segunda-feira, 30 de outubro de 2023
Isolated DC-DC Power Converters for Simultaneous Charging of Electric Vehicle Batteries: Research Review, Design, High-Frequency Transformer Testing, Power Quality Concerns, and Future-----Srinath Belakavadi Sudarshan and Gopal Arunkumar
Abstract:
The transportation industry is transitioning from conventional Internal Combustion Engine
Vehicles (ICVs) to Electric Vehicles (EVs) due to the depletion of fossil fuels and the rise in nontraditional
energy sources. EVs are emerging as the new leaders in the industry. Some essential
requirements necessary for the widespread adoption of EVs include sufficient charging stations with
numerous chargers, less to no wait time before charging, quick charging, and better range. To enable
a quicker transition from ICVs to EVs, commercial organizations and governments would have to put
in a mammoth effort, given the low number of installed chargers in developing nations such as India.
One solution to lower the waiting time is to have multiple vehicles charging simultaneously, which
might involve charging two- and four-wheelers simultaneously, even though their battery voltage
ratings differ. This paper begins by providing the details of the power sources for EV charging,
the charging levels and connector types, along with the specifications of some of the commercial
chargers. The necessity of AC-DC converters in EV charging systems is addressed along with the
power quality concerns due to the increased penetration of EVs. Next, a review of the existing
research and technology of isolated DC-DC converters for simultaneous charging of EV batteries is
provided. Further, several potential isolated DC-DC converter topologies for simultaneous charging
are described with their design and loss estimation. A summary of the existing products and
projects with simultaneous charging features is provided. Finally, insight is given into the future of
simultaneous charging.
VIEW FULL TEXT:
domingo, 29 de outubro de 2023
Técnicas de control para la conexión en paralelo de inversores aplicadas a convertidores de interconexión entre los buses de CC y CA de microrredes híbridas e inversores fotovoltaicos centralizados de alta potencia---DEPARTAMENTO DE INGENIERÍA ELECTRÓNICA Grupo de Sistemas Electrónicos Industriales
Técnicas de control para la conexión en paralelo de inversores aplicadas a convertidores de interconexión entre los buses de CC y CA de microrredes híbridas e inversores fotovoltaicos centralizados de alta potencia-
DEPARTAMENTO DE INGENIERÍA ELECTRÓNICA Grupo de Sistemas Electrónicos Industriales
Tesis Doctoral
Presentada por:
Marian Liberos Mascarell
Dirigida por:
Dr. Emilio Figueres Amorós
Dr. Gabriel Garcerá Sanfelíu
Valencia, Abril 2021 UNIVERSIDAD POLITECNICA DE VALENCIA
Resumen
En este trabajo se proponen técnicas de control específicas para la paralelización de inversores sin transformador conectados a red, en aplicaciones de interconexión de buses de microrredes híbridas e instalaciones fotovoltaicas de gran potencia. La paralelización de inversores presenta múltiples ventajas como la modularidad, la redundancia o la flexibilidad para ampliar la potencia de un sistema o de una instalación. En el caso de inversores fotovoltaicos centralizados, también permite la conexión/desconexión de módulos inversores conectados en paralelo permitiendo una mayor eficiencia global cuando se trabaja a bajas potencias. Sin embargo, la paralelización de inversores provoca la aparición de corrientes de circulación que pueden provocar efectos indeseables en el sistema o en la instalación.
Las contribuciones que se llevan a cabo en esta tesis están todas ellas orientadas a la mejora de la operación de inversores en paralelo en las aplicaciones descritas y son las siguientes:
1) Se presenta un modelo preciso en pequeña señal de n inversores conectados en paralelo con filtro de conexión a red LCL, en el cual se tienen en consideración los términos de acoplamiento entre fases de los inductores trifásicos.
2) Se propone una técnica de control en la que se emplean n-1 lazos de regulación que controlan la componente homopolar de las corrientes e imponen un valor nulo en régimen permanente, a fin de eliminar las corrientes de circulación.
3) Se propone el uso de moduladores en espacio vectorial de tres dimensiones (3D-SVM) para implementar el control de la componente homopolar de las corrientes.
