E-Mobility Engineering 015 l EMotive Scarab off-road truck dossier l In Conversation: Giulio Ornella l Hall effect and magnetic sensors focus l Challenge of batteries for heavy-duty EVs l Alpha Motor Corporation digest l Automated charging insight l HVAC systems focus

Acknowledgements The author would like to thank Motaz Khader at Allegro Microsystems, Koen Vervaeke at Magcam and Hugh Glass at Paragraf for their help with researching this article. axial motor, the rotor is flat, which is well-suited to the flat-array sensor. A version of the array sensor has been developed with a laser sensor that measures the surface of the rotor and the magnet with the magnetic field to control the distance. Alternatives Developers of DC motor control systems are now looking at replacing the magnets needed for Hall effect sensors with inductive sensors that can be integrated onto simple, compact PCBs. For example, an inductive sensor has been purpose-built for EV motor control applications with differential outputs, fast sample rates and features that make it ready for ISO 26262 functional-safety designs to the ASIL C classification. PCB-based inductive position sensors use a primary coil to generate an AC magnetic field that couples with two secondary coils. A small metal target object disturbs the magnetic field so that each secondary coil receives a different voltage whose ratio is used to calculate absolute position. By using the metal traces of the PCB rather than transformer-based magnetic windings and coil structures, the sensor has negligible size and mass compared to alternatives that weigh as much as 450 g. The accuracy of these sensors is better than other Hall effect sensors, as they do not depend on the strength of the magnet, and the design of the traces can actively reject stray magnetic fields. Conclusion Hall effect sensors are a standard component in many parts of an EV, from steering encoders to wheel and motor speed sensors. New materials such as graphene are dramatically improving their sensitivity and opening up opportunities to characterise the performance of pouch cells and battery packs. Being able to measure the current in and out of the battery pack more accurately, instantaneously and non-invasively gives EV designers and fast-charger developers far more data about powertrain performance. More integration of sensors for safety-critical designs and more effective signal processing are also driving the devices into EV platforms. Greater integration, with thousands of Hall effect sensors on an array, is also helping to improve the assessment of magnets during production. This can help improve the quality of the rotary encoders and even axial motors, boosting the performance of EVs and electric aircraft. Focus | Hall effect and magnetic sensors A magnetic camera in use on a scanning system (Courtesy of Magcam) 42 Autumn 2022 | E-Mobility Engineering