METHOD FOR CONTACTLESSLY DETERMINING THE POSITION OF A DRIVEN ROTOR OF AN ELECTRIC MOTOR, ELECTRIC MOTOR, AND PIPETTING SYSTEM FOR ASPIRATING AND DISPENSING PIPETTING LIQUID HAVING SUCH AN ELECTRIC MOTOR

摘要

A method for contactlessly determining the position of a driven rotor (4) of an electric motor (2) by means of a plurality of magnetic field sensors (8) is provided, wherein the rotor is movably arranged with respect to a stator (6) and has a plurality of permanent magnets (40) which generate a rotor magnetic field having a plurality of maxima which are periodically spaced apart, and wherein the plurality of magnetic field sensors are arranged along a movement path (43) of the rotor. The method has the following steps of: by means of the plurality of magnetic field sensors, determining a plurality of measured values (70) for an instantaneous magnetic field which is dependent on the position of the rotor and is generated by the plurality of permanent magnets; determining a specific spectral signal component (74) from the plurality of measured values, wherein the specific spectral signal component has that spatial frequency which corresponds to the distance between adjacent identical maxima of the rotor magnetic field; and determining the position of the driven rotor by means of the specific spectral signal component.