World Electr. Veh. J., Volume 4, Issue 2 (June 2010) – 28 articles , Pages 232-436

LiFePO₄ is considered as a practical cathode material because of low raw materials’ cost, excellent thermal safety, environmental friendliness, and long operational life, despite obstacles such as low tap density, low electric conductivity and slow lithium-ion diffusion. To overcome these problems, we used an antimonyion doping method to synthesize LiFePO₄/C with sebacic acid as a carbon source by a high-temperature solid-state reaction method. The effects of antimony concentration, sebacic acid content, calcination temperature, and calcination time on cell performance were investigated. After Sb³⁺ doping, LiFePO₄ was converted to a p-type semiconductor and demonstrated greater electric conductivity of about 10^-3 S cm^-1. The 1.0 mol.% Sb-doped LiFePO₄/C synthesized with 36 wt.% sebacic acid delivered an initial discharge capacity of 154 mAh g^-1 at a 0.2 C-rate between 4.0-2.8 V. The doped cathode materials were further characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), and high-resolution transmission electron microscope (TEM) techniques for structural analysis and confirmation. Full article

Almost all HEV battery control strategies keep the battery state of charge (SOC) within a lower limit (SOCmin) (these strategies also called charge sustaining strategies). The goal from sustaining the SOC in this way is to prolong the battery life. But the question is; what is the optimal value of (SOCmin) for a battery, to achieve best fuel economy and longer battery life at the same time?; knowing that when (SOCmin) is too low (around SOCmin=0.2) we get good fuel economy per one speed cycle but the battery dies soon and cannot perform a lot of cycles, but when (SOCmin) is high (around SOCmin=0.8) the battery can survive for a larger number of speed cycle but with poor fuel economy per cycle. The objective of this paper is to propose a method to investigate and solve this problem by simulation using Simulink environment; we used the manufacture’s data of a Ni-MH battery, empiric equations, and appropriate control strategy to find the optimal value of (SOCmin). The study shows that, for best fuel economy per one cycle; the (SOCmin) value must be as small as possible, for longer battery life; the (SOCmin) value is about (SOCmin=0.85) and for the optimal case (which is the total improvement brought by the battery from first time use until its end of life); the optimal (SOCmin) value is about (SOCmin=0.7). Full article

The aim of the present paper is to share our experience in battery safety testing and risk analysis from a recent project called BLIXT, which had the objective to speed up the progress of the paradigmatic shift toward electric vehicles (EV). The batteries in question have been three different configurations of lithiumion batteries (LiFePO4). The tests have involved fire, crash tests and sort circuit. Full article

Non-intrusive methods of establishing battery state offer distinct advantages to systems where complex charge and discharge profiles make implementation of conventional battery state reporting difficult. Furthermore, examination of equivalent circuit parameters for batteries and cells offers potential opportunities for State-of-Charge (SoC) and State-of-Health (SoH) reporting, irrespective of historic charge and discharge events. This paper expands the use of maximum length sequences as tools for parameter estimation within electrochemical cells, to seek to identify performance indicators within batteries. In order to facilitate this identification, Randles' model is used with Pseudo Random Binary Sequences (PRBS) as the excitation signal within the test system for the batteries being examined. Design of these sequences for experimental analysis is discussed, leading to application in the described test system, employing a monopolar current signal in order to apply the perturbation to the subject battery. Battery impedance is investigated using a frequency domain approach, leading to characteristic impedance spectra being produced for the test batteries. The experimental results obtained allow parameters to be established, and verification against conventional battery test methods, and a sampled data model, is carried out.
This analysis is used to present characteristics which can be subsequently used to inform the design of SoC and SoH algorithms, in order to develop online systems for evaluating these batteries. Full article

This article presents how active charge balancing of energy storage devices such as batteries and supercaps can be improved by using the capacity and the state of charge instead of the cell voltage as balancing criterion. Both for charging and discharging an improvement of performance is gained when using the state of charge and the capacity of the cells as information. A battery stack is modeled and a realistic driving cycle is applied to compare the difference between both methods in terms of usable energy. Finally, the simulation is validated by measurements. Full article

