Shell stages another future vision of sustainable mobility
09 June 2013
The Shell Eco-marathon is a global competition that challenges students to design, build and drive the most energy-efficient car. maxon motor uk has been working with the University of Oxford on this year’s entry. Les Hunt reports.
For 70 years the Shell Eco-marathon Challenge has been an ultimate meeting of futuristic vehicles that aims for the best performance on one gallon of fuel. The 2013 European race took place at the Ahoy Arena in Rotterdam last month, and for the second time, it was held over a street track, to test the vehicles’ performance in real world conditions. Competition to enter this race is fierce, with just 200 vehicles able to take part.
The Energy & Power Group (EPG) in the Department of Engineering Science at the University of Oxford, gained a place in the contest with its vehicle, nicknamed ‘Peggie’. The group undertake s computational and experimental energy research with particular focus on electrical machines and energy systems, and Peggie made an excellent debut performance in 2012, finishing in twelfth place with an efficiency of 366km/kWh in the battery electric class (approximately equivalent to 6,000 miles on one gallon of fuel).
For 2013, EPG has mapped the route, converting every gradient into a power requirement. With the help of the experts at maxon motor the requirement was tested on some of maxon’s most efficient off-the-shelf brushed and brushless dc motors, the RE50 and the EC60, powered by the latest Escon 50/5 drive amplifier. maxon’s senior sales engineer, Ian Bell was on hand to give advice on how to get the best performance from maxon products.
“Working with students is stimulating; they have great projects that are ideal for maxon motors. I am still working with engineers I first met when they were students designing projects 20 years ago! The decision was which motor/drive combination would be the most efficient over the course. By mapping all the gradients and assuming a fixed speed it was possible to calculate power requirements for every metre.
“With this information a load motor connected to a torque transducer was powered by the potential drive motors. The resultant measured power consumption showed that the RE50 brushed motor was best choice. However, I really didn’t think we’d get over 30km/h from one small motor!”
The competition is split into two classes: UrbanConcept and Prototype. UrbanConcept cars are 4 wheeled fuel economy vehicles that look similar to the cars we see on the road today. Peggie was entered into the Prototype category, which looks at the overall design concept to reduce drag and maximise efficiency. Vehicles in this class are one-seated, built with three or four wheels and have an opened- or closed-top driver compartment. Cars enter one of seven categories to run on conventional petrol and diesel, biofuels, fuel made from natural gas (GTL), hydrogen, solar or electricity.
Over several days, teams make up to four attempts to travel the furthest on the equivalent of one litre of fuel. Cars drive ten laps around the circuit at an average speed of 25km/h. Organisers calculate their energy efficiency based on a joulemeter installed in each vehicle and name a winner in each class and for each energy source. Off-track awards are given for other achievements including safety, teamwork, design, and technical innovation. Peter Armstrong, who heads the technical team at EPG, takes up the story:
“maxon's advice has been invaluable to us in selecting the right driveline components for our application. The team benefited from two visits from application engineers, Ian Bell and Mark Gibbons. Ian and Mark helped us to sift through their extensive range of motors, enabling us to down-select the RE 50 brushed and EC 60 brushless machines.
“We have undertaken extensive testing on both motors to map out their efficiency over the corresponding torque and speed demands which the vehicle will subject them to. During testing, we found that maxon's products surpassed the performance of all of the previous machines we tested. In addition to the high efficiency of the machines, the Escon-50/5 controllers used throughout our test programme have been flexible, robust and intuitive to use.
“There have been a number of project highlights. Whenever a company gets behind us in the way that maxon has, dedicating time and expertise to the project, team morale is boosted. One particular highlight was when our motor test rig became operational. This allowed us to both select the most appropriate machine and develop the optimum driving strategy based on the efficiency data.”
Speaking before the competition, Mr Armstrong’s expectations were that his team would improve considerably on last year's performance which amounted to driving from Oxford to Athens on the equivalent of 10 pints of petrol.
“Transitioning to a maxon drive, will make an efficiency improvement in the order of 10 percent,” he said. “This is very significant when operating so close to the margins in such a vehicle. We have a number of driveline and control ideas which we hope will give us a chance in the innovation and design award categories. By competing we also hope and expect to raise the profile of our sponsors who we feel very much indebted to.”
If you would like to sponsor the team for the 2014 competition, contact team manager, Robert Camilleri: robert.camilleri@eng.ox.ac.uk.
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