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World Electr. Veh. J., Volume 10, Issue 2 (June 2019)

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Cover Story (view full-size image) The aggregation and control of electric vehicles (EVs) via vehicle-to-grid (V2G) technologies is [...] Read more.
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Open AccessArticle
Charging Load Allocation Strategy of EV Charging Station Considering Charging Mode
World Electr. Veh. J. 2019, 10(2), 47; https://doi.org/10.3390/wevj10020047
Received: 6 May 2019 / Revised: 17 June 2019 / Accepted: 20 June 2019 / Published: 23 June 2019
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Abstract
A charging load allocation strategy for Electric Vehicles (EVs) considering charging mode is proposed in this paper in order to solve the challenge and opportunity of large-scale grid-connected charging under the background of booming EV industry in recent years. Based on the peak-to-valley [...] Read more.
A charging load allocation strategy for Electric Vehicles (EVs) considering charging mode is proposed in this paper in order to solve the challenge and opportunity of large-scale grid-connected charging under the background of booming EV industry in recent years. Based on the peak-to-valley Time-of-Use (TOU) price, this strategy studies the grid load, charging cost and charging station revenue variation of EVs connected to the grid in different charging modes. In addition, this paper proposes an additional charging mechanism for charging stations to encourage EV owners to participate in the peak and valley reduction of the grid through coordinated charging. According to the example analysis, under the same charging demand conditions, the larger EV charging power will have a greater impact on the grid than the conventional charging power. This article collects additional service fees for car owners who are not involved in the coordinated charging. When the response charging ratio is less, the more total service charges are charged, which can compensate for the decline in the sales revenue of the charging station during the valley period. While having good economy, it can also encourage the majority of car owners to participate in the coordinated charging from the perspective of charging cost. Full article
(This article belongs to the Special Issue Charging Infrastructure for Electric Vehicles)
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Open AccessArticle
Case Study of Holistic Energy Management Using Genetic Algorithms in a Sliding Window Approach
World Electr. Veh. J. 2019, 10(2), 46; https://doi.org/10.3390/wevj10020046
Received: 18 April 2019 / Revised: 25 May 2019 / Accepted: 4 June 2019 / Published: 18 June 2019
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Abstract
Energy management systems are used to find a compromise between conflicting goals that can be identified for battery electric vehicles. Typically, these are the powertrain efficiency, the comfort of the driver, the driving dynamics, and the component aging. This paper introduces an optimization-based [...] Read more.
Energy management systems are used to find a compromise between conflicting goals that can be identified for battery electric vehicles. Typically, these are the powertrain efficiency, the comfort of the driver, the driving dynamics, and the component aging. This paper introduces an optimization-based holistic energy management system for a battery electric vehicle. The energy management system can adapt the vehicle velocity and the power used for cabin heating, in order to minimize the overall energy consumption, while keeping the total driving time and the cabin temperature within predefined limits. A genetic algorithm is implemented in this paper. The approach is applied to different driving cycles, which are optimized by dividing them into distinctive time frames. This approach is referred to as the sliding window approach. The optimization is conducted with two separate driving cycles, the New European Driving Cycle (NEDC) and a recorded real-world drive. These are analyzed with regard to the aspects relevant to the energy management system, and the optimization results for the two cycles are compared. The results presented in this paper demonstrate the feasibility of the sliding window approach. Moreover, they reveal the differences in fundamental parameters between the NEDC and the recorded drive and how they affect the optimization results. The optimization leads to an overall reduction in energy consumption of 3.37 % for the NEDC and 3.27 % for the recorded drive, without extending the travel time. Full article
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Open AccessArticle
Electric Vehicle Fast Charging Needs in Cities and along Corridors
World Electr. Veh. J. 2019, 10(2), 45; https://doi.org/10.3390/wevj10020045
Received: 16 April 2019 / Revised: 3 June 2019 / Accepted: 14 June 2019 / Published: 18 June 2019
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Abstract
Fast charging is seen as a means to facilitate long-distance driving for electric vehicles (EVs). As a result, roll-out planning generally takes a corridor approach. However, with higher penetration of electric vehicles in urban areas, cities contemplate whether inner-city fast chargers can be [...] Read more.
Fast charging is seen as a means to facilitate long-distance driving for electric vehicles (EVs). As a result, roll-out planning generally takes a corridor approach. However, with higher penetration of electric vehicles in urban areas, cities contemplate whether inner-city fast chargers can be an alternative for the growing amount of slow public chargers. For this purpose, more knowledge is required in motives and preferences of users and actual usage patterns of fast chargers. Similarly, with increasing charging speeds of fast chargers and different modes (taxi, car sharing) also switching to electric vehicles, the effect of charging speed should be evaluated as well as preferences amongst different user groups. This research investigates the different intentions and motivations of EV drivers at fast charging stations to see how charging behaviour at such stations differs using both data analysis from charging stations as a survey among EV drivers. Additionally, it estimates the willingness of EV drivers to use fast charging as a substitute for on-street home charging given higher charging speeds. The paper concludes that limited charging speeds imply that EV drivers prefer parking and charging over fast charging but this could change if battery developments allow higher charging speeds. Full article
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Open AccessArticle
Research on the Anti-Disturbance Control Method of Brake-by-Wire Unit for Electric Vehicles
World Electr. Veh. J. 2019, 10(2), 44; https://doi.org/10.3390/wevj10020044
Received: 20 May 2019 / Revised: 12 June 2019 / Accepted: 13 June 2019 / Published: 15 June 2019
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Abstract
In order to improve the braking performance of electric vehicles, a novel brake-by-wire actuator based on an electro-magnetic linear motor was designed and manufactured. For the purpose of braking force regulation accuracy and high robust performance, the state observer and the anti-disturbance controller [...] Read more.
