Novel zero-current-switching PWM converters

This paper presents a new family of pulsewidth-modulated (PWM) converters, featuring soft commutation of the semiconductors at zero current (ZC) in the transistors and zero voltage (ZV) in the rectifiers, Besides operating at constant frequency and with reduced commutation losses, these new converters have output characteristics similar to the hard-switching-PWM counterpart, which means that there is no circulating reactive energy that would cause large conduction losses, the new family of zero-current-switching (ZCS)-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBT's). The advantages of the new ZCS-PWM boast converter employing IGBT's, rated at 1.6 kW and operating at 20 kHz, are presented, This new ZCS operation can reduce the average total power dissipation in the semiconductors practically by half, when compared with the hard-switching method, This new ZCS-PWM boost converter is suitable for high-power applications using Ie;BT's in power-factor correction, the principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter are provided in this paper to verify the performance of this new family of converters.

A Family of Autoconnected Transformers for 12-and 18-Pulse Converters-Generalization for Delta and Wye Topologies

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Integrated single-stage converters with Tri-state modulation suitable for photovoltaic systems

The aim of this work is to present two topological simplified converters named Tri-state Boost and Tri-state Buck-Boost integrated single-phase inverters. An important operation capability can be achieved for these converters using a Tri-state Modulation control scheme. This is the inductive power decoupling and the independent input output control. These features are directly related with the photovoltaic micro-converter needs, improving efficiency, cost and mainly lifetime. These features for the proposed modulation are confirmed through experimental results. �� 2011 IEEE.

A new family of zero-current-switching PWM converters and a novel HPF-ZCS-PWM boost rectifier

A new family of direct current (DC) to DC converters based on a zero current switching pulse width modulated (ZCS-PWM) soft commutation cell is presented. This ZCS-PWM cell is consists of two transistors, two diodes, two inductors and one capacitor; and provides zero voltage turn-on to the diodes, a zero-current turn-on and a zero-current zero-voltage turn-off to the transistors. In addition, a new commutation cell in a new ZCS-PWM boost rectifier is developed, obtaining a structure with power factor near the unity, high efficiency at wide load range and low total harmonic distortion in the input current.

Novel Inductor���less Conversion Strategy Based on Multiphase Transformer���Coupled Converters: Analysis, Design and Applications

