The aXcessaustralia Hybrid Electric Car Project

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Australian carmakers and component manufacturers havelearned to survive on small volumes that would not beeconomical in most countries. It is true that for decadesthe industry was protected by high import tariffs, but it isnonetheless a remarkable achievement that, with verysubstantially reduced tariffs, Australian automotiveindustry exports have reached more than $2.5 billion ayear.THE aXcessaustralia PROJECTSFigure 6: The Toyota Prius Hybrid-Electric CarWhen designing a hybrid electric car, engineers have hadto choose between a battery’s ability to store power andthe need to deliver a lot of power quickly.A normal car’s battery is almost always fully charged,because the alternator is generating power whenever theengine is operating. If a chemical battery has to copewith rapid and severe discharge, battery life is reducedsubstantially. The cost of replacing a battery pack canamount to half of the total operating cost of a hybridelectriccar.In February 1998 the first aXcessaustralia concept carwas shown to the global industry at the DetroitExposition of the Society of Automotive Engineers (seeFigure 7).The car attracted a great deal of interest because of itsunusual styling and its creative mix of features andtechnologies. As a vehicle to display Australianinnovation it was totally successful and helped Australiancomponent manufacturers on the way to $1 billion of newexport business. Its success provided a foundation for anew project to build a car to demonstrate that Australiahas the technology and the manufacturing capability tomake a low emissions car.The Australian Government, recognising the value ofretaining a viable industry, has joined with industry tofund a project to demonstrate Australian capabilities inmore advanced automotive technology.THE aXcessaustralia LOW EMISSIONVEHICLE PROJECTThe aXcessaustralia low emission vehicle project isbased on technologies developed by CSIRO and 80component manufacturers. The project has been used tohelp industry in a novel way to show their technologicalcapabilities. It also helps companies learn about newautomotive technologies in general.Figure 7: aXcessaustralia Concept Car Mk 1AUSTRALIA’S HISTORY OF INNOVATIONAustralia has a rich automotive history. Large distancesand cars that had difficulty coping with rough, dry anddusty conditions, inspired Australians to be self-sufficientin adapting automotive technology to suit their needs.Australia is today one of no more than 10 countries thatcan style, design, engineer and manufacture almost everycomponent of the modern car. This is the reason whyAustralia manufactures a respectable proportion of thetotal cars sold, even though the market is less than800,000 vehicles.Companies whose traditional business has been tomanufacture components designed by carmakers have theopportunity to demonstrate their innovative skills on anexample of ‘tomorrow’s car’.Technologies used in today’s car are governed mostly bycost. The processes used in manufacturing today’s car arewell understood and result in a car that can be expected toperform reliably for several hundred thousand kilometresor more.Indeed, the reliability of cars can be problematical interms of pollution and emissions. Governmentsconsidering introduction of higher standards of emissioncompliance are usually reluctant to mandate for theremoval of older vehicles from the car pool. Greaterreliability in cars therefore makes the impact of new-carregulation take longer to reduce environmental damage.David Lamb4
NOVEL AUSTRALIAN POWERTRAINTECHNOLOGIESAustralia has several novel technologies that are suitablefor hybrid-electric cars. CSIRO has research programs inbatteries, electric motors, electrical power systemmanagement, and also supercapacitors. All these areas ofexpertise can be brought together in a creative approachto hybrid-electric propulsion and attract the interest of theglobal car industry as it moves towards the take-up ofelectric propulsion systems for cars.The aXcessaustralia car uses a novel, compact engine(ESU) to drive a generator in a Series hybridconfiguration. The Surge Power Unit comprises CSIROsupercapacitors and CSIRO batteries. The traction motoris a CSIRO water-cooled electric motor that also acts as agenerator when braking.During much of the operating time, power is suppliedfrom the batteries, supplemented by the supercapacitorsfor acceleration. The internal combustion enginegenerally operates in response to the needs of the storagesystem. However, for extreme power needs, all threesources of energy are available to the drive motorenabling vehicle performance to be equivalent to aconventional car.SUPERCAPACITORSSupercapacitors are used in telecommunications devices,but until now it has not been possible to expand thedevice to be used in high-power applications. CSIROdevelopedsupercapacitors use a carbon coating in anorganic electrolyte to form what is termed a ‘double layercapacitor’ (also referred to as a supercapacitor or an ultracapacitor).batteries results in a low cost and practicable SurgePower-Unit. Using an auxiliary energy store in the formof a 60-volt battery pack, the capacitor is only used forhigh power operation. The capacitor used in theaXcessaustralia car has been designed to efficientlydeliver up to 50 kW.BATTERIESBattery capacity and power delivery is improved by usingproprietary CSIRO chemistry and unique construction.The batteries are optimised for use in hybrid electricvehicles (HEVs) where they may spend considerable timepartially discharged, unlike the battery in a conventionalcar that is always charged by the alternator.The battery pack is subject to multiple charge−dischargecycles at high rates and is required to operate for manycycles below a full state-of-charge. Lead-acid isprobably the most cost-effective technology or use inmass-produced HEVs.CSIRO’s Novel Battery Technologies Group hasdeveloped a new design of valve-regulated lead-acidbattery specifically for use in HEVs. The new battery,called the Double-Impact, has current takeoffs at bothends of the positive and negative plates and has beenshown to significantly outperform state-of-the-artcommercial batteries under both HEV and electricvehicle (EV) conditions.Figure 9: The axcessaustralia Battery PackFigure 8: The aXcessaustralia supercapacitor packCSIRO technology delivers some of the highest capacityto-weightratios reported anywhere in the world and givesthe aXcess car a unique advantage compared with otherhybrids. Supercapacitors absorb energy and deliver storedenergy very quickly. Combining supercapacitors andThe operating temperature of the double-impact batteryunder HEV and EV conditions is much reducedcompared to that of commercial equivalents. Thissimplifies the cooling requirements of the battery pack,improves system safety and reduces both degradation ofthe expander used in the negative plate and corrosion ofthe positive grid. Moreover, it minimises electrolytedryout, a condition that can increase the internalresistance of the battery and lead to problems with chargeacceptance later in life. The reduction in operatingtemperature can be attributed directly to the dual-tabdesign of the battery. In traditional units, which haveonly one current take-off or tab per plate, there is asignificant increase in current density, or ‘currentDavid Lamb5
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The aXcessaustralia Hybrid Electric Car Project

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