1,721,158 research outputs found
Power electronics solutions for BESS integration and management
Full text linkAs the space industry evolves towards more powerful spacecraft, the demand for high power output and efficient power management is more critical than ever. Spacecraft power systems must support higher bus voltages while maintaining high reliability, compact design, and minimal energy loss. Conventional power architectures, which process the full power load, are limited in efficiency and scalability, particularly under high power demands. An alternative approach that accommodates higher bus voltages without altering the solar arrays and load voltages in conventional power architectures is Partial Power Processing (PPP). This converter solution processes only a fraction of the total energy, enabling higher efficiency, reduced component stress, and flexible, scalable designs that suit space sector’s growing power demands. Nevertheless, the efficiency of a PPP converterbased system is a non-linear function of the converter’s own efficiency, which imposes constraints on the voltage gain achievable by the converter. PPP converters are generally more efficient than full-power processing systems only when narrow input-output voltage differences are applied. Additionally, PPP architectures lack inherent galvanic isolation, making them unsuitable for applications with strict isolation requirements. In these cases, alternative solutions or additional interconnection stages may be necessary, potentially reducing the overall advantages of PPP. This thesis explores four primary objectives to address these challenges. First, it identifies the contexts in which PPP architectures are advantageous, particularly in applications that demand high efficiency and power density within limited space. A detailed analysis and comparison of series and parallel PPP configurations, along with the development of a reconfigurable PPP architecture to optimize efficiency by dynamically managing voltage gaps, are addressed and deeply analyzed. Second, it focuses on the design of PPP converters, addressing component stress, architecture selection, and complex trade-offs to balance efficiency and cost. To validate these findings, a prototype flyback PPP converter was developed, achieving a peak efficiency of 99.12%, demonstrating the potential of PPP to significantly reduce energy losses and component stress in high-power BESS systems. Third, the thesis explores a capacitive coupling solution to improve cross-regulation in multi-output flyback converters, which is critical for systems requiring auxiliary power supplies or for applications like cell balancing in BESS, where load balancing accuracy is essential. Conventional methods, such as multi-loop feedback or post-regulation stages, usually add both complexity and cost. This low-cost, low-complexity capacitive coupling approach eliminates the need for complex feedback systems, effectively minimizing cross-regulation errors in applications with unbalanced loads, without compromising converter efficiency. Fourth, the thesis investigates solutions for integrating mandatory isolation within PPP converters, utilizing capacitive coupling to meet safety and operational standards without the size, cost, and efficiency limitations of traditional magnetic transformers. By leveraging Gallium Nitride (GaN) technology for high-frequency switching, this approach achieves a compact and efficient design that minimizes power losses typically associated with magnetic cores. Experimental validation confirms the isolation method’s effectiveness, demonstrating high efficiency with negligible losses. These findings advance the application of PPP in high-power systems, establishing methodologies for integrating BESS in spacecraft power systems and contributing to high-efficiency power electronics for the space industry
Hybrid Energy Storage Systems for Smart Grids and Electric Propulsion Systems
No full textHybrid Energy Storage Systems (HESSs) represent a very promising and viable solution for the widespread diffusion of both Smart Grids (SGs) and Electric Propulsion Systems (EPSs). This is because an HESS benefits from two or more energy storage technologies that are characterized by complementary features, namely high energy and high power densities. Consequently, a number of energy and power services can be provided successfully, which are hardly deliverable by a single energy storage technology unless oversizing is concerned. Therefore, HESSs installed in SGs can provide multiple grid services, ranging from peak shaving to power quality, thus achieving an economic viability. While the employment of an HESS for supplying EPSs enables improved dynamic performances and energy efficiency during both acceleration and regenerative braking, thus extending the vehicle driving range. In this context, an HESS made up of batteries and supercapacitors is the most popular combination, it being suitable for both small-scale and large-scale applications due to its inherent modularity. However, HESS technical and economic viability strictly relies on management and control, which should enable the exploitation of the HESS inherent features to the maximum extent in accordance with the application requirements.
