volume | PIER Journals

2012-04-05

Inaccuracies of Anisotropic Magneto-Resistance Angle Sensors Due to Assembly Tolerances

Udo Ausserlechner

Dr. Udo Ausserlechner

Sense and Control

Infineon Technologies Austria AG

Austria

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Progress In Electromagnetics Research B, Vol. 40, 79-99, 2012

doi:10.2528/PIERB12022805

Abstract

A large class of angle sensors uses a small permanent magnet attached to the rotor. The magnet is polarized perpendicularly to the axis of rotation, and a magnetic field sensor is placed ahead on the axis. The sensor circuit consists of two full bridges at 45^o, each having four anisotropic magneto-resistive (AMR) elements. Even though the electronic system may be calibrated to have nearly no errors like offset, nonlinearity, and mismatch, still significant angle errors may result from assembly tolerances of the magnet and the sensor. This work gives an analytical description of the angle error caused by tilts and eccentricities of magnet and sensor elements against the axis of rotation. Particular emphasis is given to worst case combinations of all tolerances. One part of the angle error can be cancelled by an optimized layout of the AMR-resistors. The remaining part is identical to the case of giant magneto-resistive (GMR) angle sensors. Errors of both AMR and GMR angle sensors are effectively reduced by identical optimization of the shape of magnets. One such optimized shape is disclosed.

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Udo Ausserlechner, "Inaccuracies of Anisotropic Magneto-Resistance Angle Sensors Due to Assembly Tolerances," Progress In Electromagnetics Research B, Vol. 40, 79-99, 2012.
doi:10.2528/PIERB12022805

References

1. Granig, W., S. Hartmann, and B. Koeppl, "Performance and technology comparison of GMR versus commonly used angle sensor principles for automotive applications," SAE World Congress & Exhibition, Detroit, USA, April 2007.

2. Wegelin, F., "Eine neue generation magnetoresistiver sensoren fuer das automobil," Vortraege der 15. ITG/GMA-Fachtagung, Nuernberg, Germany, May 18-19, 2010.

3. Tumanski, S., Thin Film Magnetoresistive Sensors, IOP Publishing, Bristol, Philadelphia, 2001, ISBN 0750307021.

4. Andreev, S. and P. Dimitrova, "Anisotropic-magnetoresistance integrated sensors," J. Optoelec. Advanced Materials, Vol. 7, No. 1, 199-206, 2005.

5. Dietmayer, K., "Magnetic sensors on the AMR-effect," TM --- Technisches Messen, Vol. 68, No. 6, 269, 2001.
doi:10.1524/teme.2001.68.6.269

6. Adelerhof, D. J. and W. Geven, "New position detectors based on AMR sensors," Sens. Actuators A, Vol. 85, No. 1-3, 48-53, 2000.
doi:10.1016/S0924-4247(00)00341-1

7. Dietmayer, K., "Integrated online diagnosis for AMR-based angular measurement systems," Sens. Actuators A, Vol. 91, No. 1-2, 12-15, 2001.
doi:10.1016/S0924-4247(01)00507-6

8. Ausserlechner, U., "Inaccuracies of giant magneto-resistive angle sensors due to assembly tolerances," IEEE Trans. Magn., Vol. 45, No. 5, 2165-2174, 2009.
doi:10.1109/TMAG.2009.2013712

9. Ausserlechner, U., "The optimum layout for giant magneto-resistive angle sensors," IEEE Sensors Journal, Vol. 10, No. 10, 1571-1582, 2010.
doi:10.1109/JSEN.2010.2040732

10. Arfken, G., Mathematical Methods for Physicists, 3rd Ed., 198-200, San Diego, Academic, CA, 1985.

11. http://cms.hlplanar.de/data-live-planar/docs/pdf/Datasheets USA/MEAS MR.pdf.

12. Hastings, A., The Art of Analog Layout, 231, Prentice Hall, Englewood Cliffs, NJ, 2001.

13. Kolbe, N. and M. Prochaska, "Ueber den einsatz von hochinte-grierten magnetfeldsensoren im antriebsstrang ," Paper 9, 42-46, Automotive Meets Electronics, Dortmund, Germany, April 15-16, 2010, ISBN 978-3-8007-3236-4, VDE VERLAG GMBH Berlin Offenbach.