POWER QUALITY CONTROL AND COMMON-MODE NOISE MITIGATION FOR INVERTERS IN ELECTRIC VEHICLES

Inverters are widely utilized in electric vehicle (EV) applications as a major voltage/current source for onboard battery chargers (OBC) and motor drive systems. The inverter performance is critical to the efficiency of EV system energy conversion and electronics system electro-magnetic interference (EMI) design. However, for AC systems, the bandwidth requirement is usually low compared with DC systems, and the control impact on the inverter differential-mode (DM) and common-mode (CM) performance are not well investigated. With the wide-band gap (WBG) device era, the switching capability of power electronics devices drastically improved. The DM/CM impact that was brought by the WBG device-based inverter becomes more serious and has not been completely understood. This thesis provides an in-depth analysis of on-board inverter control strategies and the corresponding DM/CM impact on the EV system. The OBC inverter control under vehicle-to-load (V2L) mode will be documented first. A virtual resistance damping method minimizes the nonlinear load harmonics, and a neutral balancing method regulates the unbalanced load impact through the fourth leg. In the motor drive system, a generalized CM voltage analytical model and a current ripple prediction model are built for understanding the system CM and DM stress with respect to different modulation methods, covering both 2-level and 3-level topologies. A novel CM EMI damping modulation scheme is proposed for 6-phase inverter applications. The performance comparison between the proposed methods and the conventional solution is carried out. Each topic is supported by the corresponding hardware platform and experimental validation

Advances in Rotating Electric Machines

It is difficult to imagine a modern society without rotating electric machines. Their use has been increasing not only in the traditional fields of application but also in more contemporary fields, including renewable energy conversion systems, electric aircraft, aerospace, electric vehicles, unmanned propulsion systems, robotics, etc. This has contributed to advances in the materials, design methodologies, modeling tools, and manufacturing processes of current electric machines, which are characterized by high compactness, low weight, high power density, high torque density, and high reliability. On the other hand, the growing use of electric machines and drives in more critical applications has pushed forward the research in the area of condition monitoring and fault tolerance, leading to the development of more reliable diagnostic techniques and more fault-tolerant machines. This book presents and disseminates the most recent advances related to the theory, design, modeling, application, control, and condition monitoring of all types of rotating electric machines

Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Fase Anizdun bihurgailuentzako modulazio berriak

266 p.Los convertidores multifase han adquirido una gran relevancia debido a sus ventajas sobre los convertidores trifásicos convencionales. Debido a estas ventajas, destacando la tolerancia a fallos, los sistemas multifase se emplean cada vez más en aplicaciones donde la fiabilidad es un factor clave. Sin embargo, estos sistemas no son inmunes a las faltas y, por ello, deben tomarse medidas que aumenten su fiabilidad y robustez. En concreto, esta tesis hace frente a dos de los mayores causantes de faltas en los sistemas basados en motores eléctricos (las faltas por circuito abierto y las faltas en los rodamientos debido a la tensión del modo común) mediante el uso de técnicas de modulación. Por un lado, en caso de perder una de las fases, las técnicas de modulación permiten generar tensiones equilibradas a la salida del convertidor, permitiendo a su vez que el convertidor siga funcionando aunque de forma degradada. Por otro lado, la tensión de modo común generada debido a la conmutación de los dispositivos que forman el convertidor daña los rodamientos de la máquina eléctrica. Por ello, siendo los rodamientos una pieza clave del motor, es necesario desarrollar nuevas técnicas de modulación que minimicen los efectos de la tensión de modo común. De esta forma, esta tesis, además de analizar en profundidad las fuentes causantes de las faltas mencionadas, propone nuevas técnicas de modulación capaces de mejorar el comportamiento del convertidor ante dichos problemas, con el fin de mejorar la tolerancia a fallos del convertidor y alargar la vida útil de los rodamientos del motor

An assessment of flywheel storage for efficient provision of reliable power for residential premises in islanded operation

Energy storage systems (ESS) are key devices for improving power quality, electrical system stability and system efficiency by contributing to the balance of supply and demand. They can enhance the flexibility of electrical systems by mitigating supply intermittency, which has recently become problematic due to the increased penetration of renewable generation. The subject of this thesis is flywheel energy storage system (FESS), a technology that is gathering great interest due to benefits offered over alternative energy storage solutions, including high cycle life, long calendar life, high round‐trip efficiency, high power density, operation at high ambient temperatures and low negative environmental impact. This thesis describes the modelling and assessment of small scale energy system incorporating FESS with solar photovoltaic (PV) and a diesel generator for use in islanded residential premises with highly intermittent or non‐existent grid infrastructure. In this application, incorporation of FESS is shown to be beneficial in comparison to a system without storage or one with the alternative storage technology, Li‐Ion batteries. The thesis begins with a description of flywheel storage systems configured for electrical storage which comprises of a mechanical part; flywheel rotor, bearings and containment, and an electric drive part; motor‐generator and associated power electronics. Each of these components is described in the thesis along with the equations and modelling, itself carried out in the MATLAB/Simulink environment. Finally, the flywheel model is combined with a model of an islanded residential power system incorporating a solar PV system with a diesel generator. Such a system would be particularly useful for offgrid applications or those with weak grids as occurs in developing countries

Advanced Signal Processing Techniques Applied to Power Systems Control and Analysis

