ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters

Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency

Modeling and identification of power electronic converters

Nowadays, many industries are moving towards more electrical systems and components. This is done with the purpose of enhancing the efficiency of their systems while being environmentally friendlier and sustainable. Therefore, the development of power electronic systems is one of the most important points of this transition. Many manufacturers have improved their equipment and processes in order to satisfy the new necessities of the industries (aircraft, automotive, aerospace, telecommunication, etc.). For the particular case of the More Electric Aircraft (MEA), there are several power converters, inverters and filters that are usually acquired from different manufacturers. These are switched mode power converters that feed multiple loads, being a critical element in the transmission systems. In some cases, these manufacturers do not provide the sufficient information regarding the functionality of the devices such as DC/DC power converters, rectifiers, inverters or filters. Consequently, there is the need to model and identify the performance of these components to allow the aforementioned industries to develop models for the design stage, for predictive maintenance, for detecting possible failures modes, and to have a better control over the electrical system. Thus, the main objective of this thesis is to develop models that are able to describe the behavior of power electronic converters, whose parameters and/or topology are unknown. The algorithms must be replicable and they should work in other types of converters that are used in the power electronics field. The thesis is divided in two main cores, which are the parameter identification for white-box models and the black-box modeling of power electronics devices. The proposed approaches are based on optimization algorithms and deep learning techniques that use non-intrusive measurements to obtain a set of parameters or generate a model, respectively. In both cases, the algorithms are trained and tested using real data gathered from converters used in aircrafts and electric vehicles. This thesis also presents how the proposed methodologies can be applied to more complex power systems and for prognostics tasks. Concluding, this thesis aims to provide algorithms that allow industries to obtain realistic and accurate models of the components that they are using in their electrical systems.En la actualidad, el uso de sistemas y componentes eléctricos complejos se extiende a múltiples sectores industriales. Esto se hace con el propósito de mejorar su eficiencia y, en consecuencia, ser más sostenibles y amigables con el medio ambiente. Por tanto, el desarrollo de sistemas electrónicos de potencia es uno de los puntos más importantes de esta transición. Muchos fabricantes han mejorado sus equipos y procesos para satisfacer las nuevas necesidades de las industrias (aeronáutica, automotriz, aeroespacial, telecomunicaciones, etc.). Para el caso particular de los aviones más eléctricos (MEA, por sus siglas en inglés), existen varios convertidores de potencia, inversores y filtros que suelen adquirirse a diferentes fabricantes. Se trata de convertidores de potencia de modo conmutado que alimentan múltiples cargas, siendo un elemento crítico en los sistemas de transmisión. En algunos casos, estos fabricantes no proporcionan la información suficiente sobre la funcionalidad de los dispositivos como convertidores de potencia DC-DC, rectificadores, inversores o filtros. En consecuencia, existe la necesidad de modelar e identificar el desempeño de estos componentes para permitir que las industrias mencionadas desarrollan modelos para la etapa de diseño, para el mantenimiento predictivo, para la detección de posibles modos de fallas y para tener un mejor control del sistema eléctrico. Así, el principal objetivo de esta tesis es desarrollar modelos que sean capaces de describir el comportamiento de un convertidor de potencia, cuyos parámetros y/o topología se desconocen. Los algoritmos deben ser replicables y deben funcionar en otro tipo de convertidores que se utilizan en el campo de la electrónica de potencia. La tesis se divide en dos núcleos principales, que son la identificación de parámetros de los convertidores y el modelado de caja negra (black-box) de dispositivos electrónicos de potencia. Los enfoques propuestos se basan en algoritmos de optimización y técnicas de aprendizaje profundo que utilizan mediciones no intrusivas de las tensiones y corrientes de los convertidores para obtener un conjunto de parámetros o generar un modelo, respectivamente. En ambos casos, los algoritmos se entrenan y prueban utilizando datos reales recopilados de convertidores utilizados en aviones y vehículos eléctricos. Esta tesis también presenta cómo las metodologías propuestas se pueden aplicar a sistemas eléctricos más complejos y para tareas de diagnóstico. En conclusión, esta tesis tiene como objetivo proporcionar algoritmos que permitan a las industrias obtener modelos realistas y precisos de los componentes que están utilizando en sus sistemas eléctricos.Postprint (published version

High-voltage pulse generators incorporating modular multilevel converter sub-modules