4) Se muestran resultados analíticos, de simulación y experimentales que validan el esquema de control propuesto considerando la aparición de corrientes de circulación debido a distintos factores: desbalanceo de inductancias entre las fases de un inversor y de distintos inversores, desbalanceo de potencia entre inversores y empleo de modulaciones distintas en los inversores conectados en paralelo. Los ensayos experimentales se realizan sobre un convertidor trifásico de 10 kW formado por la conexión en paralelo de dos módulos de 5 kW cada uno.
5) Se muestran resultados de simulación y experimentales de la aplicación de las técnicas de reducción de corrientes de circulación a convertidores de interconexión entre los buses de alterna y continua de microrredes híbridas. Los ensayos experimentales se particularizan a un convertidor trifásico de 7.5 kW formado por un módulo de 5 kW y otro de 2.5 kW conectados en paralelo, emulando una eventual ampliación de potencia del 50 %.
6) Se lleva a cabo el estudio por simulación de un sistema fotovoltaico de 2 MW compuesto por cuatro inversores de 500 kW conectados en paralelo, demostrando que el control de las componentes homopolares de las corrientes reduce en gran medida el valor de las corrientes de circulación y mejora el desempeño de la instalación.
7) Por último, se propone una técnica de control para mejorar la eficiencia global de inversores fotovoltaicos centralizados de potencia elevada, el cual se basa en la utilización de modelos funcionales bidimensionales de eficiencia para activar/desactivar los módulos de potencia en función del punto de operación del campo fotovoltaico.
Abstract
In this work they have been proposed specific control techniques for the parallelization of transformerless inverters connected to the grid in two specific applications: i) the interlinking converter between ac and dc bus of hybrid microgrids and ii) high power photovoltaic farms. Paralleling of inverters presents some advantages as modularity, redundancy or flexibility for increasing the power of a system or of a plant. In photovoltaic centralized inverters, the parallel inverters can be connected and disconnected in order to improve the global efficiency when the system works at low power. However, the inverters paralleling causes the appearance of circulating currents which can produce undesirable effects in the system or in the plant.
The contributions that are carried out in this thesis are all of them aimed at improving the operation of parallel inverters in the described applications and they are as follows:
1) It has been presented an accurate small signal model of n parallel inverters with an LCL grid filter, in which the mutual coupling terms of the three-phase inductors has been considered.
2) It has been proposed a control technique with n-1 control loops that control the zero-sequence current component by setting a zero value in steady state, looking for eliminating the circulating currents.
3) It has been proposed the use of three-dimension space vector modulator (3D-SVM) to implement the zero-sequence currents control.
4) The analytical results have been validated by means of simulation and experimental results, showing the performance of the proposed control scheme considering the appearance of circulating currents due to different factors: i) inductor imbalances between the phases of an inverter or ii) between different inverters, iii) power imbalances between inverters and iv) the use of different modulation techniques in the parallel inverters. The experimental tests have been carried out on a 10 kW three-phase converter composed by the parallel connection of two 5 kW modules.
5) They have been shown both simulation and experimental results of the application of circulating current reduction techniques to interlinking converters between the DC and the AC buses of hybrid microgrids. The experimental tests have been particularized to a 7.5 kW three-phase converter
composed by a 5 kW and a 2.5 kW module connected in parallel, emulating an eventual 50 % power expansion.
6) Is has been carried out the simulation study of a 2 MW photovoltaic system composed by four 500 kW inverters connected in parallel, showing that the control of the zero-sequence currents greatly reduces the value of the circulating currents and improve the system performance.
