Modeling of dimmable fluorescent lamp including the tube temperature effects

This paper presents an improved semitheoretical fluorescent lamp model by including the effect of the lamp tube temperature on the lamp electrical parameters at different dimming levels. The experimental results have verified that the lamp tube temperature is a linear function of the lamp's input power and has significant influence on the lamp's electrical parameters during the dimming process. The comparison on the simulation and measurements shows that the improved lamp model can predict the lamp electrical characteristics accurately in a wide dimming range under both low- and high-frequency operations. © 2010 IEEE.published_or_final_versio

Modelling, analysis and design of LCLC resonant power converters.

The thesis investigates the modelling, analysis, design and control of 4th -order LCLC resonant power converters. Both voltage-output and current-output variants, are considered. Key research outcomes are the derivation of new frequency- and time-domain models of the converters, based on normalised component ratios, and including the effects that parasitic elements have on circuit behaviour, and a detailed account of multi-resonant characteristics; extensions to the use of cyclicmode modelling methods for application to LCLC converters, to provide rapid steady-state analysis, thereby facilitating the use of the derived methodologies as part of an interactive design tool; the formulation of analytical methods to predict the electrical stresses on tank components-an important consideration when designing resonant converters, as they are often higher than for hard-switched converter counterparts; the characterisation of both continuous and discontinuous modes of operation and the boundary conditions that separate them; and a substantial treatment of the modelling, analysis and design of LCLC converters that can provide multiple regulated outputs by the integrated control of both excitation frequency and pulse-width-modulation. The proposed methodologies are employed, for validation purposes, in the realisation of two proof-of concept demonstrator converters. The first, to satisfy the requirements for delivering 65V (rms) to an electrode-less, SW, fluorescent lamp, to improve energy efficiency and lifetime, and operating at a nominal frequency of 2.65 MHz, is used to demonstrate capacitively-coupled operation through the lamp tube, thereby mitigating the normally detrimental effects of excitation via the electrodes. The second prototype considers the realization of an LCLC resonant power supply that can provide multiple regulated outputs without the need for post-regulation circuitry. The two outputs of the supply are independently, closed-loop regulated, to provide asymmetrical output voltage distributions, using a combination of frequency- and duty-control. Although, an analysis of the supply shows that the behaviour is extremely complex, due, in particular, to the highly non-linear interaction between the mUltiple outputs and parasitic inductances, and rectifier, an analysis to provide optimum performance characteristics, is proposed. Moreover, a PICIFPGA-based digital controller is developed that allows control of the transient performance of both outputs under start-up and steady-state conditions

A High Frequency, High Efficiency, High Power Factor Isolated On-board Battery Charger for Electric Vehicles

In this paper, a high frequency, high efficiency and high power factor isolated on-board battery charger is proposed. The proposed topology includes two parts, AC/DC power factor correction (PFC) circuit unit and DC/DC converter unit. For the PFC circuit, SiC based totem-pole interleaved bridgeless PFC is selected, the diode bridge rectifier is eliminated. In addition, it can operate in continuous conduction mode (CCM) thanks to the low reverse recovery losses of the SiC MOSFETs. Besides, the interleaved technology minimizes the input current ripple. The DC/DC converter unit is composed of two LLC resonant converters sharing the same full-bridge inverter with constant switching frequency. The outputs of two LLC resonant converters are connected in series. One of the LLC resonant converter is operating at the resonant frequency, which is the highest efficiency operation point; while magnetic control is adopted for the second LLC resonant converter to fulfill the duty of providing closed-loop control for constant voltage (CV) and constant current (CC) charge modes. The proposed topology can achieve zero voltage switching (ZVS) for all primary switches and zero current switching (ZCS) for all secondary diodes during both CC and CV modes. Furthermore, the constant switching frequency is simplified the electromagnetic interference (EMI) filter design. Simulation studies for 3.3kW power level and 100kHz switching frequency are performed, the simulation results are presented to verify the feasibility and validity of the proposed topology

Digital Control of LFSW HID Lamp Drivers with Soft Saturation Magnetic Materials and Integrated Resonant Lamp Ignition

Electronic HID ballasts provide many advantages over magnetic HID ballasts including size, weight, overall efficiency, and greater control of operating conditions. Electronic ballasts add complexity to the system, requiring a greater understanding of the operation of HID lamps. Electronic ballasts also introduce a host of issues for the HID ballast designer including possible acoustic resonances, arc stability issues, and operation across broad operating conditions. In this work, research of a Low-Frequency Square-Wave (LFSW) HID solution is performed that includes use of a non-linear soft saturation core material for the inductor. Modeling of the converter with this core is presented as well. Difficulties with operation of HID lamps are outlined, as well as the previous methods to overcome such obstacles. Ignition and steady-state operation of HID lamps occur with very different operating conditions. Ignition occurs with very little lamp current, but large lamp voltage, and steady-state operation is the opposite. Due to this mismatch, any single ignitor/ballast design requires the inductor to be able to handle both operating points. Use of a soft saturation material allows for a reduction in size and weight of the overall system due to the higher magnetic capacity of the material as compared to hard saturation alternatives. The downside to using this material is inductance varies with magnetizing force on the core. A resonant ignition approach with soft saturation material is presented, motivating the need for phase control of the system. A fast transition between resonant and LFSW mode operation is presented, which requires a large design space for possible lamp impedances. Transition times between LFSW modes are dependent on natural frequency and Q factor of a buck filter response, which is shaped beneficially by the soft saturation material. A design method for this is presented, along with considerations for core selection. A two loop control method is analyzed with an inner current loop that stabilizes the lamp arc and an outer power loop in order to obtain regulated light output. The current loop is able to monitor currents of a positive and negative buck mode operation using a single sense point. A system that uses input power sensing to ultimately control output power is analyzed and experimentation is presented

