Omar Hegazy | Vrije Universiteit Brussel (original) (raw)

Some Papers by Omar Hegazy

Energies

The increased activity in the field of Battery Electric Vehicles (BEVs) and Hybrid Electric Vehic... more The increased activity in the field of Battery Electric Vehicles (BEVs) and Hybrid Electric Vehicles (HEVs) have led to an increase in standardization work, performed by both world-wide organizations like the IEC or the ISO, as by regional and national bodies such as CEN, CENELEC, SAE or JEVA. The issues of these standards cover several topics: safety, performance and operational/dimension issues. This paper reports a brief overview of current standardization activities of lithium batteries based on IEC 62660-1/2 and ISO 12405-1/2. Furthermore, in this paper, a series of innovative test procedures for lithium-ion batteries are presented. Thanks to these tests, the general characteristics of a battery such as charge and discharge capabilities, power performances and life cycle can be determined. Then, a new approach for extracting the life cycle of a battery in function of depth of discharge has been developed.

2013 World Electric Vehicle Symposium and Exhibition (EVS27), 2013

ABSTRACT This paper is part of a research project, which aims to investigate the opportunities fo... more ABSTRACT This paper is part of a research project, which aims to investigate the opportunities for using the second life batteries after their replacement from plug-in electric vehicles (PHEVs), hybrid electric vehicles (HEVs) and battery electric vehicles (EVs) for smart grid applications. Batteries which are used for vehicular service cannot be used once that the energy capacity becomes less than 70% - 80%. The remaining capacity of the battery can still be utilized for stationary applications such as powering a building during peak load hours and reducing the environmental pollution. Owner of an electric vehicle would be benefited if a market for the used batteries is established. These batteries are called second life batteries. In these applications, the power electronics converters (PECs) play an important role in the development of a high performance integrated system. It means that the performance of the second life batteries mainly depends on the characteristics of the PECs, which are utilized to achieve the integration of the second life batteries with the smart grid. Therefore, this paper presents a comparative evaluation of different multilevel DC/DC converter topologies that can be used to connect the second life batteries to smart grid. Furthermore, the advantages and drawbacks of the most popular multilevel DC/DC converter topologies are presented in detail. In this paper, a selected harmonic elimination (SHE) technique will be used to realize the control system of the multilevel DC/DC converter, and its influence on the performance of each battery module is analyzed. These topologies are designed and verified by using MATLAB/Simulink environment

International Journal of Vehicle …, Jan 1, 2011

ABSTRACT Combining a Fuel Cell (FC), as primary power source, with a Battery Energy System (BES),... more ABSTRACT Combining a Fuel Cell (FC), as primary power source, with a Battery Energy System (BES), as an auxiliary source, for high power demands is a promising approach for future hybrid electric vehicles (HEV). The powertrain control strategy and the component sizing significantly affect the vehicle performance, cost, vehicle efficiency and fuel economy. This paper presents a developed control strategy for optimising the power sharing between sources and components sizing by using Particle Swarm Optimisation (PSO) algorithm. This control strategy implemented on FC/Battery hybrid electric vehicle in order to achieve the best performance with minimum fuel consumption and minimum powertrain components sizing for a given driving cycle with high efficiency. The powertrain and the proposed control strategy have been simulated by Matlab/Simulink. The simulation results have demonstrated that the optimal sizing of the powertrain of FC/battery components and the minimum fuel consumption have been improved by applying the PSO control strategy.

Journal of Power Electronics, Jan 1, 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have t... more The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

works.bepress.com

Interleaving techniques are widely used to reduce input/output ripples, to increase the efficienc... more Interleaving techniques are widely used to reduce input/output ripples, to increase the efficiency and to increase the power capacity of the DC/DC converters. This paper proposes an interleaved multiple-input power converter (IMIPC) that interfaces the fuel cell and energy storage systems (e.g. Batteries or/and Supercapacitors) to the powertrain of the hybrid electric vehicles. The IMIPC is responsible for the power-flow management on-board vehicle for each operating mode. In this research, the IMIPC is proposed in order to reduce the input current ripples, to reduce the output voltage ripples and to reduce the size of passive components with high efficiency. In addition, low EMI and low stress in the switches are expected. Moreover, a generalized small–signal model of the IMIPC is derived in order to design the closed-loop control strategies. The proposed power electronics interface (PEI) and its controller are designed and analyzed by using Matlab/Simulink. The simulation results have demonstrated that the proposed power electronics interface achieves a high performance for high power converter and it can be applied in the FCHEVs.