7) Finally, it has been proposed a control technique for the improvement of the global efficiency of high power photovoltaic centralized inverters, which is based in the use of bidimensional functional efficiency models to activate/deactivate the power modules according to the operation point of the photovoltaic farm.VIEW FULL TEXT:https://riunet.upv.es/handle/10251/168190
sexta-feira, 27 de outubro de 2023
Ebook: Inversores Fotovoltaicos conectados à rede-ENSAIOS E DESENVOLVIMENTO DE SISTEMAS FOTOVOLTAICOS PARA APOIO AO SETOR DE ENERGIAS RENOVÁVEIS DO RS, aprovado no Edital 01/2016 – Programa de Apoio aos Pólos Tecnológicos da Secretaria de Desenvolvimento Econômico, Ciência e Tecnologia do Estado do Rio Grande do Sul (SDECT/RS)
VIEW FULL TEXT: https://inriufsm.com.br/wp-content/uploads/2023/06/Cartilha_virtual-_Ensaio_Inversores_Fotovoltaicos.pdf
Essa cartilha virtual é resultado do projeto ENSAIOS E DESENVOLVIMENTO DE SISTEMAS FOTOVOLTAICOS PARA APOIO AO SETOR DE ENERGIAS RENOVÁVEIS DO RS, aprovado no Edital 01/2016 – Programa de Apoio aos Pólos Tecnológicos da Secretaria de Desenvolvimento Econômico, Ciência e Tecnologia do Estado do Rio Grande do Sul (SDECT/RS), Convênio DCIT 62/2016. Autores:
Prof. Leandro Michels – UFSM (organizador) Prof. Lucas Vizzotto Bellinaso – UFSM
Henrique Horst Figueira – UFSM
Ricardo Jochann Franceschi Bortolini – UFSM
Débora de Moura Steinhorst – UFSM
Alexandre Torres Ruschel – UFSM
Lucas Gais Gularte – UFSM
Alisson Mazzorani Vieira – UFSM
Igor Antônio Baldissera de Bitencourt – UFSM
Mateus Nava Mezaroba – URI/Erechim
Equipe do projeto:
Prof. Dr. Leandro Michels (coordenador) – UFSM
Prof. Dr. José Renes Pinheiro (pesquisador) – UFSM
Prof. Dr. Hélio Leães Hey (pesquisador) – UFSM
Prof. Dr. Cassiano Rech (pesquisador) – UFSM
Prof. Dr. Cassiano Rech (pesquisador) – UFSM
Prof. Dr. Julio Cezar Mairesse Siluk (pesquisador) – UFSM
Prof. Dr. Luciano Schuch (pesquisador) – UFSM
Prof. Dra. Morgana Pizzolato (pesquisadora) – UFSM
Prof. Dr. Jorge Rodrigo Massing (pesquisador) – UFSM
Prof. Dr. Elpidio Oscar Benitez Nara (pesquisador) – UNISC
Apoio:
Sonnen Energia Ltda - EPP
DISTRIBUIÇÃO ONLINE GRATUITA
Todos os direitos autorais estão reservados aos autores.
quarta-feira, 25 de outubro de 2023
Projeto de um transformador de potência de média frequência (kHz)- Pedro Filipe Francisco Reis-Dissertação para obtenção do Grau de Mestre em Engenharia Eletrotécnica e de Computadores
Projeto de um transformador de potência de média frequência (kHz) Pedro Filipe Francisco Reis
Dissertação para obtenção do Grau de Mestre em
Engenharia Eletrotécnica e de Computadores
Resumo
Neste trabalho são apresentadas as equações necessárias para realizar o projeto de um
transformador. São elaboradas considerações acerca da escolha do material do núcleo e dos
enrolamentos de forma a minimizar os problemas introduzidos pelo caracter de média frequência do
transformador. São calculados os parâmetros do transformador que se pretende construir tendo em
conta as especificações iniciais. É apresentado o modelo do transformador e os seus parâmetros são
estimados a partir de equações teóricas. Os parâmetros são estimados também recorrendo a um
analisador de redes e ensaiando o transformador (ensaios em circuito aberto, curto circuito e carga).
Um mapa de rendimento do transformador é apresentado. É elaborada uma simulação de simulink do
transformador, usando os parâmetros estimados nos ensaios, de forma a validar os resultados
obtidos.
Abstract
In this paper are described the equations needed to design a transformer. Some
considerations about the choice of the core and windings materials are made, due to the medium
frequency character of the transformer and are presented solutions to the problems. The parameters
of the prototype to build are calculated and the prototype is mounted. The model of the transformer is
presented and its parameters are estimated theoretically, with an impedance meter and testing the
transformer in open circuit, short circuit and load condition. An efficiency map of the transformer is
made. A Simulink simulation of the transformer, using the parameters obtained in the tests, is made to
validate the results obtained before.