The work published in this book is related to the application of advanced signal processing in smart grids, including power quality, data management, stability and economic management in presence of renewable energy sources, energy storage systems, and electric vehicles. The distinct architecture of smart grids has prompted investigations into the use of advanced algorithms combined with signal processing methods to provide optimal results. The presented applications are focused on data management with cloud computing, power quality assessment, photovoltaic power plant control, and electrical vehicle charge stations, all supported by modern AI-based optimization methods

Industrial Applications: New Solutions for the New Era

This book reprints articles from the Special Issue "Industrial Applications: New Solutions for the New Age" published online in the open-access journal Machines (ISSN 2075-1702). This book consists of twelve published articles. This special edition belongs to the "Mechatronic and Intelligent Machines" section

New Control Algorithms for the Distributed Generation Interface in Grid-Connected and Micro-grid Systems

Driven by economic, technical, and environmental reasons, the energy sector is moving into an era where large portions of increases in electrical energy demand will be met through widespread installation of distributed resources or what's known as distributed generation (DG). DG units can operate in parallel to the main grid or in a micro-grid mode. The later is formed by a cluster of DG units connected to a distribution network to maintain the reliability of critical loads, mainly when the grid supply is not available. Distributed resources include variable frequency sources, high frequency sources, and direct energy conversion sources producing dc voltages or currents. The majority of distributed resources are interfaced to the utility grid or to the customer load via dc-ac pulse-width-modulated (PWM) voltage source inverter (VSI) systems. However, these interfaces introduce new issues, such as the absence of the physical inertia, wide-band of dynamics, limited overload capability, susceptibility to parameters variation, and switching harmonics generation. In addition, the uncertain and dynamic nature of the distribution network challenges the stability and control effectiveness of a grid-connected inverter-based DG interface. Generally, difficulties appear in the form of grid impedance and interfacing parameter variations, fast and slow grid-voltage disturbances, grid distortion and unbalance, and interactions between the inverter ac-side filter and the grid. On the other hand, a micro-grid system will be dominated by inverter-based DG units. Unlike conventional power system generators, inverter-based DG units have no physical inertia. This fact makes the micro-grid system potentially susceptible to oscillations resulting from system disturbances. Severe and random disturbances might be initiated in a micro-grid system, due to load changes, the power sharing mechanism of the inverters and other generators, and interactions between the DG interface and the network. Motivated by the aforementioned difficulties, this thesis presents new control algorithms for the DG interface that guarantee stable and high power quality injection under the occurrence of network disturbances and uncertainties, in both the grid-connected and micro-grid systems. The control architecture of the proposed DG interface relies on the following subsystems. First, a newly designed deadbeat current regulation scheme is proposed. The proposed design guarantees high power quality current injection under the presence of different disturbing parameters such as grid voltage distortion, interfacing parameter variation, and inverter system delays. Further, it utilizes the maximum dynamic performance of the inverter in a way that provides a high bandwidth and decoupled control performance for the outer control loops. Different topologies of the ac-side filter are considered for the current control design. Second, a novel adaptive discrete-time grid-voltage sensorless interfacing scheme for DG inverters is proposed. The adaptive interface relies on a new interface-monitoring unit that is developed to facilitate accurate and fast estimation of the interfacing impedance parameters and the grid voltage vector (magnitude and position) at the point of common coupling. The estimated grid voltage is utilized to realize a grid-voltage sensorless interfacing scheme, whereas the interfacing parameters are utilized for the self-tuning control and interface-parameter monitoring. Further, a simple and robust synchronization algorithm and a voltage-sensorless average power control loop are proposed to realize an adaptive voltage-sensorless DG interface. The voltage-sensorless interface positively contributes to the elimination of the residual negative sequence and voltage feed-forward compensation errors, and to the robustness of the power sharing mechanism in paralleled inverter systems, where the power-sharing mechanism is generally based on open-loop controllers. Third, a new voltage control scheme for the DG interface featuring fast load voltage regulation and effective mitigation of fast voltage disturbances is proposed. The proposed voltage control scheme targets the problem of fast and large-signal-based voltage disturbances, which is common in typical distribution feeders. A hybrid voltage controller combining a linear with a variable-structure-control element is proposed for the DG interface. Positive and dual-sequence versions of the proposed voltage controller are developed to address the issue of unbalanced voltage disturbances. The proposed voltage controller successfully embeds a wide band of frequency modes through an equivalent internal model. Subsequently, wide range of balanced and unbalanced voltage perturbations, including capacitor-switching disturbances, can be effectively mitigated. Fourth, to constrain the drift of the low frequency modes in a conventional droop-controlled micro-grid, a new transient-based droop controller with adaptive transient-gains is proposed. The proposed power-sharing controller offers an active damping feature that is designed to preserve the dynamic performance and stability of each inverter unit at different loading conditions. Unlike conventional droop controllers, the proposed droop controller yields two-degree of freedom tunable controller. Subsequently, the dynamic performance of the power-sharing mechanism can be adjusted, without affecting the static droop gain, to damp the oscillatory modes of the power-sharing controller. The overall robust DG interface facilitates a robust micro-grid operation and safe plug-and-play integration of DG units on existing distribution systems; hence increasing the system penetration of DG. The direct result of this development is huge financial saving for utilities by capturing the salient features of deploying DG into existing utility networks. Further, these developments are significant to the industry as they provide the blue print for reliable control algorithms in future DG units, which are expected to operate under challenging system conditions