Numerical Study of Heat Transfer Enhancement in the Electric Vehicle Battery via Vortex‑Induced Agitator

Convective heat transfer plays an important role in the development of a high-performance battery cell.Electric vehicles carry a large amount of the battery cells to reach a longer range of endurance mileage.Thermal diffusion around the battery cells can be considered as obstacles to improve the convective heat transfer coefficient.In this paper,a novel agitator taking advantage of strong vortices is designed to disrupt the thermal boundary layer around the battery cells,thereby improving the fluid mixing for enhanced convective heat transfer.A fluid–structure interaction algorithm is developed to simulate the convective heat transfer rate at various flapping motion.Under the comparison with clean channel,the vortex-induced vibra-tion by the agitated beam can increase the average Nusselt number by 119.59%.This research can be applied to optimize the thermal-structure design inside the electric vehicle battery.

Driving and Braking Control of PM Synchronous Motor Based on Low-resolution Hall Sensor for Battery Electric Vehicle

Resolvers are normally employed for rotor positioning in motors for electric vehicles, but resolvers are expensive and vulnerable to vibrations. Hall sensors have the advantages of low cost and high reliability, but the positioning accuracy is low. Motors with Hall sensors are typically controlled by six-step commutation algorithm, which brings high torque ripple. This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor （PMSM） based on low-resolution Hall sensors. Field oriented control （FOC） based on Hall-effect sensors is developed to reduce the torque ripple. The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed. The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing. The braking control algorithms based on six-step commutation and FOC are studied. Two variants of the six-step commutation braking control, namely, half-bridge commutation and full-bridge commutation, are discussed and compared, which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces （EMF）, thus can deliver higher efficiency and smaller current ripple. The FOC braking is analyzed with the phasor diagrams. At a given motor speed, the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit, which is proportional to the motor speed. Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control, compared to six-step commutation braking control. Therefore, FOC braking is selected as the braking control algorithm for electric vehicles. The proposed research ensures a good motor control performance while maintaining low cost and high reliability.

Towards Realistic Vibration Testing of Large Floor Batteries for Battery Electric Vehicles (BEV)

This contribution shows an analysis of vibration measurement on large floor-mounted traction batteries of Battery Electric Vehicles(BEV).The focus lies on the requirements for a realistic replication of the mechanical environments in a testing laboratory.Especially the analysis on global bending transfer functions and local corner bending coherence indicate that neither a fully stiff fixation of the battery nor a completely independent movement on the four corners yields a realistic and conservative test scenario.The contribution will further show what implication these findings have on future vibration&shock testing equipment for large traction batteries.Additionally,it will cover an outlook on how vibration behavior of highly integrated approaches(cell2car)changes the mechanical loads on the cells.

Intelligent Vehicle Electrical Power Supply System with Central Coordinated Protection

The current research of vehicle electrical power supply system mainly focuses on electric vehicles（EV） and hybrid electric vehicles（HEV）.The vehicle electrical power supply system used in traditional fuel vehicles is rather simple and imperfect;electrical/electronic devices（EEDs） applied in vehicles are usually directly connected with the vehicle＇s battery.With increasing numbers of EEDs being applied in traditional fuel vehicles,vehicle electrical power supply systems should be optimized and improved so that they can work more safely and more effectively.In this paper,a new vehicle electrical power supply system for traditional fuel vehicles,which accounts for all electrical/electronic devices and complex work conditions,is proposed based on a smart electrical/electronic device（SEED） system.Working as an independent intelligent electrical power supply network,the proposed system is isolated from the electrical control module and communication network,and access to the vehicle system is made through a bus interface.This results in a clean controller power supply with no electromagnetic interference.A new practical battery state of charge（So C） estimation method is also proposed to achieve more accurate So C estimation for lead-acid batteries in traditional fuel vehicles so that the intelligent power system can monitor the status of the battery for an over-current state in each power channel.Optimized protection methods are also used to ensure power supply safety.Experiments and tests on a traditional fuel vehicle are performed,and the results reveal that the battery So C is calculated quickly and sufficiently accurately for battery over-discharge protection.Over-current protection is achieved,and the entire vehicle＇s power utilization is optimized.For traditional fuel vehicles,the proposed vehicle electrical power supply system is comprehensive and has a unified system architecture,enhancing system reliability and security.

Development and Verification of the Equilibrium Strategy for Batteries in Electric Vehicles

The inconsistency of the cells in a battery pack can affect its lifespan,safety and reliability in the electric vehicles. The balanced system is an effective technique to reduce its inconsistency and improve the operating performance. A hybrid equilibrium strategy based on decision combing battery state-of-charge（ SOC） and voltage has been proposed. The battery SOC is estimated through an improved least squares method. An equalization hardware in loop（ HIL） platform has been constructed. Based on this HIL platform,equilibrium strategy has been verified under the constant-current-constant-voltage（ CCCV） and dynamicstresstest（ DST） conditions. Experimental results indicate that the proposed hybrid equalization strategy can achieve good balance effect and avoid the overcharge and over-discharge of the battery pack at the same time.