Recent research established the effectiveness of applying a pulsed electric field to deactivate harmful microorganisms (such as bacteria and E. coli). Successful deactivation is achieved by lethal electroporation; a process that produces electric pores in the biological cell membrane of the harmful microorganisms when subjected to high-voltage (HV) pulses. The HV pulses are designed to create pores beyond a critical size at which the biological cell can reseal.;In contrast when applying non-lethal electroporation, the cell-membrane survives after the electroporation process. This is required, for example, when inserting protein cells in the cell-membrane. In both lethal and non-lethal electroporation, HV pulses in the kilo-Volt range (1-100 kV) with durations ranging between nanoseconds and milliseconds are required.;This thesis proposes nine pulse generator (PG) topologies based on power electronic devices and modular multilevel converter sub-modules. The proposed topologies are divided into two main groups namely: PGs fed from a HV DC supply and PGs fed from an LV DC supply. The first group presents a new family of HV DC fed topologies that improve the performance of existing HV DC fed PGs, such as flexible pulse-waveform generation and full utilisation of the DC link voltage.;The second group is dedicated to a new family of LV DC fed PG topologies which have flexible pulse-waveform generation, controlled operation efficiency, and high voltage gain.;All the proposed PG topologies share the important aspect in the newly developed HV PGs, that is modularity, which offers redundancy and robust pulse generation operation.;The presented PG topologies are supported by theoretical analysis, simulations, and experimentation.Recent research established the effectiveness of applying a pulsed electric field to deactivate harmful microorganisms (such as bacteria and E. coli). Successful deactivation is achieved by lethal electroporation; a process that produces electric pores in the biological cell membrane of the harmful microorganisms when subjected to high-voltage (HV) pulses. The HV pulses are designed to create pores beyond a critical size at which the biological cell can reseal.;In contrast when applying non-lethal electroporation, the cell-membrane survives after the electroporation process. This is required, for example, when inserting protein cells in the cell-membrane. In both lethal and non-lethal electroporation, HV pulses in the kilo-Volt range (1-100 kV) with durations ranging between nanoseconds and milliseconds are required.;This thesis proposes nine pulse generator (PG) topologies based on power electronic devices and modular multilevel converter sub-modules. The proposed topologies are divided into two main groups namely: PGs fed from a HV DC supply and PGs fed from an LV DC supply. The first group presents a new family of HV DC fed topologies that improve the performance of existing HV DC fed PGs, such as flexible pulse-waveform generation and full utilisation of the DC link voltage.;The second group is dedicated to a new family of LV DC fed PG topologies which have flexible pulse-waveform generation, controlled operation efficiency, and high voltage gain.;All the proposed PG topologies share the important aspect in the newly developed HV PGs, that is modularity, which offers redundancy and robust pulse generation operation.;The presented PG topologies are supported by theoretical analysis, simulations, and experimentation

A modular multilevel voltage-boosting Marx pulse-waveform generator for electroporation applications

In order to overcome the limitations of the existing classical and solid-state Marx pulse generators, this paper proposes a new modular multilevel voltage-boosting Marx pulse generator (BMPG). The proposed BMPG has hardware features that allow modularity, redundancy, and scalability as well as operational features that alleviate the need of series-connected switches and allows generation of a wide range of pulse waveforms. In the BMPG, a controllable, low-voltage input boost converter supplies, via directing/blocking (D/B) diodes, two arms of a series modular multilevel converter half-bridge sub-modules (HB-SMs). At start up, all the arm's SM capacitors are resonantly charged in parallel from 0 V, simultaneously via directing diodes, to a voltage in excess of the source voltage. After the first pulse delivery, the energy of the SM capacitors decreases due to the generated pulse. Then, for continuous operation without fully discharging the SM capacitors or having a large voltage droop as in the available Marx generators, the SM capacitors are continuously recharged in parallel, to the desired boosted voltage level. Because all SMs are parallelly connected, the boost converter duty ratio is controlled by a single voltage measurement at the output terminals of the boost converter. Due to the proposed SMs structure and the utilization of D/B diodes, each SM capacitor is effectively controlled individually without requiring a voltage sensor across each SM capacitor. Generation of the commonly used pulse waveforms in electroporation applications is possible, while assuring balanced capacitors, hence SM voltages. The proposed BMPG has several topological variations such as utilizing a buck-boost converter at the input stage and replacing the HB-SM with full-bridge SMs. The proposed BMPG topology is assessed by simulation and scaled-down proof-of-concept experimentation to explore its viability for electroporation applications

