Electrical engineering students from the e-racing team at the Hochschule Esslingen University of Applied Sciences, in Germany, said they have designed a 300-kg car, dubbed EVE, that is powered by two electric motors. It reaches a top speed of 140 km/h and has a range of 22 kilometers thanks to two lithium polymer batteries with a combined capacity of 8kWh.
Researchers from the Fraunhofer Institute for Integrated Circuits IIS in Erlangen developed the electronic sensor system in collaboration with industry partner Seuffer GmbH & Co.KG.
The EVE car is laden with sensors that measure braking pressure, crash, temperature and acceleration as well as sensors that monitor the accelerator and brake pedals, speed, steering angle, wheel speed and power. These last six functions are performed by the Fraunhofer HallinOne, a 3-D magnetic-field sensor realized on a standard CMOS process for monolithic integration with customer-specific electronics.
Sensors on both sides of the batteries are designed to measure the magnetic field generated by the flow of the electrical current and determine the battery's level of charge. These contactless sensors assess both the current that flows from the battery to the engine and the current that flows back again when the vehicle brakes. It also eliminates disturbances and foreign magnetic fields and measures the battery voltage and temperature. The data is then gathered and transmitted to a power control unit and battery management systems (BMS).
The BMS determines the impedance spectrum of all battery cells and tests whether the cells are working in an optimal manner. The system includes an active cell balancing system that moves energy between stronger and weaker cells. This means that all cells share the load allowing the maximum capacity of the battery to be utilized.
In parallel, researchers at Fraunhofer IIS said they developed POLKA, a polarization camera that can detect tiny cracks developing in the car’s carbon fiber body at an early stage by measuring stresses within unpainted