Fuel cells for the long haul, batteries for the spurts [electricvehicles]

Until only a few years ago, when environmentalists, automakers, and other concerned parties spoke about low-emissions vehicles, they were almost always referring to electric vehicles (EVs)-cars, trucks, and buses powered by batteries of one kind or another. Today, having so far failed in their quest for a battery that could make EVs practical, they are looking more and more to hybrid electric vehicles (HEVs), which automakers had hitherto rejected as merely an interim solution. But hybrids based on a combination of electric motors and internal combustion engines are attractive for two main reasons: they require no technology breakthroughs and no new infrastructure. They work with existing batteries since they do not rely on them for primary energy storage; rather, they can obtain fuel at any service station. An alternative to HEVs is fuel cell powered vehicles. The principles of this technology and the associated hydrogen storage issues are discussed. Other alternative fuels are briefly outlined     

A New Privacy Aware Payment Scheme for Wireless Charging of Electric Vehicles

Electric vehicles (EVs) can be considered as a revolution in the combustion industry with significant improvement in fuel utilization and decrease in pollution compared to combustion engines. However, by decreasing the size of the battery to reduce the cost, the frequency of charging EVs in a day increases. Therefore, to reduce the downtime required for charging EVs, wireless charging on the move can be an effective solution. In such a situation, paying for wireless charging on the move is an important issue. However, it can endanger the location privacy of users, since the EVs need to charge frequently in a day. In this paper, we first explain different methods of payment and problems with such payment methods in the case of wireless charging on the move. Then, we propose an efficient payment method based on ‘tokens’ for wireless charging on the move, which minimizes the communications between service providers and users during the charging process. The proposed scheme prevents users and service providers from cheating, and it is robust to support different values for the price. Finally, we compare it with other payment methods that have been proposed for plug-in electric vehicles.     

An overview of power electronics in electric vehicles

In response to concerns about energy cost, energy dependence, and environmental damage, a rekindling of interest in electric vehicles (EVs) has been obvious. Based on the “California rules” on zero emission vehicles in the United States, as well as similar tightened air pollution regulation in Europe, Asia, and much of the rest of the world, the market size of EVs will be enormous. Thus, the development of power electronics technology for EVs will take an accelerated pace to fulfil the market needs. This paper reviews the current status of multidisciplinary technologies in EVs. Various challenges of power electronics technology for EV propulsion, battery charging, and power accessories are explored     

The state of the art of electric and hybrid vehicles

In a world where environment protection and energy conservation are growing concerns, the development of electric vehicles (EV) and hybrid electric vehicles (HEV) has taken on an accelerated pace. The dream of having commercially viable EVs and HEVs is becoming a reality. EVs and HEVs are gradually available in the market. This paper will provide an overview of the present status of electric and hybrid vehicles worldwide and their state of the art, with emphasis on the engineering philosophy and key technologies. The importance of the integration of technologies of automobile, electric motor drive, electronics, energy storage, and controls and also the importance of the integration of society strength from government, industry, research institutions, electric power utilities, and transportation authorities are addressed. The challenge of EV commercialization is discussed     

Failsafe Drive Performance of FRID Electric Vehicles With the Structure Driven by the Front and Rear Wheels Independently

Failsafe performance is clarified for electric vehicles (EVs) with the drive structure driven by front and rear wheels independently, i.e., front and rear wheel independent drive type (FRID) EV. A simulator based on the four-wheel vehicle model, which can be applied to various types of drive systems like four in-wheel motor-drive-type EVs, is used for the clarification. Yaw rate and skid angle, which are related to drivability and steerability of vehicles and which further influence the safety of vehicles during runs, are analyzed under the condition that one of the motor drive systems fails while cornering on wet roads. In comparison with the four in-wheel motor-drive-type EVs, it is confirmed that the EVs with the structure focused in this paper have little change of the yaw rate and that hardly any dangerous phenomena appear, which would cause an increase in the skid angle of vehicles even if the front or rear wheel drive systems fail when running on wet roads with low friction coefficient. Moreover, the failsafe drive performance of the FRID EVs with the aforementioned structure is verified through experiments using a prototype EV.     

The great battery search [electric vehicles]

Batteries are the Achilles' heel of electric vehicles (EVs). Advocates of EVs frequently find themselves explaining why no electric car can drive far without refueling and as frequently promising things will get better any year now, as soon as the latest advance in batteries reaches maturity. As the search goes on for new electrochemical couples, designers try to avoid the pitfalls of the old ones. The article discusses the problems of batteries for EVs and discusses Li-ion, Ni-MH and Ni-Cd battery developments. The possibility of using primary batteries is briefly discussed as are battery charging technologies, safety and health issues     

