Proceedings of the FISITA 2012 World Automotive Congress

The main characteristics of the vehicle Electric Power HV safety System are briefly analyzed, and then through analysis of key technology problem of this system currently, to research to this system key parameter and flow state based on CAN network technology. The simulation and test result was testified that HV safety systems are steady and robust.

The success of electric vehicles (EVs) is strongly tied to their performance and ability to meet customer expectations. A comparison of EV battery performance against the requisite targets created by the international community is presented. The performance attributes of greatest interest are energy, power and life. It is shown that only power has achieved the level of performance required by the automotive community for mass commercialization.

As being the most important part in the energy supply system, the battery must be carefully monitored in order to optimize the performance and to prolong its life. The most affected parameter to the battery is the operating temperature as the higher operating temperature increase the performance but shorten the life and with lower operating temperature can ensure longer life but reduce the performance. With this, the battery thermal management system is created in order to keep the operating temperature at the suitable range. In order to achieve this, thermal behaviour in loaded condition must be analysed beforehand. A series of experimental procedures is designed for the selected lithium iron phosphate battery to determine the thermal properties such as heat capacity, heat generation, and cell temperature according to the electrical load applied. Derived thermal model of lithium ion battery was utilized for this purpose as it shows the relationship between the thermal, electrical properties and other parameters such as voltage, current and cell temperature. When the battery is applied with electrical load, the data of voltage, current, and surface cell temperature can be used to determine the thermal properties and at the same time, electrical properties such as open circuit voltage, state of charge and internal resistance are also obtained for the performance evaluation.

This paper presents a Novel, Low cost and Efficient Intelligent Battery Management Solution (iBMS) for Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV). The solution provides a comprehensive topology for identifying the State of Charge (SOC), State of Health (SOH), charging and discharging including isolation of defective identified battery cell from healthy ones. The highly modular and scalable solution uses Bi-directional, 4 quadrant DC–DC converter; a non-isolated four switch topology design for the charging/discharging and cell cut off (infected cell), an Artificial Intelligence (AI) module using Fuzzy Logic (FL) and Signature Pattern Analysis (SPA) for envisaging the Battery stack health. The proposed design offers an affordable On-Board monitoring & diagnostics module leveraging the above intelligent modules and Impedance Analysis. This circumvents the need of further diagnostic tools; makes the system highly portable, Scalable for any chemical composition of battery cell and considerably extend the life cycle of EV/HEV battery stacks. In this paper, we will review some of the issues and associated solutions for battery thermal management and what information is needed for proper design of battery management systems. We will discuss about the issues related to impedance management which affects the battery life.

The temperature distribution of a LiFePO₄ battery was studied by using the finite difference method in this study. The heat generation considers both Bernardi expression and current heat generation in current collectors. A temperature measurement experiment at the geometry center inside battery at 2C discharge was done to validate the model temperature prediction results. The effects of electrode configuration such as placing and center distance of current collecting tabs on battery temperature distribution were analysed. The results showed that the placing and center distance of current collecting tabs have significant effects on temperature rising and uniformity. The results could contribute to the battery design.

Thermal behaviour and model are important items should be considered when designing a battery pack cooling system. Lithium-ion battery thermal behaviour and modelling method are investigated in this paper. The temperature of the battery is measured when charging and discharging experiments in various styles including constant current charge, constant current discharge, pulse current charge, pulse current discharge, and simulation styles in EV and HEV. The lithium-ion battery temperature in various charge/discharge style are presented as a function of time. The thermal modeling is studied and compared with experiments. The results show that the battery thermal behavior is relevant with battery internal resistance, current, time and initial temperature.

The main factors which include low charge/discharge efficiency of high current, low power density and poor low-temperature performance lead to the unsatisfactory situation for hybrid electric vehicles (HEVs), which involves the inadequate braking-energy recovery and short battery lifetime and limitation of working environment. To make up the performance of single battery, a battery and ultracapacitor (UC) hybrid system is used to give full play to the energy of the battery and power of the UC. This paper aims to put forward the design method of a battery-UC hybrid system from the perspective of the vehicle requirements and parameter matching. The experiment indicates that the hybrid power system has improved the efficiency of braking-energy recovery and has decreased the demanding power of battery markedly, thus prolonged the battery lifetime. Meanwhile, the UC’s high low-temperature performance has improved the low-temperature performance of integrated power system.