VIEW FULL TEXT:
PROGRAMA COMPUTACIONAL PARA PROJETO DE TRANSFORMADORES UTILIZADOS EM FONTES DE ALIMENTAÇÃO CHAVEADAS-CLÁUDIO LUÍS EBERT-UNIVERSIDADE FEDERAL DE SANTA CATARINA-BRASIL
PROGRAMA COMPUTACIONAL PARA PROJETO DE TRANSFORMADORES UTILIZADOS EM FONTES DE ALIMENTAÇÃO CHAVEADAS
DISSERTAÇÃO SUBMETIDA À UNIVERSIDADE FEDERAL DE SANTA CATARINA PARA OBTENÇÃO DO GRAU DE MESTRE EM
ENGENHARIA ELETRICA.
CLÁUDIO LUÍS EBERT
FLORIANÓPOLIS, AGOSTO DE 1997.
RESUMO
Este trabalho apresenta uma metodologia de projeto de transformadores
para uso em freqüência elevada, utilizados em fontes de alimentação chaveadas. A
partir de estudos analíticos sobre os principais parâmetros envolvidos no projeto, a
metodologia definida é implementada através do desenvolvimento de um programa
computacional.
A implementação de tal programa é feita tomando como suporte básico o
software Borland Delphi, que combina uma interface gráfica, um compilador Pascal e
um banco de dados.
Dentre os objetivos deste trabalho destaca-se a otimização conjugada à
facilidade no projeto do transformador, além da precisão e da possibilidade de se
considerar parâmetros que normalmente são desprezados, muito embora importantes.
O programa implementado é composto por telas de projeto, telas para
seleção de materiais, um algoritmo matemático e bancos de dados. Dentre os bancos
de dados destacam-se o dos materiais ferrimagnéticos (ferrites) de alguns fabricantes,
e o dos núcleos, onde tem-se todas as características necessárias do mesmo. Desta
forma o usuário dispõe rapidamente de informações decisivas no projeto e que, dada a
estrutura do programa, podem ser completadas e atualizadas.
Para a verificação dos projetos feitos via programa computacional,
montou-se um inversor ponte completa, onde o transformador tem uma onda quadrada
simétrica em seu enrolamento primário.
A partir dos resultados obtidos experimentalmente comprova-se a eficácia
do programa, a facilidade no projeto do transformador, bem como um funcionamento
adequado do mesmo, validando desta forma a metodologia de projeto adotada.
VIEW FULL TEXT:
domingo, 22 de outubro de 2023
단상 반도체 변압기의 출력 전력 전향 보상을 통한 과도 응답 개선 = A Transient Response Improvement by Output Power Feedforward Compensation for Single-Phase Solid-State Transformer--Bang Jaehyeon Department of Electrical Engineering Graduate School of Konkuk University-
ABSTRACT
A Transient Response Improvement by Output
Power Feedforward Compensation for Single-
Phase Solid-State Transformer
Bang Jaehyeon
Department of Electrical Engineering
Graduate School of Konkuk University
This paper proposes a output power feedforward compensation method for
Dual Active Bridge(DAB) converter based 2-stage single-phase solid-state
transformer. Solid-State Transformer(SST) is a bidirectional power
converter which is capable of electrical isolation between input and output
stage. SST enables the connection of DC power sources such as PV panels,
Fuel Cells, and ESS much easier compared with conventional transformers by
forming DC bus.
Each stage of SST composes of AC-DC converter and isolated DCDC
converter. Especially, DAB converter, which has advantages of
galvanic isolation with high frequency(HF) transformer, facility of
bidirectional operation, and ease of realizing soft switching, is regarded
as one of the most fundamental elements in SST. In contrast to
conventional PWM converters, DAB converter controls output power by
adjusting the phase shift between output voltage of two H-bridges.
70
For designing output voltage feedback controller, small signal model
of DAB converter derived from output power equation with phase
reference
DAB d is applied. Also, bandwidth limitation caused by 120Hz
power ripple in DC-link voltage controller, which induces unequal input
and output voltage ratio compared with turns ratio of HF transformer, is
described. For eliminating this voltage decoupling with current peak
rising of leakage inductor, output power-based feedforward
compensation method for DC-link voltage controller is proposed.