… IEEE Transactions on, Jan 1, 2009

Page 1. 12 IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 24, NO. 1, MARCH 2009 Efficiency Optimiza... more Page 1. 12 IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 24, NO. 1, MARCH 2009 Efficiency Optimization of Two-Asymmetrical-Winding Induction Motor Based on Swarm Intelligence Amr MA Amin, Mohamed I. El Korfally, Abdallah A. Sayed, and Omar TM Hegazy ...

Dr. Eng. Omar Taha Hegazy, Jan 1, 2006

Optimization of Electrical and …, Jan 1, 2010

Abstract -- In this paper, an optimal design to minimize the cost, mass and volume of the fuel ce... more Abstract -- In this paper, an optimal design to minimize the cost, mass and volume of the fuel cell (FC) and supercapacitor (SC) in a fuel cell hybrid electric vehicle is presented. Because of the hybrid powertrain, component sizing significantly affects vehicle performance, cost ...

Dr. Eng. Omar Taha Hegazy, Jan 1, 2009

... IEEE-ACC. Conf., 2004, pp. 28112817. [10] OS El-labban, Particle swarm optimized direct tor... more ... IEEE-ACC. Conf., 2004, pp. 28112817. [10] OS El-labban, Particle swarm optimized direct torque control of induction motors, M.Sc. thesis, Cairo Univ., Cairo, Egypt, Feb. 2005. ... 20, no. 2, pp. 859866, May 2005. Amr MA Amin received the B.Sc. degree in elec-

In this paper, a novel inverter topology, Eight Switches Inverter (ESI), is proposed for HEV, esp... more In this paper, a novel inverter topology, Eight Switches Inverter (ESI), is proposed for HEV, especially PHEV system to reduce the number of switches (IGBTs), to reduce the cost and the volume of the power electronic unit, and to achieve high performance during discharging mode, braking mode and grid charging / discharging mode. Thereby, this topology gives the ability to connect the vehicle with grid at home or at work to charge the Energy Storage System (ESS) easily, especially the battery unit. The proposed converter gives the PHEV the capability of the integration with Smart Grid (SG) as Movable Energy Storage System (MESS).
In this research, there are three control strategies are tested to validate the performance of the proposed topology. These are indirect field-oriented controller (IFOC), Space Vector PWM (SVPWM), and PWM current control. The proposed scheme has been simulated by MATLAB/ SIMULINK. Simulation results have demonstrated that a novel converter topology has achieved the battery discharging/charging mode and the grid charging/discharging mode with different control techniques efficiently. It is noticed that the proposed converter has provided a reduced number of the IGBTs, a reduced their cost and has achieved the integration with Smart Grid.

The powertrain control strategy and the components sizing significantly affect the vehicle perfor... more The powertrain control strategy and the components sizing significantly affect the vehicle performance, cost and fuel economy. This paper presents a developed control strategy for optimizing the power sharing between sources and components sizing by using particle swarm optimization (PSO) algorithm. PSO method is a member of the wide category of Swarm Intelligence methods (SI). This control strategy implemented on Fuel cell/Battery hybrid electric vehicle with the aim to achieve the best performance with minimum fuel consumption and minimum powertrain components sizing for a given driving cycle. The powertrain and the proposed control strategy have been simulated by MATLAB/SIMULINK. The simulation results have demonstrated that the optimal sizing of the powertrain of Fuel cell/battery components and the minimum fuel consumption have been improved by applying the PSO control strategy.

