International Journal of Electric and Hybrid Vehicles (25 papers in press)
Smart accelerating and braking achieving higher energy efficiencies in electric vehicles
by Guido Wäger, Jonathan Whale, Thomas Bräunl
Abstract: To maximise the use of the relatively small energy storage in mainstream electric vehicles (EV), an efficient operation is critical. Regardless of the traction power or energy regeneration capabilities (recuperation), each EV motor controller operates more efficiently under certain motor rotational speeds (rpm) and loads than others. Unlike internal combustion engine (ICE) cars or hybrid cars, EVs do not have variable gearboxes that allows the rpm to be adapted to adjust the engine speed towards more efficient regions. However, the driver can actively influence the load by changing acceleration or deceleration rates. This can lead to a more efficient operation of the EV's motor and controller. Although EV efficiency tests, modelling, and multi gearbox efficiency tests have been conducted, many of these studies focused on following a speed profile with relatively small changes in acceleration and deceleration rates. This study exposes an EV to a series of high load variations in acceleration and deceleration, in order to investigate the impact on energy consumption. The results show significant improvements in efficiency and a reduction in energy consumption by applying high loads at low vehicle speeds. However, the study also found increased losses under certain high acceleration rates, which outweighed the benefits of loading an EV so that its engine speed is in its most efficient region.
Keywords: electric vehicle efficiency; motor controller efficiency; smart acceleration.
Research status of structure optimisation design for in-wheel motor-driven system
by Di Tan, Haitao Wang, Fan Song, Lidong Miao
Abstract: As one of the key technologies of the next generation 'pure electric drive' electric vehicle, the in-wheel motor-driven electric vehicle has been paid great attention by the auto industry, because of its obvious technical advantages in the overall arrangement of the vehicle, the chassis active control and the convenience of control. Domestic and international automobile group companies, scientific research institutes and automobile components suppliers have invested considerable research and development efforts on these vehicles. The in-wheel motor-driven system integrates the motor, the speed reducer, the brake and so on into a narrow space and its integrated structure and performance directly affect the driving/braking performance of the driving wheels and the driving performance of the vehicle. Therefore, as one of the core technologies of these vehicles, the optimisation design of the integrated structure has always been a difficult and hot spot in the research institutes. In this paper, the development status of the optimisation design technology for the integrated structure of the in-wheel motor driven system at home and abroad is analysed and summarised, and on the basis of this, the future research directions are discussed.
Keywords: in-wheel motor-driven system; optimisation design; electromagnetic design; thermal design; lightweight design.
Modelling and control of a bidirectional single-phase single-stage converter for plug-in electric vehicles
by Reza Sabzehgar, Yaser M. Roshan
Abstract: In this paper, the modelling and control of a bidirectional single-phase single-stage converter for plug-in electric vehicles is presented. A nonlinear sliding mode controller with boundary layer solution and a redefined sliding manifold are proposed to enforce a pseudo-resistive relation between the input voltage and current. Based on the pseudo-resistive relationship obtained between the input voltage and current, the sliding mode control approach is used to regulate the input resistance of the converter to a desired value, hence allowing charging and discharging of PEVs. Numerical simulation results are presented that evaluate performance of the proposed modelling and feedback control scheme.
Keywords: plug-in electric vehicle; vehicle-to-grid; grid-to-vehicle; bidirectional charger; power electronics converter; modelling and control; sliding mode control; sliding manifold redefinition; chattering compensation.
Electrical vehicle bearings: technological impact, applications and requirements
by Maruti Khaire
Abstract: The automotive industry is going through a major technological shift from internal combustion engines to Electric Vehicles (EV). The EV technologies are governed mainly from cleaner energy and environmental concerns besides falling fossil fuel reserves. This major technological shift is having a long-term and significant impact on the bearings industry. Bearing usage per vehicle is expected to come down with electrification of bearings. This paper discusses the impact of vehicle electrification on the bearings industry and the technological requirements for successful development of EV bearings. Enhanced bearing life, reliability improvement, power dense bearings, smart bearings capable of sensor implementation, optimised friction, NVH characteristics, special attention to lubricants and sealing are some of the key technical requirements for EV vehicle bearings. Surface engineering and application of specialty coatings have the potential to increase bearing application coverage and optimised cost of bearing for EVs. EV bearings are going to add new bearing damages, such as electrical pitting and lubricant burning. Electrical pitting and lubricant burning are going to generate internal contamination in the bearings, which may reduce the life of bearings. It is imperative for bearing engineers to build a deeper understanding of the new technological requirements for EV bearings to fulfill the new market requirements.