In order to improve the braking performance of electric vehicles, a novel brake-by-wire actuator based on an electro-magnetic linear motor was designed and manufactured. For the purpose of braking force regulation accuracy and high robust performance, the state observer and the anti-disturbance controller were designed in this paper after describing the actuator structure, braking principle, and mathematical model. The simulation and experimental results showed that the brake actuator responded rapidly, since its response time was only 15 ms. Compared to traditional PID (Proportion Integration Differentiation) methods, the controller proposed in this paper is able to regulate the braking force more precisely and has better anti-disturbance performance, thus the braking process can be accurately controlled according to the driver’s demand. The vehicle simulation results showed that the braking distance and braking time were shortened by 12.19% and 15.54%, respectively compared with those of the conventional anti-lock brake system (ABS) in the same braking conditions. Full article
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Open AccessArticle
Battery Sizing for Electric Vehicles Based on Real Driving Patterns in Thailand
World Electr. Veh. J. 2019, 10(2), 43; https://doi.org/10.3390/wevj10020043
Received: 5 April 2019 / Revised: 27 May 2019 / Accepted: 12 June 2019 / Published: 15 June 2019
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Abstract
The rising population in suburban areas have led to an increasing demand for commuter buses. Coupled with a desire to reduce pollution from the daily routine of traveling and transportation, electric vehicles have become more interesting as an alternative placement for internal combustion [...] Read more.
The rising population in suburban areas have led to an increasing demand for commuter buses. Coupled with a desire to reduce pollution from the daily routine of traveling and transportation, electric vehicles have become more interesting as an alternative placement for internal combustion engine vehicles. However, in comparison to those conventional vehicles, electric vehicles have an issue of limited driving range. One of the main challenges in designing electric vehicles (EVs) is to estimate the size and power of energy storage system, i.e., battery pack, for any specific application. Reliable information on energy consumption of vehicle of interest is therefore necessary for a successful EV implementation in terms of both performance and cost. However, energy consumption usually depends on several factors such as traffic conditions, driving cycle, velocities, road topology, etc. This paper presents an energy consumption analysis of electric vehicle in three different route types i.e., closed-area, inter-city, and local feeder operated by campus tram and shuttle bus. The driving data of NGV campus trams operating in a university located in suburban Bangkok and that of shuttle buses operating between local areas and en route to the city were collected and the corresponding representative driving cycles for each route were generated. The purpose of this study was to carry out a battery sizing based on the fulfilment of power requirements from the representative real driving pattern in Thailand. The real driving cycle data i.e., velocity and vehicle global position were collected through a GPS-based piece of equipment, VBOX. Three campus driving data types were gathered to achieve a suitable dimensioning of battery systems for electrified university public buses. Full article
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Open AccessArticle
Simulation of Future Electric Vehicle Charging Behavior—Effects of Transition from PHEV to FEV
World Electr. Veh. J. 2019, 10(2), 42; https://doi.org/10.3390/wevj10020042
Received: 19 February 2019 / Revised: 7 June 2019 / Accepted: 9 June 2019 / Published: 14 June 2019
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Abstract
The Netherlands is a frontrunner in the field of public charging infrastructure, having one of the highest number of public charging stations per electric vehicle (EV) in the world. During the early years of adoption (2012–2015), a large percentage of the EV fleet [...] Read more.
The Netherlands is a frontrunner in the field of public charging infrastructure, having one of the highest number of public charging stations per electric vehicle (EV) in the world. During the early years of adoption (2012–2015), a large percentage of the EV fleet were plugin hybrid electric vehicles (PHEV) due to the subsidy scheme at that time. With an increasing number of full electric vehicles (FEVs) on the market and a current subsidy scheme for FEVs only, a transition of the EV fleet from PHEV to FEV is expected. This is hypothesized to have an effect on the charging behavior of the complete fleet, and is reason to understand better how PHEVs and FEVs differ in charging behavior and how this impacts charging infrastructure usage. In this paper, the effects of the transition of PHEV to FEV is simulated by extending an existing agent-based model. Results show important effects of this transition on charging infrastructure performance. Full article
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Open AccessArticle
Evaluation of the Magnetic Field Leakage from Two Wireless Power Transfer Systems for EV/PHV Driven Simultaneously
World Electr. Veh. J. 2019, 10(2), 41; https://doi.org/10.3390/wevj10020041
Received: 21 May 2019 / Revised: 8 June 2019 / Accepted: 10 June 2019 / Published: 13 June 2019
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Abstract
Wireless power transfer for electric and plug-in hybrid vehicles has been developed to facilitate battery charging. In a wireless power transfer system, because the magnetic field leaks to the surroundings of the vehicle, it is important to evaluate the quantitative human exposure. The [...] Read more.
Wireless power transfer for electric and plug-in hybrid vehicles has been developed to facilitate battery charging. In a wireless power transfer system, because the magnetic field leaks to the surroundings of the vehicle, it is important to evaluate the quantitative human exposure. The International Commission on Non-Ionizing Radiation Protection provides guidelines for human exposure assessment. In this study, we evaluate the magnetic field leakage under two parking configurations and current phase differences for two vehicles being simultaneously charged (3.7 kW at 85 kHz per vehicle). The results of the analysis show that the magnetic field leakage is lower than the reference level of the guidelines for all cases and that the leakage could be reduced by controlling the phase difference between the two wireless power transfer systems equally distributed from the single high-frequency power source for each parking configuration. Full article
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Open AccessArticle
Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System
World Electr. Veh. J. 2019, 10(2), 40; https://doi.org/10.3390/wevj10020040
Received: 10 April 2019 / Revised: 23 May 2019 / Accepted: 6 June 2019 / Published: 10 June 2019
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Abstract
This paper provides a comparative study on radiation noise reduction methods for inductive power transfer systems using spread spectrum. In the spread spectrum methods, the radiation noise is reduced by continuously changing an output frequency of the inverter according to pseudorandom numbers. The [...] Read more.
