不同进出风模式和电池组位置的电动汽车气动性能分析

采用GAMBIT软件作为前处理器,应用FLUENT软件作为计算和后处理软件,对不同进出风模式和电池组位置的电动汽车气动性能进行分析,研究表明:单口上出风模式的电动汽车气动性能最佳,下出风口模式的气动性能最差;随着电池组与动力舱后壁距离增加,电动汽车气动性能先改善,再变差,满足电动汽车最优气动性能的距离为230mm.      

Development of a long cycle life sealed nickel-zinc battery forhigh energy-density applications

Nickel-zinc battery technology is being developed for commercial applications requiring high energy density and high power capability. Development cells have demonstrated the ability to deliver over 60 Watt-hours per kilogram at the one hour rate. Cycle life has been improved to more than 600 cycles at 80% depth of discharge by using a patented, reduced solubility zinc electrode and an improved sealed cell design. More than 8000 charge/discharge cycles at 10% depth-of-discharge have been completed. Large quantities of sealed prismatic cells have been manufactured, including a 140 cell, 220 V battery for a hybrid electric vehicle (HEV)     

Global avionics in the future

The following topics are discussed: new batteries for old airplanes; new charge controls for lengthening battery life; fast methods for batteries charging; AC conductance measurement based battery testing; pulse power; bipolar lead-acid batteries vs supercapacitors; Ni electrode cells for spacecraft; worn-out battery disposal; recycling technology; vehicle batteries cost; high energy content batteries; and energy storage for electric utilities     

Bipolar nickel-metal hydride battery for hybrid vehicles

Hybrid electric vehicles are receiving increased interest as an approach to decrease vehicle pollution, dependence, and consumption of liquid petroleum and meet forthcoming Government vehicle emission standards. A number of schemes are under consideration (heat engine battery, fuel cell battery, peaking battery, inner-city battery, etc.). The success of any of the approaches will be dependent on battery capabilities, i.e., power, density, life, and cost. The nickel-metal hydride system appears to be the most promising of the candidate battery chemistries. Preliminary designs and analysis have been prepared and are presented for various configurations. Initial performance characterization tests are presented. It is concluded that a bipolar package arrangement for the Ni-MH chemistry appears most suited for the hybrid vehicle application considered     

微型纯电动汽车动力舱风冷散热研究

微型纯电动汽车的进风口可以布置在多个位置,将进风口布置在微型纯电动汽车动力舱前端,研究这种进风方式的散热效率;不同进出风模式是否可以改善动力舱的散热性能也是一个值得关注的问题.研究结果表明:电池组发热量、车外环境温度及进风温度对动力舱内的温度影响较大,进风口数目及动力舱进风速度对其影响较小;当进风温度低于环境温度时,增加进风口数目和提高车速可以提高散热性能,当进风温度高于环境温度时,减少进风口数目和降低车速可以提高散热性能.上述结论为微型纯电动汽车动力舱散热方案实施提供了参考依据.      

Artificial hearts, batteries, and electric vehicles

New battery applications ranged from an implanted battery that powers an artificial heart, to powering a seismic sensor behind an oil-well drilling bit as it grinds through rock looking for oil-bearing structure. These applications require high reliability that justifies the cost of thorough qualification testing, production control, acceptance testing of every cell, and tracking every cell by its serial number through its lifetime. Electric vehicle developments ranged from electric scooters for commuting to work in Europe to electric cars connected to the electric grid when not being driven. Availability of their battery energy for carrying load peaks is so valuable that the electric utility being supported could offer to replace the vehicles batteries whenever they wear out, with no cost to the car owner.     

Market mature 1998 hybrid electric vehicles

Beginning in 1990, the major automotive passenger vehicle manufacturers once again re-evaluated the potential of the battery powered electric vehicle (EV). This intensive effort to reduce the battery EV to commercial practice focused attention on the key issue of limited vehicle range, resulting from the low energy density and high mass characteristics of batteries, in comparison to the high energy density of liquid hydrocarbon (HC) fuels. Consequently, by 1995, vehicle manufacturers turned their attention to hybrid electric vehicles (HEV). This redirection of EV effort was highlighted finally in 1997, at the 57th Frankfurt Motor Show, the Audi Duo parallel type hybrid was released for the domestic market as a 1998 model vehicle. Also at the 1997 32nd Tokyo Motor Show, Toyota Hybrid System (THS) Prius was released for the domestic market as a production 1998 model vehicle. This paper presents a comparative analysis of the key features of these two 1998 model year production hybrid systems. Among the conclusions, two issues are evident: one, the major manufacturers have turned to the hybrid concept in their search for solutions to the key EV issues of limited range; and, heating/air conditioning; and two, the focus is now on introducing hybrid EV for test marketing domestically     

