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- ectr,c The state of the art With the Solar Challenge race from Darwin to Adelaide now an international event, the prospects for electric vehicles in the future are looking decidedly rosy. But while solar electric vehicles are progressing rapidly, is the same true for conventional electric vehicles? By GERRY NOLAN Zero to 100km an hour in 6.5 seconds! Neck snapping acceleration with a just a rush and a whirr! Smooth, almost soundless, electric driving over a range of 200 kilometres at 90km/h for a fuel cost of around $6.00. That's only 3 cents per kilometre! Compare this with fuel costs of about 8 cents per kilometre for the family car at today's prices and it all sounds too good to be true. These things may to be true of electric vehicles in the future but don't rush out to your local dealer and try to buy an electric car that will turn in these performance figures today. Such a vehicle just isn't available. Recently though, I rode with David Gosden, director of the Sydney University Electric Vehicle Research Facility. He was at the wheel of their electric van, a Suzuki Carry Van with a highly modified Pope electric motor. This EV (electric vehicle) recently gained full registration with the NSW Roads and Traffic Authority for road use, a significant milestone in the 14 SILICON CHIP project which was conceived by David in 1987. Driving in the van, the initial impression is definitely not one ofnecksnapping acceleration; more one of surprise. After a few seconds wait while the Toshiba portable computer tells the controller what is expected of it - part of the "teaching" process that will later be encoded into the unit's own microprocessor - there are two decisive "clunks" as the contactors make, the computer is unplugged and put away and ... we're moving! There is no prelude to moving off, no whine of the starter or revving of the engine, no quick 'blip' of the accelerator. It's just - well - suddenly you're moving, smartly but smoothly. There is the expected whirr, but road noise, which in a conventional car is usually drowned by engine noise, is more intrusive than expected. No, the impression is not one of speed. It is more like the inexorable movement of an electric train but without all the noise. Of course, electric vehicles are not new. In fact, they were around before internal combustion engine (ICE) vehicles and for many years were direct competitors with them. Between 1902 and 1911, Studebaker alone made around 2000 electric cars and trucks. , I well remember riding the electric trolley buses that plied the streets of Adelaide in the 1950s and of course every city underground railway is electrified. Electric vehicle advantages The reasons for choosing EV s over ICE vehicles read like a shopping list for improving the environment: (1). Reduction of noxious emissions, especially in urban environments; (2). More efficient use of available energy; LEFT: THE GREEN MACHINE . the electric-powered Suzuki Carry Van looking as though it has just come back from a suburban shopping trip. This picture was taken just after it received full registration from the NSW RTA. The Sydney University Electric Vehicle Research Facility project is sponsored by Pope Electric Motors, the Electricity Commission, Exide Batteries, Traction Controls and Siemens Ltd. drive, as we approached a pedestrian crossing, one of the potential problems of electric vehicles manifested itself - it was very obvious that noone had heard us! David Gosden said that it's something he has to be alert for all the time he is driving the EV. Perhaps we'll have to resurrect those red flags that had to be carried along in front of the original horseless carriages! Why aren't they popular? PHOTOGRAPHS BY ROBERT McDONNELL (3). Reduction of audible noise in urban areas; (4). Reduced consumption of petroleum; and (5). Greater flexibility of vehicle design and reduc.e d vehicle maintenance costs and times. One of the main objections to EVs has been that they "don't have anywhere near enough range between recharges". Like a lot of such objections, this one is usually based on gut feeling rather than facts . Surveys have shown that around 90% of all daily one-way car trips are less than 35 kilometres long and over 50% are less than 10 kilometres long. Most of these trips are made at a low average speed and with relatively low acceleration. Also, typically the urban vehicle carries an average of only 1.2 persons. The Sydney University Suzuki is designed for a top speed of l00km/h and a range of 100km without recharging. This 100km range is expected to later increase to 130-140km with the addition of solar cells. Obviously, EVs are suitable for many driving requirements. Nevertheless, when all things are considered, including some of the technological developments we will be discussing over the next few issues, the conventional motor vehicle Will probably show an advantage over the EV for quite some time to