This paper deals with a fractional order state space model for the lithium-ion battery and its time domain system identification method. Currently the equivalent circuit models are the most popular model which was frequently used to simulate the performance of the battery. But as we know, the equivalent circuit model is based on the integer differential equations, and the accuracy is limited. And the real processes are usually of fractional order as opposed to the ideal integral order models. So here we propose a lithium-ion battery fractional order state space model, and compare it with the equivalent circuit models, to see which model fit with the experiment results best. Then the hybrid pulse power characterization (HPPC) test has been implemented in the lithium-ion battery during varied state-of-charge (SOC). Based on the Levenberg–Marquardt algorithm, the parameters for each model have been obtained using the time-domain test data. Experimental results show that the proposed lithium-ion fractional order state space model has a better fitness than the classical equivalent circuit models. Meanwhile, five other cycles are adopt here to validate the prediction error of the two models, and final results indicate that the fractional model has better generalization ability.

Safety and lifetime issues are the dominant properties of a battery management system (BMS) in automotive applications. To ensure this at first a methodology for an exact determination of the current battery health state represented by the State of Health (SOH) value will be introduced by using electro-impedance spectroscopy (EIS) for determining of the battery model parameters. In the second step an accurate measurement of the relevant measures for the current dynamic operating mode of the battery (voltage, current, temperature…) the mid-(10 s) and intermediate-time (30 s) must be performed. The operating strategy can then be optimised for the lifetime requirements of the battery by using the measured and calculated values. Due to EIS measurements cannot be performed in dynamic operation an estimation of the relevant parameters must be performed by applying the Kalman-filtering. The paperwork shows the first results of this approach.

A scale-model hydrogen fuel-cell truck has been designed and its performance tested to gain an improved understanding of the technical challenges of full- scale trucks employing on-board storage and hydrogen fuel-cell systems. A 1/14th scale battery-based replica of a Scania R470 Highline truck was equipped with two 30-W PEM fuel cell stacks and their control units, four metal-hydride hydrogen bottles storing in total 6 g hydrogen. A bank of super-capacitors was employed to smooth out the load placed on the fuel cells and meet the maximum demand of the truck. The hydrogen fuel cell system with the super-capacitor buffer was able to maintain stable operation and continuously supply the dynamic load of the truck over a full range of driving conditions, including during purging periods of the fuel cells. The fuel cell system was found to be more responsive to the changing load than the original batteries. The gravimetric energy density of the fuel cell system was measured to be about 30 % better than the original batteries of the truck.

With the development of technology and economy, people’s demand for energy has been increasing. But the environmental pollution caused by the use of traditional energy sources has threatened to the people’s lives. In order to avoid reducing the welfare of human’s future, we must find new, clean, sustainable energy systems, and apply them to human beings’ real life. Fuel cell vehicles are hydrogen’s specific applications in transportation field. The power of this new energy vehicle is provided by the electricity produced by hydrogen and oxygen through fuel cells, and its emission is only water which has no pollution to the environment. However, if a new energy system wants to get the promotion and application, its safety should be firstly concerned comparing to conventional cars. Hydrogen has its own characteristics, such as the phenomena of leakage, dispersion, flammability, detonation and embrittlement, which make the board hydrogen system have certain security risks. In order to further develop and promote fuel cell vehicles, it is necessary to do hydrogen safety research. This study is based on the theory at home and abroad. Firstly, the article introduces the basic principles of fuel cell vehicles and basic characteristics of hydrogen. Secondly, we discuss the special safety problems of hydrogen, such as the safety of hydrogen supply system, car-inside, components and pipe and hydrogen fuel cells engines. Lastly, facing these hydrogen safety issues, we put forward corresponding improvement measures and control strategies through testing and analysis to help the development and promotion of fuel cell vehicles.

This paper presents the results of a Fuel Cell Hybrid Electric Vehicle (FCHEV) modeling, in which the fuel cell system is integrated with an on-board rechargeable energy storage system (RESS) for electric energy supply to propulsion and auxiliary systems. The objectives of the model is to design a tool suitable for predicting hydrogen consumption, dynamic performances analysis and power management optimization. The global model is the integration of vehicle longitudinal dynamic equations, transmission model and validated models for power sources and power electronics. The model was developed using Matlab/Simulink programming environment with SimPowerSystems library. In order to adapt the steep voltage drop in respect to electrical current load of the fuel cell to a more constant voltage requirement, a DC/DC converter was implemented between the fuel cell and the high power Li-ion battery. The results indicate the suitability of the model in predicting vehicle range and dynamic performances.

