Comparison of sensing modes for stray-field-immune magnetic angle sensors
2022-01-0757
03/29/2022
- Event
- Content
- Magnetic angle sensors play a major role in engine control, steering, and numerous other automotive applications like pedal, wipers and gear shift position sensing. With vehicle electrification, these sensors are increasingly exposed to parasitic magnetic stray fields. When shielding is not an option, a differential scheme is an alternative, where the sensor responds to magnetic field gradients. Two such schemes were previously introduced to reject stray fields to some degree. For these two modes, there are engineering trade-offs between the key performance parameters (noise, thermal drift, angular range). Often, these trade-offs are misunderstood by sensor users. This paper investigates these trade-offs by comparing the two stray-field-immune magnetic sensing modes. We use a single programmable integrated sensor supporting both modes for a direct comparison. The integrated sensor is designed for safety critical automotive applications. Two independent dies are integrated in the same compact PCB-less package without the need for external passive components. The two dies are stacked vertically to keep the magnetic centers aligned. We experimentally characterized a batch of productions parts in the two modes in terms of the the key performance parameters. For each key parameter, comparative side-by-side plots are presented to highlights the pros and cons of each mode—thereby clarifying the trade-offs. Both modes achieve angle drift below 1° over the automotive temperature range (from −40°C to 160°C) with one mode significantly outperforming the other at the expense of a reduced angle range. Overall, our results provide design guidance for selecting the proper magnetic mode depending on the application's performance needs.
- Citation
- Lefebvre, C., Mazzilli, F., Laville, A., Bidaux, Y. et al., "Comparison of sensing modes for stray-field-immune magnetic angle sensors," SAE Technical Paper 2022-01-0757, 2022, .