come. However, the twin considerations of greenhouse effect and the depletion of oil supplies raises the reduced consumption of petroleum and low emissions of EVs to paramount importance. Just a few hundred metres into our Apart from the politics surrounding the production of conventional ICE vehicles, there are immense infrastructures for producing, distributing and using them and an enormous investment in plant, equipment and human skills. These create massive inertia which must be overcome before a different technology, like electric vehicles, can be implemented. For the same reason, lead acid cells will continue to be manufactured despite other types being more efficient. The overwhelming majority of people don't even think of electric vehicles as an alternative - yet. It is even doubtful that many realise that the exotic, high-profile solar powered cars are actually electric vehicles us. ing the latest technology in computer design, batteries, motors, controllers, construction materials and even tyres. Continued finance for research and the. acceptance of EVs both depend on increasing public knowledge and awareness. Today more and more people worry about environmental deterioration and hope that governments will do something about it. When they realise that EVs are a viable alternative they will put pressure on their governments to favour EVs and to penalise conventional vehicles. For example, a city council may put a tax on all conventional motor vehicles entering the city boundaries JANUARY 1991 15 A CLOSE UP VIEW of the battery ventilation intakes under the registration plate of the Sydney University EV. The battery compartment must be well ventilated to make sure that hydrogen does not build up. UNIQUE MOBILITY'S MODEL M-91 hybrid electric vehicle prototype is a modified Chrysler minivan which uses a small petrol engine powered generator to charge the batteries. This extends the driving range to more than 160km. BATTERY TRAY UnlQ ELECTRIC DRIVE UNIQUE MOBILITY'S M-91 hybrid vehicle uses a large removeable battery tray and the electric motors drive the front wheels. 16 SILICON CHIP THE DRIVING COMPARTMENT in the Suzuki van looks quite normal, even to the "ignition" switch! Despite the fact that the vehicle has no ignition, this key-operated switch is a requirement for registration. There is no clutch; just the go and stop pedals. The lever with the round black knob between the seats is the forward/ reverse selector. The instruments and warning lights are in the neat console above the radio. while, at the same time, state governments might reduce registration and insurance costs for EVs and add an "environment" tax to ordinary vehicle registrations. As far as the introduction of EV s is concerned, initially municipalities will lt::ad the way, then utilities and other delivery and service organisations. Eventually, electric vehicles will become the accepted means of individual commuting transport and then family transport. As stated above, growing city pollution fears, the greenhouse effect and oil supply worries have provided a new impetus to EV development. Figures released by the South Coast Air Quality Management District in Los Angeles and shown in Table 1 compare emissions from an internal combustion eI).gined (ICE) passenger car with EVs, including power generation, for every 100,000km travelled. These figures show that, in total, electric vehicles are 98% less polluting than ICE powered cars, per kilometre travelled. Early in September 1990, the city of Los Angeles awarded a $7 million contract to the Swedish Clean Air Transport Company, with another $7 million expected to go to Unique Mobility, a Colorado company, for the design and engineering work to eventually produce 30,000 electric vehicles by 1995. These are intended for use in private and public fleets throughout the city. Municipal authorities may lead the way but no matter how economical and pollution-free electric vehicles may seem, the average motorist will not accept them until they lose their "clunky" image and offer similar performance for about the same price as ICE powered cars now do. L00KING INTO THE REAR of the van gives a clear impression of the size of the lead-acid battery compartment and the great strength that has been built into it. The size could be reduced to less than half by using more recent battery developments such as silver-zinc, but at much higher cost. The battery charger is mounted on the side of the van to the left and the compartment exhaust fans, used to vent hydrogen during charging, are below the reversing light. The large panel with heatsinks and capacitors is the power control panel. Perhaps this is just around the corner. General Motors in the USA claim acceleration figures of 0 to lO0km/h in 6.5 seconds and a range of 200 kilometres at 90km/h for its 2-seater Impact car. And they say that it is ready to go into production as soon as there is sufficient demand. These greatly improved performances have been made