Critical Design Criterion for Achieving Zero Voltage Switching in Inductorless Half-Bridge-Driven Piezoelectric-Transformer-Based Power Supplies

A methodology for predicting the ability of inductor-less driven piezoelectric transformer (PT) based power supplies to achieve zero voltage switching (ZVS) is presented. A describing function approach is used to derive an equivalent circuit model of the PT operating in the vicinity of ZVS and the subsequent application of the model provides a quantitative measure of a PT's ability to achieve ZVS when driven by an inductor-less half-bridge inverter. Through detailed analysis of the analytical model, the limitations of the inductor-less half-bridge driven PT are exposed from which guidelines for designing both the PT and inverter are derived

Piezoelectric Transformer Integration Possibility in High Power Density Applications

The contents of this work investigate the capability of integrating the PT in applications by invoking the ratio of the throughput power to volume represented by the term: power density. The fundamentals of the PT are introduced in chapter two. In chapter three, the fundamental limitations of the PT's capability of transferring power to the load are studied. There are three major limitations: temperature rise due to losses during operation, electromechanical limits of material, and interactions with output rectifier. The analysis and estimation are then verified by experiments and calculations implemented on three different PT samples fabricated from three different manufacturers. The subject of chapter four is the behavior of the PT's power amplifier. This chapter concentrates on two main amplifier topologies, optimized based on the simplicity of structure and minimization of components (passive and active): class D and class E amplifiers. The operational characteristics of these amplifiers with the PT are then comparison. Methods to track the optimum frequency and discontinuous working mode of the PT are proposed as the approaches to improve the energy transfer of the PT. In chapter five, prototypes of four devices using a PT are developed and introduced as illustrations of the integration of PTs into practical applications: an igniter for high intensity discharge (HID) lamps, high DC voltage power supplies, and electronic ballasts for LEDs, and stand-alone ionizers for food sterilizers. Some concluding statements and ideas for future works are located in the last chapter - chapter six

Impact of modern lighting technology on the power line communications channel

Abstract: In this study, we look at the impact of modern lighting technology on Power Line Communications (PLC). Power Line Communications has become important due to the Smart Grid and Internet of Things (IoT) development. Modern lighting technology has been developed to make efficient use of electric energy. This technology uses power converters to enable the use of different lighting sources. A byproduct of this conversion process is electronic noise. This noise can interfere with the PLC channel. In this study, different lighting technologies are investigated from a noise standpoint and compared to PLC signal levels. Both narrowband and broadband PLC frequency ranges are investigated. This study shows that the influence of noise on the PLC channel depends predominantly on the conversion topology as well as whether filters have been used. The measurement results show that the influence on data communication system can vary in impact from low to severe. Results were obtained for low energy, high energy, indoor and outdoor lighting sources. A common front end topology encounted is the bridge rectifier and high frequency DC-DC converter combination. These topologies are investigated in details. The study presented here shows that lighting technology (causing interference) needs special consideration when designing PLC systems. Of particular importance is the use of filters which ensure compliance with interference standards and limit the noise effects on the PLC signal.D.Ing. (Electrical and Electronic Engineering Science