This paper provides a comparative study on radiation noise reduction methods for inductive power transfer systems using spread spectrum. In the spread spectrum methods, the radiation noise is reduced by continuously changing an output frequency of the inverter according to pseudorandom numbers. The effects of the radiation noise reduction are evaluated with the inductive power transfer (IPT) system with series-parallel compensation and series-series compensation. The results show that the peak values of the radiation noise around the fundamental frequency are reduced by 7.8 and 8.1 dBμA in maximum with the series-series compensation method and the series-parallel compensation method, respectively in comparison with the constant frequency operation. From these results, the proposed methods are effective for both the series-series compensation and series-parallel compensation method. Moreover, the efficiency of the IPT system with spread spectrum method is evaluated. The maximum DC-to-DC efficiency with the spread spectrum is 94.1% and 92.0% with the series-series compensation and the series-parallel compensation, respectively. Full article
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Open AccessArticle
Research on Regenerative Braking of Pure Electric Mining Dump Truck
World Electr. Veh. J. 2019, 10(2), 39; https://doi.org/10.3390/wevj10020039
Received: 10 May 2019 / Revised: 4 June 2019 / Accepted: 5 June 2019 / Published: 8 June 2019
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Abstract
When the pure electric mining dump truck is working, it mainly ascends the slope at full load and descends the slope at no load. The loading state of the vehicle and the slope of the road will directly affect its axle load distribution [...] Read more.
When the pure electric mining dump truck is working, it mainly ascends the slope at full load and descends the slope at no load. The loading state of the vehicle and the slope of the road will directly affect its axle load distribution and braking force distribution. In this paper, the slope dynamics analysis of the pure electric double-axle four-wheel drive mining dump truck was carried out. Based on the regenerative braking priority strategy, four regenerative braking control methods were developed based on the Matlab/Simulink platform and ADVISOR 2002 vehicle simulation software to study the ability of regenerative braking energy recovery and its impact on vehicle economic performance. The simulation results show that the regenerative braking priority control strategy used can maximize the regenerative braking force of the vehicle; the regenerative energy recovery capability of pure electric mining dump truck is proportional to the regenerative braking force that can be provided during braking; the two-axis braking strategy based on the I curve and the β line can make full use of the front and rear axle regenerative braking force when the braking intensity is large, and recover more braking energy; under road drive cycle, the single-axis braking force required to the braking strategy based on the maximized front axle braking force is the largest among all strategies, the motor braking efficiency is the highest, and the recovered braking energy is the most. For the studied drive cycle, the regenerative braking technology can reduce the vehicle energy consumption by 1.06%–1.56%. If appropriate measures are taken to improve the road surface condition and reduce the rolling resistance coefficient from f = 0.04 to f = 0.02, the regenerative braking technology can further reduce the vehicle energy consumption to 4.76%–5.73%. The economic performance of the vehicle is improved compared to no regenerative braking. In addition, the vehicle loading state and the driving motor working efficiency also directly affect the regenerative braking energy recovery capability of the pure electric mining truck. Full article
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Open AccessArticle
Newly Developed Motor Cooling Method Using Refrigerant
World Electr. Veh. J. 2019, 10(2), 38; https://doi.org/10.3390/wevj10020038
Received: 9 April 2019 / Revised: 13 May 2019 / Accepted: 1 June 2019 / Published: 4 June 2019
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Abstract
One of the greatest issues for electric vehicles such as an electric vehicle (EV), a hybrid vehicle (HV), a plug-in hybrid electric vehicle (PHEV) and a fuel cell vehicle (FCV) is further improvement of effective motor cooling, since higher rated torque is achieved [...] Read more.
One of the greatest issues for electric vehicles such as an electric vehicle (EV), a hybrid vehicle (HV), a plug-in hybrid electric vehicle (PHEV) and a fuel cell vehicle (FCV) is further improvement of effective motor cooling, since higher rated torque is achieved with higher cooling performance. In this paper, we introduce and propose a newly developed motor cooling method we tested using refrigerant, comparing with conventional water cooling. Test results show higher cooling performance of refrigerant cooling, which achieved the rated torque 60% higher than that of water cooling. Full article
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Open AccessArticle
Stand-Alone Battery Thermal Management for Fast Charging of Electric Two Wheelers—Integrated Busbar Cooling
World Electr. Veh. J. 2019, 10(2), 37; https://doi.org/10.3390/wevj10020037
Received: 18 April 2019 / Revised: 29 May 2019 / Accepted: 30 May 2019 / Published: 4 June 2019
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Abstract
This paper presents a thermal interface for cylindrical cells using busbar-integrated cooling channels. This interface is available due to the use of a stand-alone refrigerant circuit for the thermal management of the battery. A stand-alone refrigerant circuit offers performance and efficiency increases compared [...] Read more.