Keywords: electrical vehicle bearings; reliability improved bearing; power dense bearing; smart bearing; friction optimisation in bearing.
Analysis and research of in-wheel motor temperature field for electric vehicles
by Jiwen Ren, Juanlin Huang, Qiping Chen, Qiang Xiao, Sheng Kang
Abstract: Electric vehicles with in-wheel driving motors have broad market prospects. The in-wheel motor is regarded as the key component of electric vehicles, it has important theoretical and engineering application value to analyse and research. This paper describes the current situation and existing problems of the in-wheel motor, analyses the mechanisms of iron loss, copper loss, and mechanical loss, and studies four types of motor temperature field analysis method, including the equivalent heat road method, the equivalent thermal network, the finite element method, and the coupling method of temperature field and fluid field. By comparing the methods of gas cooling and liquid cooling, the research progress of in-wheel motor cooling is analysed, and the development trend of in-wheel motor cooling technologies is discussed.
Keywords: electric vehicles; in-wheel motor; temperature field; cooling; motor loss.
Optimisation of control strategy of a range-extended electric bus
by Yunfei Zha, Jinlong Song, Qingyong Zhang, Guoqing Liu, Ronghui Guo
Abstract: The aim of the present study was to optimise the cycle fuel consumption and energy consumption of a range-extended electric bus. The optimal variables included the final drive ratio of the main decelerator, the upper and lower limits of the power unit, and the speed threshold. NSGA-II was used as the optimisation algorithm. The optimisation results showed that the overall economy behaviour of the bus was improved, while climbing performance increased by 43.77%. The stability of dynamic performances was acceptable because only slight fluctuations were found in the maximum speed and the acceleration duration from 0 to 50 km/h. Although the power consumption increased by 0.6%, the per 100 km fuel consumption decreased by 32.98%. The results showed that the optimisation strategies, optimisation objectives and optimisation variables applied were reasonable and effective.
Keywords: range-extended vehicle; control strategy; CRUISE simulation; optimisation.
Study on the influence of sorting parameters on lithium-ion battery pack life-cycles Based on cell consistency
by Qiuting Wang
Abstract: Lithium-ion batteries have been applied as the most extensive and stable power sources in electric vehicles (EVs). The variation of cell parameters is a critical factor to the safety, energy density, life and stability of the battery pack. The main efforts of our studies are, firstly, the current distribution of two parallel cells is obtained based on the equivalent circuit method (ECM) in actual operation condition; the distribution model was verified and can be used in serial, parallel and mixed constructions. Secondly, the self-discharge rate is certificated as an important parameter to affect cell-consistency in the ageing process. The rate value was deduced based on the solid electrolyte interface (SEI) membrane growth model. Thirdly, a reliable theoretical basis for optimising the cell sorting method is provided. Lastly, the ageing tests using 18 cells in parallel construction were conducted. The experimental results indicate that our new sorting method and sorting parameters can improve the cell consistency performance in the ageing process.
Keywords: lithium-ion battery; sorting parameters; current distribution; cell consistency; equivalent circuit method; solid electrolyte interface.
Improvement of economic and ecological characteristics of a car with a start-stop system
by Vladimir Dvadnenko, Shchasiana Arhun, Aleksandr Bogajevskiy, Svitlana Ponikarovska
Abstract: The work analyses the existing start-stop systems. Most of them have the following drawbacks: low efficiency, increased load on the battery, starter and engine, noise, jerks and vibrations at the start, the start delay time, etc. The proposed improvements to the start-stop system allow increasing its efficiency. The main feature is a second generator, and, thanks to it, the increased time and power of recuperative braking; besides, the engine can be stopped in a vehicle that is running by inertia or downward. At a certain speed of the car the engine is started without a starter, and the energy of recuperative braking is used for electrical heating of the coolant. The paper presents a kinematic diagram of the transmission of a car with an improved start-stop system. A poly-V-belt drive has been chosen as a drive of the second generator. Experimental studies of the engine start in various modes have been carried out, and graphs of the dependence of the vehicle speed on the time are presented.