Convertisseurs à bobine variable pour applications de transport durables

Abstract: Power electronics converters are key components and enable efficient conversion and management of electrical energy in a wide range of applications. For vehicular use, there is an inevitable need to improve their performance and reducing their size. This is particularly important in case of powertrain DC-DC converters as they are required to have improved performance while respecting the specifications, characteristics and stringent space limitations. These objectives define research targets and a particular progress is essential in the field of passive components, semiconductor devices, converter topologies and control. At the current state of technologies, the passive components particularly the power inductors are dominant components which affect the overall volume, cost and performance of power electronic converters. Considering the aforementioned critical aspects, this thesis proposes a variable inductor (VI) concept in order to reduce the weight and size power inductors which are traditionally bulky and have fairly limited operating range. By modulating the permeability of the magnetic material, this concept enhances the current handling capability of power inductors, controls the current ripples, reduces the magnetic and switching losses, as well as the stresses applied to switching devices. Furthermore, it enables the use of smaller cores which leads to the reduction of mass and volume allowing improvements in the converter operation and its overall performance. However, to integrate it into powertrain DC-DC converters, it is fundamental, to question the design of the component itself, the selection of suitable magnetic core materials, and the control of current in the auxiliary winding and saturation management of magnetic cores. This thesis systematically addresses these different research challenges. A particular attention is paid to the experimental study of a VI prototype to demonstrate the concept on a small-scale in order to explore its viability. Subsequently a detailed characterization was developed using finite element analysis to determine the intrinsic functionality of the passive component. Furthermore, this thesis proposed an RMS current based VI design to reduce oversizing of power inductors for electric vehicles application. In this methodology, the selection of a suitable magnetic core material is a crucial step to assure smaller and efficient converters. Hence, this thesis proposes a simplified approach based on weighted property method (WPM) for an appropriate selection of magnetic core in accordance to the needs of the user. Furthermore, to validate the integration of this concept in DC-DC converter topology used in the powertrain of electrified vehicles, an affine parameterization method is used to design the control parameters and a simple management strategy is proposed to enable dynamic control of the VI. The converter control and the proposed strategy are evaluated through simulations of a complete powertrain of a three-wheel recreational vehicle. The small-scale experimental and simulations, and full-scale simulations have demonstrated an interesting capacity of the VI for improving the performance of DC-DC converters for electrified vehicles and manage the saturation of the magnetic core while reducing the size and weight of magnetic components.Les convertisseurs d’électroniques de puissance sont des composants clés de la conversion et gestion efficace de l’énergie électrique dans une large gamme d’applications. Pour des utilisations véhiculaires, il est inévitablement nécessaire d’améliorer leurs performances et de réduire leur taille. Ceci est particulièrement important dans le cas des convertisseurs à courant continu (CC) de la chaine de traction où des performances améliorées en réponse à une large gamme de variations de charge sont recherchées tout en respectant les spécificités, caractéristiques et limitation d’espace nécessaires aux véhicules électrifiés. Ces objectifs définissent une cible de recherche et en particulier des progrès sont essentiels dans le domaine des composants passifs, des dispositifs semi-conducteurs, des topologies des convertisseurs et leurs commandes pour généraliser l’utilisation de véhicules électriques. Les composants passifs, en particulier les inductances de puissance, sont des composants dominants qui affectent le volume global, le coût et les performances de ces convertisseurs d’électroniques de puissance. Compte tenu de ces aspects, cette thèse propose un concept de bobine variable afin de réduire le poids et la taille des inductances de puissance qui sont traditionnellement encombrantes et ont une gamme de fonctionnement assez limitée. En modulant la perméabilité du matériau magnétique, ce concept améliore la capacité de gestion du courant des bobines de puissance, contrôle les ondulations du courant et réduit les pertes magnétiques et par commutation, bien comme les contraintes appliquées aux dispositifs de commutation. En outre, il permet l’utilisation de noyaux plus petits, ce qui entraîne une réduction de masse et de volume, en permettant une amélioration du fonctionnement du convertisseur et de ses performances globales. Cependant, pour l’intégrer aux convertisseurs CC-CC utilisés dans la chaine de traction, il est fondamental de se questionner sur la conception du composant lui-même, la sélection du matériau magnétique, la commande du courant de l’enroulement auxiliaire et la gestion de la saturation du noyau magnétique. Cette thèse aborde de manière systématique ces différents défis de recherche. Une attention particulière est accordée à l’étude expérimentale d’un prototype de bobine variable pour faire la preuve de concept à petite échelle afin d’explorer sa viabilité. Par la suite, une large caractérisation par éléments finis a été développée pour déterminer le fonctionnement intrinsèque de ce composant passif. De plus, cette thèse propose une méthode systématique de design de bobine variable basée sur le courant RMS pour réduire le surdimensionnement traditionnellement associer aux inductances de puissance pour des applications véhiculaires. Dans cette méthodologie, la sélection appropriée du matériau pour le noyau magnétique est une étape cruciale pour garantir des convertisseurs plus petits et efficaces, donc une démarche de sélection simplifiée basée sur la méthode des propriétés pondérées pour le choix de noyau magnétique approprié au besoin de l’application a été mis au point. De plus, pour valider l’intégration de ce concept dans une topologie de convertisseur CC-CC traditionnellement utilisée dans la chaine de traction des véhicules électrifiés, une méthode de synthèse affine a été utilisée pour définir les paramètres des contrôleurs de courant et une stratégie de gestion de la saturation du noyau a été proposée pour permettre le contrôle dynamique de la bobine variable. La commande du convertisseur et la stratégie ont été évaluées par simulation d’une chaine de traction complète d’un véhicule récréatif réel. Les résultats expérimentaux à petite échelle et simulations à pleine échelle ont démontrés des capacités intéressantes de cette bobine variable pour l’amélioration des performances des convertisseurs CC-CC, ayant la capacité de gestion de la saturation du noyau magnétique tout en réduisant la taille et le poids de ces composants passifs, dans le but de son utilisation dans la chaine de traction des véhicules électrifiés