This paper presents a thermal interface for cylindrical cells using busbar-integrated cooling channels. This interface is available due to the use of a stand-alone refrigerant circuit for the thermal management of the battery. A stand-alone refrigerant circuit offers performance and efficiency increases compared to state-of-the-art battery thermal management systems. This can be achieved by increasing the evaporation temperature to the requirements of the Li-ion cells and the use of alternative refrigerants. The solution proposed in this paper is defined for electric two-wheelers, as the thermal management of these vehicles is currently insufficient for fast charging where high heat losses occur. Three channel patterns for the integrated busbar cooling were examined regarding their thermal performance to cool the li-ion cells of a 16p14s battery pack during fast charging. A method of coupling correlation-based heat transfer and pressure drop with thermal finite element method (FEM) simulations was developed. The symmetric channel pattern offers a good compromise between battery temperatures and homogeneity, as well as the best volumetric and gravimetric energy densities on system level. Average cell temperatures of 22 °C with a maximum temperature spread of 8 K were achieved. Full article
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Open AccessArticle
Ride Blending Control for Electric Vehicles
World Electr. Veh. J. 2019, 10(2), 36; https://doi.org/10.3390/wevj10020036
Received: 18 April 2019 / Revised: 26 May 2019 / Accepted: 28 May 2019 / Published: 31 May 2019
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Abstract
Vehicles equipped with in-wheel motors (IWMs) feature advanced control functions that allow for enhanced vehicle dynamics and stability. However, these improvements occur to the detriment of ride comfort due to the increased unsprung mass. This study investigates the driving comfort enhancement in electric [...] Read more.
Vehicles equipped with in-wheel motors (IWMs) feature advanced control functions that allow for enhanced vehicle dynamics and stability. However, these improvements occur to the detriment of ride comfort due to the increased unsprung mass. This study investigates the driving comfort enhancement in electric vehicles that can be achieved through blended control of IWMs and active suspensions (ASs). The term “ride blending”, coined in a previous authors’ work and herein retained, is proposed by analogy with the brake blending to identify the blended action of IWMs and ASs. In the present work, the superior performance of the ride blending control is demonstrated against several driving manoeuvres typically used for the evaluation of the ride quality. The effectiveness of the proposed ride blending control is confirmed by the improved key performance indexes associated with driving comfort and active safety. The simulation results refer to the comparison of the conventional sport utility vehicle (SUV) equipped with a passive suspension system and its electric version provided with ride blending control. The simulation analysis is conducted with an experimentally validated vehicle model in CarMaker® and MATLAB/Simulink co-simulation environment including high-fidelity vehicle subsystems models. Full article
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Open AccessArticle
Performance Status Evaluation of an Electric Vehicle Charging Infrastructure Based on the Fuzzy Comprehensive Evaluation Method
World Electr. Veh. J. 2019, 10(2), 35; https://doi.org/10.3390/wevj10020035
Received: 31 March 2019 / Revised: 26 April 2019 / Accepted: 21 May 2019 / Published: 30 May 2019
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Abstract
Performance status evaluation is essential for the safe running of electric vehicle (EV) charging infrastructure. With the development of the EV industry, the EV charging infrastructure industry has advanced considerably. Safe and reliable operation of the charging infrastructure is important for the development [...] Read more.
Performance status evaluation is essential for the safe running of electric vehicle (EV) charging infrastructure. With the development of the EV industry, the EV charging infrastructure industry has advanced considerably. Safe and reliable operation of the charging infrastructure is important for the development of EVs. As such, we propose a comprehensive evaluation method to assess the performance condition of an EV charging infrastructure. First, based on the analysis of the existing EV charging principles, we established an evaluation index system for EV charging infrastructure. Second, the subjective weight, objective weight, and comprehensive weight of the index system were determined through analytic hierarchy processes (AHP) and the entropy weight method. Then, we used fuzzy comprehensive evaluation to appraise the performance of the charging infrastructure through expert investigation. Finally, based on the actual data from an EV charger, the performance conditions of the EV charging infrastructure were evaluated to demonstrate the feasibility of the method and the reliability of the index system. Full article
(This article belongs to the Special Issue Charging Infrastructure for Electric Vehicles)
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Open AccessArticle
Sideslip Angle Fusion Estimation Method of an Autonomous Electric Vehicle Based on Robust Cubature Kalman Filter with Redundant Measurement Information
World Electr. Veh. J. 2019, 10(2), 34; https://doi.org/10.3390/wevj10020034
Received: 7 May 2019 / Revised: 27 May 2019 / Accepted: 28 May 2019 / Published: 30 May 2019
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Abstract
Accurate and reliable estimation information of sideslip angle is very important for intelligent motion control and active safety control of an autonomous vehicle. To solve the problem of sideslip angle estimation of an autonomous vehicle, a sideslip angle fusion estimation method based on [...] Read more.
Accurate and reliable estimation information of sideslip angle is very important for intelligent motion control and active safety control of an autonomous vehicle. To solve the problem of sideslip angle estimation of an autonomous vehicle, a sideslip angle fusion estimation method based on robust cubature Kalman filter and wheel-speed coupling relationship is proposed in this paper. The vehicle dynamics model, tire model, and wheel speed coupling model are established and discretized, and a robust cubature Kalman filter is designed for vehicle running state estimation according to the discrete vehicle model. An adaptive measurement-update solution of the robust cubature Kalman filter is presented to improve the robustness of estimation, and then, the wheel-speed coupling relationship is introduced to the measurement update equation of the robust cubature Kalman filter and an adaptive sideslip angle fusion estimation method is designed. The simulations in the CarSim-Simulink co-simulation platform and the actual vehicle road test are carried out, and the effectiveness of the proposed estimation method is validated by corresponding comparative analysis results. Full article
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Open AccessArticle
Low-Frequency Road Noise of Electric Vehicles Based on Measured Road Surface Morphology
World Electr. Veh. J. 2019, 10(2), 33; https://doi.org/10.3390/wevj10020033
Received: 27 March 2019 / Revised: 8 May 2019 / Accepted: 11 May 2019 / Published: 30 May 2019
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Abstract
In this paper, the noise vibration harshness (NVH) road surface morphology of a test site is scanned to establish a data processing system for the road surface, which can be used to transform the road surface morphology into the road surface excitation required [...] Read more.