This paper proposes an optimal energy management strategy for a range extended fuel cell city bus, which is powered by a Proton Exchange Membrane (PEM) fuel cell system and a Li-ion battery system. Targeting at minimizing the daily operating cost, the strategy is deduced based on the dynamic programming (DP) algorithm for a global optimized problem. The strategy is compared with several other strategies in simulating model, e.g. Charge Depleting and Charge Sustaining (CDCS) and two-stage linear blended strategies. The operating cost with the linear blended strategy is the lower than other two-stage linear blended strategies. The operating cost with the CDCS strategy is 1.3 % less than that of the linear blended strategy. The operating cost with the DP strategy is 10 % less than that of the linear blended strategy. The hydrogen cost occupies more than 95 % of the entire operating cost. To minimize the hydrogen consumption is the key to reduce the operating cost. With the DP strategy, the efficiency of fuel cell system is 58.7 %, compared to an average level of 53 % with other strategies. The battery efficiency influent the daily operating cost slightly. In order to apply the optimal strategy into a vehicle, the optimal State of Charge (SOC) trajectory curve is fitted with a nonlinear exponential formula. An iterative algorithm based on this formula is deduced, and can be applied to an embedded digital control unit.

This paper presents the technology trends for wireless power transfer (WPT) for electric vehicles (EV), and analyzes the factors affecting its power transfer efficiency (PTE) and describes the techniques currently used for its optimization. The review of technology trends encompasses both stationary and moving vehicle charging systems. The study of the stationary vehicle charging technology is based on developments at WiTricity and Oak Ridge National Lab (ORNL). The moving vehicle charging technology is primarily described through the results achieved by the Korea Advanced Institute of Science and Technology (KAIST). The factors affecting the PTE are determined through the analysis of the equivalent circuit of magnetic resonant coupling. The air gap between both transmitting and receiving coils along with the magnetic field distribution and the relative impedance mismatch between the related circuits are the primary factors affecting WPT efficiency. Currently the industry is looking at an air gap of 20 cm or below. To control the magnetic field distribution, KAIST has recently developed the Shaped Magnetic Field In Resonance (SMFIR) technology that uses optimized shaped ferrite material to provide a low reluctance path or maximum exposure of the magnetic field to the resonant coils. The PTE can be further improved by means of impedance matching. As a result, Delphi’s current implementation of WiTricity’s technology exhibits WPT efficiency above 90 % for stationary charging with power capacity of 3.3 kW, while KAIST has demonstrated a maximum efficiency of 83 % for moving vehicle with its On-Line Vehicle (OLEV) project with the power capacity of 100 kW.

The limited range, high cost and long charging time of electric vehicles continue to stand in the way of their widespread adoption. In response to this, our research group has created the “Waseda Electric mini Bus (WEB)” series of vehicles based on a short range, frequent charging concept that minimises the weight and cost of batteries compared to other electric vehicles. This paper reports on the design, construction and performance evaluation of the new “Waseda advanced Electric mini Bus 3 (WEB-3)”, which is larger than previous vehicles and utilises an improved inductive power supply (IPS) for non-contact rapid charging. A diesel bus was converted to an EV, and the engine, flywheel and clutch were removed, reducing the vehicle’s rotating weight by 80 %. A new inductive charging system was designed and fabricated, allowing non-contact rapid charging from a transmission coil in the road surface over a longer air gap of 140 mm, at 92 % efficiency.The finished WEB-3 was tested on public roads in Honjo and Kumagaya cities, Saitama prefecture, Japan. An effective reduction in CO₂ emissions of 60 % over the original diesel bus was achieved.

Due to the difference on powertrain configuration and energy supply, there must be new business models from that of CVs. Moreover, as the change of internal and external conditions, EV business models will also do some adjustment. In this paper, firstly, the traditional auto industry and business model of China is analysed to see what the value chain of CV is like. Secondly, as the technical and organizational innovation of electric mobility happens, what changes will happen to the EV industry is discussed. Thirdly, the concept of re-construction is introduced to illustrate the transformation of EV business model. There are two types of methodology used. One is the value chain analysis, which was developed and popularized in 1985 by Michael Potter, the professor of Harvard Business School. In this paper, the value chain analysis is extended to the EV industry chain to understand the generation of margin in business models. The other is re-construction method, which is put forward originally to illustrate the mechanism of transformation of EV business model from systematic angle. The results of this paper concentrate on the following areas, one is that the main internal reason of the transformation of EV business model is the change of industry value chain, the second is that the re-construction of EV business model is the outcome of the adjustment to technical and organizational innovation, and the third is that by re-construction the business models achieve the innovation, which plays the positive role in promoting EVs. Lack of effective quantitative tools, we only discuss the re-construction of value chain and business model by the systematic framework, so the comparison of margins between new business models and old business models after re-construction cannot be done precisely. The innovation of this paper is as follows, one is introducing the value chain analysis to the research of EV business model; another is setting up the concept of re-construction of EV business model. In this paper, the existed value chain method is developed to analyse the internal reasons of the transformation of EV business model, the re-construction concept is projected to construct the new business models systematically. At the end of paper, one example of demonstration city is used to explain the re-construction method of EV business model. The main inadequacy of this paper is the lack of quantitative analysis, which may be the direction for improvement in the future.