Equalization Charging and Protection System for Electric Vehicle

A system is developed to improve the series battery packs uniformities and charging protection and the implementation of battery equalization charging and protection system is also introduced. The functions of equalization charging and overcharging protection are analyzed and the control model of series battery packs equalization charging is setup. The diverting-current and feedback bus voltage are measured during the series Li-ion battery packs equalization charging experiment. The field operation on Electric luxury transit bus BFC6100EV shows that the system betters the battery series charging uniformities and overcharging protection, improves the battery performance and extends the battery life.

The Future Trend of E-Mobility in Terms of Battery Electric Vehicles and Their Impact on Climate Change: A Case Study Applied in Hungary

The transportation sector is responsible for 25% of the total Carbon dioxide (CO2) emissions, whereas 60.6% of this sector represents small and medium passenger cars. However, as noted by the European Union Long-term strategy, there are two ways to reduce the amount of CO2 emissions in the transportation sector. The first way is characterized by creating more efficient vehicles. In contrast, the second way is characterized by changing the fuel used. The current study addressed the second way, changing the fuel type. The study examined the potential of battery electric vehicles (BEVs) as an alternative fuel type to reduce CO2 emissions in Hungarys transportation sector. The study used secondary data retrieved from Statista and stata.com to analyze the future trends of BEVs in Hungary. The results showed that the percentage of BEVs in Hungary in 2022 was 0.4% compared to the total number of registered passenger cars, which is 3.8 million. The simple exponential smoothing (SES) time series forecast revealed that the number of BEVs is expected to reach 84,192 in 2030, indicating a percentage increase of 2.21% in the next eight years. The study suggests that increasing the number of BEVs is necessary to address the negative impact of CO2 emissions on society. The Hungarian Ministry of Innovation and Technologys strategy to reduce the cost of BEVs may increase the percentage of BEVs by 10%, resulting in a potential average reduction of 76,957,600 g/km of CO2 compared to gasoline, diesel, hybrid electric vehicles (HEVs), and plug-in hybrid vehicles (PHEVs).

Operation Strategy of EV Battery Charging and Swapping Station

An operation strategy of the electric vehicle （EV） battery charging and swapping station is proposed in the paper. The strategy is established based on comprehensively consideration of the EV charging behaviors and the possible mutual actions between battery charging and swapping. Three energy management strategies can be used in the station： charging period shifting, energy exchange between EVs, and energy supporting from surplus swapping batteries. Then an optimization model which minimizes the total energy management costs of the station is built. The Monte Carlo simulation is applied to analyze the characteristics of the EV battery charging load, and a heuristic algorithm is used to solve the strategy providing the relevant information of EVs and the battery charging and swapping station. The operation strategy can efficiently reduce battery charging during the high electricity price periods and make more reasonable use of the resources. Simulations prove the feasibility and rationality of the strategy.

Modeling and Optimization of Heat Dissipation Structure of EV Battery Pack

In order to solve the problems of high temperature and inconsistency in the operation of electric vehicle（ EV） battery pack,computational fluid dynamics（ CFD） simulation method is used to simulate and optimize the heat dissipation of battery pack. The heat generation rate at different discharge magnifications is identified by establishing the heat generation model of the battery. In the forced air cooling mode,the Fluent software is used to compare the effects of different inlet and outlet directions,inlet angles,outlet angles,outlet sizes and inlet air speeds on heat dissipation. The simulation results show that the heat dissipation effect of the structure with the inlet and outlet on the same side is better than that on the different sides; the appropriate inlet angle and outlet width can improve the uniformity of temperature field; the increase of the inlet speed can improve the heat dissipation effect significantly. Compared with the steady temperature field of the initial structure,the average temperature after structure optimization is reduced by 4. 8℃ and the temperature difference is reduced by 15. 8℃,so that the battery can work under reasonable temperature and temperature difference.

