SUN AND SWEAT. THE ITALIAN SOLAR CAR RUNS ALONG THE FAMOUS VIA EMILIA WHICH LINKS RIMINI TO PIACENZA
Emilia 1 (2005): It was a prototype developed after two years of research, it took third place in the World Solar Challenge: 3000 km of pedaling under the Australian sun.
Emilia 2 (2011): it was number 9 for this electric car with a carbon fibre shell, with its “bones and nerves” made up of in nomex and kevlar, 6 square meters of skin, covered with highly efficiency solar panels. Built after years of hard work, it took part in the World Solar Challenge 2011 competing against 40 teams from 22 nations. Onda Solare was the only Italian team on the Stuart Highway in Australia which divides the country from north to south.
Emilia 3 (October 2013): again with the number 9 at this year’s WSC. Once again, the only Italian team. A structural carbon fiber body. A new prototype. New ideas, renewed passion, ambitious goals and cutting-edge Italian solar technology which dreams of winning.
With only a 1.3 kW engine and with over 3000 km to travel in just 10 days, aerodynamics plays a very important role.
This year the task of designers has been made even more difficult because of the new technical regulations which requires the vehicle to have four wheels (before it had three) and imposing a cone of visibility for the driver within which there must not be any body parts (absent in the previous the regulations). With these new rules, there are five items under the wing, very near to each other, creating possible problems of aerodynamic interference.
Specific requirements for the management and storage of energy captured by photovoltaic cells require sophisticated and reliable solutions, tailored made for the vehicle.
This delicate research, carried out by the electronic department of the Onda Solare team, was focused on the assembly of the batteries, the creation of the control system of these items, the electronics of the car and of course management systems of data transmission. The efficiency of the engine and its driver, 92% and 97% respectively, is excellent, a 32-bit microprocessor system suitable for defined mission critical systems, manages to control the energy and the equalization of power among the various pieces of equipment.
The redundant firmware should enable an optimum management by using an integrated algorithm system, renewable energy sources both automatically and semi-automatically (so that the driver can change some parameters of the cruise control) and also manually. This mode means that the car can be managed via the commands given by the team radio which is located on board as means of support.
The control system sends information to the driver who will then choose the correct gear ratios, depending on the torque needed to maintain the fastest speed on a particular road and bearing in mind the energy available: therefore race strategy is highly important.
Emilia III will be powered by 21 kg of lithium-ion batteries, which will provide an operating range of over 300 km in case of low solar radiation. The battery package consists of 442 cells whose assembly has been specially designed to ensure reliability and safety.
For this purpose it is essential to use the Battery Management System, developed by the collaboration between the Department of Electricity and Information, and the company of industrial automation TBE. The BMS has the task of keeping under constant control voltages and temperatures of all the cells in the battery pack, in order to ensure perfect equalization.
One of the main challenges faced in the design of Emilia III was the integration of electric motors in the rear wheels: an ambitious and highly technological project that allows for the total elimination of the transmission, which increases the efficiency of the vehicle.
The motor wheel is composed of a permanent magnet synchronous electrical machine with an external rotor, which, thanks to the advanced calculation algorithms, the use of simulation software and finite elements used in the design, is amazingly efficient (up to 97%).
A large amount of attention has been paid to the study of the motor support, looking for solutions that could reduce weight, by using cutting-edge materials and construction techniques.
A special inverter has been created which guarantees the correct functioning of the motor wheels. It can control the motor in order to achieve maximum performance.
An enormous thank you goes to our technical sponsors, TEM, Renishaw RLS, Sonatron Futura and Fagandini Tranciature who have provided their best materials and their expertise and experience.
The hundreds of photovoltaic cells installed on Emilia III convert the Sun’s energy into electricity. This is the only form of energy which may be used during the race.
The 6 square metres of monocrystalline silicon solar cells provide little more than 1.3 kW thanks to their excellent performance, over 22%.
The research that led to the creation of the solar panels for Emilia III has been focused on maximum cell efficiency, reliability and weight optimization in order to make the car as light as possible.
The lamination of the photovoltaic panel was carried out by one of our main sponsors: Solbian Energie Alternative.
Lamination is an extremely delicate process. Photovoltaic cells, consisting of silicon and just slightly thicker than a tenth of a millimeter, must be encapsulated to adapt to the surface of the solar vehicle without being damaged.
The Maximum Power Point Tracking is a fundamental device. It enables the extraction of the maximum output power from the PV panels.
The boards of these devices have been developed entirely within the Department of Electricity and Information Engineering at Bologna University, pursuing the objective of maximum efficiency and maximum reliability.
The excellent result was achieved thanks to the high professionalism and experience of our technical sponsors whom, by embracing our project, have ensured the use of the best materials on the market.
Our thanks in particular to STMicroelectronics, Würth Elektronik and PreventLab.