Keywords: energy recuperation; environmental safety; hybrid car; start-stop system.
Second-hand electrical vehicles: a first look at the secondary market of modern EVs
by Gabriel Pedrosa, Helena Nobre
Abstract: The first mass-produced electrical vehicles (EVs) reached the ten years mark and their future remains uncertain. Both practitioners and researchers have devoted much attention to the marketing of new EVs. However, the secondary market remains unapproached. In the automotive sector, this market can be as much as three times the size of the new car market. Yet, it remains unknown how EVs will be received. This study takes the first step to understanding the reception of second-hand EVs by addressing this research gap through a qualitative design based on 17 in-depth interviews with drivers of conventional fuel vehicles. Based on the analysis of the drivers attitudes towards second-hand EVs, willingness to pay, and the role of battery condition and warranty options, the paper proposes some recommendations for the practice and future research venues on the secondary market of EVs.
Keywords: electric vehicle; secondary market; second hand EV; battery; warranty.
Development and analysis of series/series resonant wireless system for electric two-wheeler battery charging
by Panugothu Srinivasa Rao Nayak, Kishan Dharavath
Abstract: In recent years Wireless Power Transfer (WPT) for electric vehicle battery charging is a developing technology. It allows electric power transfer without any physical connection between a transmitter and a receiver over a certain distance. However, to improve the power transfer capability over a longer distance, the coupled coils must be compensated with an appropriate capacitor. This paper deals with implementation and analysis of series/series resonant wireless battery charging system for electric two-wheeler at resident parking garages or at public parking places. The charging profiles such as charging current and time with various misalignment conditions of the coupled coils are presented and also the efficiency of the system is analysed. The experimental result conveys the appropriateness of the proposed design can be implemented for real-time heavy-duty vehicles.
Keywords: wireless power transfer; series/series compensation; Buck converter; mutual inductance.
Parameter design and characteristic analysis of the interior non-uniform air-gap permanent magnet synchronous motor for electric vehicles
by Ma Shilun, Zhang Xueyi, Du Qinjun, Geng Huihui
Abstract: Aiming at the demand for high torque and wide speed range of permanent magnet synchronous motor (PMSM) used in electric vehicles, a PMSM with fractional slot concentrated winding and the rotor of non-uniform airgap is designed. Fourier harmonic analysis theorem is used to calculate the harmonic content and peak value of cogging torque of different rotor eccentricities. Combined with finite element simulation software, the influence of rotor of uniform airgap and the rotor of non-uniform airgap on the q axis and d axis magnetic circuit is analysed, so the optimal rotor eccentricity is determined. Compared with the rotor of uniform airgap, the peak value of cogging torque and the waveform distortion rate is reduced, while the salient rate is increased. Performance tests are done and results show that reasonable rotor eccentricity can effectively improve the motor of flux weakening
Keywords: permanent magnet synchronous motor; non-uniform air gap; harmonic; salient ratio; flux-weakening expansion rate.
Using the health benefits of electric vehicles to justify charging infrastructure incentives.
by Mitchell House, David Wright
Abstract: Health benefits from switching from internal combustion vehicles to electric vehicles (EVs) include reduction of healthcare costs from treating cardiopulmonary illness, less sick leave taken from work, and quality and length of life improvements. This paper compares the financial value of those benefits with the cost of building an EV charging infrastructure. When the number of charging stations increases with the number of EVs the net benefit is positive, unless the cost of all charging stations is at the high end of the empirical range or when the number of charging stations per EV is higher than in Norway. In scenarios with a rapid build-out of charging stations over 2-4 years, there is a net cost during the build-out period and net benefits from 2021 onwards. These results justify the use of government incentives for charging station deployment and this paper quantifies the impact of different levels of incentive.
Keywords: electric vehicles; charging infrastructure; health benefits; government policy; risk analysis.
