Analisi e confronto prestazionale tra un inverter custom ed uno commerciale per la Formula SAE Electric = Performance comparison and analysis between a commercial and a custom inverter for Formula SAE Electric

The advent of silicon carbide (SiC) technologies is leading to increasingly performant power converters, allowing for an increase in power density, voltage / current levels, and switching frequencies. Therefore, in recent years, the need to compare the performance of the SiC based converters with those of the counterparts using silicon (Si) technology has arisen, so to justify the additional costs and technical issues introduced from this new technology. According to this scenario, the goal of this thesis is to perform a fair comparison between the performance of a Si-based voltage source inverter (VSI) with those of a custom-made one that uses SiC technology. Both VSIs have been designed for Formula SAE, a competition organized by the Society of Automotive Engineers to inspire students to design, build and develop a full-electric single-seater vehicle and make it race against other universities’ teams. The SiC-based inverter has been made thanks to the cooperation between the Power Electronic Innovation Center, an interdepartmental center of Politecnico di Torino, and Squadra Corse Polito, a student team of the same university that participates to the Formula SAE competition mentioned above. Conversely, the Sibased VSI is sold integrally to an electric drive that is compatible with the Formula SAE regulation. The comparison between the VSIs has been made in terms of performance, volume, weight, and efficiency. Besides, this thesis shows the performance obtained with the SiC-based VSI when it feeds the electric motor, and the latter is controlled using the direct flux vector control (DFVC) approach. Compared to the conventional field-oriented control (FOC) algorithm provided with the commercial Si-based VSI, it is shown how the DFVC better accomplishes the needs of the drive, especially in the high-speed range of the vehicle. The thesis is structured in three main parts. The first part describes the Formula SAE championship and the electric powertrain of the racing vehicle. In detail, the battery pack and electric motor are analyzed. The second part concerns the analysis of the VSIs, thus performing a comparison in terms of power losses, weight, and geometric dimensions.Simulation results are provided, validating the performed analysis. Finally, the third part concerns the motor control firmware, describing the structure of the DFVC algorithm, together with simulation results providing a preliminary validation.