The electrochemical performance of LiFePO₄/C cathode in a carbonate-based electrolyte (1.0M LiPF₆/EC-DMC-PC-FEC) was tested in coin type cells at low temperatures. The discharge capacities of the LiFePO₄/C cathode were about 161.6mAh/g (20℃), 141.4mAh/g (-10℃) and 112.9mAh/g (-20℃) at 0.1C charge-discharge rate. The electrode kinetics of LiFePO4/C cathode was determined at different temperatures using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The analyses demonstrate that the sluggish of charge-transfer reaction on the LiFePO₄/C-electrolyte interface and the dramatic decrease in lithium ion diffusivity in the bulk LiFePO₄/C material were the key performance limiting factors at low temperature. Full article

This paper describes research into the definition of experimental protocols, and the development of a numerical model of a battery, associated with a parameterization assistant tool in order to follow battery ageing. This work was carried out as part of the SIMSTOCK program. The experimental characterizations (ageing cycle tests and characterization protocols) are defined in association with the different research lab partners of the project. They were performed on Lithium-ion VL6P cells supplied by Johnson Control - SAFT (J.C.S). The characterization protocols are performed at different phases of a program: initially to establish the reference value parameters and periodically, in order to follow all the changes occurring during the ageing of a Li-Ion battery. The different numerical tools presented in this paper are adapted to the LMS-Imagine Lab AMESim simulation platform. The present model makes it possible to simulate the dynamical voltage response of the battery as a function of inlet current and temperature. The identification tool associated is able to determine from a temporal experimental characterization of the battery (U and I), the data necessary for the implementation of the parameters in the model. The assistant tool identifies the parameters of the numerical model at different ages of the Li-Ion battery. Its results are used in order to quantify the influence of ageing phenomena on the performance of the battery considered. Full article

A low cost battery charger is introduced in this paper. The charging feature meets the requirement of a Li-Ion rechargeable cell designed for electric vehicles and manufactured by E company. The charger is capable of constant current/constant voltage charging strategy, double over current/voltage protection and automatically offloaded with a sound alarm when the charging current is smaller than about 40mA. A detail circuit diagram and its operation principle are proposed and some experimental results are also given. All devices used in the charger circuit are very common and easily purchased. Because of its simple structure only a few modifications are needed to make one’s own specific charger. Full article

This paper proposes a smart lithium-ion battery capacity estimation method for electric bicycles. Battery capacity information informs the electric vehicle driver of the residual battery working time, thus facilitating the estimation of mileage of electric bicycle and timing of battery charging to avoid overcharging or over-discharging. Factors such as different discharge rates, environmental temperature, battery charge and discharge efficiency and battery aging affect the released capacity of battery, which is an electrochemical reaction of battery. In addition to integrating the advantages of the coulometric measurement and open circuit voltage measurement methods, and the proposed smart lithium-ion battery capacity estimator also incorporates discharge current, temperature, battery aging, as well as charging efficiency factors into capacity correction to develop a highly accurate PIC single-chip lithium-ion battery capacity estimation system. Full article

Ultracapacitors are potentially promising power-augmentation devices in hybrid powertrains. A commercial ultracapacitor module was characterized under standard procedures to assess its performance. Tests were carried out on a platform, with which ambient temperature can be regulated and charge/discharge procedures can be implemented. Key parameters of the ultracapacitor module obtained from tests were used to develop a control-oriented ultracapacitor model proposed in the paper. Simulation results of this model in a stable discharge procedure and in dynamic procedures (i.e. driving cycles) showed excellent agreement with results obtained from experiments, indicating that the ultracapacitor model is accurate enough to be used in further electric powertrain control simulation. Full article

Battery cost and battery capacity are key factors to determine whether or not electric vehicles would be used widely. Having a high energy density, lithium-ion battery can improve the mileage range of electric vehicles, yet the battery cost remains high. Although lead-acid battery has lower energy density than that of lithium-ion batteries, lead-acid battery cost less. Moreover, lithium-ion battery features an excellent discharge characteristic, whereas load current significantly impacts the capacity of lead-acid battery. This paper proposes a novel scheme to improve the efficiency of electric vehicle battery. In addition to connecting lead-acid battery with lithium-ion battery in parallel to the power supply, the proposed method combines their discharge characteristics to optimize the power management in order to improve the efficiency of attery and lower the cost of electric vehicle battery. The experimental result demonstrates that the available capacity can improve 30~50% of the rated capacity of the lead-acid battery. Full article