Power Electronics Transactions, Nov 1, 2012

Abstract This paper presents a DSP based direct digital control (DDC) design and implementation f... more Abstract This paper presents a DSP based direct digital control (DDC) design and implementation for a high power boost converter. A dual loop voltage control is digitally implemented using DSP. The real time workshop (RTW) is used for automatic real-time code generation. A laboratory prototype of a 20 kW boost converter based on TMS320F2808 DSP is presented. The proposed controller performance is investigated using MATLAB simulation and laboratory experiments during reference voltage changes, input voltage changes, and ...

IEEE Transactions on Power Electronics, 2012

Multiphase converter topologies for use in high-performance applications have received increasing... more Multiphase converter topologies for use in high-performance applications have received increasing interest in recent years. This paper proposes a novel multidevice interleaved boost converter (MDIBC) that interfaces the fuel cell with the powertrain of hybrid electric vehicles. In this research, a multidevice structure with interleaved control is proposed to reduce the input current ripples, the output voltage ripples, and the size of passive components with high efficiency compared with the other topologies. In addition, low EMI and low stress in the switches are expected. The proposed dc/dc converter is compared to other converter topologies such as conventional boost converter (BC), multidevice boost converter (MDBC), and two-phase interleaved boost converter (IBC) to verify its dynamic performance. Furthermore, a generalized small-signal model is derived for these dc/dc converters, which has not been previously discussed. A digital dual-loop control is designed to achieve the proper regulator for the converters with fast transient response. The dc/dc converter topologies and their controller are designed and investigated by using MATLAB/Simulink. Finally, the proposed converter (MDIBC) is experimentally validated with results obtained from a 30-kW prototype that has been built and tested in our laboratory based on TMS320F2808 DSP. The simulation and experimental results have demonstrated that the proposed converter is more efficient than other dc/dc converter topologies in achieving high performance and reliability for high-power dc/dc converters.

Energies

2013 World Electric Vehicle Symposium and Exhibition (EVS27), 2013

International Journal of Vehicle …, Jan 1, 2011

Journal of Power Electronics, Jan 1, 2011

works.bepress.com

… IEEE Transactions on, Jan 1, 2009

Dr. Eng. Omar Taha Hegazy, Jan 1, 2006

Optimization of Electrical and …, Jan 1, 2010

Dr. Eng. Omar Taha Hegazy, Jan 1, 2009

Power Electronics Transactions, Nov 1, 2012

IEEE Transactions on Power Electronics, 2012

Energies

Recently, multilevel converters (MLCs) have gained significant attention for stationary applicati... more Recently, multilevel converters (MLCs) have gained significant attention for stationary applications, including static compensators, industrial drives, and utility-grid interfaces for renewable energy sources. Compared to two-level voltage-source inverters (VSI) MLCs feature high-quality AC voltage with reduced harmonic content despite the lower switching frequency of the semiconductor devices. On the DC side, MLCs can integrate multiple isolated/non-isolated battery modules instead of a single battery pack. This helps to keep the system in service in case of a malfunction of one or more battery modules, as well as active balancing among the modules, a feature not possible with two-level VSI. In general, MLCs can be classified into two types: (i) two-port MLCs, which provide a single interface to connect with the battery pack, and (ii) multiport MLCs, which provide multiple interfaces to allow connection at the module or cell level. The classical topologies of both MLC types (e.g., ...

Energies

The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand... more The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand for faster charging necessitate the research and development of power electronic converters to achieve high-power, compact, and reliable EV charging solutions. Although the fast charging concept is often associated with off-board DC chargers, the importance of on-board AC fast charging is undeniable with the increasing battery capacities. This article comprehensively reviews gallium nitride (GaN) semiconductor-based bidirectional on-board charger (OBC) topologies used in both 400 V and 800 V EV applications. Moreover, comparative evaluations of GaN-based bi-directional OBC topologies regarding power conversion losses (conduction loss and soft switching capabilities), power density, implementation considerations, power quality, electromagnetic interference, and reliability aspects have been presented. The status of commercially available GaN power modules, advancements in GaN technology,...

