach is verified experimentally by applying a commercial EMI filter to a power supply and comparing the predicted attenuation with the measured one. / Master of Science