Computer modelling has helped ensure that the aXcessaustralia concept car makes the most of its sophisticated power generation systems.

The aXcessaustralia car, launched in Melbourne today, is poised to show the world how to make low emission vehicles with all the power, performance and affordability of a normal car (see CSIRO press release 00/148).

"The aXcessaustralia car's novel drive train, with its three sources of driving power, presented us with a new challenge," said David Lamb, Chairman of the aXcessaustralia project. "We needed to know how to make the best use of these power sources, to achieve our goals for the efficiency and performance of the car."

CSIRO scientists used computer modelling to determine the best way to operate the aXcessaustralia vehicle. This involved balancing the many factors which contribute to the vehicle's performance and economy to find an intelligent, co-ordinated strategy for using the car's power systems.

"Our model of the car's power system served as a test bed for designing its power management strategy," says Dr Mark Westcott, one of the CSIRO mathematicians who did the modelling.

"We were able to find how best to use the power systems, before the car was put together."

"We tested a range of possible power management strategies by simulating how the car would run, during typical journeys, under each strategy," he says. "The model gave us information about the car's efficiency and performance, so we could find the best strategy."

CSIRO scientists then encapsulated the results of the modelling in the car's power management software, ensuring that the optimal strategies found by the modelling are used as the car is driven.

"The car actually has three separate driving modes," says Dr Westcott. "The driver selects one of these modes at any time, depending on the particular situation and power demands on the car, making the car effectively three cars combined."

In one mode, the power system is optimised for fuel efficiency. In another, the responsiveness and performance of the car is optimised. A third mode maximises the distance that can be driven without using the petrol engine, for use in zero-emission zones that may be enforced in city centres in the future.

"For each mode, the computer modelling showed how to combine the car's different power systems to achieve the particular goal," says Dr Westcott.

"For example, for maximum fuel efficiency, the petrol engine is operated at its 'sweet spot' - where it is most efficient and emits less pollution. But at this point, the engine often produces more power than is needed to run the car. So, this extra energy is used to re-charge the batteries and supercapacitors. When these are nearly fully charged, the power management system turns off the engine, and uses the stored power."

Each mode also makes the most of 'regenerative braking', where the energy from the momentum of the car, which is usually lost during braking, is captured and stored for future use.

For further information about the power management strategy:

Dr Mark Westcott, CSIRO (02) 6216 7253  Mark.Westcott@cmis.csiro.au

For further information about the aXcessaustralia car:

Mandy Parry-Jones Marketing Manager aXcessaustralia (03) 9484 8624

Media Assistance:

Janelle Kennard (02) 6216 7157  Janelle.Kennard@cmis.csiro.au