Advanced Technologies in Electric Vehicles: Challenges and Future Research Developments

Advanced Technologies in Electric Vehicles: Challenges and Future Research Developments discusses fundamental and advanced concepts, challenges, and future perspectives surrounding EVs. Sections cover advances and long-term challenges such as battery life span, efficiency, and power management systems. In addition, the book covers all aspects of the EV field, including vehicle performance, configuration, control strategy, design methodology, modeling and simulation for different conventional and modern vehicles based on mathematical equations. By tackling the fundamentals, theory and design of conventional electric vehicles (EVs), hybrid electric vehicles (HEVs), and fuel cell vehicles (FCVs), this book presents a comprehensive reference. Investment in hybrid and electric vehicle (EV) technology research has been increasing steadily in recent years, both from governments and within companies. The role of the combustion engine in causing climate change has put the automobile industry on a path of rapid evolution towards electric vehicles, bringing experts with a range of backgrounds into the field.

• Provides the latest advances in battery management systems to address power quality issues
• Explains step-by-step methodologies for the testing of EV battery systems
• Explores the technological options for charging systems and charging infrastructure

• Language: English
• Publisher: Academic Press
• Release date: Feb 26, 2024
• ISBN: 9780443190001

Book preview

Preface

Vijayakumar Gali, Luciane Neves Canha, Mariana Resener, Bibiana Ferraz and Madisa V.G. Varaprasad

Electric vehicle (EV) technology has come a long way since its inception. The journey of EVs can be traced back to the 19th century when inventors such as Thomas Davenport and Thomas Edison experimented with early versions of EVs. However, it was in the 20th century that significant progress was made in EV technology. The early 20th century saw the rise of EVs as a viable mode of transportation. EVs were popular among urban dwellers, and companies such as Thomas B. Jeffery Company, Baker Motor Vehicle Company, and Detroit Electric began producing them commercially. These early EVs were often used for short-distance commuting and were limited by their range and battery technology. In the mid-20th century, internal combustion engine (ICE) vehicles increase notoriety due to advancements in gasoline engine technology, mass production, and lower fuel costs. As a result, the focus on EV technology diminished, and it took a backseat for several decades.

Nevertheless, recent times have witnessed a resurgence in EV technology, marked by rapid advancements. Especially, in the 21st century, when a remarkable surge in the popularity of EVs has been driven by substantial investments from both established automakers and emerging startups. With advancements in technology and increasing awareness about sustainable transportation, EVs have emerged as a viable alternative to traditional ICE vehicles. Significant breakthroughs in battery technology, such as the introduction of lithium-ion batteries, have remarkably enhanced the range and overall performance of EVs. Moreover, progress in power electronics, electric motor design, and regenerative braking has played a role in creating more energy-efficient EVs. Nowadays, vehicle electrification is considered by the researchers as a game changer for the transportation sector due their energy efficiency, zero tailpipe emissions, and reduced petroleum dependency.

There has been significant research and development in the field of EVs, focusing on various aspects such as battery technology, charging infrastructure, vehicle design, sustainability, policy frameworks, and vehicle-to-everything communication. EVs are now available in several forms, including fully electric cars, plug-in hybrid EVs, and electric buses and trucks. Considered as a promising solution to address environmental concerns associated with fossil fuel consumption and to promote energy transition, EVs have gained widespread acceptance, with many automakers announcing plans to electrify their entire vehicle lineups in the coming years. Moreover, governments around the world have implemented policies and regulations to promote the adoption of EVs to reduce greenhouse gas emissions and combat climate change. This has further fueled the development of EV technology, including the establishment of a robust charging infrastructure network and the integration of smart grid technologies. Thus ongoing research and development focus on enhancing battery performance, improving charging infrastructure, and exploring new materials and technologies for even more efficient and sustainable EVs. The resurgence of electromobility evidences a promising future for EV technology.

This book gathers the state-of-the-art research on topics related to EV technology and challenges and opportunities for the future directions. To address those topics, the content of the book covers six areas: (1) overview, (2) environmental and social aspects, (3) distribution grid, (4) business and economics, (5) power electronics, and (6) final remarks/challenges, based on which 23 chapters are organized.