There are many the requirements that modern power converters should fulfill. Most of the applications where these converters are used, demand smaller converters with high efficiency, improved power density and a fast dynamic response. For instance, loads like microprocessors demand aggressive current steps with very high slew rates (100A/mus and higher); besides, during these load steps, the supply voltage of the microprocessor should be kept within tight limits in order to ensure its correct performance. The accomplishment of these requirements is not an easy task; complex solutions like advanced topologies - such as multiphase converters- as well as advanced control strategies are often needed. Besides, it is also necessary to operate the converter at high switching frequencies and to use capacitors with high capacitance and low ESR. Improving the dynamic response of power converters does not rely only on the control strategy but also the power topology should be suited to enable a fast dynamic response. Moreover, in later years, a fast dynamic response does not only mean accomplishing fast load steps but output voltage steps are gaining importance as well. At least, two applications that require fast voltage changes can be named: Low power microprocessors. In these devices, the voltage supply is changed according to the workload and the operating frequency of the microprocessor is changed at the same time. An important reduction in voltage dependent losses can be achieved with such changes. This technique is known as Dynamic Voltage Scaling (DVS). Another application where important energy savings can be achieved by means of changing the supply voltage are Radio Frequency Power Amplifiers. For example, RF architectures based on ���Envelope Tracking��� and ���Envelope Elimination and Restoration��� techniques can take advantage of voltage supply modulation and accomplish important energy savings in the power amplifier. However, in order to achieve these efficiency improvements, a power converter with high efficiency and high enough bandwidth (hundreds of kHz or even tens of MHz) is necessary in order to ensure an adequate supply voltage. The main objective of this Thesis is to improve the dynamic response of DC-DC converters from the point of view of the power topology. And the term dynamic response refers both to the load steps and the voltage steps; it is also interesting to modulate the output voltage of the converter with a specific bandwidth. In order to accomplish this, the question of what is it that limits the dynamic response of power converters should be answered. Analyzing this question leads to the conclusion that the dynamic response is limited by the power topology and specifically, by the filter inductance of the converter which is found in series between the input and the output of the converter. The series inductance is the one that determines the gain of the converter and provides the regulation capability. Although the energy stored in the filter inductance enables the regulation and the capability of filtering the output voltage, it imposes a limitation which is the concern of this Thesis. The series inductance stores energy and prevents the current from changing in a fast way, limiting the slew rate of the current through this inductor. Different solutions are proposed in the literature in order to reduce the limit imposed by the filter inductor. Many publications proposing new topologies and improvements to known topologies can be found in the literature. Also, complex control strategies are proposed with the objective of improving the dynamic response in power converters. In the proposed topologies, the energy stored in the series inductor is reduced; examples of these topologies are Multiphase converters, Buck converter operating at very high frequency or adding a low impedance path in parallel with the series inductance. Control techniques proposed in the literature, focus on adjusting the output voltage as fast as allowed by the power stage; examples of these control techniques are: hysteresis control, V 2 control, and minimum time control. In some of the proposed topologies, a reduction in the value of the series inductance is achieved and with this, the energy stored in this magnetic element is reduced; less stored energy means a faster dynamic response. However, in some cases (as in the high frequency Buck converter), the dynamic response is improved at the cost of worsening the efficiency. In this Thesis, a drastic solution is proposed: to completely eliminate the series inductance of the converter. This is a more radical solution when compared to those proposed in the literature. If the series inductance is eliminated, the regulation capability of the converter is limited which can make it difficult to use the topology in one-converter solutions; however, this topology is suitable for power architectures where the energy conversion is done by more than one converter. When the series inductor is eliminated from the converter, the current slew rate is no longer limited and it can be said that the dynamic response of the converter is independent from the switching frequency. This is the main advantage of eliminating the series inductor. The main objective, is to propose an energy conversion strategy that is done without series inductance. Without series inductance, no energy is stored between the input and the output of the converter and the dynamic response would be instantaneous if all the devices were ideal. If the energy transfer from the input to the output of the converter is done instantaneously when a load step occurs, conceptually it would not be necessary to store energy at the output of the converter (no output capacitor COUT would be needed) and if the input source is ideal, the input capacitor CIN would not be necessary. This last feature (no CIN with ideal VIN) is common to all power converters. However, when the concept is actually implemented, parasitic inductances such as leakage inductance of the transformer and the parasitic inductance of the PCB, cannot be avoided because they are inherent to the implementation of the converter. These parasitic elements do not affect significantly to the proposed concept. In this Thesis, it is proposed to operate the converter without series inductance in order to improve the dynamic response of the converter; however, on the other side, the continuous regulation capability of the converter is lost. It is said continuous because, as it will be explained throughout the Thesis, it is indeed possible to achieve discrete regulation; a converter without filter inductance and without energy stored in the magnetic element, is capable to achieve a limited number of output voltages. The changes between these output voltage levels are achieved in a fast way. The proposed energy conversion strategy is implemented by means of a multiphase converter where the coupling of the phases is done by discrete two-winding transformers instead of coupledinductors since transformers are, ideally, no energy storing elements. This idea is the main contribution of this Thesis. The feasibility of this energy conversion strategy is first analyzed and then verified by simulation and by the implementation of experimental prototypes. Once the strategy is proved valid, different options to implement the magnetic structure are analyzed. Three different discrete transformer arrangements are studied and implemented. A converter based on this energy conversion strategy would be designed with a different approach than the one used to design classic converters since an additional design degree of freedom is available. The switching frequency can be chosen according to the design specifications without penalizing the dynamic response or the efficiency. Low operating frequencies can be chosen in order to favor the efficiency; on the other hand, high operating frequencies (MHz) can be chosen in order to favor the size of the converter. For this reason, a particular design procedure is proposed for the ���inductorless��� conversion strategy. Finally, applications where the features of the proposed conversion strategy (high efficiency with fast dynamic response) are advantageus, are proposed. For example, in two-stage power architectures where a high efficiency converter is needed as the first stage and there is a second stage that provides the fine regulation. Another example are RF power amplifiers where the voltage is modulated following an envelope reference in order to save power; in this application, a high efficiency converter, capable of achieving fast voltage steps is required. The main contributions of this Thesis are the following: The proposal of a conversion strategy that is done, ideally, without storing energy in the magnetic element. The validation and the implementation of the proposed energy conversion strategy. The study of different magnetic structures based on discrete transformers for the implementation of the proposed energy conversion strategy. To elaborate and validate a design procedure. To identify and validate applications for the proposed energy conversion strategy. It is important to remark that this work is done in collaboration with Intel. The particular features of the proposed conversion strategy enable the possibility of solving the problems related to microprocessor powering in a different way. For example, the high efficiency achieved with the proposed conversion strategy enables it as a good candidate to be used for power conditioning, as a first stage in a two-stage power architecture for powering microprocessors.

