Electric Vehicle Components Research Articles

Evaluation of electric vehicle component performance over eco-driving cycles

Battery electric vehicles (BEVs) are a critical pathway towards achieving energy independence and meeting greenhouse and criteria pollutant gas reduction goals in the current and future transportation sector. Emerging connected and automated vehicle (CAV) technologies further open the door for developing innovative applications and systems to leverage vehicle efficiency and substantially transform transportation systems. Therefore, we present a simulation study of various BEV types and compare the performance when driving on real-road drive cycles to highly optimized eco-driving cycles using advanced CAV technologies. The results demonstrate that eco-driving has a high potential to reduce energy consumption for all types of BEVs considered. The investigated BEVs include a compact vehicle, a transit city bus, and a Class 7 delivery truck. The impact of eco-driving on conventional vehicles was also compared to comparable BEVs. Compared to the BEVs, eco-driving provides a larger reduction in the conventional vehicle's braking energy loss, and also provides conventional vehicles with greater reductions in the engine mechanical energy output but the fuel savings did not show a consistent trend among all the conventional vehicle types. As part of the study, a comprehensive EV powertrain model was developed to account for key EV components and powertrain configurations.

Reliability investigation of electric vehicle

Investigation of reliability is of vital importance to design, implement and manage the operation of vehicles. This can be used as an important tool for the proper design and control of vehicles. The main components of the electric vehicle (EV) are the batteries and the electric drive. This paper focuses on the reliability aspects of the lead acid battery, motor controller and electric motor employed for the operation of electric vehicles. Battery is the most important and also the least reliable component in EV, which has a crucial effect on the reliability and cost of EV. The heat generation model, the methods of cooling and air flow in the battery are investigated. This paper presents the simulation model using MATLAB/SIMULINK for analyzing the reliability of electric vehicles. The model takes into account the variation of driving cycles, thermal stress, thermal cycling and fault analysis. This model is discussed in detail and the result of reliability estimation based on an electric vehicle is presented and analyzed. The results are verified experimentally with the working model of electric vehicle available in the laboratory. With this model and analysis, more accurate reliability prediction can be carried out by the designer.

Quantifying Electric Vehicle Battery’s Ohmic Resistance Increase Caused by Degradation from On-board Data

Power battery, as the power source and one of the most significant components in electric vehicles, influences the vehicle’s dynamic performance, service life and safety directly. A deeper understanding of the battery characteristics on real-world electric vehicle applications is beneficial for its energy management optimization, service life prolongation and safe operation. This paper presents a novel method which can estimate the ohmic resistance of lithium-ion power battery accurately with only current and voltage information based on a combination of model linearization, least square algorithm and data-pieces idea. Real-world battery operational data of three electric vehicles over around two years are collected in high frequency and analyzed by the proposed method. The battery ohmic resistance increase is quantified by comparing the resistance-temperature fitting curves of adjacent two years. Results show that the investigated power batteries’ ohmic resistances are sensitive to ambient temperature and ohmic resistance can serve as a suitable index for evaluating battery degradation.

Multiobjective Optimization Design of a Double-Rotor Flux-Switching Permanent Magnet Machine Considering Multimode Operation

The multimechanical-port double-rotor machine, as a core component in hybrid electric vehicles, has attracted considerable attention due to the merits of compact structure, control flexibility, and diverse performances. However, since there often exist two electric or mechanical ports in one compound machine frame, traditional design theory cannot be applied to it directly. Besides, because of the relatively complex machine structure and multiple design parameters, design objectives often influence even conflict with each other. In this paper, a new multiobjective optimization design approach is proposed to design and optimize a flux-modulated double-rotor flux-switching permanent magnet machine, where multiple driving modes are considered. To verify the feasibility of the double-rotor machine and the effectiveness of an optimization design method, the electromagnetic characteristics of the machine are investigated in detail. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the proposed machine and multiobjective optimization design approach.