Interaction magnetic field formulation of permanent magnets based on Bakers rotational magnetic propulsion device
by Jihad Rishmany, Guitta Sabiini
Abstract: This paper presents a semi-analytical approach for calculating the magnetic interaction field between two permanent magnets based on Bakers rotational magnetic propulsion device. A theoretical formulation of the configuration is derived and solved numerically in order to obtain the interaction magnetic field between cuboidal permanent magnets based on the charge model method. A simple case is considered where the magnets are made of the same material and magnetized uniformly along their axes of symmetry. Numerical solution of the analytical system of equations permits proposing a configuration for a permanent magnet motor having the proper combination of materials, geometry and magnetic concentration. This configuration is capable of ensuring three aspects: a self-starting nature, continuity of the magnetic field, and overcome of the lock-point. Finally, part of the permanent magnet motor is constructed and tested. Experimental results are in accordance with numerical results confirming the self-starting nature and overcome of the lock-point.
Keywords: charge model method; discretization technique; interaction magnetic force; magnetization charges; permanent magnet.
Artificial neural network based adaptive control for plug-in hybrid electric vehicles
by Kavya Prabha Divakarla, Sanjaka Wirasingha, Ali Emadi, Saiedeh Razavi
Abstract: Plug-in Hybrid Electric Vehicles (PHEV) have become vital for oil consumption reduction. They have not achieved their maximum potential owing to control strategy limitations. Existing controllers are often tuned to achieve the best fuel economy for specific conditions. It is impractical to optimise a controller for every scenario. A control strategy for PHEVs using Artificial Neural Networks (ANN) is presented. The advantages of implementing a controller using ANN include independence from drive cycle or user, precision and robustness, and updatable training set. Existing PHEV control strategies are used to model a base for city and highway driving. Simulation data was extracted to form an ANN training set, which was used to develop a new strategy that was better than existing ones. The controller was validated using different drive cycles. Furthermore, the sensitivity of ANN controllers is presented. The controller is also used to validate the charge depleting mode of PHEVs.
Keywords: adaptive control; artificial neural network; charge depleting; classification; control strategy; drive trains; dynamic programming; efficiency; fuel economy; hybrid electric vehicles; intelligent control; plug-in hybrid electric vehicles; power electronics; markov dynamic programming; optimization and propulsion systems.
PMSM control for electric vehicles based on fuzzy PI
by Qiping Chen, Sheng Kang, Liping Zeng, Qiang Xiao, Conghui Zhou, Minming Wu
Abstract: A fuzzy PI speed controller based on fuzzy control theory is proposed, which makes the drive control system of electric vehicles insensitive to disturbance and parameter change. The mathematical model of PMSM in d-q reference frame is established, the fuzzy PI speed controller is designed based on fuzzy control theory, and a simulation model of PMSM based on fuzzy PI control theory and sliding mode control theory is built. Two simulation models are simulated and analysed by Simulink, and simulation results show that fuzzy PI control has faster dynamic response speed, better dynamic performance and better anti-jamming ability than sliding mode control. Therefore, fuzzy PI control is an ideal control method, which has a certain reference value in vector control of PMSM for electric vehicles.
Keywords: electric vehicle; PMSM; fuzzy PI; vector control; simulation analysis.
Electric vehicles in India: financial and environmental perspectives
by Rajeev Goswami, Gireesh Chandra Tripathi
Abstract: Worldwide, reducing vehicular emissions is a cumbersome task to save our planet from climate change. The introduction of electric vehicles could be one of the approaches to reduce the emissions. In this paper, various factors of total cost of ownership of conventional and electric cars from both financial and environmental perspectives were studied. To equalise the cost drivers of vehicles with diverse lives, equivalent annual annuity procedure was used to show that the total cost of ownership of an electric car is more economical than the fossil-fuelled ones. Additionally, electric cars were found to be more environmentally benign than conventional cars, even if EV is energised with electricity generated from coal-based thermal power plants. Therefore, this research would encourage promoting EVs for fast adoption for societal benefits and helping governments to frame e-mobility related policies.
Keywords: electric vehicles; air pollution; emissions; ownership cost; energy efficiency; government incentives; India.