Furthermore, the effectiveness of feedforward term is identified by
confirming the reduction in output impedance of converter based on
small signal model. In comparison of experimental results, proposed
method verified the improvement in transient DC-link voltage decrease
by 24.8% and leakage inductor current peak increase by 27.7% during
load step input. It also yielded improvement in DC-link voltage increase
by 23% while unload transient.
Keyword : Solid-State Transformer(SST), Dual Active Bridge(DAB) converter
ALTERNATIVE LINK:
domingo, 15 de outubro de 2023
배터리 에너지 저장 시스템에 사용되는 전력 변환 시스템의 디지털 제어 Digital Control of Power Conversion System Used in Battery Energy Storage System-Wan, Kim Department of Marine Electronic, Communication and Computer Engineering, Graduate School, Mokpo National Maritime University
Digital Control of Power Conversion System Used in Battery Energy Storage System
BY Wan, Kim
Department of Marine Electronic, Communication and Computer
Engineering,
Graduate School, Mokpo National Maritime University
(Supervised by Professor : Kwang-Woon, Lee)
ABSTRACT
quarta-feira, 11 de outubro de 2023
A comprehensive design approach for a three-winding planar transformer Shenli Zou1 Chanaka Singhabahu2 Jianfei Chen2 Alireza Khaligh2
A comprehensive design approach for a three-winding planar transformer
Shenli Zou1 Chanaka Singhabahu2 Jianfei Chen2 Alireza Khaligh2
1Electric Power Conversion, Rivian Automotive,
Inc, USA
2Maryland Power Electronics Laboratory (MPEL),
Department of Electrical and Computer
Engineering, Institute for Systems Research,
University of Maryland, College Park, Maryland,
USA
Abstract
In this paper, a new three-winding planar transformer design with the integrated leakage inductor is proposed for a triple-active-bridge converter. It enables two output voltage levels: a high voltage (HV) output port and a low voltage (LV) output port. The primary and secondary windings are split unevenly in both side legs while the tertiary winding is connected in parallel. The unique winding configuration enables: (i) enhanced efficiency with low volume; and (ii) suppressed parasitic capacitances. Detailed transformer reluctance and loss models are developed in the design process. The core geometry is optimized using a reluctance-model-based mathematical computation. Moreover, comprehensive high-fidelity simulations are conducted to analyse the trade-offs among parasitic capacitances, losses, and inductances. The customized core and the non-overlapping winding boards are assembled, characterized, and tested under various power flow conditions.
VIEW FULL TEXT
domingo, 8 de outubro de 2023
Full-SiC Integrated Power Module Based on Planar Packaging Technology for High Efficiency Power Converters in Aircraft Applications O. Raab, M. Guacci, A. Griffo, K. Kriegel, M. Heller, J. Wang, D. Bortis, M. Schulz, J. W. Kolar
Proceedings of the 11th International Conference on Integrated Power Electronics Systems (CIPS 2020), Berlin, Germany, March 24-26, 2020
Full-SiC Integrated Power Module Based on Planar Packaging Technology for High
Efficiency Power Converters in Aircraft Applications
O. Raab,
M. Guacci,
A. Griffo,
K. Kriegel,
M. Heller,
J. Wang,
D. Bortis,
M. Schulz,
J. W. Kolar
Full-SiC Integrated Power Module based on Planar Packaging Technology for High Efficiency Power Converters in Aircraft Applications
Oliver Raaba
, Mattia Guaccib
, Antonio Griffoc
, Kai Kriegela
, Morris Hellerb
, Jiabin Wangc
, Dominik Bortisb
, Martin
Schulza
, and Johann W. Kolarb
aSiemens AG, Corporate Technology, Munich, Germany
bPower Electronic Systems Laboratory, ETH Zurich, Zurich, Switzerland
cDepartment of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK
Abstract
Compact, light-weight, efficient and reliable power converters are fundamental for the future of More Electrical Aircraft
(MEA). Core elements supporting the electrification of the aerospace industry are power modules (PMs) employing
exclusively SiC MOSFETs. In order to fully exploit the high switching speeds enabled by SiC, and to address the
challenges arising from the parallelization of power devices, novel PM concepts must be investigated. In this paper,
highly symmetrical layouts, low inductance planar interconnection technologies, and integrated buffer capacitors are
explored to realize a high efficiency, fast-switching, and reliable full-SiC PM for MEA applications. A comprehensive
assessment of a number of performance metrics against state-of-the-art full-SiC PMs demonstrates the benefits of the
proposed design approach and manufacturing technologies. Moreover, by integrating temperature and current sensors,
intelligent functions, which are crucial for the safe application of power electronics in MEA, are added to the developed
PM. In this context, the use of MOSFETs’ Temperature Sensitive Electrical Parameters for online junction temperature
estimation is demonstrated, allowing for non-invasive, i.e. without the need for dedicated sensors, thermal monitoring.