A methodology to analyze, design and implement very fast and robust controls of Buck-type converters

La electr��nica digital moderna presenta un desaf��o a los dise��adores de sistemas de potencia. El creciente alto rendimiento de microprocesadores, FPGAs y ASICs necesitan sistemas de alimentaci��n que cumplan con requirimientos din��micos y est��ticos muy estrictos. Espec��ficamente, estas alimentaciones son convertidores DC-DC de baja tensi��n y alta corriente que necesitan ser dise��ados para tener un peque��o rizado de tensi��n y una peque��a desviaci��n de tensi��n de salida bajo transitorios de carga de una alta pendiente. Adem��s, dependiendo de la aplicaci��n, se necesita cumplir con otros requerimientos tal y como proveer a la carga con ���Escalado din��mico de tensi��n���, donde el convertidor necesitar cambiar su tensi��n de salida tan r��pidamente posible sin sobreoscilaciones, o ���Posicionado Adaptativo de la Tensi��n��� donde la tensi��n de salida se reduce ligeramente cuanto m��s grande sea la potencia de salida. Por supuesto, desde el punto de vista de la industria, las figuras de m��rito de estos convertidores son el coste, la eficiencia y el tama��o/peso. Idealmente, la industria necesita un convertidor que es m��s barato, m��s eficiente, m��s peque��o y que a��n as�� cumpla con los requerimienos din��micos de la aplicaci��n. En este contexto, varios enfoques para mejorar la figuras de m��rito de estos convertidores se han seguido por la industria y la academia tales como mejorar la topolog��a del convertidor, mejorar la tecnolog��a de semiconducores y mejorar el control. En efecto, el control es una parte fundamental en estas aplicaciones ya que un control muy r��pido hace que sea m��s f��cil que una determinada topolog��a cumpla con los estrictos requerimientos din��micos y, consecuentemente, le da al dise��ador un margen de libertar m��s amplio para mejorar el coste, la eficiencia y/o el tama��o del sistema de potencia. En esta tesis, se investiga c��mo dise��ar e implementar controles muy r��pidos para el convertidor tipo Buck. En esta tesis se demuestra que medir la tensi��n de salida es todo lo que se necesita para lograr una respuesta casi ��ptima y se propone una gu��a de dise��o unificada para controles que s��lo miden la tensi��n de salida Luego, para asegurar robustez en controles muy r��pidos, se proponen un modelado y un an��lisis de estabilidad muy precisos de convertidores DC-DC que tienen en cuenta circuiter��a para sensado y elementos par��sitos cr��ticos. Tambi��n, usando este modelado, se propone una algoritmo de optimizaci��n que tiene en cuenta las tolerancias de los componentes y sensados distorsionados. Us ando este algoritmo, se comparan controles muy r��pidos del estado del arte y su capacidad para lograr una r��pida respuesta din��mica se posiciona seg��n el condensador de salida utilizado. Adem��s, se propone una t��cnica para mejorar la respuesta din��mica de los controladores. Todas las propuestas se han corroborado por extensas simulaciones y prototipos experimentales. Con todo, esta tesis sirve como una metodolog��a para ingenieros para dise��ar e implementar controles r��pidos y robustos de convertidores tipo Buck. ABSTRACT Modern digital electronics present a challenge to designers of power systems. The increasingly high-performance of microprocessors, FPGAs (Field Programmable Gate Array) and ASICs (Application-Specific Integrated Circuit) require power supplies to comply with very demanding static and dynamic requirements. Specifically, these power supplies are low-voltage/high-current DC-DC converters that need to be designed to exhibit low voltage ripple and low voltage deviation under high slew-rate load transients. Additionally, depending on the application, other requirements need to be met such as to provide to the load ���Dynamic Voltage Scaling��� (DVS), where the converter needs to change the output voltage as fast as possible without underdamping, or ���Adaptive Voltage Positioning��� (AVP) where the output voltage is slightly