possible by the exciting combination of recent developments in energy storage, rareearth magnet motors, electronic motor control technology, on-board computers, materials technology and by the dedicated group of people who have continued to work steadily on electric vehicles while they have been out of the news. Two key factors in improving electric vehicle performance are energy to weight ratio (energy density) of the storage system and power to weight ratio of the motor and controller. When you realise that one kilogram of petrol stores the equivalent of 12,000 watt-hours of energy while the trusty lead acid cell can only offer up to 50 watt-hours per kilogram, it is obvious that electrical energy storage JANUARY 1991 17 Block Diagram of a Typical Electric Vehicle {EV) Drivetrain WHEEL SPEED OR POSITION DRIVER ELECTRICAL INPUT, EG ACCELERATOR PEDAL CONTROL LOGIC CURRENT LEVEL REAR AXLE ENERGY STORAGE DRIVESHAFT POWER CONTROLLER DRIVE MOTOR DIFFERENTIAL ENERGY STORAGE SYSTEM FIG.1: THE POWER TRAIN of a typical electric vehicle. In the future, it seems likely that electric vehicles will use mains power and solar cells to keep the batteries charged. One of the main areas for innovation is in transmissions. The electric motor may be used to replace an internal combustion engine, driving through the existing tailshaft & differential, or it may be connected through a chain drive or geared belt to the rear wheels. systems have a long way to go to compete. In fact, there is an enormous research effort into energy storage worldwide with, it seems, everyone looking at every possibility except lead-acid cells. Some of the combinations available, with their energy <lensities in watt-hours per kilogram in brackets, include: aluminium-air (300), nickel-iron (60), nickel-zinc (90), zinc-chlorine (90), nickel-cadmium (30), silver-zinc (100), lithium metal sulfide (170) and sodium-sulfur (300). Other high temperature batteries, fuel cells and hybrid batteries are also being researched, as well as batteries that use liquid vanadium of different valences as electrodes, which are simply replaced to recharge the battery. Flywheel energy storage Flywheels have also been used in vehicles for energy storage since the 1930s and as far back as 1973 researchers were predicting energy 18 SILICON CHIP densities of 870 watt-hours per kilogram using fused silica as a material for super flywheels, Although research is still going on, neither the fused silica or the high energy densities have materialised. Nevertheless, the availability oflight, high-tensile fibres, magnetic levitation bearings, high vacuum enclosures and electronic commutation and control have enabled flywheel energy densities of more than 40 watt-hours per kilogram to be obtained. After the storage system, the next links in the EV power chain are the motor and its controller, both of which have progressed rapidly in recent years. Rare earth magnets Brushless permanent magnet motors, both AC and DC, now use rare earth magnets such as samariumcobalt and neodymium-iron-boron (Nd-Fe-B) with sophisticated Mosfet controllers to replace sliprings and commutators and to permit precise control over motor speed and torque. Readers familiar with the greasy end of electronics will remember that series DC motors, while having high starting torque, have very poor load/ speed regulation, And DC shunt motors tend to have very good load/speed regulation but do not have high torque at start up and suffer from very high starting currents, Permanent magnet motors are virtually equivalent to shunt DC motors in this regard. But now, by using electronic motor controllers, torque and speed characteristics can be optimised. Until recently too, both AC and DC motors needed brushes and sliprings or commutators that required careful bedding in and frequent maintenance, as well as being inherently inefficient. They also produce considerable radio frequency interference (RFI) and are difficult to cool. With electronic commutation, brushes and sliprings are eliminated. Using a permanent magnet rotor insteai:l of a wire wound rotor also cuts out FR losses in the rotor. DC permanent magnet motors with peak efficiencies of up to 97% and power to weight ratios of up to 3,000 watts per kilogram are actually in production. An example of these are the UNIQ motors, produced by Unique Mobility in Colorado USA. These were used to power 18 of the You Can Now Upgrade to EGA Graphics For Less Than $600 Only the first 100 orders at this price Purchase this EGA Color Monitor for $599.00 and we'll give you the control card FREE EGA MONITOR This EGA full colour monitor provides both text and graphics capability with all EGA interface cards. It has a dot pitch of 0.31 mm picture tube which also features a anti-reflective coating. The other feature you will fi nd very useful is the tilt and swivel stand. 