Large area magnetic field camera for inline motor magnet inspection

This paper reports on a further development of the award-winning [1] magnetic field camera technology [2-4] for advanced inspection of permanent magnets, into solutions for the inspection of large magnets, as used e.g. in electric drives. The innovation consists of combining multiple redesigned modular magnetic field camera sensor modules into a single large area magnetic field camera that can record the magnetic field distribution in a virtually unlimited area with high spatial resolution, at high speed, thanks to parallel read-out. The modular design of the system gives it a high degree of flexibility, allowing rearrangement of modules in various patterns and making multiple operation modes possible, such as direct 2D area magnetic field mapping or operating the system in line scan mode, requiring only a fast 1D scan to result in a quantitative 2D area magnetic image of large magnets. The resulting large area 2D magnetic field images can be analyzed in the same way as a single small area image, allowing high speed extraction of various quantitative key magnet characteristics that can be objectively used for quality control. Newly developed system software allows flexible measurement and data processing chains to be defined in a modular way, allowing both manual and automated magnet inspection tasks to be implemented in a straightforward way. However, in this paper the focus is on the hardware part. The development of the large area magnetic field camera system opens up new possibilities for fast and accurate inspection of large magnets, allowing the flexibility to perform automated inline magnet inspection in production lines, automated or manual quality control and R&D for a wide variety of magnetic systems.