In this paper, the noise vibration harshness (NVH) road surface morphology of a test site is scanned to establish a data processing system for the road surface, which can be used to transform the road surface morphology into the road surface excitation required for the road noise simulation analysis. The road surface morphology of the test site is used as the excitation input of the simulation analysis. The results obtained from the simulation analysis are equivalent to the experimental results. Using the actual scanning road surface morphology to simulate the excitation of a vehicle, the noise, as well as the vibration response of the vehicle under the actual road excitation of NVH in the early stage of vehicle development, can be accurately predicted. In the physical prototype stage, the rectification of vehicle road noise and the optimization to provide the needed excitation for the simulation analysis can be done, which will reduce the labor costs of the relevant experiment. Therefore, this method of road noise research has important engineering significance. Full article
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Open AccessArticle
A Conceptualized Hydrail Powertrain: A Case Study of the Union Pearson Express Route
World Electr. Veh. J. 2019, 10(2), 32; https://doi.org/10.3390/wevj10020032
Received: 11 January 2019 / Revised: 12 April 2019 / Accepted: 29 April 2019 / Published: 28 May 2019
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Abstract
A hydrogen rail (hydrail) powertrain is conceptualized in this study, using drive cycles collected from the trains currently working on the Union Pearson Express (UPE) railroad. The powertrain consists of three preliminary different subsystems: fuel cell, battery, and hydrogen storage systems. A backward [...] Read more.
A hydrogen rail (hydrail) powertrain is conceptualized in this study, using drive cycles collected from the trains currently working on the Union Pearson Express (UPE) railroad. The powertrain consists of three preliminary different subsystems: fuel cell, battery, and hydrogen storage systems. A backward design approach is proposed to calculate the time-variable power demand based on a “route simulation data” method. The powertrain components are then conceptually sized according to the calculated duty cycle. The results of this study show that 275 kg of hydrogen is sufficient to satisfy the daily power and energy demand of a hydrogen locomotive with drive cycles similar to the ones currently working on the UPE rail route. Full article
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Open AccessArticle
Electrical Steels and Their Evaluation for Automobile Motors
World Electr. Veh. J. 2019, 10(2), 31; https://doi.org/10.3390/wevj10020031
Received: 17 April 2019 / Revised: 17 May 2019 / Accepted: 20 May 2019 / Published: 27 May 2019
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Abstract
Achieving high efficiency and high torque is an important target in EV motors. This paper describes the effect of the magnetic properties of electrical steels used as core materials for synchronous motors with permanent magnets, which are commonly used as the EV traction [...] Read more.
Achieving high efficiency and high torque is an important target in EV motors. This paper describes the effect of the magnetic properties of electrical steels used as core materials for synchronous motors with permanent magnets, which are commonly used as the EV traction motors. It was confirmed that electrical steels, which have high flux density and low iron loss properties can realize high motor efficiency and torque. When PWM excitation is considered, thinner electrical steels are advantageous to suppress increased loss due to higher harmonics. Based on these results, electrical steels having high flux densities and low iron losses at high frequencies were developed. Full article
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Open AccessArticle
Electric Safety Challenges with a Conductive Electric Road System—Chassis Potential Modeling and Measurement
World Electr. Veh. J. 2019, 10(2), 30; https://doi.org/10.3390/wevj10020030
Received: 19 April 2019 / Revised: 10 May 2019 / Accepted: 20 May 2019 / Published: 24 May 2019
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Abstract
Conductive Electric Road Systems (ERS) appear as a promising solution for the electrification of transportation, particularly for heavy vehicles and long-distance trips but also for light vehicles. Significant research efforts are currently devoted to the development of conductive ERS systems, with up to [...] Read more.
Conductive Electric Road Systems (ERS) appear as a promising solution for the electrification of transportation, particularly for heavy vehicles and long-distance trips but also for light vehicles. Significant research efforts are currently devoted to the development of conductive ERS systems, with up to four pilot test sites with different technologies in operation only in Sweden. With the help of electric models and experimental measurements on a pilot test track, this article assesses the potential safety challenges associated with one aspect of this technology: the absence of a reliable protective earth connection while the vehicle is connected to the ERS power supply. The results highlight the importance of monitoring the chassis potential at all times and the need of an active safety mechanism to disconnect the vehicle from the ERS supply if a severe fault occurs. Full article
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Open AccessReview
Intelligent Hydrogen Fuel Cell Range Extender for Battery Electric Vehicles
World Electr. Veh. J. 2019, 10(2), 29; https://doi.org/10.3390/wevj10020029
Received: 28 February 2019 / Revised: 11 May 2019 / Accepted: 14 May 2019 / Published: 24 May 2019
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Abstract
Road transport is recognized as having a negative impact on the environment. Policy has focused on replacement of the internal combustion engine (ICE) with less polluting forms of technology, including battery electric and fuel cell electric powertrains. However, progress is slow and both [...] Read more.