We would like to thank all the authors for their contributions, the referees for their valuable and constructive reviews, and the publisher for helping to produce this handbook. A special thanks to Mr. Tom Mearns and his team for continuous support in handling this book project.

Part 1

Overview

Outline

Chapter one An overview of hybrid electric vehicles

Chapter two Plug-in hybrid electric vehicle system and its future advanced technology

Chapter three A review on modeling and estimation of state of charge of lithium-ion battery

Chapter one

An overview of hybrid electric vehicles

Ch. Chandra Sekhar, Nidhi Chandrakar, Jude Prakash and Harinaik Sugali,    NIT, Tiruchirappalli, Tamil Nadu, India

Abstract

Electric and hybrid electric vehicles (EV/HEV) are part of a potential solution for the conservation of fossil fuels and the reduction of emissions towards ensuring sustainable transportation and a clean environment. The inclusion of the electric power train in a hybrid vehicle facilitates efficient use of energy by reducing the dependence on fossil fuel-based IC engines. The principal hardware of an HEV includes the electric motor, the IC engine, the transmission gear, power electronic converters, and the energy storage devices. Energy management with fuel and battery, and choice of speed control form the control aspects of the drive. This study gives a summary of the literature on the topic and tries to review the various configurations, associated control systems, and issues still to be resolved concerning the wide usage of HEVs.

Keywords

Internal combustion engine; series HEV; parallel HEV; series parallel HEV; complex HEV; hybrid electric vehicles; induction motor; voltage source inverter; hybrid energy storage system; current source inverter; impendence source inverters; permanent magnet synchronous motor; battery; supercapacitor; ultracapacitor

1.1 Introduction

In the transportation industry, roads account for 75% of overall energy use, followed by railroads, ships, and air travel. The vehicle sector has a tremendous impact on the global economy, which in turn affects everyone. When it comes to greenhouse gas emissions, the transportation field of the internal combustion engine (ICE) vehicle is the reason for 25%–30% of overall emissions [1]. As part of the fuel combustion process, ICE generates a variety of gases, such as carbon dioxide (CO2), nitrous oxide (NO2), and carbon monoxide (CO), all of which contribute to environmental degradation [2]. To combat this issue, the transportation industry has been actively engaged in producing electric vehicles (EVs) run on renewable energy sources. The prototype of an electric car is powered by a large battery pack. These cars have a restricted range due to the requirement of heavy and bulky batteries for a long drive [3].

Since charge sustaining mode is limited by its reliance on regenerative braking and fuel, plug-in hybrid electric vehicles (PHEVs) have been recommended as an improvement. PHEVs have added convenience of being able to charge from an external source, such as a regular wall socket compared to hybrid electric vehicles (HEVs). In a PHEV, the electric motor (EM) is the main and the ICE is used only as a backup. When the battery decreases to a low percentage of state of charge (SOC), the ICE takes control and the PHEV functions like a conventional HEV. As their name implies, they typically function in charge depletion mode, when the SOC is depleted to a predetermined level. PHEVs have a longer range than purely EVs, better air quality, and can be able to connect with the grid. As solar energy becomes more widely available, PHEVs that use solar power to charge their batteries are entering the market. PHEVs use solar energy to recharge their batteries constantly, which eliminates the need for fuel. Hybrid cars have a major hurdle in the form of reliable and reasonably priced batteries. Lithium-ion derivatives have historically produced the greatest results among the many HEV battery compositions tested. It is feasible to have three degrees of battery pack integration in a vehicle: (1) single battery cell, (2) module, and (3) battery pack. The battery needs to be able to deliver peak power for brief durations while also being able to survive millions of shallow charge-discharge cycles. An ultracapacitor (UC) may be used in conjunction with a battery to increase the battery’s life cycle, increase the pace at which it can be charged and discharged, and reduce the internal resistance of the battery, all of which results in less heat loss and improved dependability. From 80% to 90%, UC enhances the efficiency cycle [4]. The efficiency of a hybrid energy storage system (HESS) is better than the battery or an UC. To effectively propel a hybrid or electric vehicle, the traction motor employed must be able to deliver torque across a wide speed range. Permanent magnet (PM) and induction motors (IM) are the two most often utilizes in HEV propulsion motors. Numerous automakers, including BMW, Audi, Chevrolet, Honda, Ford, Mercedes-Benz, Nissan, McLaren, Mitsubishi, Porsche, Hyundai, Toyota, and Tesla have introduced hybrid models in recent years.

