When we normally think of electric race cars we envision ones used for traditional racing around a track in a competition designed to generate a winner from a crowd of competitors. Electrical engineering students from the e-racing team at the Hochschule Esslingen University of Applied Sciences in Germany though, along with scientists from German research organization Fraunhofer, plan to equip an electric racer with sensors and other equipment to demonstrate solutions for better measuring EV performance – all while hoping to still win a few races as well.
Eve, as the car is named, will be on display at the Sensor + Test measurement fair in Nuremberg from May 14 -16, according to Fraunhofer. The racing car, which already competed in at the international Formula Student Electric race in Italy, is designed by students to be quite the little speed demon. It goes 0 to 62 MPH in 3.6 seconds and is powered by two electric motors, one for each rear wheel.
Maximum output of these motors, measured at 60 kW, helps Eve to hit a top speed of nearly 87 miles per hour over a maximum range of 13.6 miles. The motors are powered by two lithium polymer batteries, with a combined capacity of 8 kWh.
As to what researchers hope to gain knowledge of from this vehicle, they first have attached sensors to the batteries which make use of 3D magnetic-field sensor technology to
measure the magnetic field generated by the flow of electrical current and thus to determine the battery’s level of charge. What’s special about this is that the contactless sensors measure both the current that flows from the battery to the engine and the current that flows back again when the vehicle brakes. The integrated sensor system is able to eliminate disturbances and foreign magnetic fields, thus guaranteeing very precise measurements. A further advantage is that the system is also able to measure other aspects of the battery such as its voltage and temperature. The data is collected and sent to the power control unit (PCU) and the battery management system (BMS), which controls the charging and discharging processes.
The BMS itself is something specially designed by scientists. It determines the impedance spectrum of all battery cells, always testing to see if they are functioning properly. Through this testing, said Fraunhofer, “cells’ condition, current capacity and potential service life” can be better measured and running times be predicted more accurately. The ultimate goal is optimizing battery cell utilization, achieved in part by the BMS actively moving energy between stronger and weaker cells to ensure the energy load is carried more evenly and the maximum capacity of the battery made use of.
Finally, the vehicle’s compact design, built around a tubular steel space frame housed within a carbon fiber body, is studied through a special polarization camera that looks for tiny cracks which develop in the material as a result of the stress from racing. The resulting data collected from this camera can help the students look for wear and tear on the vehicle which might inhibit performance before it becomes a serious issue.
Plans call for this technology to be on the vehicle as it competes in student races around Europe, with the goal of allowing it to “perform very well while demonstrating excellent environmental awareness.”