Road transport is recognized as having a negative impact on the environment. Policy has focused on replacement of the internal combustion engine (ICE) with less polluting forms of technology, including battery electric and fuel cell electric powertrains. However, progress is slow and both battery and fuel cell based vehicles face considerable commercialization challenges. To understand these challenges, a review of current electric battery and fuel cell electric technologies is presented. Based on this review, this paper proposes a battery electric vehicle (BEV) where components are sized to take into account the majority of user requirements, with the remainder catered for by a trailer-based demountable intelligent fuel cell range extender. The proposed design can extend the range by more than 50% for small BEVs and 25% for large BEVs (the extended range of vehicles over 250 miles), reducing cost and increasing efficiency for the BEV. It enables BEV manufacturers to design their vehicle battery for the most common journeys, decreases charging time to provide convenience and flexibility to the drivers. Adopting a rent and drop business model reduces the demand on the raw materials, bridging the gap in the amount of charging (refueling) stations, and extending the lifespan for the battery pack. Full article
(This article belongs to the Special Issue Propulsion Systems of EVs)
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Open AccessArticle
Implementation of an Energy Management Strategy with Drivability Constraints for a Dual-Motor Electric Vehicle
World Electr. Veh. J. 2019, 10(2), 28; https://doi.org/10.3390/wevj10020028
Received: 18 April 2019 / Revised: 10 May 2019 / Accepted: 20 May 2019 / Published: 23 May 2019
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Abstract
This paper presents a real-time energy management strategy to distribute the power demand between two independent motors properly. Based on the characteristics of the novel transmission system, an enumeration-based searching approach is used to hunt for the optimal working points for both motors [...] Read more.
This paper presents a real-time energy management strategy to distribute the power demand between two independent motors properly. Based on the characteristics of the novel transmission system, an enumeration-based searching approach is used to hunt for the optimal working points for both motors to maximize the overall efficiency. Like many energy management strategies, approaches that focus on reducing energy consumption can result in frequent gearshifts. To improve drivability and make a balance between energy consumption and gearshifts, a cost function is designed. To verify the effectiveness of the proposed method, a mathematical model is built, and the simulation results demonstrate the achieved improvements. Full article
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Open AccessArticle
85 kHz Band 44 kW Wireless Rapid Charging System for Field Test and Public Road Operation of Electric Bus
World Electr. Veh. J. 2019, 10(2), 26; https://doi.org/10.3390/wevj10020026
Received: 19 April 2019 / Revised: 18 May 2019 / Accepted: 20 May 2019 / Published: 23 May 2019
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Abstract
Wireless charging technology for heavy-duty vehicles has been investigated for eco-friendly transportation. We present a new wireless power transfer system for 44 kW rapid charging of electric buses. The transmission distance between the charging pads is from 10 to 13 cm. The large [...] Read more.
Wireless charging technology for heavy-duty vehicles has been investigated for eco-friendly transportation. We present a new wireless power transfer system for 44 kW rapid charging of electric buses. The transmission distance between the charging pads is from 10 to 13 cm. The large air gap can be fulfilled by the ordinary kneeling function, equipped on most low-floor buses. Dual-block parallel transmission with opposite-phase-current-feeding suppresses magnetic radiation. The system operates in the common 85 kHz band with the light-duty vehicle system. The result of the field test and the public road operation of two electric buses confirm the CO2 reduction effect described. Full article
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Open AccessArticle
Auxiliary Power Supply System for Electric Power Steering (EPS) and High-Heat-Resistant Lithium-Ion Capacitor
World Electr. Veh. J. 2019, 10(2), 27; https://doi.org/10.3390/wevj10020027
Received: 19 April 2019 / Revised: 15 May 2019 / Accepted: 18 May 2019 / Published: 22 May 2019
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Abstract
Advanced Driver Assistance System (ADAS) and Automated Driving (AD) are the two major topics for the current and next generations of vehicles. To realize them in full-size vehicles equipped with a 12 V power supply, the need for electric power steering (EPS) is [...] Read more.
Advanced Driver Assistance System (ADAS) and Automated Driving (AD) are the two major topics for the current and next generations of vehicles. To realize them in full-size vehicles equipped with a 12 V power supply, the need for electric power steering (EPS) is increasing. Currently, the steering system of full-size vehicles is equipped with hydraulic power steering due to electric power shortage. An auxiliary power supply system using a lithium-ion capacitor was developed in order to solve the concern. In addition, to mount the system in the vehicle with no cooling–heating equipment, development of expanding the operating temperature range of the lithium-ion capacitor was conducted. Several improvements have made the capacitor operate stably in high-temperature environments above 100 °C. Full article
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Open AccessArticle
Stabilization of Vehicle Dynamics by Tire Digital Control—Tire Disturbance Control Algorithm for an Electric Motor Drive System
World Electr. Veh. J. 2019, 10(2), 25; https://doi.org/10.3390/wevj10020025
Received: 16 April 2019 / Revised: 17 May 2019 / Accepted: 18 May 2019 / Published: 21 May 2019
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Abstract
We propose an algorithm with disturbance control for tires on electric vehicles (EVs) so as to improve the steering stability of the vehicle. The effect was validated on EVs equipped with twin independent electric motors on a skid pad. The algorithm with the [...] Read more.
We propose an algorithm with disturbance control for tires on electric vehicles (EVs) so as to improve the steering stability of the vehicle. The effect was validated on EVs equipped with twin independent electric motors on a skid pad. The algorithm with the disturbance controller can remove the external noise generated on tires in order to suppress the abrupt slip and micro vibration generated between the tire and road surface, especially on low friction surfaces at the critical speed of the vehicle. The effective frequency corresponded to tire scale length. The effect was verified by the fact that the hysteresis loop with control on the chart of steer angle and yaw rate showed a smaller loop than those without control. The hysteresis loop with control also appeared at the oversteering area, which can be interpreted as evidence that the algorithm can make the vehicle more stable and gain faster speed on the skid pad. It is concluded that the tire digital control works well without any information from sensors on the vehicle body and without any cooperative control between tires. Full article
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Open AccessArticle
Effects of Environmental Conditions on Cathode Degradation of Polymer Electrolyte Fuel Cell during Potential Cycle
World Electr. Veh. J. 2019, 10(2), 24; https://doi.org/10.3390/wevj10020024
Received: 28 February 2019 / Revised: 15 May 2019 / Accepted: 16 May 2019 / Published: 21 May 2019
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Abstract
We investigated the effects of cell temperature and the humidity of gas supplied to the cell during the load cycle durability test protocol recommended by The Fuel Cell Commercialization Conference of Japan (FCCJ). Changes in the electrochemically active surface area (ECA) and in [...] Read more.