Energies

Along with the technology boom regarding electric vehicles such as lithium-ion batteries, electri... more Along with the technology boom regarding electric vehicles such as lithium-ion batteries, electric motors, and plug-in charging systems, inductive power transfer (IPT) systems have gained more attention from academia and industry in recent years. This article presents a review of the state-of-the-art development of IPT systems, with a focus on low-voltage and high-current electric mobility applications. The fundamental theory, compensation topologies, magnetic coupling structures, power electronic architectures, and control methods are discussed and further considered in terms of several aspects, including efficiency, coil misalignments, and output regulation capability. A 3D finite element software (Ansys Maxwell) is used to validate the magnetic coupler performance. In addition, a 2.5 kW 400/48 V IPT system is proposed to address the challenges of low-voltage and high-current wireless charging systems. In this design, an asymmetrical double-sided LCC compensation topology and a pa...

Batteries

Active Front-End (AFE) rectifiers have regained momentum as the demand for highpower Electric Veh... more Active Front-End (AFE) rectifiers have regained momentum as the demand for highpower Electric Vehicle (EV) charging infrastructure increases exponentially. AFE rectifiers have high efficiency and reliability, and they minimize the disturbances that could be generated due to the operation of the EV charging systems by reducing harmonic distortion and operating close to the Unity Power Factor (UPF). The purpose of this review is to present the current state-of-the-art AFE rectifiers used in fast chargers, focusing on the comparison between different AFE topologies and their components, as well as modular AFE solutions. Furthermore, different control strategies of AFE converters are presented and compared. Some of their more widely used control techniques, namely Voltage Oriented Control (VOC), Direct Power Control (DPC), Hysteresis Current Control (HCC), and Model Predictive Control (MPC), have been implemented, and their performance compared. Centralized and distributed control syste...

Energies

Electric vehicles (EVs) are expected to take over the transportation and mobility market over tra... more Electric vehicles (EVs) are expected to take over the transportation and mobility market over traditional internal combustion engine (ICE) vehicles soon. The internal power demands of EVs are expected to increase. The reason for this is to achieve a longer driving range for the EV and to provide the required power for the low-voltage (LV) network auxiliary loads. To illustrate, there are extra added sensors, cameras, and small actuating motors, especially for future autonomous vehicles. Therefore, a new electrical/electronic (E/E) architecture is required to convert the high-voltage (HV) traction battery voltage (e.g., 320–800 V DC) to the standard LV levels with high current ratings of 5 kW and more. This HV-LV DC-DC converter is known in the literature as an auxiliary power module (APM). The standard LV rails in an EV are the 12 V/24 V rail to supply for an instant the EV’s lighting and electronic control units (ECUs), while the 48 V rail is required for propulsive loads, such as ...

Batteries

The global promotion of electric vehicles (EVs) through various incentives has led to a significa... more The global promotion of electric vehicles (EVs) through various incentives has led to a significant increase in their sales. However, the prolonged charging duration remains a significant hindrance to the widespread adoption of these vehicles and the broader electrification of transportation. While DC-fast chargers have the potential to significantly reduce charging time, they also result in high power demands on the grid, which can lead to power quality issues and congestion. One solution to this problem is the integration of a battery energy storage system (BESS) to decrease peak power demand on the grid. This paper presents a review of the state-of-the-art use of DC-fast chargers coupled with a BESS. The focus of the paper is on industrial charger architectures and topologies. Additionally, this paper presents various reliability-oriented design methods, prognostic health monitoring techniques, and low-level/system-level control methods. Special emphasis is placed on strategies t...