Engineering the EV future

Continuing environmental concerns are moving electric vehicles (EV) into high gear at development facilities everywhere. The General Motors EV1 and the Ford Ranger EV are old news, the 106 Electric from PSA Peugeot-Citroen is established in France, where more than 1500 have been sold, and Toyota's Prius hybrid electric vehicle has exceeded all expectations in Japan, with plans afoot for an early introduction in the United States. In share-of-market terms, electric vehicles (EVs) are just beginning their infancy, total worldwide sales will be measured in the thousands of cars in 1998, compared with perhaps 20 million vehicles sold in all. But the big companies at long last are taking EVs seriously. The question now seems to be not whether automobiles will go electric but when. Battery, fuel cell and hybrid vehicles are briefly reviewed in this article     

Optimal Scheduling of Utility Electric Vehicle Fleet Offering Ancillary Services

Vehicle‐to‐grid presents a mechanism to meet the key requirements of an electric power system, using electric vehicles (EVs) when they are parked. The most economic ancillary service is that of frequency regulation, which imposes some constraints regarding the period and duration of time the vehicles have to be connected to the grid. The majority of research explores the profitability of the aggregator, while the perspective of the EV fleet owner, in terms of their need for usage of their fleet, remains neglected. In this paper, the optimal allocation of available vehicles on a day‐ahead basis using queuing theory and fuzzy multi‐criteria methodology has been determined. The proposed methodology is illustrated on the daily scheduling of EVs in an electricity distribution company.     

Requirements for the application of ECUs in e-mobility originally qualified for gasoline cars

Electronic control units (ECUs) are widely spread over the automotive industry with lots of applications. At this time more than 100 ECUs are used in a medium-sized vehicle. Development, test and qualification of ECUs are time and cost extensive. That is why they are often used in more than one generation and more than one model of vehicles. Present ECUs are developed and qualified for vehicles with combustion engines. Since the introduction of hybrid and fully electrical cars the requirements on the ECUs changed drastically. With respect to the engine ECUs temperature maxima is lower. On the other hand due to charging the batteries and other continuous voltage stresses, the time of operation (active and passive) is massively growing. The central question is: Is it possible to use ECUs qualified for gasoline car in electric cars without any reliability risks?To answer this question we start with a comparison of mission profiles of electrical cars and combustion engine cars. Based on the mission profiles we show the different requirements on the electronics robustness and use time. Afterwards we investigate the qualification process of an exemplary ECU from a combustion engine car and identify differences in comparison to the hybrid and fully electrical variant. As an example, a measurement of temperatures in a car driven under reasonably realistic conditions indicates the influence of the combustion engine on the thermal behaviour of the electronics as a key driver for failures. We provide a generic procedure that can be used for the design of future ECUs and compare it with expected temperature distributions in electric cars. Based on our results recommendations for the applicability of the use of existing ECUs in electric cars are discussed.     

Hybrids: then and now

Very different from their turn-of-the-century forebears, modern hybrid electric vehicles (HEV) are almost as clean as pure EVs and have the range of conventional cars. The author discusses the advantages of HEV and describes the two basic types of HEV, parallel and serial. The serial type has a downsized engine on board that drives a generator that supplements the batteries and can charge them when they run low. In the parallel type the ICE and the electric motor can both deliver propulsion power to the wheels. The advantages of these two types of HEV are discussed. The parallel HEV is then discussed in more detail     

Overview of Permanent-Magnet Brushless Drives for Electric and Hybrid Electric Vehicles

With ever-increasing concerns on our environment, there is a fast growing interest in electric vehicles (EVs) and hybrid EVs (HEVs) from automakers, governments, and customers. As electric drives are the core of both EVs and HEVs, it is a pressing need for researchers to develop advanced electric-drive systems. In this paper, an overview of permanent-magnet (PM) brushless (BL) drives for EVs and HEVs is presented, with emphasis on machine topologies, drive operations, and control strategies. Then, three major research directions of the PM BL drive systems are elaborated, namely, the magnetic-geared outer-rotor PM BL drive system, the PM BL integrated starter-generator system, and the PM BL electric variable-transmission system.     

Innovative iteration algorithm for a vehicle simulation program

Resulting from Ph.D. research, a vehicle simulation program is proposed and continuously developed, which allows simulation of the behavior of electric, hybrid, fuel cell, and internal combustion vehicles while driving any reference cycle. The goal of the simulation program is to study power flows in the drivetrains of vehicles and the corresponding component losses, as well as to compare different drivetrain topologies. This comparison can be realized for energy consumption and emissions, as well as for performance (acceleration, range, maximum slope, etc.). The core of this program, consisting of a unique iteration algorithm, will be highlighted in this paper. This algorithm not only allows the calculation of the limits of vehicle acceleration in the function of drivetrain component characteristics, but at the same time is able to develop and evaluate the different power-management strategies of hybrid vehicles, combining combustion engines and electric motors. Furthermore, the comprehensive iteration algorithm is demonstrated to be very efficient in handling any type of working limit for all components in different types of drivetrains, which results in an accurate and modular vehicle simulation program with high data flexibility.     