China's battery electric vehicles lead the world:achievements in technology system architecture and technological breakthroughs

Developing new energy vehicles has been a worldwide consensus,and developing new energy vehicles characterized by pure electric drive has been China's national strategy.After more than 20 years of high-quality development of China's electric vehicles(EVs),a technological R&D layout of“Three Verticals and Three Horizontals”has been created,and technological advantages have been accumulated.As a result,China's new energy vehicle market has ranked first in the world since 2015.To systematically solve the key problems of battery electric vehicles(BEVs)such as“driving range anxiety,long battery charging time,and driving safety hazards”,China took the lead in putting forward a“system engineering-based technology system architecture for BEVs”and clarifying its connotation.This paper analyzes the research status and progress of the three core components of this architecture,namely,“BEV platform,charging/swapping station,and real-time operation monitoring platform”,and their key technological points.The three major demonstration projects of the 2008 Beijing Olympic Games,the 2022 Beijing Winter Olympics,and the intelligent and connected autonomous battery electric bus project are discussed to specify the applications of BEVs in China.The key research directions for upgrading BEV technologies remain to be further improving the vehicle-level all-climate environmental adaptability and all-day safety of BEVs,systematically solving the charging problem of BEVs and improving their application convenience,and safeguarding safety with early warning and implementing active/passive safety protection for the whole life cycle of power batteries on the basis of BEVs'operation big data.BEVs have acquired new technological features such as intelligent and networked technology empowerment,extensive integration of control-by-wire systems,a platform of chassis hardware,and modularization of functional software.

Performance of the Transmission Parking Mechanism of a Battery Electric Vehicle Simulated with Adams Software

The electric parking mechanism is studied for an electrically controlled two-speed auto transmission that is being developed for electric vehicles.Safety requirements include low-speed safe parking,reliable self-lock and the avoidance of abnormal parking.A dynamic model of the parking mechanism is established and analyzed using Adams software.Finally,failure of the parking mechanism due to wear is observed in bench testing and compared with experimental results after optimization.

Evaluation of Transmission Losses of Various Battery Electric Vehicles

Transmission losses in battery electric vehicles have compared to internal combustion engine powertrains a larger share in the total energy consumption and play therefore a major role.Furthermore,the power flows not only during propulsion through the transmissions,but also during recuperation,whereby efficiency improvements have a double effect.The investigation of transmission losses of electric vehicles thus plays a major role.In this paper,three simulation models of the Institute of Automotive Engineering(the lossmap-based simulation model,the modular simulation model,and the 3D simulation model)are presented.The lossmap-based simulation model calculates transmission losses for electric and hybrid transmissions,where three spur gear transmission concepts for battery electric vehicles are investigated.The transmission concepts include a single-speed transmission as a reference and two two-speed transmissions.Then,the transmission lossmaps are integrated into the modular simulation model(backward simulation)and in the 3D simulation model(forward simulation),which improves the simulation results.The modular simulation model calculates the optimal operation of the transmission concepts and the 3D simulation model represents the more realistic behavior of the transmission concepts.The different transmission concepts are investigated in Worldwide Harmonized Light Vehicle Test Cycle and evaluated in terms of transmission losses as well as the total energy demand.The map-based simulation model allows the transmission losses to be broken down into the individual component losses,thus allowing transmission concepts to be examined and evaluated in terms of their efficiency in the early development stage to develop optimum powertrains for electric axle drives.By considering transmission losses in detail with a high degree of accuracy,less efficient concepts can be eliminated at an early development stage.As a result,only relevant concepts are built as prototypes,which reduces development costs.

Energy Management Strategy for Hybrid Electric Vehicle Based on System Efficiency and Battery Life Optimization

A novel method to calculate fuel-electric conversion factor for full hybrid electric vehicle（HEV）equipped with continuously variable transmission（CVT）is proposed.Based on consideration of the efficiency of pivotal components,electric motor,system efficiency optimization models are developed.According to the target of instantaneous optimization of system efficiency,operating ranges of each mode of power-train are determined,and the corresponding energy management strategies are established.The simulation results demonstrate that the energy management strategy proposed can substantially improve the vehicle fuel economy,and keep battery state of charge（SOC）change in a reasonable variation range.

A comprehensive review on energy storage in hybrid electric vehicle

The sharp inclination in the emissions from conventional vehicles contribute to a significant increase in environmental issues,besides the energy crises and low conversion efficiency leads to the evolution of electric vehicles(EV).Hybrid electric vehicles(HEV) have efficient fuel economy and reduce the overall running cost,but the ultimate goal is to shift completely to the pure electric vehicle.Despite this,the main obstruction of HEV is energy storage capability.An EV requires high specific power(W/kg) and high specific energy(W$h/kg) to increase the distance travelled and reduce the time required for charging.The main focus of this paper is on the energy sources as these are the main components in EVs towards making them eco-friendly and cost-effective.Various topologies of EV technology such as HEVs,plug-in HEVs,and many more have been discussed.These topologies of EVs are based on the diverse combination of batteries,fuel cells,super-capacitor,flywheels,regenerative braking systems,which are used as energy sources and energy storage devices.