Energies

Recently, there has been significant attention given to the electrification of transportation due... more Recently, there has been significant attention given to the electrification of transportation due to concerns about fossil fuel depletion and environmental pollution. Conventional drive systems typically include a clutch, reduction gear, and mechanical differential, which results in power loss, noise, vibration, and additional maintenance. However, in-wheel motor drive technology eliminates the need for these components, providing benefits such as higher system efficiency, improved wheel control, and increased passenger comfort. This article offers a comprehensive review of the technology and development of in-wheel motor drives. It begins with an overview of in-wheel motor drives in electric vehicles, followed by an exploration of the types of electric motors suitable for in-wheel motor drives. The paper then presents an industrial state of the art of in-wheel motors, comparing them with conventional motor drives, and reviews the implemented power electronics, control system, and c...

Applied Sciences

This study presents the optimization and tuning of a simulation framework to improve its simulati... more This study presents the optimization and tuning of a simulation framework to improve its simulation accuracy while evaluating the energy utilization of electric buses under various mission scenarios. The simulation framework was developed using the low fidelity (Lo-Fi) model of the forward-facing electric bus (e-bus) powertrain to achieve the fast simulation speeds necessary for real-time fleet simulations. The measurement data required to verify the proper tuning of the simulation framework is provided by the bus original equipment manufacturers (OEMs) and taken from the various demonstrations of 12 m and 18 m buses in the cities of Barcelona, Gothenburg, and Osnabruck. We investigate the different methodologies applied for the tuning process, including empirical and optimization. In the empirical methodology, the standard driving cycles that have been used in previous studies to simulate various use case (UC) scenarios are replaced with actual driving cycles derived from measureme...

Energies

Multiphase drives (MPDs) have been the subject of research for the last two decades. Despite bein... more Multiphase drives (MPDs) have been the subject of research for the last two decades. Despite being a technology that is still in the process of development, a significant number of research studies and developments have been reported in scientific literature over the past few years. This article aims to collect and present a review of these recent contributions, providing a comprehensive and insightful state of the art on this topic and future technology trends. The elaborated aspects include the advantages of multiphase machines, a general introduction to five-phase and six-phase machines, and their modelling techniques. In addition, new promising MPD topologies are covered. Recent advances in modulation techniques and the control of multilevel converters are also discussed. Finally, future trends and challenges in further developing this technology are discussed.

Energies

Nowadays, the implementation of smart charging concepts and management strategies with vehicle-to... more Nowadays, the implementation of smart charging concepts and management strategies with vehicle-to-everything (V2X) functionalities, is required to address the increasing number of battery electric buses (BEBs) in cities. However, the introduction of these new functionalities to the charging systems might affect the lifetime of the charging infrastructure. This has not been investigated yet, although it is an important aspect for the BEB operators. Therefore, this paper performs a detailed reliability assessment to study the impact of smart and bidirectional (V2X) charging on the lifetime of SiC-based high-power off-board charging infrastructure used for BEBs in a depot for overnight charging. In this paper, four different charging current profiles, generated by a smart charging algorithm, are considered. In addition, an electro-thermal model of the charging system is developed to accurately estimate the junction temperature of the switching devices when subjected to the applied char...

Energies

This paper presents the comparisons between two types of switched reluctance machines (SRMs) and ... more This paper presents the comparisons between two types of switched reluctance machines (SRMs) and SRM converters. An SRM with a segmental rotor is compared with a conventional SRM (CSRM), and an SRM converter containing a passive boost circuit is compared with a conventional asymmetric half-bridge (AHB) converter. The segmental SRM has an asymmetric rotor with a segmented structure. The four rotor segments are made of steel laminations. Two segments are misaligned with the other two by 15 degrees. The torque ripple of the SRM with this structure is decreased, and the static torque is increased compared to a conventional SRM. The boost converter comprises a front-end circuit and a conventional AHB converter. The front-end circuit boosts the voltage level. The boosted voltage accelerates the rising and falling progress of the phase current. In this way, the SRM can obtain a greater speed and a smaller torque ripple. The comparison is conducted in simulation and validated through the ex...