Additionally, a highly compact gate driver, reducing the overall system volume and complexity, is designed and integrated
in the housing of the PM. Finally, switching waveforms are measured during operation of the PM at 500V and 200A,
proving the performance improvement enabled by the low inductance layout, the integrated snubber, and the gate driver.
VIEW FULL TEXT:
sexta-feira, 6 de outubro de 2023
The MEGACube 166kW/20kHz Medium-Frequency Transformer
The MEGACube 166kW/20kHz Medium-Frequency Transformer
ABSTRACT
High power DC-DC conversion constitutes the key enabling technology for the implementation of solid-statetransformers.
Within these high-power DC-DC converters, the Medium Frequency (MF) transformer is one of the
main components, as its task is to provide the primary to secondary isolation and the step-up ratio between the
different voltage levels. Several options for the construction of this MF transformer have been reported with
different considered core materials, winding arrangements, isolation concepts and thermal management, whereby the
main realizations will be revised in this paper. Thereafter, the details of a 166kW/20kHz MF transformer will be
presented together with the designed test-bench utilized for the continuous testing of the transformer.
Design and Experimental Analysis of a Medium-Frequency Transformer for Solid-State Transformer Applications M. Leibl, G. Ortiz, J. W. Kolar
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, VOL. 5, NO. 1, MARCH 2017
Design and Experimental Analysis of a
Medium-Frequency Transformer for
Solid-State Transformer Applications
Michael Leibl, Member, IEEE, Gabriel Ortiz, Member, IEEE, and Johann W. Kolar, Fellow, IEEE
Abstract— Within a solid-state transformer, the isolated dc–dc
converter and in particular its medium-frequency transformer
are one of the critical components, as it provides the required
isolation between primary and secondary sides and the voltage
conversion typically necessary for the operation of the system.
A comprehensive optimization procedure is required to find a
transformer design that maximizes power density and efficiency
within the available degrees of freedom while complying with
material limits, such as temperature, flux density, and dielectric
strength as well as outer dimension limits. This paper presents
an optimization routine and its underlying loss and thermal
models, which are used to design a 166 kW/20 kHz transformer
prototype achieving 99.4% efficiency at a power density of
44 kW/dm3. Extensive measurements are performed on the
constructed prototype in order to measure core and winding
losses and to investigate the current distribution within the litz
wire and the flux sharing between the cores.
VIEW FULL TEXT:
quarta-feira, 4 de outubro de 2023
Fast Charging, State of Charge Estimation, and Remaining Useful Life Prediction of Lithium-Ion Battery for Smart Battery Management System = 스마트 배터리 관리 시스템을 위한 리튬 이온 배터리의 급속충전, 충전 상태 및 잔여 수명 예측
Dissertation for the degree of Doctor of Philosophy Fast Charging, State of Charge Estimation, and Remaining Useful Life Prediction of Lithium-Ion Battery for Smart Battery Management System]
BY Muhammad Umair Ali-February 2020
Department of Electrical and Computer Engineering
The Graduate School
Pusan National University
ABSTRACT
Due to the escalation in environmental pollution and energy prices, electric vehicles
(EVs) have widely explored in the past few years. Battery electric vehicles (BEVs), plug-in
hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs) are the different
variants of EVs. These EVs consist of energy storage and the motor system as the auxiliary
or primary energy source (FCEVs and PHEVs) or the sole energy source (BEVs). The
lithium-ion (Li-ion) batteries are preferred as an energy storage system because of its longlife
cycle, reliability, high energy density, low toxicity, low self-discharge rate, high power
density, and high efficiency. In EVs, a smart battery management system (BMS) is one of
the essential components; it not only measures the states of battery accurately but also
ensures safe charging/discharging operation and prolongs the battery life. The issues of
accurate estimation of the state of charge (SOC), remaining useful life prediction (RUL),
and reduction in charging time of the Li-ion battery is still a bottleneck for the
commercialization of EVs because the Li-ion battery is a highly time-variant, non-linear,
and complex electrochemical system. In this dissertation, a novel fuzzy logic and
temperature feedback-based method, Lagrange multiplier approach, and partial discharge
data (PDD) based support vector machine (SVM) model are presented for reduction of the
charging time, SOC estimation, and RUL prediction of the Li-ion battery, respectively.
