System Engineering Overview

From Trevipedia

Here's some text to get this section going:

TREV is a vehicle designed to meet a subset of personal mobility needs.

This wiki is structured to permit a user to see overall system matters and to drill into each of TREV's sub-systems to see the detail necessary for the overall package to meets its design parameters...

Overall design parameters

When the Trev project was starting in 2004, some informal observations of vehicle occupancy showed that 70% of cars had only one occupant, and over 90% had only one or two occupants. Furthermore, most households in Australia have more than one car. On this basis, a 1 + 1 configuration will meet a good proportion of motorised personal mobility needs.

Commuting distances in Australia are also low. A 2009 AutoCRC project on Planning for Electric Vehicles in Australia found that:

• In Adelaide, over 95% of cars travel less than 100 km per day. The average daily distance travelled by car drivers is 32 km.
• In Sydney, over 85% of cars travel less than 100 km per day. The average daily distance travelled by car drivers is 53 km.

On this basis, a range of 100-150km will meet a good proportion of daily vehicle based personal mobility commuting needs.

The following requirements were compiled for TREV:

• Two comfortable seats, luggage space, easy entry & exit, and good all round vision
• A small, aerodynamic body
• Mass, without occupants, less than 350 kg (prototype was about 300 kg)
• Energy-efficient tyres, brakes and suspension
• An efficient electric drive system
• Performance at least as good as conventional cars
• Compliance with road safety and worthiness regulations
• Cost comparable to that of small conventional cars
• Commuting range of 100-150 km
• Electrical energy use less than 200 kJ/km (60 Wh/km)

Photovoltaic panels

Photovoltaic panels are more effective on the roof of a building than on the roof of a vehicle; they can be angled to face the path of the sun, and buildings are less likely to be parked in the shade.

A 1 m² photovoltaic panel on Trev might generate 1000 Wh of energy on a sunny day—enough to drive about 15 km. (Solar racing cars are much lighter, have much lower aerodynamic drag, and have 6 m² of very expensive photovoltaic cells.)

A small PV array could be used to power ventilation fans when the car is parked in the sun.

Prototype performance

In the 2007 World Solar Challenge, Trev was driven 3000 km from Darwin to Adelaide. It cruised at 80-90km/h, traveling an average of 431 km per day with an average energy consumption of 6.2 kWh/100km. This energy use was at high cruising speeds. Similar or lower energy use is likely for urban commuting.

Under the race conditions, the prototype Trev achieved a range of 120 km. A motor that is more efficient at light loads would give an even greater range.

The overall size of the prototype Trev is good, but more usable and more accessible luggage space would be nice.