Laser Welding for EVs

Application of laser welding during electric vehicle component production can save time and materials, and create new opportunities for flexible product development

Numerical Comparison of Driving Cycles with Different Electric Motors (IM and PM) Operated in a Hybrid Electric Vehicle

The motor / generator instrument, which is the one of the key important components of hybrid electric vehicles, influence vehicle efficiency and emission scale with its types and features. For that reason, the electric motor (electric machine-EM) selection and identification are playing a crucial role. In this simulation study, effects of two different motors, Induction and Permanent Magnet (IM and PM) to emission and performance were compared for two driving cycles (FTP75 and NEDC) on a serial configuration hybrid electric vehicle which modeled with AVL Cruise. The general purpose of the work is, selecting electric motors that they have same output powers although the rotational speeds are different; and modeled for the same vehicle and identifing the effects of different driving cycles on the vehicles were compared. HEVs performance and emission results illustrated and electric machines performances and efficiency maps are graphically charted. Overall performance and emission outputs for two different driving cycles are discussed detailed. Also, a general concluded summary table that related the performance and emission outputs of different machines usage is presented. As a result, according to these modeling and test results, PM motor is more efficient than IM motor on overall simulation results, especially decreases the emission values at high speeds.

Modular battery charge equalization circuit based on state of charge for electric vehicle application

Electric Vehicle (EV)/Hybrid Electric Vehicle (HEV) enabled by high-efficiency electric motor and controller, provide the means for a clean, efficient and environmental friendly transportation system. Portable rechargeable batteries are the essential basic component in EVs. In EV/HEV system a large number of cells should be connected in series to supply enough energy, while the voltage balancing problem between cells leads to poor performance. This paper attempts modular battery charge equalization based on state of charge (SOC) under MATLAB Simulink environment.

Hyundai partners with Audi to develop FCEV components business

Hyundai Motor Group in South Korea and Audi AG in Germany have entered into a multi-year patent cross-licensing agreement, covering a broad range of fuel cell electric vehicle components and technologies, to accelerate development towards volume production.

Optimization Strategy for Economic Power Dispatch Utilizing Retired EV Batteries as Flexible Loads

With the increasing penetration of new and renewable energy, incorporating variable adjustable power elements on the demand side is of particular interest. The utilization of batteries as flexible loads is a hot research topic. Lithium-ion batteries are key components in electric vehicles (EVs) in terms of capital cost, mass and size. They are retired after around 5 years of service, but still retain up to 80% of their nominal capacity. Disposal of waste batteries will become a significant issue for the automotive industry in the years to come. This work proposes the use of the second life of these batteries as flexible loads to participate in the economic power dispatch. The characteristics of second life batteries (SLBs) are varied and diverse, requiring a new optimization strategy for power dispatch at the system level. In this work, SLBs are characterized and their operating curves are obtained analytically for developing an economic power dispatch model involving wind farms and second life batteries. In addition, a dispatch strategy is developed to reduce the dispatch complex brought by the disperse spatial and time distribution of EVs and decrease the system operating cost by introducing incentive and penalty costs in regulating the EV performance. In theory, SLBs are utilized to reduce the peak-valley difference of power loads and to stabilize the power system. Test results based on a ten-unit power system have verified the effectiveness of the proposed dispatch model and the economic benefit of utilizing SLBs as flexible loads in power systems. This work may provide a viable solution to the disposal of waste batteries from EVs and to the stable operation of fluctuating power systems incorporating stochastic renewable energy.

Use of reluctance network modelling and software component to study the influence of electrical machine pole number on hybrid electric vehicle global optimization

In the paper, the global optimization of hybrid electric vehicle (HEV) components and control is performed using genetic algorithm and dynamic programming. Reluctance network modelling (RNM) is used to describe the behaviour of the electrical machine (EM). The pole number is considered as a design variable in the EM model. A software component is built from this model and is used in Matlab for a sizing by optimization. The influence of the EM pole number on the system optimization is analysed. Contrary to the low differences observed on the energy efficiency of the vehicle, the machine shape is highly impacted.

An electrochemical model based degradation state identification method of Lithium-ion battery for all-climate electric vehicles application

The Lithium-ion batteries (LiBs) are the core component of the all-climate electric vehicles. The aging state recognition is carried out based on the proposed electrochemical model (EM) instead of the traditional equivalent circuit model (ECM) and black boxes model in this paper. Firstly, a group of mathematical equations are built to describe the physical and chemical behaviors of batteries based on the electrochemical theory. Then, the finite analysis method and the numerical computation method are used to solve the mathematical equations and the model has been built. Next, the optimization algorithm is used for identifying the parameters of the model. The aging state recognition of the battery on whole lifetime is carrying out based on the ageing data. Five aging characteristic parameters are determined to describe the health state of the battery, and their degradation trajectories are obtained. Finally, a battery-in-loop approach is employed to verify the model based degradation recognition. Results show that the maximum voltage error is within 50 mV and the state of health estimation error is bounded to 3%.