reduced the greater the output power. Of course, from the point of view of the industry, the figures of merit of these converters are the cost, efficiency and size/weight. Ideally, the industry needs a converter that is cheaper, more efficient, smaller and that can still meet the dynamic requirements of the application. In this context, several approaches to improve the figures of merit of these power supplies are followed in the industry and academia such as improving the topology of the converter, improving the semiconductor technology and improving the control. Indeed, the control is a fundamental part in these applications as a very fast control makes it easier for the topology to comply with the strict dynamic requirements and, consequently, gives the designer a larger margin of freedom to improve the cost, efficiency and/or size of the power supply. In this thesis, how to design and implement very fast controls for the Buck converter is investigated. This thesis proves that sensing the output voltage is all that is needed to achieve an almost time-optimal response and a unified design guideline for controls that only sense the output voltage is proposed. Then, in order to assure robustness in very fast controls, a very accurate modeling and stability analysis of DC-DC converters is proposed that takes into account sensing networks and critical parasitic elements. Also, using this modeling approach, an optimization algorithm that takes into account tolerances of components and distorted measurements is proposed. With the use of the algorithm, very fast analog controls of the state-of-the-art are compared and their capabilities to achieve a fast dynamic response are positioned de pending on the output capacitor. Additionally, a technique to improve the dynamic response of controllers is also proposed. All the proposals are corroborated by extensive simulations and experimental prototypes. Overall, this thesis serves as a methodology for engineers to design and implement fast and robust controls for Buck-type converters.

Hardware-in-the-loop implementation of single- and dual-phase shift control for dual active bridge converters in EV applications

Isolated DC-DC converters play a significant role in fast charging and maintaining the variable output voltage for EV applications. This study aims to investigate the different Isolated DC-DC converters for onboard and offboard chargers, then, once the topology is selected, study the control techniques and, finally, achieve a real-time converter model to accomplish Hardware-In-The-Loop (HIL) results. Among the different isolated DC-DC topologies, the Dual Active Bridge (DAB) converter has the advantage of allowing bidirectional power flow, which enables operating in both Grid to Vehicle (G2V) and Vehicle to Grid (V2G) modalities. Recently, DAB has been used in the offboard chargers for high voltage applications due to SiC and GaN MOSFETs; this new technology also allows the utilization of higher switching frequencies. By empowering soft switching techniques to reduce switching losses, higher switching frequency operation is possible in DAB. There are four phase shift control techniques for the DAB converter. They are Single Phase shift, Extended Phase shift, Dual Phase shift, Triple Phase shift controls. This thesis considers two control strategies; Single-Phase, and Dual-Phase shifts, to understand the circulating currents, power losses, and output capacitor size reduction in the DAB. Hardware-In-The-Loop (HIL) experiments are carried out on both controls with high switching frequencies using the PLECS software tool and the RT box supporting the PLECS. Root Mean Square Error is also calculated for steady-state values of output voltage with different sampling frequencies in both the controls to identify the achievable sampling frequency in real-time. DSP implementation is also executed to emulate the optimized DAB converter design, and final real-time simulation results are discussed for both the Single-Phase and Dual-Phase shift controls.