Electro-mechanical transmission (EMT) is a transmission pattern of hybrid electric vehicles. This paper analyzes and calculates the required electric power of EMT. The requirement to the hybrid energy storage system of EMT is analyzed and calculated in this paper. Then according to the calculation results, the parameters of hybrid energy storage system consisted of batteries and supercapacitors for EMT are matched. Based on the analysis of required electric power, three fuzzy control strategies for different modes are proposed in this paper. The model of HESS and control block is built based on Matlab/Simulink. Simulation results indicate that the required electric power and energy is satisfied, and the control strategy proposed in this paper is feasible. The supercapacitors play an important role to diminish the impacts on batteries.

The authors developed long-term scenarios for reducing CO₂ emissions by using CEAMAT. CEAMAT is an energy analysis model for considering long-term effects of future automotive technologies in the Japanese automotive sector. At first, future automotive data and demand of the automotive sector of the IEEJ2050 model were entered into CEAMAT, then open literature was reviewed, and interviews were conducted with relevant organizations. Secondly, the authors developed long-term scenarios for the Japanese automotive sector using CEAMAT. According to these scenarios, by the year 2050 the share of next-generation vehicles in use will increase by 43 % for passenger cars and 48 % for medium-sized and large trucks, and CO₂ emissions will be reduced by 47 % compared to the year 2005. Finally, calculations were made of the potential for integrated approaches of eco-driving and improving traffic flow to reduce CO₂ emissions. CEAMAT indicated that the integrated approaches could help reduce CO₂ emissions by 55 % compared to the year 2005.

Modelling and stability analysis of DC–DC switching converters is the key step to study, analyze and design switching power supplies. The equivalent circuit model in the continuous conduction mode (CCM) is presented in this paper. The DC/DC transfer functions are derived based on the main circuit model, the compensation network circuit model, and the PWM waveform generator circuit model. The analysis and simulation of the small-signal model are discussed based on it. Finally, DC/DC sample are tested with network analyzer. The results show that the modeling approaches taking converter parasitic parameters into account is feasible, which can help optimize and improve the performance of switching power supply design and efficiency. It has practical engineering value.

As the development of electric vehicle, we have to face the questions about HV safety. If the HV system, especially the battery system, is not designed properly, it will be impossible to make a safety car to the customer. Under certain circumstance, it may cause direct threatens to the people life. So it is very important to have a good analysis of the battery system safety design. This paper mainly pays attention to the safety solution of battery system in electric vehicle. From different levels, including battery cell design, battery system design and vehicle system safety design, we provide some safety concept. It will help a lot of the electric vehicle’s safety.

The objective of the presented research work is the demonstration of the working principle as energy efficient and environmental friendly, low cost vehicle propulsion system of the free piston Stirling principle coupled with the alternant hydraulic transmission in order to use the alternant displacement of the Stirling principle, also to the hydraulic transmission and convert the alternant movement of the liquid using a free wheel based hydraulic motor. The design methodology considers the advantages of efficiency, noise and low emissions of Stirling principle, that can be further improved by a free piston solution and the advantages of a direct alternant energy transfer to the liquid column that is converted in a free wheel based hydraulic motor. An analytical and 1D multi-domain model is used in order to demonstrate the running principle, performance and parameter influences that allow the simulation of the combined Stirling principle with alternant hydraulic transmission integrated on a vehicle. For the heat transfer and flow simulation of the Stirling prime mover, 3D CFD software is used to simulated the temperature distribution. Experimentally the solution was demonstrated on a test rig and integrated on a ATV type demonstration vehicle equipped with the alternant hydraulic propulsion system. Flow, thermal and mechanical parameters are measured to evaluate overall system performance. The former research work of the authors was focused on the demonstration and performance evaluation of the alternant hydraulic propulsion, being demonstrated its efficiency (up to 95 %), adaptability and low mass qualities. Main advantages of the Stirling principle may be improved by using a proper transmission. Coupling also the transmission based on the same alternant principle is a low cost, simple, efficient way to maintain the advantages of the Stirling energy conversion in the same time with an application of the hydraulic transmission that works also alternant in a more efficient way.