This chapter presents an overview of HEVs in the recent literature. Section 1.2 deals with trends in HEVs, while Section 1.3 describes HESS. Sections 1.4 and 1.5 describe the power converters and the motors used in HEVs. Sections 1.7 and 1.8 list the challenges and scope for improvement. Section 1.8 describes the various costs involved while Section 1.9 presents the conclusions.

1.2 Trends in hybrid electric vehicles

Dr. Ferdinand Porsche of Germany produced the first HEV, which he called the Lohner Electric Chaise, in the year 1898. Porsche uses an ICE to start a generator that powers the EM. This HEV could travel more than 60 km on its batteries alone. In 1903, the Krieger Company developed the first HEV, whose battery pack was powered by a gasoline engine. A Belgian Company produced commercial automobiles between the years 1906 and 1912 based on patents that were developed by Pieper [5]. Henry Ford created hybrid automobiles that were inexpensive, lightweight, and noiseless in 1904 as a retort to the problems caused by IC engines, such as bad smell, pollution, vibration, and noise. By 1920, Henry Ford ceased the production of HEV vehicles altogether. H. Flute, an American inventor, submitted a patent application for a petroleum EV in 1905. He proposed using an EM to support the ICE, which enabled him to achieve a speed of 25 miles per hour. In the 1970s, there were also other attempts made to create HEVs for the consumer market. Toyota introduced the world’s first modern HEV, known as the Prius, in 1997. This resulted in a revitalization of interest in the method. After the Toyota Prius, the Honda Insight was the subsequent HEV to hit American roads. Since then, virtually every automaker has included a PHEV in their line-up [6,7]. Fig. 1.1 shows the block diagram of the design HEVs.

Figure 1.1 Detailed flowchart for hybrid electric vehicle system design.

By the year 2018, the annual sales of hybrid and EVs had reached 1.6 million units throughout the world. These numbers were projected to increase to 2 million in the year 2019, 7 million by the year 2020, 30 million by the year 2030, and 100 million by the year 2050 [8].

1.2.1 Architectures of hybrid electric vehicles

The drive train, energy storage system (ESS), and controller unit are the three primary elements that make up a HEV. Combining these components can produce a wide variety of HEV combinations. The ICE is primarily responsible for providing propulsion and extending the vehicle’s cruising range, and the EM is in charge of meeting the high-vehicle-power requirements of the ICE while also maximizing fuel efficiency. The ICE can produce additional power when the vehicle is not in use. The vehicle can use the vehicle’s motion (kinetic energy) to replenish the power supply. To construct and run a power train of this kind; advanced control algorithms and an electronic management system are necessary. These are needed to simultaneously optimize the ICE fuel efficiency and battery SOC, all while staying within the bounds of the system’s restrictions and driving limits [9].

The range of a HEV in all-electric mode varies depending on the specific design and model of the vehicle. It is determined by the capacity of the battery pack and the power consumption of the EM. Generally, most HEVs have an electric-only range of 20–50 miles before the gasoline engine kicks in to recharge the battery pack or provide additional propulsion. The range is also affected by driving conditions such as speed, weather, terrain, and driving habits. Some manufacturers provide estimated ranges based on testing procedures set by regulatory bodies.

In a parallel HEV, the power split between the engine and the EM is controlled by a power split device, such as a planetary gearset or a clutch. The power split device allows the engine, the EM, or both to deliver power to the wheels, depending on the driving conditions and the power demand. During low-speed, high-torque driving situations, such as urban driving or acceleration from a stop, the EM delivers most of the power to the wheels, while the engine operates at low speed or shuts off completely. During high-speed, low torque driving situations, such as highway cruising, the engine delivers most of the power to the wheels, while the EM assists or operates in regeneration mode to recharge the battery. The power split between the engine and the EM in a parallel HEV is often optimized by a hybrid control system that monitors various parameters, such as vehicle speed, load, battery state-of-charge, and driver inputs, and adjusts the power flow accordingly for maximum efficiency and performance.