Practical implementation of the concept of converted electric vehicle with advanced traction and dynamic performance and environmental safety indicators

The objective of the work presented in this paper is to describe the implementation of the technical solutions have been developed, with regard to structure, composition, and characteristics, for an experimental prototype of an electric vehicle which has been converted from a conventional vehicle. The methodology of the study results is based on the practical implementation of the developed concept of the conversion of conventional vehicles into electric vehicles. The main components of electric propulsion system of the experimental prototype of electric vehicle are developed and manufactured on the basis of computational researches, taking into account the criteria and principles of conversion within the framework of presented work. The article describes a schematic and a design of power conversion and commutation electrical equipment, traction battery, electromechanical transmission. These results can serve as guidance material in the design and implementation of electric propulsion system (EPS) components of electric vehicles, facilitate the development of optimal technical solutions in the development and manufacture of vehicles, including those aimed at autonomy of operation and the use of perspective driver assistance systems. As part of this work, was suggested a rational structure for an electric vehicle experimental prototype, including technical performance characteristics of the components of EPS.

Multiobjective Optimal Sizing of Hybrid Energy Storage System for Electric Vehicles

Energy storage system (ESS) is an essential component of electric vehicles, which largely affects their driving performance and manufacturing cost. A hybrid energy storage system (HESS) composed of rechargeable batteries and ultracapacitors shows a significant potential for maximally exploiting their complementary characteristics. This study focuses on optimal HESS sizing of an example electric vehicle using a multi-objective optimization algorithm, with the overarching goal of reducing the ESS cost while prolonging battery life. To this end, a battery state-of-health model is incorporated to quantitatively investigate the impact of component sizing on battery life. The wavelet-transform-based power management algorithm is adopted to realize the power coordination between the batteries and ultracapacitors, in which the ultracapacitors are responsible for handling high-frequency power transients, whereas the batteries deal with average power leveling. The Urban Dynamometer Driving Schedule is used to represent real power demands.

Performance test and analysis of key components of pure electric vehicles

Tests are performed in this article to analyse the lithium iron phosphate (LiFePO4) battery performance and drive motor system performance, so as to give a sufficient understanding of performance characteristics of key components of pure electric vehicles (EV). The EV powertrain system performance test bed is applied for the tests. Applying a LiFePO4 battery (192 V/100 A·h) as the research object, a calculation method is developed for battery charging/discharging efficiency. Tests are performed to analyse the influence of battery temperature on terminal voltage, as well as the influence of battery SOC and charging/discharging current on the battery efficiency. Applying an AC asynchronous motor (rated power 32 kW) as the research object, tests are performed to analyse the influence of battery voltage on the performance of motor system, the efficiency characteristics of drive motor within the high-speed field weakening area, and the efficiency characteristics of drive motor in normal working conditions. Through the tests and analysis for the performance of EV battery and motor, it can provide guidance for the matching of EV powertrain system, and gives basis for development of high-efficient EV control strategies.

Material selection and assembly method of battery pack for compact electric vehicle

Battery packs become the key component in electric vehicles (EVs). The main costs of which are battery cells and assembling processes. The battery cell is indeed priced from battery manufacturers while the assembling cost is dependent on battery pack designs. Battery pack designers need overall cost as cheap as possible, but it still requires high performance and more safety. Material selection and assembly method as well as component design are very important to determine the cost-effectiveness of battery modules and battery packs. Therefore, this work presents Decision Matrix, which can aid in the decision-making process of component materials and assembly methods for a battery module design and a battery pack design. The aim of this study is to take the advantage of incorporating Architecture Analysis method into decision matrix methods by capturing best practices for conducting design architecture analysis in full account of key design components critical to ensure efficient and effective development of the designs. The methodology also considers the impacts of choice-alternatives along multiple dimensions. Various alternatives for materials and assembly techniques of battery pack are evaluated, and some sample costs are presented. Due to many components in the battery pack, only seven components which are positive busbar and Z busbar are represented in this paper for using decision matrix methods.

