Sinusoidal behavior of a di-pole magnetization for position sensing applications

Magnetic position sensing is based on the measurement of the magnetization pattern of a di-pole, or multipole, magnetic ring using a Hall sensor, which shows the variation of the magnetic field density along the circumference of the ring. The ideal magnetic behavior of the permanent magnet ring has a sinusoidal hall-sensor output, which makes it suitable for sensing applications. However, practical measurements show that the sinusoidal behavior sometimes occurs with errors. This paper describes the investigation of these errors by means of mismatch in the magnetization pattern of the dipole permanent magnet (PM)-ring.