1.2.1.1 Series hybrid electric vehicles

EM requires most of the traction force need for vehicle propulsion in the series design. To charge the batteries, the IC engine is operated to drive a generator. The traction EM is powered by the combination of both the generator and battery via the power converter. Traction flexibility can be achieved with this system because of the electrical separation of the ICE from the driving shaft. This is like how diesel-electric locomotives are constructed.

In a series HEV, the transmission of power from the engine and the EM is coordinated through a power control unit (PCU) or an electronic control unit (ECU). In this type of hybrid architecture, the gasoline engine drives a generator that produces electricity to power the EM that drives the wheels of the vehicle. The PCU or ECU manages the power flow between the generator, EM, and battery, depending on the driver’s demand and the state of the battery charge. The gasoline engine does not directly drive the wheels; instead, its sole function is to generate electricity to charge the battery or provide additional power to the EM when required. The PCU or ECU ensures that the EM provides the necessary power for propulsion, while the gasoline engine runs at its optimum efficiency to charge the battery and minimize emissions. In summary, in a series HEV, the transmission of power from the engine to the wheels is indirect and is coordinated through the PCU or ECU.

A series HEVs function in the following ways.

1. There is no coupling between the ICE and the transmission unit;

2. Easy speed control can be obtained by single torque operation;

3. EM torque–speed eliminates multigearbox;

4. While the car is parked, the ICE can power the generator and charge the batteries.

The advantages of an EV with an ICE battery charger are also present in the series HEV. The series system has the limitation that it necessitates many high-power mechanical-to-electrical-to-mechanical conversions, each with its associated conversion inefficiencies, to power the vehicle. Locomotives and other large vehicles designed for long-distance travel that may have supplementary electrical demands, such as those used by the military, might benefit from this layout. Because of their massive dimensions and the exorbitant expense of maintaining their maximum power demands is complex. A series HEV [10] can improve the performance of city buses and other big urban vehicles in congested environments. Fig. 1.2 depicts a series HEV that can offer as many as six alternative modes of operation.

1. Alone ESS [like batteries, UCs, fuel cells (FCs), etc.];

2. Alone ICE (not coupled mechanically with EM);

3. Both the ICE and battery contribute to the vehicle’s drive power;

4. There is a power split mode, where an ICE generator is used for both propulsion and battery charging;

5. Charging at a fixed location;

6. Regenerative braking

Figure 1.2 Series HEV. HEV, Hybrid electric vehicles.

1.2.1.2 Parallel hybrid electric vehicles

When combined, the ICE and EM could provide a synergistic boost to the vehicle’s propulsion. The drive shaft is attached to the ICE and EM by using two clutches. Electric or ICE supply the traction power, or both. When the ICE produces more power than is required to turn the wheels, the EM may function as a generator, replenishing the energy lost during braking [11]. Thus, both the ICE and EM are used as propulsion power in the parallel mode. Electromechanical power losses can be reduced, and lower power ratings for these components, especially EM is one benefit compared to the series arrangement. The parallel HEV, on the other hand, may not be as well adapted for stop-and-go driving as typical of metropolitan environments [12]. The HEV’s parallel configuration is shown in Fig. 1.3.

Figure 1.3 Parallel HEV. HEV, Hybrid electric vehicles.

In a parallel HEV, the power split between the engine and the EM is controlled by a power split device, such as a planetary gearset or a clutch. The power split device allows the engine, the EM, or both to deliver power to the wheels, depending on the driving conditions and the power demand. During low-speed, high-torque driving situations, such as urban driving or acceleration from a stop, the EM delivers most of the power to the wheels, while the engine operates at low speed or shuts off completely. During high-speed, low torque driving situations, such as highway cruising, the engine delivers most of the power to the wheels, while the EM assists or operates in regeneration mode to recharge the battery. The power split between the engine and the EM in a parallel HEV is often optimized by a hybrid control system that monitors various parameters, such as vehicle speed, load, battery SOC, and driver inputs, and adjusts the power flow accordingly for maximum efficiency and performance.