Projeto de um conversor eletr��nico para utiliza����o num sistema e��lico de produ����o de energia

Disserta����o para obten����o do grau de Mestre em Engenharia Electrot��cnica no Ramo de Automa����o e Electr��nica Industrial

Desenvolvimento de um BMS para aplica����es de mobilidade el��trica

Disserta����o de mestrado integrado em Engenharia Eletr��nica Industrial e de Computadores

Boost converter

In this project, we want to implement a theoretical typology of a converter, the Boost converter, which is also named ���Step-up converter���. We also want to bring it to the practical area, where we could work and obtain a useful service, particularly our objective is to obtain a power supply for a notebook. We will give the possibility to work, charge etc. our device in the car and obtain another work station

Vertailu kahden erityyppisen virtasy��tetyn hakkurin soveltuvuudesta polttokennok��ytt��ihin

Concerns about condition of the environment and rising fossil fuel prices have accelerated the research of finding new cheap and environmental friendly energy source. Fuel cells are one of the most promising green technologies, especially in the field of distributed energy generation, backup power systems, transportation and mobile power generation. In this bachelor���s thesis use of fuel cells is studied, especially from the DC-DC converter point of view. This bachelor���s thesis concentrates on study of two different DC-DC converters. The aim of this thesis is to study design and steering methods for proposed converters. The ultimate aim of this thesis is to determine which one of proposed converters is most suitable for fuel cell applications.

Vuotasapainon hallinta kokosiltasy��tetyss�� muuntajassa

Keskitaajuudella toimivia muuntajia k��ytet����n laajalti tehoelektroniikkasovelluksissa kuten DC/DC-konverttereissa ja muissa hakkuritehol��hteiss��. Muuntaja on induktiivinen komponentti, jonka magneettisen tasapainon s��ilytt��minen hakkuritehol��hteiss�� on laitteen virheett��m��n toiminnan kannalta t��rke����. Muuntajaa sy��tt��v��n virtapiirin on muodostettava symmetrinen sy��tt��j��nnite, jotta muuntajan vuo ei ajaudu positiiviseen tai negatiiviseen kyll��stykseen. T��ss�� diplomity��ss�� esitet����n muuntajan s��hk��magneettinen toimintaperiaate, kyll��stymisen syyt hakkuritehol��hteiss�� sek�� kehitet����n aktiivinen ohjaus vuotasapainon s��ilytt��miseksi. Hakkuritehol��hteiss�� k��ytett��viss�� muuntajissa on monesti useampi kuin kaksi k����mi��. T��ss�� ty��ss�� tutkittavassa muuntajassa on useita ensi��it�� ja useita toisioita ja muuntajaa sy��tet����n keskitaajuudella. T��m�� tuo uusia ongelmia verrattuna perinteiseen yksivaiheiseen DC/DC-konvertteriin. N��ihin ongelmiin esitet����n ratkaisut diplomity��n tutkimuksessa.