Current source back to back converter for wind energy conversion systems

This paper proposes a new back-to-back current source converter (BTB-CSC) suitable for mediumvoltage high power wind energy conversion systems (WECS). It employs a dual three-phase permanent magnet synchronous generator and two current source inverters with a phase-shift transformer at the grid side. The proposed BTB-CSC has the following advantages: reduced power circuit and control complexity; low switching losses (zero switching losses at the inverter side); and independent control of active and reactive power. PSCAD/EMTDC simulations are used as to assess the steady-state and dynamic behaviour of the proposed system under different operating conditions. It is shown that the proposed WECS can ride-through ac faults. Experimental results from scaled prototype of the proposed WECS are used to validate the simulations

Design and development of multiphase buck converters for voltage regulator modules

Modern microprocessors in high-power applications require a low input voltage and a high input current, necessitating the use of multiphase buck converters. As per microprocessor computing complexity, the power requirements of the switching converter will also be more important and will be increasing as per load demand. Previous studies introduced some methods to achieve the advantages associated with multiphase regulators. This paper presents an effective closed closed-loop control scheme for multiphase buck converters that reduces ripple and improves transient response. It is suitable for applications that require regulated output voltage with effectively reduced ripple. The analysis began with a simulation of the entire design using the OrCAD tool, followed by the construction of a hardware setup. Experiments on a 200 Khz, 9 V, 12 A, 2-phase buck voltage regulator were conducted and the proposed experiment found to be useful

A modular multilevel based high-voltage pulse generator for water disinfection applications

The role of irreversible electroporation using pulsed electric field (PEF) is to generate high voltage (HV) pulses with a predefined magnitude and duration. These HV pulses are applied to the treatment chamber until decontamination of the sample is completed. In this paper, a new topology for HV rectangular pulse generation for water disinfection applications is introduced. The proposed topology has four arms comprised of series connected half H-bridge modular multilevel converter cells. The rectangular pulse characteristics can be controlled via a software controller without any physical changes in power topology. The converter is capable of generating both bipolar and monopolar HV pulses with micro-second pulse durations at a high frequency rate with different characteristics. Hence, the proposed topology provides flexibility by software control, along with hardware modularity, scalability, and redundancy. Moreover, a cell's capacitance is relatively small which drastically reduces the converter footprint. The adopted charging and discharging process of the cell capacitors in this topology eliminate the need of any voltage measurements or complex control for cell-capacitors voltage balance. Consequently, continuity of converter operation is assured under cell malfunction. In this paper, analysis and cell-capacitor sizing of the proposed topology are detailed. Converter operation is verified using MATLAB/Simulink simulation and scaled experimentation

Estimation and control techniques in power converters

This thesis develops estimation and control techniques in power converters. The target applications are voltage regulators for modern microprocessors (VRM) and distributed DC power systems (DPS). A method for the on-line calibration of a circuit board trace resistance at the output of a buck converter is described. This method is applied to obtain an accurate and high-bandwidth measurement of the load current in the VRM applications, thus enabling an accurate DC load-line regulation as well as a fast transient response. Experimental results show an accuracy well within the tolerance band of this application, and exceeding all other popular methods. A method for estimating the phase current unbalance in a multi-phase buck converter is presented. The method uses the information contained in the voltage drop at the input capacitor's ESR to estimate the average current in each phase. The method can be implemented with a low-rate down-sampling A/D converter and is not computationally intensive. Experimental results are presented, showing good agreement between the estimates and the measured values. An online adaptation method of the gain of an output current feedforward path in VRM applications is developed. The feedforward path can improve substantially the converter's response to load transients but it depends on parameters of the power train that are not known with precision. By analyzing the error voltage and finding its correlation with the parameter error, a gradient algorithm is derived that makes the latter vanish. Experimental results show a substantial improvement of the transient response to a load current step in a prototype VRM. Impedance interactions between interconnected power subsystems are analyzed. Typical examples of these interconnections are a power converter with a dynamic load, a power converter with an input line filter, power converters connected in parallel or cascade, and combinations of the above. A survey of the most relevant results in this area is presented together with detailed examples. Fundamental limits on the performance of the interconnected systems are exposed and a system-level design approach is proposed and corroborated with simulations