Battery group parameter selection and dynamic simulation of pure electric vehicle

The battery pack is one of the core components of pure electric vehicle, dynamic performance of the whole vehicle is closely related to the matching design of the battery, and is affected by the air resistance coefficient and the windward area of the whole vehicle. The dynamic indicators include maximum driving speed, 0-100km/h acceleration time and climbing grade, the battery parameters are designed and matched before the vehicle design, mainly analyze influence on the vehicle dynamic performance of the types of batteries, air resistance coefficient, windward area by the simulation software ADVISOR, and optimize the combination of these parameters. The results show that the dynamic performance of the vehicle reaches the initial design index and the dynamic performance of the vehicle is improved significantly.

Investigation of challenges in interior and surface permanent magnet synchronous machines during integrated charging operation in electric vehicles

The beneficial nature of employing power electronics and drive components in conventional electric vehicle (EV) towards level 3 charging capability has propelled research activities towards integrated charging (IC) technology. However, alternating magnetic fields produced in the air-gap by AC charging currents and the stationary nature of the rotor leads to unusual loss and magnet operating characteristics. Since the same permanent magnet synchronous motor (PMSM) will be used for both traction and IC, it is important to understand the machine's behaviour during IC to optimally design the machine for both applications. Hence, this paper exclusively investigates: 1) permanent magnet operation; 2) electrical and magnet losses; 3) temperature rise; and 4) effect of winding inductances on voltages and currents, in both surface and interior traction PMSMs employed for IC in EVs. Results obtained from investigations conducted on laboratory interior and surface PMSMs using finite element analysis and experimentation are analysed and discussed.

Analysis and Optimization of the Vibration and Noise of a Double Planetary Gear Power Coupling Mechanism

As the key component of a hybrid electric vehicle (HEV), the dynamic performance of the power coupling mechanism is found to have a significant effect upon the vibration and noise of the whole vehicle. In this paper, a dynamic model with rigid and flexible bodies of a double planetary gear power coupling mechanism is established. Then, the characteristics of the bearing constraining forces in time domain and frequency domain are simulated and analysed. At the same time, the finite element model of the housing of the power coupling mechanism is established. Then, the vibration response of the housing is analysed under the excitation of the bearing constraining forces, and the vibration displacement of the housing surface is obtained. Furthermore, based on the vibration displacement of the housing surface, a prediction model of housing radiating noise is established. Then, the radiating noise characteristics of the housing and the acoustic contribution of each panel are analysed. Finally, the free damping structure and new stiffener structure are adopted to optimize the rear end cover of the housing. The optimization model based on the vibration acceleration of the rear end cover surface is established by applying K‐S function and response surface method. Then, the optimization model is solved by applying the sequential quadratic programming to obtain the optimal structure of the housing. The optimization results demonstrate that the acoustic power level after optimization is decreased by 3.94 dB, 3.92 dB, 5.59 dB, and 2.84 dB at frequencies of 770 Hz, 870 Hz, 1650 Hz, and 2480 Hz, respectively. Therefore, the optimization effect of the housing structure is obvious, and this can be the theoretical basis and reference for reducing the vibration and noise of the power coupling mechanism.

Performance test and analysis of key components of pure electric vehicles

Performance test and analysis of key components of pure electric vehicles

Parameters Affecting the Sustainability Trade-off between Production and Use Stages in the Automotive Lightweight Design

Nowadays, lightweight materials and design is one of the means carmakers employ to reduce CO2 emissions according to EU's goals and sustainability principles. In this paper, a comparative analysis between alternative design solutions for Electric Vehicles (EVs) components was carried out using Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) methodologies to evaluate the trade-off between impacts from production and use stages. This work is part of the activities of the ENLIGHT European Green Vehicles project, where the objective was to advance highly innovative lightweight material technologies for application in EVs structural parts. The purposes of the study are: i) to evaluate the parameters influencing the trade-off from the environmental and economic perspective; ii) to combine LCA and LCC results interpretations. The results stressed that the trade-off becomes much more sensitive when innovative materials and technologies are applied to EVs lightweighting.