Nonconventional on-board charger for electric vehicle propulsionbatteries

Electric vehicles (EVs) are needed in densely populated urban areas to reduce air pollution. Battery chargers are needed to supply DC voltage to charge the high-energy battery parks used in EVs. This paper deals with an on-board battery charger arrangement that is fully based on the use of the power components of the EV motor drive. Desired features for EV battery chargers such as minimum volume, low cost, high efficiency, and high reliability are fully matched by means of the proposed solution. The proposed on-board charger arrangement has been installed on an electric scooter prototype being developed for the Far East markets. Design analysis and experimental results of the on-board charger prototype are presented     

Electric vehicles-the great battery barrier

Research efforts aimed at developing an effective and economical electrochemical power source for electric road vehicles (EVs) are examined. The two goals are to extend the range of EVs, i.e. the distance they can go on a simple charge, and to cut the recharging time. The various kinds of battery are described, and their advantages and drawbacks are identified     

Neural network-based residual capacity indicator for nickel-metal hydride batteries in electric vehicles

This paper presents a new estimation approach for the battery residual capacity (BRC) indicator in electric vehicles (EVs). The key of this approach is to model the EV battery by using a neural network (NN) with a newly defined output and newly proposed inputs. The inputs are the discharged and regenerative capacity distribution and the temperature. The output is the state of available capacity (SOAC) which represents the BRC. Various SOACs of the nickel-metal hydride (Ni-MH) battery are experimentally investigated under different EV discharge current profiles and temperatures. The corresponding data are recorded to train and verify the proposed NN. The results indicate that the NN can provide an accurate and effective estimation of the BRC. Moreover, this NN can be easily implemented as the BRC indicator or estimator for EVs by using a low-cost microcontroller.     

基于模糊控制的电动汽车再生制动系统的研究

再生制动能够降低能源的消耗量和延长电动汽车的行驶里程。它广泛的受到诸多学者的关注。本文提出了一个新颖的再生制动控制系统。该系统基于无刷直流电机的控制特性和电动汽车刹车时的制动特性,直流无刷电机采用传统的PID控制,刹车力采用模糊逻辑控制,刹车力矩可以由PID控制器实时的控制。通过Matlab/Simulink软件,仿真分析了电池的充电状态、制动力和直流侧线电流。实验和仿真结果均证实了在具有良好的刹车性能的前提下,该方法可以实现良好的再生制动性能和延长电动汽车的行驶里程,在工程上更加易于实现也具有更好的鲁棒性和更高的效率。     

Development of a linear alternator-engine for hybrid electricvehicle applications

This paper examines the design and operation of a generation system that utilizes a linear crankless internal combustion engine in conjunction with a linear alternator. This system directly utilizes the linear motion of the piston to drive the alternator rather than first converting to rotary motion. The result is a more compact, reliable, and efficient unit as the system has only one moving part, making the system ideal for use in series hybrid electric vehicles. This paper describes the overall system design as well as the subsystems including the engine and alternator. A dynamic simulation is then presented which utilizes the model developed to determine the output characteristics of the system. The prototype system was successfully tested, and experimental results are also included     

Electric vehicles-pursuing efficiency

The approaches being used to make electric vehicles (EVs) highly efficient given the limitations of EV batteries are described. They include reducing vehicle weight, aerodynamic drag, tire rolling resistance, and bearing friction; eliminating brake drag; and increasing the efficiency of the electric motor and its control electronics. The intrinsic efficiency of electric motors and the choice of power electronics are discussed. Energy management and the use of regenerative braking are examined     

Electric vehicles-architecting the system

Standardized charging hardware and procedures that must be put in place before the first electric vehicles (EVs) go on sale in the mid-90s are discussed. Other requirements considered include charging installations, facilities for replacing and recycling batteries, training and deployment of technicians for emergency road service and for manning quick-charge stations, training for police and firefighting personnel on dealing with EV accidents, appropriate electrical system capacity, appropriate rate structures, and public education     

Three-phase modular permanent magnet brushless Machine for torque boosting on a downsized ICE vehicle

The paper describes a relatively new topology of 3-phase permanent magnet (PM) brushless machine, which offers a number of significant advantages over conventional PM brushless machines for automotive applications, such as electrical torque boosting at low engine speeds for vehicles equipped with downsized internal combustion engine (ICEs). The relative merits of feasible slot/pole number combinations for the proposed 3-phase modular PM brushless ac machine are discussed, and an analytical method for establishing the open-circuit and armature reaction magnetic field distributions when such a machine is equipped with a surface-mounted magnet rotor is presented. The results allow the prediction of the torque, the phase emf, and the self- and mutual winding inductances in closed forms, and provide a basis for comparative studies, design optimization and machine dynamic modeling. However, a more robust machine, in terms of improved containment of the magnets, results when the magnets are buried inside the rotor, which, since it introduces a reluctance torque, also serves to reduce the back-emf, the iron loss and the inverter voltage rating. The performance of a modular PM brushless machine equipped with an interior magnet rotor is demonstrated by measurements on a 22-pole/24-slot prototype torque boosting machine.