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GM’s Advanced Technology Vehicles Joining GM’s EV1 electric car is a range of other vehicles developed from the same basic platform. These new vehicles could well indicate your motoring future but which one will win out? 80  Silicon Chip E ARLIER THIS YEAR, General Motors in the United States introduced a series of new prototype cars based on the EV1 – the world’s first commercially available purpose-designed electric passenger car. The new vehicles include three hybrid-powered cars and a vehicle fuelled by compressed natural gas (CNG). In greater detail, the three new hybrid powered cars include a parallel hybrid electric, a series hybrid electric and a fuel cell electric. These vehicles were developed to overcome one of the main limitations of pure battery By JULIAN EDGAR electric vehicles – poor range. We’ll take a look at each of the new vehicles in turn, starting with the parallel hybrid electric car – see photo. Parallel Hybrid Electric In addition to a battery pack, the Parallel Hybrid Electric car also uses a diesel engine which, as the name suggests, can be used in parallel with the electric motor. The vehicle weighs 1450kg and is based on a standard EV1, with the aluminium space-frame, front suspension and AC induction motor propulsion system generally unmodified. However, the car’s wheelbase has been increased by 48.3cm to provide greater interior space and a longer central tunnel for storage. Instead of the T-shaped battery pack used in the EV1, the Parallel Hybrid uses 44 nickel metal hydride (NiMH) batteries wired in series and mounted in-line down the centre of the car. This gives room for the second propulsion system, which is mounted at the rear of the vehicle. At the back of the car sits an Isuzu 3-cylinder 1.3-litre turbocharged diesel engine. This develops 56kW and drives the rear wheels through a 5-speed manual transaxle. The diesel engine uses direct injection and features double overhead camshafts. The transaxle, developed by Opel, uses electronically controlled servos to provide fully automatic gear selection and clutch engagement. In addition to powering the rear wheels, the diesel engine also drives a 4.9kW permanent magnet DC brush­ less motor/generator unit. This motor/ generator serves four purposes: it is used as a starter motor for the diesel engine; it provides regenerative braking through the rear wheels; it is powered by the battery pack to provide supplementary power for maximum acceleration; and it acts as an alternator to recharge the battery pack. It just Parallel Hybrid Electric Vehicle ABOVE & BELOW: the Parallel Hybrid Electric vehicle uses a 3-cylinder 1.3-litre turbocharged diesel engine plus a battery pack consisting of Nickel Metal Hydride (NiMH) batteries. When full power is required, 163kW can be mustered by simultaneous use of the diesel engine, a front-mounted electric motor and a rear motor/generator unit. December 1998  81 ABOVE & BELOW: the Fuel Cell Electric vehicle uses a battery of fuel cells supplied with hydrogen and oxygen, as well as a battery pack. The 1377kg vehicle has a range of 480km, can accelerate to 100km/h in about 9 seconds and has a petrol-equivalent economy of about 3 litres/100km. Fuel Cell Electric Vehicle 82  Silicon Chip doesn’t do all of these things at once! In the standard hybrid mode, the car moves off from a stop using the electric motor to drive the front wheels. If battery charge falls below a nominal 80%, the diesel engine starts, recharging the battery pack. In slippery conditions, the power sources at each end of the car can provide 4- wheel drive – leading GM to state that the Parallel Hybrid Electric is the world’s first environmentally conscious all-wheel-drive performance car! When full power is required, a not-inconsiderable 163kW can be mustered by the simultaneous use of the diesel engine, the front-mounted electric motor and the rear motor/ generator unit. When driven flat out, the vehicle can accelerate to 100km/h in around 7 seconds. This represents outstanding performance! The range of the car in full hybrid mode is quoted as 880km, while in “Zero Emission Vehicle” mode (ie, with the diesel engine not running) the car can travel 50km. Its fuel economy is about 3 litres/100km. Series Hybrid Electric In many ways the Series Hybrid Silicon Chip Binders REAL VALUE AT $12.95 Plus $5 ea p&p These binders will protect your copies of SILICON CHIP. They feature heavy-board covers & are made from a dis­tinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. Series Hybrid Electric Vehicle Electric vehicle is very similar to the car discussed above. However, instead of a diesel engine, this car has a gas-turbine engine tucked in the tail! The gas turbine engine drives an electric generator and this works with an NiMH battery pack to provide the motive power. The turbine is the product of a three-year collaboration between GM and Williams International, an aerospace turbine engine manufacturer based in Michigan. Dubbed the “Auxiliary Power Unit” (APU), the device consists of a single stage, single shaft, recuperated gas-turbine engine coupled to a high-speed permanent magnet AC generator. The cylinder-shaped APU has a mass of 100kg and is 50cm in dia­ meter and 55cm long. Running at shaft speeds of between 100,000rpm and 140,000 rpm, it can develop up to 40kW of electrical power. This is sufficient to power the car’s electric drive system and