There have been a number of recent reports of the current and projected costs of advanced batteries for electric, hybrid, and plug-in hybrid electric vehicles (PHEVs). These studies have focused on lithium-ion batteries as the most attractive option for future deployment in these vehicles. The reported costs have varied widely. The objective of this paper is to examine the basis of these assessments, taking particular note of the varying assumptions used regarding such important factors as power-to-energy ratio, battery chemistry, production scale, rated capacity vs. useable capacity, and beginning-of-life vs. end-of-life. A high-power battery at low production volume will have a drastically different cost per kWh compared with a high-energy battery at high-volume production. Furthermore, other factors that are, or are not, included in the costs as reported, such as marketing, warranty, and profit, can have a significant impact on reported costs; the manner in which these factors are treated can account for large differences between a manufacturer’s production cost and the battery selling price. Full article

The widespread introduction of electrically-propelled vehicles is currently part of many political strategies and introduction plans. These new vehicles, ranging from limited (mild) hybrid to plug-in hybrid to fully-battery powered, will rely on a new class of advanced storage batteries, such as those based on lithium, to meet different technical and economical targets. The testing of these batteries to determine the performance and life in the various applications is a time-consuming and costly process that is not yet well developed. There are many examples of parallel testing activities that are poorly coordinated, for example, those in Europe, Japan and the US. These costs and efforts may be better leveraged through international collaboration, such as that possible within the framework of the International Energy Agency (IEA). Here, a new effort is under development that will establish standardized, accelerated testing procedures and will allow battery testing organizations to cooperate in the analysis of the resulting data. This paper reviews the present state-of-the-art in accelerated life testing procedures in Europe, Japan and the US. The existing test procedures will be collected, shortly described, compared and analyzed with the goal of defining a process and a possible working plan for the establishment of an international collaboration. Full article

The sulfur-containing PAN composite cathode materials for lithium/sulfur batteries were prepared by suspension polymerization method and electrochemical properties of lithium/sulfur cells were investigated. The sulfur composite cathode was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The structure analysis showed that the sulfur composite is constituted by homogenous flake-like crystallites with the size about 100 nm. The sulfur composite cathode showed a not very high initial capacity of 546.6 mAh•g⁻¹, but the cycle performance was excellent and had a slowly capacity fade after the second cycle, and remained at a reversible capacity of 400mAh•g⁻¹ after 30 cycles. Full article

A 288V/8Ah manganese type Li-ion battery system for hybrid electric vehicle was developed. The performances of single-cell and battery system were tested. For the single-cell, the discharge power and regen power are more than 312.5W and 250W at 45-85% DOD, respectively, and the cycle life is more than 2000 cycles. For the battery system, the continuous discharge power is 41kW at 20C rate, and an 80% charge capacity can be achieved in 10 minutes. The values of voltage difference of 80 single-cells are stable with 0.05V, 0.1V and 0.2V at 1C, 10C and 20C rate in the range of 15%-75% DOD in the battery system, respectively. The discharge power and regen power of battery system are more than 25kW and 20kW at 45-85% DOD, respectively, and its available energy is about 1000Wh. The 288V/8Ah battery system with a good discharge rate performance and a fast charging capability could be used in HEV. Full article

Electric vehicle is considered to be the solution for energy crisis and environment pollution in individual transportation. However, electric vehicles are still not competitive with conventional vehicles limited by the driving range with the state-of-art power battery technology. Therefore, energy efficiency is of crucial importance for battery electric vehicles due to the limited stored energy. In order to optimize the energy efficiency of a four-wheel independently driven electric vehicle, the model consisting of the vehicle dynamics model, wheel motor model and PNGV model of LiFePO4 power battery was developed in Matlab/Simulink. As the motor efficiency is low in small torque range, motors should work as much as possible in high efficiency range in order to extend the driving range. A new control algorithm was developed to distribute the total torque requirement dynamically to four wheel motors. When the total torque requirement is low, only two motors drive the vehicle and when the total torque requirement is high, four motors should work together to deliver the required torque. The vehicle switches between 2-wheel drive mode and 4-wheel drive mode according to the driving condition using the new control algorithm. Simulations of the new control algorithm were carried out on a modified urban drive cycle. The result showed that an improvement in driving range was achieved with the new control algorithm. Full article