Energies

Long-haul heavy-duty vehicles, including trucks and coaches, contribute to a substantial portion ... more Long-haul heavy-duty vehicles, including trucks and coaches, contribute to a substantial portion of the modern-day European carbon footprint and pose a major challenge in emissions reduction due to their energy-intensive usage. Depending on the hydrogen fuel source, the use of fuel cell electric vehicles (FCEV) for long-haul applications has shown significant potential in reducing road freight CO2 emissions until the possible maturity of future long-distance battery-electric mobility. Fuel cell heavy-duty (HD) propulsion presents some specific characteristics, advantages and operating constraints, along with the notable possibility of gains in powertrain efficiency and usability through improved system design and intelligent onboard energy and thermal management. This paper provides an overview of the FCEV powertrain topology suited for long-haul HD applications, their operating limitations, cooling requirements, waste heat recovery techniques, state-of-the-art in powertrain control...

Energies

Vehicle-to-Grid (V2G) technology is viewed as a viable solution to offer auxiliary power system s... more Vehicle-to-Grid (V2G) technology is viewed as a viable solution to offer auxiliary power system services. Currently, V2G operation is only possible through DC chargers using the CHAdeMO connector with the necessary communication protocol. However, in Europe, for high-power DC charging (>50 kW), the Combined Charging Service (CCS) Type 2 is preferred over CHAdeMO. Therefore, this work presents the development of a V2G testing system with a Combo CCSType 2 charger including communication via the ISO 15118-2 protocol. The BOSCH passenger car with a 400 V battery pack is used to test and validate the technical feasibility of V2G charging via a Combo CCS Type 2 connector standard. The V2G feature is characterized in terms of efficiency, signal delay, response proportionality, magnitude accuracy and noise precision. A data driven V2G charger simulation model based on the real-time data is also developed in MATLAB/Simulink. The performance under various operating settings is presented i...

Energies

This article aims to calculate, analyse and compare the optimal powertrain sizing solutions for a... more This article aims to calculate, analyse and compare the optimal powertrain sizing solutions for a long-haul plug-in series hybrid coach running on diesel and hydrotreated vegetable oil (HVO) using a co-design optimisation approach for: (1) lowering lifetime carbon footprint; (2) minimising the total cost of ownership (TCO); (3) finding the right sizing compromise between environmental impact and economic feasibility for the two fuel cases. The current vehicle use case derived from the EU H2020 LONGRUN project features electrical auxiliary loads and a 100 km zero urban emission range requiring a considerable battery size, which makes its low carbon footprint and cost-effective sizing a crucial challenge. Changing the objective between environmental impact and overall cost minimisation or switching the energy source from diesel to renewable HVO could also significantly affect the optimal powertrain dimensions. The approach uses particle swarm optimisation in the outer sizing loop whil...

Energies

The development of electric vehicles (EVs) is an important step towards clean and green cities. A... more The development of electric vehicles (EVs) is an important step towards clean and green cities. An electric powertrain provides power to the vehicle and consists of a charger, a battery, an inverter, and a motor as the main components. Supplied by a battery pack, the automotive inverter manages the power of the motor. EVs require a highly efficient inverter, which satisfies low cost, size, and weight requirements. One approach to meeting these requirements is to use the new wide-bandgap (WBG) semiconductors, which are being widely investigated in the industry as an alternative to silicon switches. WBG devices have superior intrinsic properties, such as high thermal flux, of up to 120 W/cm2 (on average); junction temperature of 175–200 °C; blocking voltage limit of about 6.5 kV; switching frequency about 20-fold higher than that of Si; and up to 73% lower switching losses with a lower conduction voltage drop. This study presents a review of WBG-based inverter cooling systems to inves...

Energies

This paper develops a multi-objective co-design optimization framework for the optimal sizing and... more This paper develops a multi-objective co-design optimization framework for the optimal sizing and selection of battery and power electronics in hybrid battery energy storage systems (HBESSs) connected to the grid. The co-design optimization approach is crucial for such a complex system with coupled subcomponents. To this end, a nondominated sorting genetic algorithm (NSGA-II) is used for optimal sizing and selection of technologies in the design of the HBESS, considering design parameters such as cost, efficiency, and lifetime. The interoperable framework is applied considering three first-life battery cells and one second-life battery cell for forming two independent battery packs as a hybrid battery unit and considers two power conversion architectures for interfacing the hybrid battery unit to the grid with different power stages and levels of modularity. Finally, the globally best HBESS system obtained as the output of the framework is made up of LTO first-life and LFP second-li...

