Solar Car Power Management

Purpose of Research

© 1996
Paul Vincent Craven
All Rights Reserved


Every two years General MotorsGeneral Motors (GM), Electronic Data Systems (EDS), and the Department of EnergyDepartment of Energy (DOE) sponsor SunrayceSunrayce, a cross-country race for cars powered entirely by the sun. This race has several purposes: providing research into alternate power sources, promoting conservation of environment, and offering real-world education for university students. Students involved in the project range from mechanical engineers to English and management majors. Not only do students build a solar car, but they also raise funds, document procedures, and coordinate the activities among dozens of members.

At the end of Sunrayce '95, I sat at the final reception dinner for the Sunrayce teams. While there I had the distinct impression that here are the leaders of tomorrow. Even among the lower-placing teams, you saw incredible resourcefulness to do whatever it took to keep the car on the road. These students graduate with more than just a textbook education, they have the experience to immediately apply themselves to business and industry. Although I have no proof to support the claim, I would guess that these students would be the most likely to rise to the top of the business world.



Figure 1: Measuring the UMR Solar Car at qualifiers

Sunrayce provides for an excellent opportunity to allow the public to see science and engineering at work. The race shows the importance of continuing the support of research and education to keep America technically competitive. Children can see that engineering can be both fun and fulfilling. Hopefully it helps some to aspire to seek greater heights in career and education.

This report centers around the research I did in power management. To run well, it is necessary to make best use of all available resources. The primary resource we are interested in during the race is the sun, from which all of our energy is received. The power management software has an extensive underlying structure that allows it to adapt to the changing needs and theories of power management. The object-oriented design allows components of the program, such as communications protocols, to be modified without extensive changes to other portions of code. The display capabilities allow for human interpretation should the automatic power usage algorithms fail. Almost any type of power management algorithm may be plugged into the program to access the map and sensor databases. Because solar car power management is still mostly unexplored, the power management software was built to be expandable, maintainable, and adaptable.

There are many ways to optimize the use of solar energy while on the road, a few of which are discussed in this paper. As such, some parts of this paper fall under the science of Operations Research, which is the process of optimizing the use of resources. While many theories for such optimization exist, we only explored a couple. The primary emphasis was the creation of a flexible framework into which such theories could be coded and tested.



Figure 2: Signing autographs



Figure 3: Charging the solar car

The results of power optimization presented in this paper are not solely applicable to solar powered cars. By helping optimize vehicle energy usage, concepts learned from this research can help conserve energy usage on any other land-based vehicle type. The results are particularly well suited for public and rail transportation, where vehicles travel the same set path and can more tightly regulate their speed. While interviewing for employment I conversed with a former employee of Honeywell who said that there was similar research happening in the rail transportation industry. Using GPS systems on trains, speed could automatically be controlled to save fuel by anticipating hills and increase safety by automatically slowing down for towns and curves. Here, by providing a good framework for data collection and analysis, we are set to perform similar experiments with solar powered vehicles.