An energy management system to improve electric vehicle range andperformance

An electric vehicle (EV) energy management system (EMS) developed to accurately predict and extend the usable driving range and the life of the battery pack is discussed. The EMS monitors and records battery state of charge, vehicle performance, power consumption of key components, and driver's actions. Convenient drive inputs in conjunction with memorized energy consumption profiles allow accurate prediction of driving range and selection of appropriate recharging profiles. EV range extension is accomplished by identifying inefficient use of energy, resulting in EMS modification of energy usage by offending subsystems or EMS suggestion to the driver of improved driving habits or vehicle use. Factors affecting the accuracy of range prediction and the amount of range extension are described     

Charge measurement circuit for electric vehicle batteries

Calculating the state of charge (SOC) of an electric vehicle (EV) battery is an inherently error prone process that depends on several variables. However, the accuracy of the required charge flow measurements can be greatly improved by using a voltage to frequency (V/F) converter in conjunction with a digital counter to integrate the measured battery current.     

Heating and cooling battery electric vehicles-the final barrier

Battery electric vehicles (EVs) present a particular challenge to the development of more efficient and effective heating and cooling systems for automotive applications. Because heating-ventilating-air-conditioning (HVAC) systems are electrically powered, vehicle range is reduced when the HVAC system is operating. The alternative solutions to HVAC battery electric vehicles are identified and evaluated. These include a basis for determining HVAC boundary design assumptions and showing mathematical methods for estimating the HVAC load and energy requirements, and evaluation of the new European and Japanese approaches to wintertime heating, such as NaS battery, motor and component waste heat recovery, electric seat warmer, radiant foot warmer, electric windshield and backlight defrost, molten salt latent heat storage, metal hydride hydrogen storage and catalytic heater, and liquid fueled heater     

Ultracapacitors + DC-DC converters in regenerative braking system

An ultracapacitor system for an electric vehicle has been implemented. The device allows higher accelerations and decelerations of the vehicle with minimal loss of energy and minimal degradation of the main battery pack. The system uses a DC-DC power converter, which is connected between the ultracapacitor and the main battery pack. The design has been optimized in weight and size, by using water-cooled heat sinks for the power converter, and an aluminum coil with air core for the smoothing inductance. The ratings of the ultracapacitor are: nominal voltage: 300 Vdc; nominal current: 200 Adc; capacitance: 20 Farads. The amount of energy stored allows us to have 40 kW of power during 20 seconds, which is enough to accelerate the vehicle without the help of the traction batteries. The vehicle uses a brushless DC motor with a nominal power of 32 kW and a peak power of 53 kW. A control system based on a Digital Signal Processor (DSP) manipulates all the aforementioned variables and controls the Pulse Width Modulation (PWM) switching pattern of the converter transistors. The car used for the implementation of this system is a Chevrolet LUV truck.     

Commercialization of advanced batteries

Mader & Associates has been working as a contractor for the South Coast Air Quality Management District (District) as well as domestic and off-shore battery developers for the past several years. During this period, it has performed various assessments of advanced battery technology as well as established the Advanced Battery Task Force. The following paper is Mader's view of the status of battery technologies that are competing for the electric vehicle (EV) market being established by the California Air Resources Board's Zero Emission Vehicle (ZEV) mandate. The ZEV market is being competed for by various advanced battery technologies. And, given the likelihood of modifications to the Mandate, the most promising technologies should capture the following market share during the initial 10 years: lead-acid-8.4%; nickel metal hydride-50.8%; sodium nickel chloride-7.8%; and lithium ion-33.0%. However, today there is much less certainty associated with EV market prediction due to changes in the ZEV regulations     

Fuel cells for “personal electricity”

Cars powered by fuel cells have been built and tested; however, the aerospace fuel cells could not deliver high power quickly when the driver wanted to accelerate his car. Today's hybrid electric cars carry a battery that supplies the acceleration power, and the prime power source, whether an engine or fuel cell, is not stressed with sudden load peaks. Zero air pollution becomes attainable when fuel-cells supply the prime power on a hybrid vehicle     

电动固旋翼无人机动力系统建模与优化设计

为解决电动固定翼四旋翼复合布局无人机(eHAV)动力系统设计选择缺乏相应理论方法的问题,提出了一套动力系统的建模和优化设计方法。通过推质比计算提出了动力系统需求,利用螺旋桨和旋翼理论建立了螺旋桨的设计和性能计算模型,通过统计分析和1阶电动机模型建立了无刷直流电动机的计算模型,通过电动机与电池电压、电流之间的关系建立了电池选择方法,在经过电压修正的放电特性经验公式基础上建立了无人机航时计算方法。根据动力系统匹配方法,建立了动力系统优化设计流程。对某电动固旋翼无人机动力系统进行了优化设计和选择,结果表明:所建螺旋桨和旋翼模型计算结果与CFD结果的误差在10%以内,电池放电模型与试验数据的拟合度在0.97以上,飞行测试结果表明所提方法选择的动力系统使得无人机航时测试值与设计值误差小于4%,证明了该方法有较高的准确性和可行性。      