We investigated the effects of cell temperature and the humidity of gas supplied to the cell during the load cycle durability test protocol recommended by The Fuel Cell Commercialization Conference of Japan (FCCJ). Changes in the electrochemically active surface area (ECA) and in the amount of carbon support corrosion were examined by using the JARI standard single cell. The ECA declined more quickly when the gas humidity was raised, and the carbon corrosion was at the same level. These results suggest that the agglomeration of platinum was accelerated by the same agglomeration mechanism, i.e., by raising the humidity of the gas supplied to the cell. Full article
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Open AccessArticle
Hardware Architecture and Configuration Parameters of a Low Weight Electronic Differential for Light Electric Vehicles with Two Independent Wheel Drive to Minimize Slippage
World Electr. Veh. J. 2019, 10(2), 23; https://doi.org/10.3390/wevj10020023
Received: 19 April 2019 / Revised: 12 May 2019 / Accepted: 15 May 2019 / Published: 20 May 2019
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Abstract
This article presents a design and performance analysis of an Electronic Differential (ED) system designed for Light Electric Vehicles (LEVs). We have developed a test tricycle vehicle with one front steering wheel and two rear fixed units in the same axis with a [...] Read more.
This article presents a design and performance analysis of an Electronic Differential (ED) system designed for Light Electric Vehicles (LEVs). We have developed a test tricycle vehicle with one front steering wheel and two rear fixed units in the same axis with a brushless DC (BLDC) motor integrated in each of them. Each motor has an independent controller unit and a common electronic Arduino CPU that can plan specific speeds for each wheel as curves are being traced. Different implementations of sensors (input current/torque, steering angle and speed of the wheels) are discussed related to their hardware complexity and performance based on speed level requirements and slipping on the traction wheels. Two driving circuits were generated (slalom and circular routes) and driven at different speeds, monitoring and recording all the related parameters of the vehicle. The most representative graphs obtained are presented. The analysis of these data presents a significant change of the behaviour of the control capability of the ED when the lineal speed of the vehicle makes a change of direction that passes 10 Km/h. In this situation, to obtain good performance of the ED, it is necessary to include sensors related to the wheels. Full article
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Open AccessArticle
Development of Hybrid Vehicle Energy Consumption Model for Transportation Applications—Part II: Traction Force-Speed Based Energy Consumption Modeling
World Electr. Veh. J. 2019, 10(2), 22; https://doi.org/10.3390/wevj10020022
Received: 18 April 2019 / Revised: 25 April 2019 / Accepted: 5 May 2019 / Published: 9 May 2019
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Abstract
In the transportation sector, the fuel consumption model is a fundamental tool for vehicles’ energy consumption and emission analysis. Over the past decades, vehicle-specific power (VSP) has been enormously adopted in a number of studies to estimate vehicles’ instantaneous driving power. Then, the [...] Read more.
In the transportation sector, the fuel consumption model is a fundamental tool for vehicles’ energy consumption and emission analysis. Over the past decades, vehicle-specific power (VSP) has been enormously adopted in a number of studies to estimate vehicles’ instantaneous driving power. Then, the relationship between the driving power and fuel consumption is established as a fuel consumption model based on statistical approaches. This study proposes a new methodology to improve the conventional energy consumption modeling methods for hybrid vehicles. The content is organized into a two-paper series. Part I captures the driving power equation development and the coefficient calibration for a specific vehicle model or fleet. Part II focuses on hybrid vehicles’ energy consumption modeling, and utilizes the equation obtained in Part I to estimate the driving power. Also, this paper has discovered that driving power is not the only primary factor that influences hybrid vehicles’ energy consumption. This study introduces a new approach by applying the fundamental of hybrid powertrain operation to reduce the errors and drawbacks of the conventional modeling methods. This study employs a new driving power estimation equation calibrated for the third generation Toyota Prius from Part I. Then, the Traction Force-Speed Based Fuel Consumption Model (TFS model) is proposed. The combination of these two processes provides a significant improvement in fuel consumption prediction error compared to the conventional VSP prediction method. The absolute maximum error was reduced from 57% to 23%, and more than 90% of the predictions fell inside the 95% confidential interval. These validation results were conducted based on real-world driving data. Furthermore, the results show that the proposed model captures the efficiency variation of the hybrid powertrain well due to the multi-operation mode transition throughout the variation of the driving conditions. This study also provides a supporting analysis indicating that the driving mode transition in hybrid vehicles significantly affects the energy consumption. Thus, it is necessary to consider these unique characteristics to the modeling process. Full article
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Open AccessArticle
Test and Modelling of Commercial V2G CHAdeMO Chargers to Assess the Suitability for Grid Services
World Electr. Veh. J. 2019, 10(2), 21; https://doi.org/10.3390/wevj10020021
Received: 14 February 2019 / Revised: 12 April 2019 / Accepted: 18 April 2019 / Published: 24 April 2019
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Abstract
Aggregation and control of electric vehicles (EVs) via vehicle-to-grid (V2G) technologies is seen as a valid option for providing ancillary power system services. This work presents results from V2G-ready equipment tests and modelling. The technical capabilities of an EV connected to a commercial [...] Read more.