Design of a Hydraulic Control Unit for a Two-Speed Dedicated Electric Vehicle Transmission

Two-speed automatic transmission is one solution to increase the economic efficiency and dynamic performance of battery electric vehicles(BEV).Hydraulic control unit(HCU)is a key component in automatic transmissions,which determines the quality of shifting directly.Based on the structural scheme and shift logic of a two-speed dedicated electric vehicles transmission(2DET)with two wet clutches,we designs a 2DET hydraulic control unit composed of three subsystems:pressure regulating and flow control system,shift operated and control system and cooling and lubrication system.The results of the experiments,including the valve body bench test,transmission bench test and vehicle test,show that the design of hydraulic control unit meets the requirements.

Storage technologies for electric vehicles

This review article describes the basic concepts of electric vehicles(EVs)and explains the developments made from ancient times to till date leading to performance improvement of the electric vehicles.It also presents the thorough review of various components and energy storage system(ESS)used in electric vehicles.The main focus of the paper is on batteries as it is the key component in making electric vehicles more environment-friendly,cost-effective and drives the EVs into use in day to day life.Various ESS topologies including hybrid combination technologies such as hybrid electric vehicle(HEV),plug-in HEV(PHEV)and many more have been discussed.These technologies are based on different combinations of energy storage systems such as batteries,ultracapacitors and fuel cells.The hybrid combination may be the perspective technologies to support the growth of EVs in modern transportation.The advanced charging systems may also play a major role in the roll-out of electric vehicles in the future.The general strategies of advanced charging systems are explained to highlight the importance of fast charging time with high amount of power and its cost-effectiveness for electric vehicles.Furthermore,the battery pack designing calculation is briefly explained along with all mechanical,electrical and environmental battery tests,which helps in the evaluation of batteries.Moreover,this paper also has a brief summarizing with the help of a flow chart,which clearly demonstrates all the parts of electric vehicles in a much simpler way.

Techno-economic analysis of the adoption of electric vehicles

Significant advances in battery technology are creating a viable marketspace for battery powered passenger vehicles.Climate change and concerns over reliable supplies of hydrocarbons are aiding in the focus on electric vehicles.Consumers can be influenced by marketing and emotion resulting in behaviors that may not be in line with their stated objectives.Although sales of electric vehicles are accelerating,it may not be clear that purchasing an electric vehicle is advantageous from an economic or environmental perspective.A technoeconomic analysis of electric vehicles comparing them against hybrids,gasoline and diesel vehicles is presented.The results show that the complexity of electrical power supply,infrastructure requirements and full life cycle concerns show that electric vehicles have a place in the future but that ongoing improvements will be required for them to be clearly the best choice for a given situation.

Cumulant-based correlated probabilistic load flowconsidering photovoltaic generation and electric vehiclecharging demand

This paper applies a cumulant-based analytical method for probabilistic load flow (PLF) assessment in transmission and distribution systems. The uncertainties pertaining to photovoltaic generations and aggregate bus load powers are probabilistically modeled in the case of transmission systems. In the case of distribution systems, the uncertainties pertaining to plug-in hybrid electric vehicle and battery electric vehicle charging demands in residential community as well as charging stations are probabilistically modeled. The probability distributions of the result variables (bus voltages and branch power flows) pertaining to these inputs are accurately established. The multiple input correlation cases are incorporated. Simultaneously, the performance of the proposed method is demonstrated on a modified Ward-Hale 6-bus system and an IEEE 14-bus transmission system as well as on a modified IEEE 69-bus radial and an IEEE 33-bus mesh distribution system. The results of the proposed method are compared with that of Monte-Carlo simulation.

Multi-Criteria Decision Analysis for Usage Based Optimization of Powertrains

The electrification of powertrains leads to an increasing diversification of powertrain configurations. Each single configuration has its specific advantages which appear depending on the usage profile. To find the usage based optimal powertrain in consideration of a variety of evaluation criteria, the powertrains have to be optimized for the usage profile and characteristics have to be extracted from the usage profile. The carbon dioxide emissions of the optimized powertrains and usage based criteria are used in a multi-criteria decision analysis to determine the optimal powertrain for a specific usage profile. The description of characteristic maps forms the objective function of a minimization problem. The determined carbon dioxide emissions are one criterion in a multi-criteria decision process. All considered criteria are at least partly objective so that subjective ratings are eliminated as far as possible. The result is an optimized powertrain for a desired usage under the consideration of objective criteria that are extracted from the usage profile.

Recent advances in electrocatalysts for non-aqueous Li-O2 batteries

As one of the next-generation energy-storage devices,Li-O_2 battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500Wh/kg and low cost.However,Li-O_2 battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electrocatalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O_2 batteries which are relatively simpler than other Li-O_2 batteries＇ structures.Electrocatalysts were summarized including noble metals,nanocarbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiO_x storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work.