Design and development of the electrical systems in an electric formula SAE race car
Thesis DisciplineElectrical Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
Formula SAE is a global competition which challenges students to design and build a formula-style race car, which they then compete with in a series of dynamic and static events. In 2016, the University of Canterbury Motorsport team endeavoured to produce a four-wheel drive electric race car; the first of its kind for a New Zealand team.
The race car, named UCM16, featured four individually controllable AMK DD5-14-10-POW permanent-magnet synchronous servo motors controlled by an AMKASYN KW26-S5-FSE-4Q quad-package three-phase full-bridge inverter. Two revisions of a vehicle control unit were developed in-house, which relayed driver commands to the inverter via a dual-CAN communication bus. Torque vectoring, traction control and tractive power limiting algorithms were developed on the later revision of the control unit, dramatically increasing UCM16’s dynamic performance.
A 588 Vdc, 8.8 kWh tractive battery pack was initially designed; consisting of 980 Samsung 18650-25R5 LiNiCoAlO2 cells in eight interchangeable battery modules. However, post-manufacturing tolerances meant the tractive pack had to be reduced to a 7.9 kWh, 529.2 Vdc variant. The cells in each battery module were connected by resistance welding bespoke nickel busbars to each terminal. Modules were then connected in series to complete the tractive pack.
The race car was initially tested in a rear-wheel drive configuration. During the testing sessions, the vulnerability of the purchased battery management system to the electromagnetic interference emitted by the inverter caused the tractive system to disable mid-drive. To resolve this, the core functionality of the unit was transferred to a custom controller PCB, which also incorporated the remaining monitoring systems for the tractive battery. Testing also highlighted key areas which needed to be refined for reliability and system cohesiveness.
UCM16 placed 12th overall in the 2016 Formula SAE Australasian competition, held at Calder Park Raceway, Melbourne, Australia. A first-place finish in the skid-pad event made the University of Canterbury Motorsport team the first electric team to win a dynamic event at the Australasian competition. Unfortunately, reliability issues with the electric powertrain meant UCM16 was unable to finish either of the endurance events. Whilst numerous causes were speculated, data recorded throughout the event (and pre-event testing) could not validate any theories.