Energies

Nowadays, Wireless Power Transfer (WPT) technology is receiving more attention in the automotive ... more Nowadays, Wireless Power Transfer (WPT) technology is receiving more attention in the automotive sector, introducing a safe, flexible and promising alternative to the standard battery chargers. Considering these advantages, charging electric vehicle (EV) batteries using the WPT method can be an important alternative to plug-in charging systems. This paper focuses on the Inductive Power Transfer (IPT) method, which is based on the magnetic coupling of coils exchanging power from a stationary primary unit to a secondary system onboard the EV. A comprehensive review has been performed on the history of the evolution, working principles and phenomena, design considerations, control methods and health issues of IPT systems, especially those based on EV charging. In particular, the coil design, operating frequency selection, efficiency values and the preferred compensation topologies in the literature have been discussed. The published guidelines and reports that have studied the effects ...

2020 IEEE Vehicle Power and Propulsion Conference (VPPC)

Charging Management Strategy is a critical aspect in electric bus fleets to minimize the impact o... more Charging Management Strategy is a critical aspect in electric bus fleets to minimize the impact on the local electricity grid and to minimize the financial cost to the bus operators. To realize a fleet of battery electric public transport buses in a city depends on two major stakeholders, namely the city bus operator and the electricity distribution systems operator. The cost of the electric charging infrastructure, including the high powered ultrafast DC chargers for opportunity charging and lower powered depot chargers for overnight charging is a significant investment for the city bus operator in terms of capital, installation, and grid connection costs, while the distribution system operator has to contend with significant power load on the electricity grid when multiple ultrafast chargers are in operation. This paper investigates a Use Case of an electric bus fleet plying a route, and the optimal selection of chargers, charging duration, and battery State of Charge that will minimize the impact on the local grid and minimize the total cost of ownership. A Simple Optimization algorithm was utilized for this purpose. Results show that the objectives are mutually exclusive, and there need to be a tradeoff to achieve the optimal balance between grid impact and total cost of ownership. Results also show that grid impact and the total cost of ownership are both minimized when opting for low crate charging instead of high crate charging or when charging only for short durations. Finally, an ECO-charging technique based on utilizing short-duration pulsed charging followed by cool-down periods instead of charging in one continuous longduration pulse was investigated to determine its efficacy in lowering the energy requirements of the bus by reducing the battery heat generation due to high crate charging. The optimum charging-to-cooldown ratio and the optimum charging pulse was found using brute force method to determine the lowest cooling energy consumption for a variety of charging rates. Results show that up to 5% reduction in grid impact can be achieved due to implementation of ECO-charging technique.

2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)

This paper proposes a small signal modeling approach of a bidirectional integrated converter conf... more This paper proposes a small signal modeling approach of a bidirectional integrated converter configuration, which utilizes the traction inverter, motor windings and interleaved DC/DC converter for charging applications. This modeling technique represents the power electronic converters (AC/DC and DC/DC) as a transfer function that facilitates both Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) operations. During the G2V mode, the traction inverter converts into an AC/DC converter, while during the V2G mode, it operates as a DC/AC inverter, and the 3-phase interleaved DC/DC converter operates in buck and boost modes for the G2V and V2G operations, respectively. Moreover, the controller design based on the plant transfer functions is also a focal point of this paper. The inner current and outer voltage loop controllers of the DC/DC converter are designed based on the k-factor approach. For DC- link voltage control of the AC/DC converter, a dual loop control approach is adopted. Finally, the performance of both control systems has been validated via performance comparison between switch- based model and small-signal average system model in MATLAB/Simulink®.