Robust current control of a phase shifted full-bridge buck converter

In this thesis, the main point of interest is the robust control of a DC/DC converter. The use of reactive components in the power conversion gives rise to dynamical effects in DC/DC converters and the dynamical effects of the converter mandates the use of active control. Active control uses measurements from the converter to correct errors present in the converter���s output. The controller needs to be able to perform in the presence of varying component values and different kinds of disturbances in loading and noises in measurements. Such a feature in control design is referred as robustness. This thesis also contains survey of general properties of DC/DC converters and their effects on control design. In this thesis, a linear robust control design method is studied. A robust controller is then designed and applied to the current control of a phase shifted full bridge converter. The experimental results are shown to match simulations.

An optically coupled power stimulus isolation unit with high voltage and fast rise time output

Recent technological developments have created new devices that could improve and simplify the construction of stimulus isolators. HEXFET transistors can switch large currents and hundreds of volts in nanoseconds. The newer opto-isolators can give a pulse rise time of a few nanoseconds, with output compatible with MOSFET devices, in which delays are reduced to nanoseconds. Integrated DC/DC converters are now available. Using these new resources we developed a new electrical stimulus isolator circuit with selectable constant-current and constant-voltage modes, which are precise and easy to construct. The circuit works like a regulated power supply in both modes with output switched to zero or to free mode through an opto-isolator device. The isolator analyses showed good practical performance. The output to ground resistance was 1011 ohms and capacitance 35 picofarads. The rise time and fall time were identical (5 ��s) and constant. The selectable voltage or current output mode made it very convenient to use. The current mode, with higher output resistance values in low current ranges, permits intracellular stimulation even with tip resistances close to 100 megaohms. The high compliance of 200 V guarantees the value of the current stimulus. The very low output resistance in the voltage mode made the device highly suitable for extracellular stimulation with low impedance electrodes. Most importantly, these characteristics were achieved with a circuit that was easy to build and modify and assembled with components available in Brazil.

Hardware design of a multiconverter for hybrid vehicle applications

Hybridiajoneuvosovellukset vaativat usein sek�� korkea- ett�� matalaj��nnitej��rjestelm��n. Korkeaj��nnitej��rjestelm�� sis��lt���� yleens�� energiavaraston, joka on joko superkondansaattori tai korkeaj��nniteakusto, dieselgeneraattorin tai range extenderin ja ajok��yt��n. Korkeaj��nnitej��rjestelm����n liitet����n usein my��s erilaisia apuk��ytt��j�� kuten kompressoreita ja hydraulipumppuja. Matalaj��nnitej��rjelm�� koostuu yleens�� ohjausyksik��ist��, ajovaloista, yms. laitteista. Perinteisesti matalaj��nnitej��rjestelm���� on sy��tetty dieselmoottorin laturista, mutta korkeaj��nnitej��rjestelmien my��t�� DC/DC-hakkurin k��ytt��minen korkea- ja matalaj��nnitej��rjestelmien v��lill�� on her��tt��nyt kiinnostusta, koska t��ll��in laturin voisi poistaa ja matalaj��nniteakustoa pienent����. T��ss�� ty��ss�� kuvatun monil��h��isen tehonmuokkaimen invertterisilta soveltuu apuk��ytt��jen ajamiseen, ja erotettu DC/DC-hakkuri matalaj��nnitej��rjestelm��n sy��tt��miseen. T��ss�� ty��ss�� k��yd����n l��pi edell�� mainitun tehonmuokkaimen suunnittelu, keskittyen eritoten laitteen korkeaj��nniteosien mitoitukseen ja termiseen suunniteluun. DC/DC-hakkurin osalta perinteisi�� piist�� valmistettuja IGBT transistoreja vertaillaan piikarbidi MOSFET transistoreihin. L��mp��mallilaskujen paikkaansapit��vyytt�� tutkitaan suorittamalla prototyyppilaitteelle hy��tysuhdemittaus, jonka tuloksia verrataan laskettuihin tuloksiin. L��mp��mallin parannusmahdollisuuksia k��sitell����n my��s hy��tysuhdemittauksen tulosten perusteella.