Aggregation and control of electric vehicles (EVs) via vehicle-to-grid (V2G) technologies is seen as a valid option for providing ancillary power system services. This work presents results from V2G-ready equipment tests and modelling. The technical capabilities of an EV connected to a commercial V2G charger are investigated when controlled either locally or remotely. The charger is characterized in terms of efficiency characteristics, activation time, response granularity, ramping-up/down time, accuracy and precision. Test results show the performance for different operating conditions, highlighting the importance of a good calibration and knowledge of the employed hardware when providing standard-compliant grid regulation services via V2G technology. Ultimately, a set of simulations demonstrates that the designed EV charger model replicates accurately the operating conditions of the real hardware. Full article
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Open AccessArticle
The Impact of Different Incentive Policies on Hybrid Electric Vehicle Demand and Price: An International Comparison
World Electr. Veh. J. 2019, 10(2), 20; https://doi.org/10.3390/wevj10020020
Received: 20 February 2019 / Revised: 18 April 2019 / Accepted: 18 April 2019 / Published: 23 April 2019
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Abstract
Significant efforts to incentivize the uptake of energy efficient vehicles (EEVs) are evident across the globe. Given EEV markets are dynamic, and consumer demand may fluctuate in response to incentives, this may also lead to other market forces influencing prices. An analysis of [...] Read more.
Significant efforts to incentivize the uptake of energy efficient vehicles (EEVs) are evident across the globe. Given EEV markets are dynamic, and consumer demand may fluctuate in response to incentives, this may also lead to other market forces influencing prices. An analysis of EEV incentives, therefore, must account for the possible endogeneity between demand and pricing. Here we estimate the effects of different types of incentives on the demand and price premiums of a specific group of EEVs: plug-in and conventional hybrid electric vehicles (HEVs). For the first time we dis-entangle the endogeneity between HEV demand and price, using error components three-stage least squares (EC3SLS) regression, and establish that increased HEV price premiums lead to reduced demand. In turn, we also establish that increased HEV demand leads to lower price premiums. Additionally, we find that one-off subsidies are associated with higher consumer demand, however, unlike other types of incentives, are also associated with higher HEV price premiums. This finding suggests that HEV manufacturers and/or dealers are absorbing a significant monetary benefit from one-off subsidies, raising a question regarding the appropriateness of HEV subsidies, particularly in non-HEV manufacturing nations. We also find that higher fuel prices are associated with higher HEV demand and price premiums. Full article
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Open AccessTechnical Note
EV Range Extender in a Two-Battery HEECS Chopper-Based Powertrain
World Electr. Veh. J. 2019, 10(2), 19; https://doi.org/10.3390/wevj10020019
Received: 27 February 2019 / Revised: 28 March 2019 / Accepted: 4 April 2019 / Published: 19 April 2019
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Abstract
This paper first presents a new powertrain based on a two-battery High-Efficiency Energy Conversion System (HEECS) chopper that is suitable for electric vehicles (EVs). The HEECS chopper is based on the principle of a partial power conversion circuit, and the overall efficiency is [...] Read more.
This paper first presents a new powertrain based on a two-battery High-Efficiency Energy Conversion System (HEECS) chopper that is suitable for electric vehicles (EVs). The HEECS chopper is based on the principle of a partial power conversion circuit, and the overall efficiency is over 99% in a wide load range. The efficiency of this powertrain was measured in the steady state by two types of powertrains, a non-chopper powertrain and an HEECS chopper-based powertrain, using a motor test bench. On the basis of these data, several driving tests, such as the Worldwide-harmonized Light vehicles Test Cycle (WLTC), were simulated, and four driving cycle patterns were included. A 6.4% reduction in energy consumption was observed in WLTC low mode compared with the energy consumed by the non-chopper powertrain in the experiments. Thus, the HEECS chopper-based powertrain is more suitable for low-speed driving ranges than high-speed ranges. Full article
(This article belongs to the Special Issue Power Electronics Subsystems)
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Open AccessArticle
A Comparison of Internal and External Preheat Methods for NMC Batteries
World Electr. Veh. J. 2019, 10(2), 18; https://doi.org/10.3390/wevj10020018
Received: 14 March 2019 / Revised: 3 April 2019 / Accepted: 10 April 2019 / Published: 15 April 2019
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Abstract
Lithium-ion batteries (LiBs) performance can be significantly declined when operated at cold climates in terms of capacity loss, resistance increase and accelerated aging rates. To prevent this downgrade and to maintain the optimal operation of battery cells, a preheat process is taking place, [...] Read more.
Lithium-ion batteries (LiBs) performance can be significantly declined when operated at cold climates in terms of capacity loss, resistance increase and accelerated aging rates. To prevent this downgrade and to maintain the optimal operation of battery cells, a preheat process is taking place, which can be implemented either by internal or external techniques. The former is performed actively, by circulating a constant amplitude and frequency alternative pulse current (APC) at the battery cell’s terminal and preheating it internally by harvesting its generated Joule losses. The latter is achieved passively, by enclosing the cell into thermal blankets. In this work, a comparison of these two preheating strategies is presented, by proposing electro-thermal and lifetime models of a lithium nickel manganese cobalt oxide (NMC/G) 20 Ah pouch battery cell. Heat transfer, energy efficiencies and degradation costs are estimated during operation of the preheat techniques. Validation of the model showed a good agreement between the model and experimental data, and a study case is proposed to estimate and compare the cost efficiency of the methods as based for an economic study. Full article
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World Electr. Veh. J. EISSN 2032-6653 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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