Based on a systematic analysis of the dual power supply for electrical vehicle powertrain and on its control strategy, a simplified control algorithm which meets both continuous and heavy duty vehicular power needs was designed and integrated into the BDC control software. With this main component and super-capacitor module as a second assistant power source, and battery as the first primary one, a dual power supply system for short distance electric vehicle was designed and tested. Through rational design and selection of the energy sources and their parameters and optimal matching of powertrain energies in system level, the electric vehicle installing super-capacitors as an auxiliary power source can not only improve the electric vehicle performance, but also increase its vehicle range.

Currently in the automotive sector both hybrid and completely electric drives are being discussed and developed. The comparatively compact design of electric motors permits considerably more flexible installation in the vehicle than is the case with conventional internal combustion engines. Thus, depending on the category of vehicle, in addition to classic placement in the conventional engine or differential installation space (conversion design), configurations with the motor positioned close to the wheel or integrated into the chassis are conceivable, permitting selective wheel drive, with elimination of the classic differential and driveshaft. On the one hand, close-to-wheel configurations involve increased system complexity, since they require more than an electric motor and a transmission, for instance. However, on the other hand they are particularly attractive with respect to space requirements, because they permit integration into the installation package that is required in any case for the chassis. The space thus saved in the middle of the vehicle can then be used for a comparatively large energy storage system or for additional electronic/electrical components. At the IAA 2011 in Frankfurt, in an early concept study, ZF presented a driven chassis system for the minicar and sub-compact segment, where the electric motors and the transmission are integrated close to the wheel in the chassis. In contrast to familiar close-to-wheel drives, in the concept presented, the unsprung mass is only slightly increased. The total system weight continues to be attractive, since the comparatively heavy side shafts and the differential are eliminated. The chassis system can be integrated into the floor assembly of a global sub-compact vehicle platform with no significant changes in the vehicle body, and has the additional advantage that both standard-size wheel rims and conventional brakes can be used.

Objective Already for many years, fuel consumption and operating cost were the major technology drivers for commercial vehicles. Today, in order to achieve agreed CO₂ goals and to reduce the dependency on crude oil, governments are implementing CO₂ or fuel consumption legislation. Even more, reduction of fuel consumption and consequently low operating costs are continuously an important focus for manufacturers and owners of commercial vehicles. New powertrain technologies, which will further reduce fuel consumption, are able to combine these three drivers, to reduce CO₂ emission, to reduce the dependency on crude oil and to address the need of lower total cost of ownership of the owners of commercial vehicles. Conclusions The efficiency of commercial powertrains can be significantly increased in future. Several potentials for improvement are seen specifically in those technologies, which are able to provide a global optimum of the whole powertrain system, from engine to exhaust aftertreatment to cooling system up to transmission and the final drive. In total a fuel efficiency potential of 20 % is seen for long haul trucks. Results AVL has developed a whole line of technologies, which can be implemented to the commercial powertrain in the future to address the requirements above. The individual measures are the optimization of the balance between engine and aftertreatment systems, reduced engine friction by advanced thermal management systems, reduced parasitic losses of the auxiliaries in real life driving cycles, conversion of exhaust energy in driving power, application of new and advanced transmission technologies and shift strategies as well as degrees of electrification of the powertrain. Additionally, alternative fuels provide another field of CO₂ friendly technologies as well as reduced operating cost. Here specifically, the availability of local resources drive short term applications. This paper will compare the individual saving potentials of these technologies, will rate it against criteria like market readiness, cost efficiency and others. It will be demonstrated that major reductions in CO₂ emissions and operating cost are still possible by commercial vehicle powertrain measures. Methodology To quantify the fuel saving potentials of the individual technologies AVL applied its proven seamless system simulation environment to analyze the whole vehicle system. Interlinked sub-models for all relevant vehicle, respectively engine sub-systems, are the core of this simulation environment. Where necessary, the individual models have been aligned with specific test bed and vehicle measurements. For some of the analyzed technologies the predicted fuel saving potential could already be confirmed by transient operation on test bed using prototype components. To analyze the cost efficiency for the individual technologies the predicted additional product costs have been rated against the saving in operational cost for the final vehicle owner. A return of investment calculation analysis has been made for each individual technology. To predict the market readiness of the individual technology, relevant boundary conditions like estimated development effort, components availability, established supplier base, development risk, etc. have been considered. Limitations Basically the results of this study can be transferred to all commercial powertrain systems. However, the main focus of the study is on the long haul truck application since it has the most significant impact to total CO₂ emissions caused by the high mileage as well as the high absolute fuel consumption level of this vehicle category.