ECE.06M – SAE Formula Electric Precharge Discharge circuits

• Pierrelouis Bessenet
• Anastasios Georgiafentis
• Jaime Jimenez
• Phillip Koval
• Bindu Mukundappa

The rise of Electric Vehicles (EVs) presents an exhilarating opportunity in both the racing world and for car enthusiasts, offering zero CO2 emissions and impressive torque performance. As members of UIC’s SAE team, we have embarked on a journey into the performance electric vehicle domain with a primary goal: to design a competitive car while prioritizing safety. With our vehicle boasting a high-voltage battery (approximately 400V), ensuring safety through vigilant monitoring of voltage readings has been our top priority. To address safety concerns head-on, our team has diligently implemented both a precharge circuit and a discharge circuit. The precharge circuit serves the critical function of initiating the inverter in the motor, while the discharge circuit has been carefully engineered to safely shut down the vehicle for maintenance or in emergency situations. Monitoring the completion of the precharge stage has been facilitated by a PIC18 microcontroller, which transmits data through the car’s communication system. Additionally, we have integrated monitoring for the car’s AIRs (big voltage switches responsible for directing battery voltage to the precharge circuit). Another PIC18 microcontroller has been dedicated to this task, transmitting data over CAN to detect any instances where these switches may become permanently closed. In our project, we made the strategic decision to scale down the voltage requirements due to limitations in our available battery size. This approach has allowed us to showcase what we believe SAE teams should implement when they eventually acquire larger batteries for their electric vehicles. By demonstrating these safety measures with our scaled-down voltage system, we aim to provide a valuable blueprint for future endeavors when higher voltage systems are integrated. Through this approach, we have been able to focus on the fundamental principles of safety and performance, setting a strong foundation for future innovations in the electric vehicle racing world. As members of UIC’s SAE team, we are proud to contribute to the advancement of electric vehicle technology and safety standards.