This paper describes the results from Annex XII “Heavy-duty hybrid vehicles” of the International Energy Agency (IEA) Implementing Agreement on “Hybrid and Electric Vehicles” (IA-HEV). Since 1993, this Implementing Agreement has provided a platform to exchange knowledge, experience and strategies among the member states on the latest developments in hybrid and electric vehicles, mostly passenger cars. Because heavy-duty vehicles have specific technical requirements and economic boundary conditions compared to the passenger car market, a dedicated Annex was started in 2007 and has run for several years until the end of 2010. Six countries (Belgium, Canada, Finland, Switzerland, the Netherlands and the United States) have been participating to collect and share relevant information on the latest technical and market developments in “electrified” trucks, buses and mobile work machines. This information will broaden the insight in the existing applications of heavy-duty vehicles electrification and can provide essential information for future heavy-duty hybrid vehicle deployment projects. Full article

In recent years, the research of Battery Electric Vehicle (BEV) focuses on energy storage systems, drive system and control strategy. However, one of the important subjects to enhance the performance of BEV is to research the parameters of transmission until the power battery and other technologies are mellow. For the BEV drive system parameters design, such as motor power and output torque as well as transmission gear ratio and the matching have significant impacts on each other for driving range and performance of BEV. Hence, in BEV research and developmental phase, in order to meet the requirements of vehicle performance access to the best structure, generally it must base on different needs to optimize the parameters of the drive system and to consider the combination of vehicle operation among the various components. For this reason, it will be conducive to the rapid development and be widely used for BEV. Therefore, in this paper, the discussion of the design, analysis, matching and system integration of BEV component parameters is proposed, which can be used as a reference for the future development of BEV. Full article

In this study, a double-wheel self balanced unicycle is proposed. Because of the shortage of energy resource and parking space in city, the idea of this light-weight electrical aid personal unicycle can hopefully be used in future transportation system. The unicycle has the features of small longitudinal length, with two coaxial wheels and pedal by human with electric control system to balance the unicycle. It is known that when the rider rides the unicycle, the paddle force disturbs the balance of the vehicle. This unbalance force comes from the gravity center is not at the point of the ground contact points of the vehicle. To balance the unbalance force, two servo-motors to drive the two wheels are used. The unbalance condition is detected by sensors. A transmission mechanism to combine human power and electric power is designed. Planetary gear set is considerable to be the basic concept of transmission mechanism design. The sequence of study processes would be helpful to design the layout of the transmission about chassis, bike frame, and wheels. The mechanism design could link up the mechanical system with the motors and electro-control system. Full article

The paper proposes a fault processing strategy based on classification principle. Detail the realization of the strategy for a fuel cell vehicle which is developed by Tongji University and shanghai fuel cell vehicle powertrain Co., Ltd. Emphasis on the definition of fuel cell vehicle fault classification and the processing strategy of three grade faults. The practicability of the fault processing strategy has been proved by the application in fuel cell vehicle of Shanghai Fuel Cell Vehicle Powertrain Co., Ltd (Copyright 2010 EVS25). Full article

This work implements a smart boost converter to enable an electric bicycle to be powered by a battery/supercapacitor hybrid combination. A 36V, 250W front hub motor was retrofitted onto a normal geared bike powered by a 36V; 12Ah lithium ion phosphate battery pack. A 16.2V, 58F supercapacitor module was connected in parallel to the battery pack via a custom made microcontroller-based boost converter which arbitrates power between the battery and supercapacitor. The control algorithm for the boost converter was developed using a practical approach by using various sensor inputs (battery/supercapacitor current and voltage, bike speed) and comparing the robustness of control scheme. Also energy efficient components were used in designing the boost converter to ensure maximum power transfer efficiency.
Based on the implemented system experimental results show an improvement in the up-hill acceleration of the bicycle as a direct result of the boost converter being responsive enough to harvest the extra current from the high power complementary supercapacitor module avoiding deep discharges from the battery. This enhanced battery life. The maximum speed remained unchanged while the improvement in range per charge was subjective to the terrain i.e. flat land; not significant improvement, hilly terrain; significant. However, recharging the supercapacitor via regenerative braking proved to be an arduous task since the boost converter was not designed to be bi-directional. Copyright Form of EVS25. Full article

In order to lighten abrasion of braking system of hybrid electric tracked vehicle, according to characteristic of hybrid electric transmission, electric-mechanical composite braking method was proposed. By means of analyzing performance of electric braking and mechanical braking and three-segment composite braking strategy, two-segment electric-mechanical composite braking strategy was put forward in this paper. Simulation results of Matlab/Simulink indicated that the two-segment electric-mechanical composite braking strategy might reduce the demand of mechanical braking force and was well applied. Full article