Performance and characteristics of large lithium ion cells with lowtemperature electrolyte

The US Army and Saft have developed a large lithium ion battery to replace the BE-622 silver zinc battery for application for the ITAS System. The Army discovered that using the 1M LiPF6 1EC:1EMC:1DMC electrolyte can meet ITAS low temperature requirements at -40°C and still provide 71% of the room temperature capacity. This is about 40% better than silver zinc at low temperature     

Battery package design optimization for small electric aircraft

The increasing gross weight of electric Unmanned Aerial Vehicle (UAV) poses a challenge in practical applications. The range and endurance of the electric UAV are limited by the fixed mass of the battery package. In this work, a design optimization method for the battery package topology of small electric UAV is proposed to enhance the performance. To improve the accuracy of the method, the dynamic battery model and simplified electric component models are presented. These models are utilized by the trajectory optimization method, which takes the dynamic characteristic into consideration to calculate the aircraft performance. The direct optimal control method is used for solving the trajectory optimization problem, and this method is tested on a small blended-wing-body electric aircraft. The test result shows that the range and energy-consumption are mainly influenced by the parallel topology of the battery package, while the flight time in climb phase is more sensitive to the series topology. It is deduced that the range- and energy-optimal design points can be considered concurrently in design optimization. The work proves the feasibility of integrating the trajectory optimization and battery package design.     

9th Annual Battery Conference on Advances and Applications

The developments in batteries reported at the 8th Annual Battery Conference on Advances and Applications, are discussed. It was sponsored by the electrical engineering department of California state university, long beach, CA, with IEEE-AESS cooperation. Previous well-funded battery research had been directed toward getting low weight in spacecraft batteries, which had to be boosted into orbit with expensive rockets. Ni-H₂ batteries, even though costly, won the race. Their demonstrated life, like 30,000 charge-discharge cycles, gives an earth-orbiting satellite decades of usable life. Other types of batteries discussed are: aircraft batteries; electric vehicle batteries; Ni-Cd cells; Zn-Br batteries; industrial Pb-acid batteries; rechargeability; computer controlled charging; and small rechargeable and primary batteries     

Segmented battery charger for high energy 28 V lithium ion battery

Since they were first introduced in the early 1990s, lithium ion batteries have enjoyed unprecedented growth and success in the consumer marketplace. Combining excellent performance with affordability, they have become the product of choice for portable computers and cellular phones. Building on the same energy and life cycle attributes, which marked their consumer market success, but adding new high power storage capability, lithium ion technology is now poised to play a similar role in the transportation, military, and space sectors. With major program in various aspects of electric and hybrid electric vehicles, Saft has developed a family of battery products that address the power and energy storage where lightweight, long life, and excellent energy or power storage capabilities are needed. Significant progress in the packaging and control of high power, yet compact, batteries has been accomplished for a variety of vehicle applications. This paper discusses the charger and balancing strategies of one of this family of products     

Working group 3: Coronal streamers

The working group on coronal streamers convened on the first day of the 2nd SOHO Workshop, which took place in Marciana Marina, Isola d'Elba, 27 September –1 October 1993. Recent progress in streamer observational techniques and theoretical modeling was reported. The contribution of streamers to the mass and energy supply for the solar wind was discussed. Moreover, the importance of thin electric current sheets for determining both the gross dynamical properties of streamers and the fine-scale filamentary structure within streamers, was strongly emphasized. Potential advances to our understanding of these areas of coronal physics that could be made by the contingent of instruments aboard SOHO were pointed out.     

小型电动无人机航程航时估算模型

小型电动无人机通常采用锂电池、无刷电机和螺旋桨组成能源动力系统,飞行过程中锂电池的实际工作电压发生变化,但飞机的总重量不变,其航程航时的估算方法与传统的燃油飞机有所不同。为了准确评估动力系统对飞机设计的影响,建立了以锂电池为动力的电动飞机推进系统模型,通过与实验数据比较,验证了各部分模型的准确性。利用该动力系统模型,对某款小型电动无人机进行了航程和航时估算,结果表明本文的建模方法准确有效,航程航时估算接近实验数据,可作为小型电动无人机设计的重要参考。