accessories, and/or charge its batteries while travelling at speeds of up to 130km/h. The turbine is fuelled with “reformulated” petrol. In daily hybrid-mode use, the APU automatically starts charging the battery whenever its charge drops below 40%. If the vehicle were to be driven solely on a fully recharged battery pack, the APU would start after about 40km. The series nature of the propulsion system allows the driver to select from either a 560km range of hybrid travel or up to 65km of electric-only travel. Flicking a single switch makes this choice. The 1340kg car has a maximum power of 102kW and can accelerate to 100km/h in around 9 seconds. Its fuel economy is about 4 litres/100km. Fuel Cell Electric The Fuel Cell vehicle uses one device to drive the front wheels and multiple sources of power for that device. The driving device is the 102kW, 3-phase, AC induction motor from the EV1. It drives through a single-speed, dual-reduction gear-set with a ratio of 10.946:1. The battery pack consists of 44 NiMH battery modules connected in series and mounted in-line down the centre of the car. This pack can be recharged from the domestic supply to augment the power provided by the fuel cells. It is also used during regenerative braking. As in a conventional battery, a fuel   Hold up to 14 issues   80mm internal width  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A12.95 plus $A5 ea p&p. Buy 5 & get them postage free. Available only in Australia. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Use this handy form Enclosed is my cheque/money order for $________ or please debit my  Bankcard    Visa    Mastercard Card No: ________________________________ Card Expiry Date ____/____ Signature ________________________ Name ___________________________ Address__________________________ __________________ P/code_______ December 1998  83 or other hydrocarbon fuels. An expander/compressor, located at the rear of the car, improves the efficiency of the vehicle by capturing energy that would otherwise be lost in the stream of exhaust gases from the fuel cells. The remaining hydrocarbons are burnt and the hot gas passed through an expander. The expander produces mechanical energy which is then used (together with an electric motor) to drive a compressor that supplies compressed air to the fuel cells. The 1377kg Fuel Cell Electric vehicle has a range of 480km, can accelerate to 100km/h in about 9 seconds and has the petrol-equivalent economy of about 3 litres/100 km. The Compressed Natural Gas (CNG) vehicle does not use any form of electric propulsion. Instead, a modified 3-cylinder Suzuki engine fitted with sequential port injection and a turbocharger is used to provide the motive power. The vehicle’s range on full tanks of CNG is about 650km. Compressed Natural Gas Vehicle cell utilises chemical reactions at its electrodes to convert energy from chemical to electrical form. Unlike a battery however, a fuel cell stores the reactants separately from the electrodes, feeding them instead to the cell as “fuel” for the reaction. In simple terms, a fuel cell consists of two electrodes separated by a membrane that conducts hydrogen ions but not electrons. Electrical power is generated by the reaction to hydrogen at one electrode to form hydrogen ions. The hydrogen ions migrate through the membrane and combine with oxygen at the other electrode to form water. 84  Silicon Chip When hydrogen and oxygen are fed into the cell, an open-circuit voltage of about 1 volt (1V) is created between the electrodes. As power is drawn from the cell, the voltage drops slightly. To minimise this voltage drop, the electrodes are coated with minute quantities of platinum. The fuel cell stack consists of many individual cells sandwiched together and wired in series. In this case, the GM car uses a multi-stage fuel processor to generate a hydrogen-rich mixture from methanol. Methanol was chosen because it is an ideal source of the hydrogen needed and it has fewer impurities than petrol Compressed Natural Gas The CNG EV1 does not use any form of electric propulsion. Instead, a completely new powertrain is fitted, with compressed natural gas used as the fuel. The motive power consists of a 1-litre, 3-cylinder, sequential port injected, turbocharged engine developing 54kW at 5500 rpm. Modified from an existing Suzuki engine, the design uses an all-alloy construction, single overhead camshaft and two valves per cylinder. The engine drives the front wheels through a Continuously Variable Transmission (CVT), which uses a steel belt and two V-shaped pulleys. This gives stepless power delivery and excellent fuel efficiency. The fuel supply system uses two CNG tanks with a total useable capacity of about 38 litres. One tank is positioned longitudinally in the central tunnel, while the other is positioned laterally behind the rear seats. The tanks and their internal plumbing are designed for a maximum operating pressure of 3000 psi, with a single stage regulator lowering the pressure to 75 psi before injection occurs. As a safety measure, the system uses intank solenoids which are interlocked with the ignition system. These solenoids shut off the fuel during refilling and when the engine is not operating. A special commercial station can refuel the CNG EV1 in 3.5 minutes, while a domestic compressor allows overnight fuelling. The CNG car has a range of 650km, a petrol equivalent economy of 4 litres/100km and a SC 0-100km/h time of 11 seconds.