In this regard, the presentation will focus on most recent advancements in management and control of HESS for both SG and EPS. Particularly, the most popular HESS configurations, management and control approaches will be introduced at first, highlighting their most important advantages and drawbacks. Subsequently, a highly-integrated HESS configuration will be presented, which is well suited for SGs, but especially for EPSs. This is because it benefits from the advantages of both passive and active HESS configurations due to its inherent flexibility. An Optimal HESS Power and Energy Management (OPEM) for SGs will be presented as well; this has been developed analytically in order to achieve an optimal trade-off between peak shaving and reduced grid energy buffering, providing power quality and preventing an excessive battery cycling at the same time. Preliminary and advanced results will be presented and discussed extensively, which highlight the effectiveness of the proposed solutions in terms of HESS configuration, management and control
Vehicles to Grid (V2G) concept applied to a Virtual Power Plant Structure
No full textRenewable energy sources will play an increasingly central role in the power network of the future. The will to reduce the dependence on fossil sources as well as growing environmental awareness, both individually and governmentally, is forcing governments throughout the world to invest an enormous amount of capital in renewable energy sources. The European Union, through its Energy and Climate Policy, has fixed an ambitious target: to provide, 20% of electricity from renewable sources by 2020. The additional volatility introduced by renewable energy source to the grid can be compensated by energy storage systems as well as by demand control measurements and by the reinforcement of the power grid. These solutions can improve the system reliability of the electric grid and the efficiency of the energy supply and give more flexibility to the system. This study analyzes the possibilities to use electric vehicles connected to the grid as energy storage system within a Virtual Power Plant structure. Through the formulation of an optimization problem the optimal number of electric vehicles has been evaluate
An adaptive Rotor Flux Observer for Direct Field Oriented Induction Motor Drives
No full textAt the present time the direct field oriented (DFO) control is the widely used control technique in high-performance induction motor (IM) drive. It requires the implementation of a state vector observer for the detection of rotor flux vector. The IM drive performance is strictly connected to that of the rotor flux observer. The motor parameter variations cause the observer mismatching and hence, the IM drive performance degradation. In the present paper an adaptive observer is proposed which allows the on-line rotor time-constant tuning. The identification of the rotor time constant is performed by an MRAS approach. The adaptive observer is synthesized using the Lyapunov stability theory. To improve the speed convergence of the identifier and the selectivity characteristic of the proposed adaptive observer, a time-varying gain has been introduced. The stability of the overall system has been verified using the Lyapunov stability theory. The simulation results evidence the good performance of the proposed observer and of the overall DFO controlled drive. In particular, the interactive effects between observer and identifier gains are evidenced and, thus, used for the selection of the identifier time-varying gain
Sistemi per la Produzione Integrata di Energia Elettrica ed Idrogeno da Fonte Rinnovabile
No full textA Sliding Mode Control Technique for Direct Speed Control of Induction Motor Drives
No full textIn the present paper a sliding mode based 1M drive control technique is proposed. It allows to control the speed and the stator flux magnitude, using just their measure and/or estimation, imposing directly the inverter voltage configuration. The mathematical modellisation of the proposed algorithm and the simulation results are reported to confirm the goodness of the proposed control technique
A simplified charging battery model for smart electric vehicles applications
No full textThis paper proposes a simple and generalized battery model dedicated to lithium rechargeable batteries of electric vehicles, oriented to the energy management of off-board charging stations. In particular, the mathematical description of the used algorithm, the identification of model parameters and the validation of its use for time emulation of fast charging processes are reported and discussed in detail. The comparison between the emulated charging battery behaviours of a Lithium Iron Phosphate battery and the experimental results is reported in order to confirm the accuracy of the model. Finally, an application control scheme for the coordination and energy management of off-board charging stations within the smart grid paradigm is described
A Non-Linear Dynamic Electrical Model of Sodium-Nickel Chloride Batteries
No full textIn this paper a non-linear second order circuit model of high temperature Sodium-Nickel Chloride batteries (SNBs) is presented. The aim is the development of an accurate model easily implementable in microgrids Energy Management System and suitable for their real-time control. The proposed model is based on the analysis of the experimental performance of a commercial 23.5 kWh SNB. In particular, the mathematical description of the used algorithm, the model parameters identification method as well as the measurement tests carried out for their evaluation are reported and discussed in detail. Then, the model is validated using a measured current-voltage profile, developed in order to trigger the whole battery operative range. The comparison between the experimental data and simulations has confirmed the good accuracy of the proposed model in a defined SOC range. However, due to the particular chemical composition of the battery positive electrode, a novel modelling approach specific for the SNB technology has been finally demonstrated to be necessary
Analysis of Vehicle to Grid and Energy Storage Integration in a Virtual Power Plant
No full textIn this paper the integration between the Vehicle to
Grid technology and a stationary energy storage system in a
Virtual Power Plant (VPP) has been investigated. In order to
evaluate the effects of such energy storage systems in an
autonomous VPP, an Energy Management System (EMS),
oriented to improve the local matching between electrical energy
demand and production, has been proposed. To achieve this
target and optimize the local energy production exploitation, an
energy system design procedure, based on the minimization of
the VPP total cost through an annual emulation of the VPP’s
EMS strategy, has been applied. The proposed methodology,
tested on a benchmark VPP, considers the contribution of both
electric vehicles and stationary battery in different possible
configurations. The comparison among three different cases of
study has finally presented at the aim of pointing out the
technical and economic benefits
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