Traditional mobility mostly relies on fossil fuels (e.g. the oil), but they will run out. Before the arrival of the depletion, we must get rid of our mobility dependence on the oil and prepare ourselves well for the advent of that day. Globally under urgent environmental protection mission and further tension between energy supply and demand, the transition of vehicular powertrains combined with the change or yet the revolution in mobility pattern is the trend of the times. Some thoughts and prospect are given here about the mobility pattern and its promotion. Similar to the Internet, a kind of Enternet (energy exchange network) could be constructed for the grid power to be shared and selected by energy users, in which distributed renewable power plants play a role as a "network terminal", and large-scale power plants (e.g. nuclear power plant, large-scale hydropower) as a "network server". It is here proposed to promote and introduce electric mobility in the near of renewable network terminals. Full article

Accurate estimation of battery State of Charge (SOC) is essential for battery control and effective energy management of Hybrid Electric Vehicles (HEV). Taking the dynamic hysteresis characteristic of battery into account, an equivalent circuit model is built. Based on the Hybrid Pulse Power Characterization (HPPC) test data, the parameters was adopt by means of on-line least-square regression. The accuracy of SOC estimation algorithm was verified by the energy balance test, the energy consumption test, New Europe Driving Cycle (NEDC) test and real vehicle driving cycle test, respectively. The experimental results show that this method is with high accuracy and reliability. Full article

This paper presents a methodology dedicated to component sizing and fuel consumption evaluation of different degree of hybridization for light duty vehicles applications. The methodology will be described together with vehicle and components simulation and sizing principles. To ensure a systematic approach, with no bias for any of the cases considered, the energy management of the hybrid drivetrain will be carried out thanks to an optimization based on the Pontryagin's Minimum Principle. As hybrid fuel consumption is highly dependant on vehicle type of use, the hybrid vehicles will be evaluated on different actual use driving patterns as well as on missions representing the daily usage of the vehicle. The methodology and a panel of results are presented in the paper. Full article

Determinant factors of time interval for sending reference message in Time Triggered Controller Area Network, called TTCAN below, was analyzed. A software method for fault diagnosis and tolerance of time master was also proposed and the method was validated in a network of hybrid electric vehicle topology. The results indicate that it does work to monitor local time counter in each potential time master and to compare it with basic cycle to diagnose the fault of current time master and that it does make sense to set multi-potential time masters to get tolerance of current time master’s fault and to guarantee proper operation and reliability of TTCAN system. Full article

In order to reduce the carbon emission, saving fuel energy and for the convenience of personal transportation in urban area, a two-wheel-driven self-balancing vehicle was developed, which utilize the well-known inverted pendulum control technique, can carry one person and travels at a maximum speed of 20km/h. The vehicle which is called “Tiny” ， consists up of two brushless DC motors, the motors are placed coaxially. A gravity sensor and a gyro are mounted on the vehicle, signals from the two sensors are combined with Kalman Filter to indicate the tilt angle of the vehicle. By controlling the tilt angle to be 0 degree (which means the vehicle body is perpendicular to ground), the vehicle can perform travelling forward and backward. In this paper, the implementation of the Kalman filter is discussed by using Matlab simulations, and the mathematical model of the vehicle is also presented, then the controlling diagram is presented. In the end of this paper, some experimental parameter is presented. Full article

Safety control and protection strategy of high-voltage system of electric vehicles include analysis of circuit condition before connection to high voltage terminal, transient current prevention for capacitive load, real-time monitoring and analysis of high-voltage system during operation, disconnecting strategy of high voltage terminals, vehicle dynamic safety and cooperative management of electrical systems, etc. Monitoring and analysis of some critical parameters of high voltage system such as insulation, electrical harness and connector condition are the basis and difficulties in high-voltage safety and protection. This paper presents several mathematical models of monitoring critical parameters, and experiments were also done to evaluate the model. Disadvantages of the commonly used calculation method are discussed. Single point insulation defect model is introduced and diagnosis method of multiple points defect is also discussed. To satisfy high voltage safety management system based on micro-controller, online diagnosis method of related parameters is studied. Hardware-in-loop (HIL) and complete vehicle experiment were conducted to prove the validity, response and reliability of the proposed method. Full article