Portland State University. Department of Electrical and Computer Engineering
Date of Award
Master of Science (M.S.) in Electrical and Computer Engineering
Electrical and Computer Engineering
1 online resource (xiv, 134 pages)
Electric automobiles -- Design and construction, Electric automobiles -- Testing, Racing automobiles
The Formula SAE Electric competition is a collegiate autocross event in which teams design, build, and race an open-wheeled electric race car. The main motivation is the efficiency advantage of electric motors over internal combustion motors. This thesis presents the design and evaluation of two generations of Portland State University electric race cars.
The constraints are the competition rules, finances, human resources, and time required to complete a race car in one year. The design includes the implementation of existing components: battery cells, controllers, electric motors, drivetrains, and tire data for an optimized race car. Also, several circuits were designed and built to meet the rules, including the shutdown, precharge, discharge, brake system plausibility, tractive system active light, and an electric vehicle control unit.
The car's performance was modeled with calculations and OptimumLap simulation software, then track tested for actual data. Performance data such as torque, power, and temperatures were logged, and the Formula SAE events were tested. The data were compared to the simulations and records from past competitions, and the car was 21% to 30% behind the best times.
The motor generated 410 Nm of peak torque, as expected, but the maximum power was 51 kW, 15% less than the calculated 60 kW. Compared to the best times of past competitions, the car completed Skid-pad in 6.85 seconds (21% slower), and Acceleration in 5.65 seconds (25% slower). The first generation car was tested for range, and raced 31.4 km on a cold, wet track, so tire forces were decreased 6% to 69% from a dry track. During the 22 km. Endurance test with the second generation car, there were problems with imbalanced cell voltages, limiting the test to 4.9 km. Later, there was a catastrophic drivetrain failure, and Endurance testing on a dry track was not completed.
In dynamic event simulations, a lighter, axial flux permanent magnet synchronous motor with a decreased counter EMF yielded improved times. Reconfiguring the battery pack from 200 VDC 300 VDC would provide 50% more peak power. Further testing is required to determine the actual average power use and making design decisions with an improved
Sullivan, Quinn Jasha Bryan, "The Design, Implementation, Evaluation and Results of a Race Car for the Collegiate Formula SAE Electric Competition" (2016). Dissertations and Theses. Paper 3016.