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IAN'S PERSONAL GUARANTEE * All products carry a 14 day money back guarantee ( except software and hard disks). * All prices include sales tax. * All motherboards carry a full 12 month warranty. * All other products carry a full 3 month warranty. WHOLESALE ENQUIRIES WELCOME Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guar- t~;;::n:~::;.;og~s::g:,:::::d::.:;.::.::11.,i:i15==-=-~,., I I I I I I this coupon to receive your copy. Mr/Mrs/Ms: Address:._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Suburb: State:._ _ __ _ Postcode: I I I I I I ~--------------------------~ . Electronic Solutions I 5 Waltham StArtarmon 2064 PO Box 426 Gladesville 21 11 Telephone: (02) 906 6666 Fax: (02) 906 5222 32 entrants, including three of the top four finishers, in the July 1990 Sunrayce from Orlando, Florida to Detroit, Michigan. A similar number were used in the second World Solar Challenge race in November, from Darwin to Adelaide. Its very high power density makes the UNIQ motor ideal for solar powered vehicles and other applications where size and weight have to be kept to a minimum and efficiency is essential to reduce energy consumption. (Editor's note: motors with even higher power densities are now being used in electrically powered model aircraft. For information on this topic, see Bob Young's article on Remote Control in the November 1990 issue of SILICON CHIP). The powertrain As with conventional ICE vehicles, there is a minimum number of elements required to get the energy from the storage unit to the wheels. Called the "powertrain", it is formally defined as the electromechanical system between the vehicle 's energy source and the road. In the case of electric vehicles, we also need a path to get the energy from the wheels back to the storage unit during regenerative braking. For the purposes of future discussion, we will define an electric vehicle as one in which the tractive effort is supplied by an electric motor and the energy source is portable and electrochemical or electromechanical in nature. Fig.1 shows the powertrain of a typical electrical vehicle. Any one or A MAJOR DIFFERENCE between the electric vehicle and the ICE vehicle is the male socket for connection of 240VAC mains power. 20 SILICON CHIP THIS VIEW SHOWS the UNIQ brushless DC motor and its controller. A motor like this, 163mm in diameter and 147mm long, has a 15kW (20HP) power rating. all of the elements may be varied in themselves and related or matched to each other in several ways, depending on the requirements of the designer. From the diagram we can see that the elements in the direct chain are: (1) energy source; (2) energy storage; (3) power controller - with inputs; (4) drive motor; (5) transmission; and (6) wheels. The powertrain may vary at almost every point in the diagram. For example, in a solar powered vehicle, the energy storage charger is naturally the bank of solar cells on the roof instead of a mains powered unit. In a hybrid electric vehicle, the energy source is likely to be a small petrol power generator which continually charges a small battery and also drives the electric motor directly. The drive controller will vary depending on the budgetted price for the vehicle and it may or may not incorporate circuitry for regeneration (ie, charging the battery) during braking. Similarly, depending on price constraints, the drive motor could be AC or DC, brush-type or brushless. One of the main areas for innovation is in the area of transmissions. The electric motor could possibly just drive the existing tailshaft and differential of a conventional vehicle or it could be directly connected to the wheel(s) via gearing, a chain drive or belt drive. No matter what the details of the drivetrain, future electric vehicles are likely to look fairly similar to the vehicles we are driving today. Syd- TABLE 1 Emission Reactive organic gases Carbon monoxide Nitrogen oxides ICE kg 745 731 49 EVs kg 1.5 2.6 18 ney University's electric vehicle seems to carry this to extremes. For example, the driver's compartment looks quite normal, even to the extent of having an "ignition" key. Despite the fact that the vehicle has no ignition system, this key operated switch is still a requirement for registration. There is no clutch of course, just the go and stop pedals. And in place of the normal gearbox lever, there is a forward/reverse lever, mounted between the seats. On the other hand, most of the cargo compartment is occupied by the large battery box. The size of the battery could be reduced to less than half by using more recent battery developments such as silver-zinc, but at much higher cost. The battery charger is mounted on the side of the van to the left and the compartment exhaust fans, used to vent hydrogen during charging, are below the reversing light. Future articles. will look at batteries and flywheels; electronic power controllers; electric motors and the new generation of power transducers; transmission systems and wheels; and the future of electric and solar electric vehicles in Australia. SC