Study on optimal deceleration of electric vehicle with serial regenerative braking: a multi-objective approach
by Arup Nandi, Debasri Chakraborty, Mousumi Khanra
Abstract: In order to improve the fuel economy and range of electric vehicles, as much energy regeneration as possible is needed during braking. It is noticed that prolonged deceleration can increase the regenerative energy, but shorter deceleration is important to avoid an accident and decrease the overall trip time. To resolve these conflicting objectives, a study is conducted here to find the optimal deceleration based on a multi-objective approach so that regenerative energy will be maximised while reducing the deceleration duration. Considering the journey comfort is another concern to the passengers health, so an optimal driving zone is designed for different speed changes for a typical configuration of electric vehicle with serial regenerative braking system. Simulation results suggest that using two decelerations during braking is most appropriate to fulfill the above objectives. Analysis of published experimental drive data of an electric bus confirms the similar notion. The proposed approach is implemented in planned braking mode in which the driver well before knows the desired location where the vehicle is required to be slowed to a certain speed or stopped. The proposed approach improves the fuel economy and range of the electric vehicle, which builds confidence to electric vehicle users for trip planning.
Keywords: electric vehicle; optimal driving; regenerative braking; energy; trip time; comfort; multi-objective optimisation.
Barriers to the implementation of electric vehicles in metropolitan areas of India
by Umakant Panwar, Anil Kumar, Deepankar Chakrabarti
Abstract: The electric vehicle is not a new concept, it has been in existence from 1828 but owing to improvements in internal combustion engine technology it got relegated to the sidelines. This concept has resurfaced in the past decade or two as a tool for a sustainable and green future, but faces a lot of barriers to implementation. Indias dependency on fossil fuels, the lack of lithium reserves, the grid-integration problems, along with a lack of charging station infrastructure in metropolitan areas, have become major barriers to the acceptance of electric vehicles. This paper deals with the barriers to the introduction of electric vehicles in metropolitan areas. India needs to improve and enforce the regulatory framework, and work on consumer and public awareness to overcome these barriers.
Keywords: electric vehicle; barriers; regulatory framework; charging station; public awareness; India.
Parameter matching and braking performance advantage study for all-electric independent driving and braking electric vehicle with four wheels
by Kun Yang, Jie Wang, Di Tan, Xueyi Zhang, Jishun Liu
Abstract: All-electric integrated brake system is the feature for all-electric independent driving and braking electric vehicle with four wheels (AEIDBEV). Based on its advantages, an integrated simulation platform for parameter matching and performance verification is built. The vehicle control strategy is given. The results of simulation show that the all-electric integrated brake system can meet the drivers braking demand and has three advantages. The first is that its braking effectiveness is slightly better than the purely mechanical brake system. The second is the work time and the torque capacity for electromechanical brake (EMB) can be reduced remarkably. This provides a basis for optimising EMB. The third is that it can improve vehicle economy obviously. AEIDBEV has obvious energy-saving effect compared with no braking energy recovery scheme and coupled braking energy recovery scheme at three drive cycles of NEDC, Beijing and Changchun.
Keywords: electric vehicle; all-electric integrated brake; in-wheel motor; electromechanical brake; parameter matching; braking performance.
The effect of perceived risk on the purchase intention of electric vehicles: an extension to the technology acceptance model
by Thilina Dk, Nisal Gunawardhane
Abstract: Electric cars will be the future of the transportation industry as it records a significant market penetration including Sri Lanka. The purchasing mechanism that drives customers to make purchasing decisions is a critical notion to investigate since it engages many connected factors. Accordingly, this study reviews how the perceived risk factor influences purchase intention referring to electric vehicles in Sri Lanka. The review is based on the theoretical rationale and supportive empirical findings. A descriptive statistical review is presented to signify why Sri Lanka is considered as a context to be examined whilst empirical evidence is presented to support the arguments. The paper concludes with research propositions to examine how perceived risk influences the purchasing mechanism of electric vehicles, whilst buying intention is referred as a main notion within.
Keywords: electric vehicles; consumer buying behaviour; perceived risk; purchase intention; Sri Lanka; technology acceptance model; alternative fuel vehicles; hybrid vehicles; Purchasing Determinants.
