Arrangement, method and sensor for measuring an absolute angular position using a multi-pole magnet

摘要

Arrangement (1) for measuring an angular position (a) of a rotor (2) with respect to a stator (3), the arrangement comprising a multi-pole magnet (5) mounted on the rotor (2) and a sensor (6) mounted on the stator (3). The sensor comprises a plurality of sensor elements located substantially on a circle (Fig and are organized in two groups for measuring the radial and/or tangential magnetic field component (Br, Bt). The sensor is located substantially centred around the rotation axis and located in a plane (β) substantially perpendicular to the rotation axis. The method for calculating the angular position (a) comprises making a sum of signals of the elements of each group, a ratio of the two sums and an arctan function. The multi-pole magnet may have a central cylindrical opening. The sensor elements may comprise of vertical Hall Effect elements having a plate with a normal that is tangential to the circle. Each sensing element may comprise of a pair of horizontal Hall Effect elements located on the circle adjacent to each other and having plates oriented substantially perpendicular to the rotation axis and IMC segments.