A parallel HEV functions in the following ways

1. Alone EM;

2. Alone ICE (coupled mechanically with transmission);

3. ICE and EM are used together;

4. The ICE power shared between propulsion and battery recharging (power is generated using EM);

5. Charging at a fixed location;

6. Regenerative braking.

Through-the-road HEV is a kind of parallel HEV in which the EM and ICE drive the front and back wheels, respectively. The many modes of operation of the parallel configuration are outlined.

1. Both ICE and EM contributed to the initial thrust of a vehicle or at maximum acceleration. The typical split of power between ICE and EM is 80%–20%;

2. The ICE supplies the propulsion power when the EM is in standby mode during normal driving;

3. ICE can provide both battery charging power and propulsion power to drive the vehicle;

4. EM functions as a regenerative generator to replenish the battery in light load conditions.

1.2.1.3 Series parallel hybrid electric vehicles

When it comes to HEVs, a series-parallel arrangement offers the benefits of both parallel and series HEVs. The ESS and EM sizes are reduced compared to the series configuration, while the ICE size is reduced compared to the parallel configuration in this layout [13]. Parallel and series models are effective at high and low speeds. On the other hand, the system’s difficulty and the accumulation of a planetary gear both increase the likelihood of failure. The series parallel HEV configuration is shown in Fig. 1.4. The hybrid nature of the system allows for a wide range of possible modes of operation, the most basic of which are those in which ICE or EM predominates [14]. The scheme of working is shown in Table 1.1.

Figure 1.4 Series parallel HEV. HEV, Hybrid electric vehicles.

Table 1.1

1.2.1.4 Complex hybrid electric vehicles

The complex HEV is identical to the series parallel HEV with the addition of a bidirectional converter. This is made possible by the EM’s bidirectional converter. This two-way power exchange permits many modes of operation, including the integrated ICE and two independent EMs. There is a high price to pay for the complexity that this setup requires [7].

1. The IC engine is turned off, and the EMs can generate the traction power required for starting;

2. Both the ICE and the EMs contribute to power generation during full-throttle acceleration. While the ICE is running, it powers the front wheel and the first EM, which in turn recharges the battery;

3. When the car is under a light load, at starting the EM will supply the necessary traction power to the front wheel. There is no power supplied to the second EM or the ICE;

4. The front and back wheel EMs work together to charge the batteries by regenerative during braking and deceleration.

Both complex and simpler HEVs use regenerative braking systems, but there are some differences between the two. Regenerative braking in simpler HEVs uses a single EM and generator to capture the kinetic energy generated during braking and convert it into electrical energy, which is then stored in the battery. The system can only capture and convert the energy from the motor connected to the wheels. On the other hand, complex HEV shown in Fig. 1.5 systems use a combination of alternating current (AC) and direct current (DC) motors and generators to capture and convert more energy during regenerative braking. This is because complex HEVs typically operate in both series and parallel hybrid modes, and the different motors and generators are used in different modes of operation.

Figure 1.5 Complex HEV. HEV, Hybrid electric vehicles.

In complex HEVs, regenerative braking is often achieved through a dual-motor system in which one motor acts as a generator to convert the kinetic energy from the wheels into electrical energy, while the other motor can be used to help slow down the vehicle or to charge the battery.

Another difference between regenerative braking systems in complex and simpler HEVs is the way they manage braking force. In simpler HEVs, the regenerative braking force usually reaches a maximum level, after which mechanical brakes take over to complete the deceleration process. In contrast, in complex HEVs, the regenerative braking force can be modulated to allow for a smoother and more efficient transition between regenerative and mechanical braking, resulting in a more comfortable and controlled driving experience.

Table 1.2 provides a summary of the four driving cycles findings that were obtained in each of the five different vehicle drive trains [9]. Table 1.2 includes columns for each vehicle’s drive train that detail its weight as well as the complexity of its management system. The control complexity was found by evaluating the complexity of the system controller that was used to operate the components that provided propulsion to the wheels. For example, the controller for the parallel HEV controls both the ICE and the electric machine. This allowed the complexity of the control system to be calculated. After tabulating each driving cycle, the following parameters were found to be significant.