Comparing battery electric vehicle powertrains through rapid component sizing
by Pier Giuseppe Anselma, Giovanni Belingardi
Abstract: The current transition from internal combustion engine vehicles to battery electric vehicles requires the development and implementation of novel design methodologies. This paper introduces an original design procedure for battery electric light vehicle powertrains based on rapid brute force optimization. At first, a large design space is generated by sweeping the relevant design parameters, specifically the motor size, the number of gears and the transmission ratios. Analytical modelling for electric vehicle powertrains is then presented and combined with hookup tables for the actual system components. The feasible candidate designs are identified by introducing evaluation criteria for the transmission ratios according to the vehicle and electric machine data considered. Subsequently, these candidate designs are evaluated both in terms of launching performance and energy consumption by adopting an efficiency based gear-shifting strategy. Optimal designs can finally be graphically identified through a Pareto frontier analysis as effectively demonstrated in the case of four actual vehicles of different classes. The methodology introduced efficiently addresses the nonlinear multidimensional optimization problem of electric vehicle powertrain design.
Keywords: battery electric vehicle; component sizing; design optimisation; gear-shifting strategy; powertrain; rapid design.
Economic, environmental and congestion impact on the life-cycle cost of ownership: a case study in the Delhi transit bus system
by Rajeev Goswami, Gireesh Chandra Tripathi
Abstract: Fast growth of urbanisation and motorisation has resulted in deteriorated air quality and increased burden on most cities, globally. Cities use two-thirds of the global energy and account for about 70% of GHG emissions. Therefore, it is important to consider electric buses as an eco-friendly alternative to conventional buses. To study the financial and environmental impact on the life-cycle cost of ownership of conventional and electric buses, we have established the total cost of ownership (TCO) model by considering direct cost (acquisition and operation: owned by the fleet owner) and indirect cost (environmental damage and congestion: owned by the society). This study showed that EVs TCO would be economic, giving 30-40% advantage on fuel and maintenance. Further, EVs powered with renewable energy mix could prove to be a positive multiplier for socio-economic and environmental gain.
Keywords: urban transport; sustainability; electric bus; government policy; congestion cost; noise pollution.
Parameter matching and sensitivity analysis for the power system of micro-electric vehicle
by Jiyan Qi, Jingshun Fu, Jiaqi Jin
Abstract: The parameter matching for the power system with a micro-electric vehicle is carried out based on the prototype. The performance of the micro-electric vehicle is verified using the ADVISOR software. The mathematical model and calculation method of sensitivity analysis for the complete vehicle curb mass to maximum acceleration of evaluating indicator is established as the example。 The maximum acceleration and SOC are selected as the evaluation indexes of the micro-electric vehicle performance, and the typical vehicle structural parameters are selected as the influence factors based on many simulation comparisons and comprehensive analysis. The non-parametric statistical method is proposed to analyse the sensitivity of typical structural factors affecting its performance by drawing on one-at-a-time sensitivity measures. Analysis results show that the windward area，, the air resistance coefficient, and the centroid height are the most important factors affecting the two evaluation indexes. The final conclusion is significant for the design and application of micro-electric vehicles.
Keywords: micro-electric vehicle; in-wheel motor; power system; sensitivity; parameters matching.
Modelling of the wide frequency equivalent circuit of the three-phase AC motor based on vector fitting method
by L.I. Lihui, L.I. Xu
Abstract: The prediction of conducted interference in the motor drive system is an important part of the automotive EMC analysis. The accuracy of the motor EMI model directly affects the accuracy of the conducted interference prediction. For this purpose, based on the measured data, this paper proposes a broadband equivalent circuit model for the three-phase AC motor. The motor is regarded as a single-port network, and its common mode and differential mode impedances are measured. Combining the measured data, a rational function expression is established by the vector fitting method. The influence of different fitting orders is analysed under different parameters, and then an equivalent circuit model of the three-phase AC motor is established. The comparison between simulation and experiment shows that the modelling method is simple, accurate, and highly applicable.
Keywords: EMI model; measurement data; vector fitting method; AC motor.
Review on control of permanent magnet brushless DC motor for electric vehicle
by Zeng Song, Xiaobin Fan, Jing Gan
Abstract: As people's incomes increase, the number of cars is increasing, and global warming, energy depletion and ecological crisis are intensifying. Electric vehicles have received our attention. Countries have successively issued a ban on the sale of fuel vehicles, and plans to achieve zero emissions of automobiles in 2030-2050. The motor is an important part of electric vehicles, and many kinds of motor for electric vehicles have been developed. The brushless DC motor will be widely used in the future development for its superior performance. Brushless DC motors will become more sophisticated as technology evolves.
Keywords: traditional fuel vehicle; brushless DC motor; control method.