Position detector
A method for determining the position of a rotor in an electronically commuted motor. The method comprises the steps of calculating the rotation angle using three Hall-sensors; identifying and correcting phase errors; and determining and correcting cyclic errors.
1. A method for determining the position of a rotor in an electronically commuted motor, comprising the steps of
bringing the rotor of a new or successful maintained motor to a speed using a constant motor voltage for obtaining a precise concentricity;
measuring deviations of actually measured positions from an ideal straight line using three Hall-sensors for obtaining sinus signals
calculating the rotation angle by using a Clarke transformation for converting the three sinus signals, which are constantly checked for their minimums and maximums, from the Hall-sensors into a rotation angle;
identifying and correcting phase errors;
determining and correcting cyclic errors.
2. The method of claim 1 , using sinus signals from three Hall-sensors that are shifted by 120°.
3. The method of claim 1 , wherein the signals from the Hall-sensors are constantly checked for normalizing them.
4. The method of claim 1 , wherein signal peak outliners are removed, and an average value is formed from the remaining maximal values.
5. The method of claim 1 , wherein a factor calculated from a phase-offset per phase is used for correcting sinusoidal position errors per phase.
6. The method of claim 1 , wherein the position of the rotor is determined and stored cyclically at equidistant time intervals.
7. The method of claim 1 , wherein a calibration is carried out in error-free condition, in a new condition or after a maintenance.
8. The method of claim 1 , wherein the measured deviation of the actually measured positions from an ideal straight line is directly measured and assigned to a rotation angle.