Table 1.2

1.3 Hybrid energy storage system

Charging rate, energy density, lifespan, cost, weight, and size are only a few of the factors that should be considered when selecting an ESS [15,16]. According to the present trajectory that despite new developments, batteries and UC are still the primary options for ESS [17]. Compared to UCs, batteries have a high energy density and low cost per watt hour; however, they have a limited cycle life and poor specific power [18–23]. UCs keep their high peak power, extended cycle life, higher cost per watt, and lower energy density. With a practically infinite cycle life and the ability to withstand large swings in power consumption [24,25], UCs may be relied upon. UCs are tasked with lowering sulfation levels in lead acid batteries for EVs [26]. Battery power is used for low-frequency, whereas UCs offer both high frequency and high power for demanding applications. No single energy storage solution is sufficient to meet global demand [27]. Their drawback can be mitigated by combining the battery and UC [28–33]. To keep the DC-bus voltage stable, the UCs can handle surges during battery operation, while the batteries keep the UCs’ SOC stable. As a result, a combination of battery and UC the system is more stable [34,35].

When a UC is added to an EV, the battery is shielded from damage and may be used for much longer [36–39]. Because the UC can smooth out the spikes in energy demand, the batteries may be put to good use [40,41]. One resistance capacitor (RC) and numerous RC branches may represent the batteries; an additional UC turns the system into a HESS. Power management is a complex task that has implications on the size of both the battery and the UC. The following are short summaries of some studies that address this power imbalance.

Curve fitting methods may be used to evaluate the UC and battery parameters for the expected responses. It is important to think about cell balance and redistribution while developing ESS mechanisms like high temperature, discharge/overcharge, and over/undervoltage protection systems [42,43]. In Ref. [44], models based on Karush-Kuhn-Tucker (KKT) and a model which is based on neural networks (NN) EMS are utilized to allocate current between the UC and the battery. The NN-based EMS is more reliable as well as effective in gauging the health of the battery. KKT, on the other hand, has better computational performance and is easier to implement.

The residual capacity of a UC may be computed with great accuracy using an artificial NN [45]. An HESS also included an EMS based on fuzzy logic (FL) to improve runtime without increasing power consumption. Here, a battery lifetime deprivation model was used to simulate the impact of charge or discharge cycles on battery life [46,47]. To maximize efficiency in a parallel battery and UC setup with a DC bus voltage controller, a feed-forward load compensator and PI controllers [48,49] were utilized. In [50], the UC was charged efficiently using the wireless charging method. A rule-based control technique was provided in [51,52] to efficiently regulate the UC’s SOC in addition to unloading the peak of currents from the battery [53]. The power flow in an HESS was managed by a model predictive controller (MPC). Steady output voltage could be obtained while meeting the load requirements. As a means of regulating HESS, a logical threshold control strategy was created for EVs [54–58] for the efficient use of the power from UCs. Using an adaptive FL-based EMS, depending on the situation, the system will either use the battery or the UC pack. FL controllers are utilized because they can handle complicated real-time control difficulties without requiring any advanced awareness of the driving cycle. It improves its performance and reduces battery current fluctuations [59]. To reduce battery degradation and high-power requirement in EVs, a linear quadratic regulator with HESS was developed [60]. To balance the load in the middle of the UC and battery, the equivalent consumption reduction technique is given [61]. There have been limited implementations of other HESS, such as the UC with the FC, and such combination interfaced with the ant colony technique [62]. FC-UC hybrids are equipped with a dynamic MPC to keep the load side demand and voltage consistent throughout UC. For the inner PI control loop, values for the FC and UC currents are referenced from the single MPC in the outer loop [63]. There are at least three key benefits to using HESS: decreased battery costs, more autonomy, and a longer lifespan [64,65]. Moreover, there are other methods to connect a battery to UC via DC/DC bidirectional converter [66]. Topologies are mostly chosen according to the pros and cons listed in Table 1.3. The needs of a bidirectional cell are best met by the boost half-bridge, for the battery/UC interface [67].

Table 1.3

A simple setup is shown in Fig. 1.6A, where UC and battery pack are passively coupled with the motor drive set without requiring the DC-DC converter. Even though the system is simple, the major problem with it is that there is no control on the DC side. This problem gets fixed in the controlled HESS [80], which is shown in Fig. 1.6B and C. The UC has no direct connection with the DC bus, and power from the UC is controlled through a bidirectional DC-DC converter. The optimal size of the DC-DC converter is a major challenge for these