This dissertation comprises of four studies, each of which constitutes a step towards a
smarter BMS for EV applications. The first study proposes an efficient, real-time, fastcharging
methodology of Li-ion batteries. Fuzzy logic was adopted to drive the charging
current trajectory for series-connected Li-ion batteries. The voltage and temperature of the
cells were fed to the controller to find the optimal charge current value within the safe
temperature limit. A temperature control unit was also implemented to evade the effects of
fast charging on the aging mechanism. The proposed method of charging also protects the
battery from overvoltage and overheating. Extensive testing and comprehensive analysis
were conducted to examine the proposed charging scheme. The results show that the
proposed charging strategy favors a full battery recharging in 9.76% less time than the
conventional constant-current–constant-voltage (CC/CV) method. The methodology
charges the battery at a 99.26% SOC without significant degradation. The entire scheme
was implemented in real-time, using Arduino interfaced with MATLABTM Simulink. This
decrease in charging time assists in the fast charging of cell phones and notebooks and the
large-scale deployment of EVs.
The second work presents a new online data-driven battery model identification
method, where the battery parameters are updated using the Lagrange multiplier method. A
battery model with unknown battery parameters was formulated in such a way that the
terminal voltage at an instant time step is a linear combination of the voltages and load
current. A cost function was defined to determine the optimal values of the unknown
parameters with different data points measured experimentally. The constraints were added
in the modified cost function using the Lagrange multiplier method, and the optimal value
of the update vector was determined using the gradient approach. An adaptive open-circuit
voltage (OCV) and SOC estimator was designed for the Li-ion battery. The experimental
results showed that the proposed estimator is highly accurate and robust. The proposed
method effectively tracks the time-varying parameters of a battery with high accuracy.
During the SOC estimation, the maximum noted error was 1.28%. The convergence speed
of the proposed method was only 81 s with a deliberate 100% initial error. Owing to the
high accuracy and robustness, the proposed method can be used in the design of a smarter
BMS for real-time applications.
In the third work, the sensitivity analysis is performed for the first and second-order
RC autoregressive exogenous (ARX) battery model to check the influence of voltage and
current transducer measurement uncertainty. The sensitivity analysis is performed under
the following conditions: Current sensor precision of ±5 mA, ±50 mA, ±100 mA, and ±500
mA and voltage sensor precision of ±1 mV, ±2.5 mV, ±5 mV, and ±10mV. The comparative
analysis of both models under the perturbed environment has been carried out. The effects
of the sensor’s sensitivity on the different battery structures and complexity are also
analyzed. Results show that the voltage and current sensor sensitivity has a significant
influence on SOC estimation. This research outcome assists the researcher in selecting the
optimal value of sensor accuracy to accurately estimate the SOC of the Li-ion battery for a
smarter BMS.
In the last work, a novel partial discharge data (PDD) based support vector machine
(SVM) model is proposed for RUL prediction. The proposed algorithm extracts the critical
features from the voltage and temperature of PDD to train the SVM models. The
classification and regression attributes of SVM are utilized to classify and predict accurate
RUL. The different ranges of PDD were analyzed to find the optimal range for training the
SVM model. The SVM model trained with optimal PDD features classifies the RUL into
six different classes for gross estimation, and the support vector regression is used to
estimate the accurate value of the last class. The classification and predictive performance
of SVM model trained using the full discharge data and PDD are compared. Results show
that the SVM classification and regression model trained with PDD features can accurately
predict the RUL with low storage pressure on BMS. The PDD-based SVM model can be
utilized for online RUL estimation in Li-ion battery BMS.
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