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The GM EV1 electric vehicle – on sale this year in the United States. Electric Vehi Where are they now? During the early 1990s there was great media publicity concerning electric cars. They were to be the solution to the world’s pollution problems, with some of the more optimistic industry experts predicting that we would be driving them before the turn of the century. So where are they now? By SAMMY ISREB 4  Silicon Chip icles Several of the world’s leading car manufacturers have been developing electric vehicle technology during the past few dec­ades, with Ford and General Motors leading the way. Ford’s latest electric vehicle, the 1998 Ford Ranger EV, is due for release in the near future, GM has the EV1 passenger car and Toyota has an electric version of the RAV4. The Ford Ranger EV was designed using data obtained from the Ford Ecostar test program, which began in 1993 and involved 103 Ecostar two-passenger EV delivery vans, operating throughout the US, Canada and some of Europe. Powered by a sodium-sulphur battery, the Ecostar fleet has covered over 1,000,000 kilometres, the greatest of any EV fleet so far. Much of the new technology to be incorporated in future electric vehicles has been tested in the Ecostar. This includes: (1). Traction Battery: An advanced sodium sulphur battery oper­ates at a temperature of over 200°C and features an energy density three times greater than conventional lead acid batteries. (2). PEC (Power Electronics Centre): The Ford Ecostar contains an advanced power control system, incorporating an inverter to produce AC power for the motor. (3). DDLM (Diagnostic Data Logger Module): Records every aspect of the vehicle’s performance, allowing for later engineering analysis. (4). Solar Energy: Using solar panels mounted above the wind­ shield, accessories such as fans can be powered from the sun, saving on air-conditioning and thus the battery. (5). Multiplexing: Because of the complexity of the different electronics modules in the Ecostar, conventional wiring would require 200 separate circuits. Multiplexing allows the eight different modules to communicate over a single pair of wires. To be released in the United States next year, the 1998 Ford EV Ranger shares the body of the petrol-driven Ranger but that is where the similarities end. This pickup truck features 4-wheel ABS brakes, dual airbags, climate control, power steering and regenerative braking. The Ranger uses a 90 horsepower 3-phase AC induction motor with no gearbox and it is rear-wheel driven. An inverter works with the 312V, 23kW sealed lead-acid battery system to convert the high voltage DC to 3-phase AC. Low rolling resistance tyres and lightweight aluminium wheels, together with the regenerative braking, give the Ford Ranger a range of about 90 kilometres, with an electronically-governed top speed of 120km/h. Both the Ecostar and the Ranger use a conductive charging system. This system automatically checks for a proper electrical connection to the vehicle, checks that the charging station is ready to charge the battery, confirms the battery type and charge station capacity, and ensures that all safety systems are working before proceeding to charge the vehicle. A full charge is achieved in 4-6 hours, depending on the state of battery dis­ charge. GM’s EV1 electric vehicle Set to challenge Ford in the EV market place is General Motors, with their new electric vehicle, inventively named the EV1. It has recently gone on sale in America and sells for about $US35,000. The EV1 is a front wheel driven aluminium-bodied 2-door passenger coupe. The designers of the EV1 have tried to boost the range of the vehicle, not by using special batteries but by taking other measures, such as lowering body weight and drag. In fact, the EV1 has a drag coefficient of 0.19, compared to between 0.30 and 0.40 for a standard production car. This was achieved by taking extraordinary steps such as closing off the underside of the car, covering the rear wheels with skirts, using low rolling resistance tyres, and even building the radio antenna into the roof rather than having a standard extendable antenna. A 137-horsepower 3-phase AC-motor drives the EV1. This motor is water cooled and revs from 0 - 13,500 rpm. This wide rpm range, coupled with a broad torque curve, eliminates the need for a transmission. Acceleration is quite good, with the motor propelling the EV1 from 0 to 100km/h in around nine seconds. Powering the EV1 is a 312V battery pack, made up of 26 maintenance-free, valve-regulated, lead-acid modules. Environmen­talists will be able to drive the EV1 knowing that the batteries are 98% recyclable. Because safety is a crucial factor in any electric vehicle, the batteries are of sealed construction in which all the liquid acid is encapsulated in a diaper-like mate­rial between the individual lead plates. This results in a bat­tery so safe that a hole could be made in the case and no liquid would flow out. Clever electronics At the heart of the vehicle’s electronics system is the inverter. This uses six Insulated Gate Bipolar Transistors (IGBTs) which perform the high power switching needed to convert the 312V DC from the battery system to AC for the motor. These IGBTs can July 1997  5 passes it through the car in order to heat it. Cooling is achieved through a CFC-free energy efficient air-conditioning system. Inductive charging A 137 horsepower 3-phase AC motor drives the EV1. It is powered by 312V battery pack, made up of 26 maintenance-free lead-acid modules. The motor is water-cooled and revs from 0 - 13,500 rpm which eliminates the need for a transmission. handle up to 600V at 750A, making them very rugged indeed. An inventive electronic circuit controls the drive and braking system. Known as the Galileo Braking System, it uses software to constantly monitor the driving conditions and selects ABS braking or traction control when appropriate. This electronic system also monitors tyre pressure and inflates the tyres when necessary. In addition, a regenerative braking system is used to charge the battery during braking and this significantly boosts the range of the vehicle. Another major design feature of the EV1 is the inclusion of a heat pump. This works as a heat exchanger to move hot or cool air inside and outside the car. The pump takes coolant from the motor and inverter electronics and Toyota plans to release an electric version of its RAV4 to fleet buyers in the United States in early 1998. The EV RAV4 is basically a reworked petrol RAV4 featuring a nickel metal hydride battery. 6  Silicon Chip The EV1 features an inductive charging system that is far superior to the chargers used by many other electric vehicles. Instead of using a conventional electrical connector, it uses a fairly bulky paddle, encapsulated in an insulating material, that is plugged into the car. The great plus of this system is that there are no exposed conductive parts, as the electrical energy is transferred inductively; a great safety feature. The paddle can be immersed in water, run over by a car and so on, without any risk. If the cable to the charging paddle is severed, this will be detected and the power shut off within a few microseconds. Whilst the complexity of this charging system will boost its price, inductive charging seems the way of the future. Toyota’s RAV4 Set to rival both Ford and GM, Toyota plans to release an electric version of its RAV4 to fleet buyers in the United States in early 1998. The EV RAV4 will basically be a reworked petrol RAV4 featuring a nickel metal hydride battery. With a top speed of 125km/h and a range of 190km, the RAV4 is competitive. However, the RAV4 will not become eco­nomically viable for the mass market in the near future, due to the high price of the nickel metal hydride batteries and the fact that (unlike the EV1) large scale production is not envisaged for the moment. Over the next few years, only 320 EV RAV4s will be produced for fleet trials. Although this article has described the market-leading electric vehicles that have emerged in the past few years, there are quite a few others from smaller car manufacturers that have not been mentioned. And although the EV1, Ecostar and Ranger are set for large-scale production, their sales are likely to be limited to the US and parts of Europe. As yet, no electric vehicle is widely available in Austra­ lia and none is likely to be for some time. It will probably be the better part of a decade before we see serious EV trials SC in Australia.