New rotor position detector for permanent magnet synchronous machines using the „inform”︁‐method

A new method for detecting the rotor position of permanent magnet synchronous machines is presented which can be used in any given operating point of the machine including low speed and standstill. The basic idea is to measure the differential inductance in several space phasor directions. Because of the magnetic saturation mainly in the stator teeth, caused by the permanent magnets, the inductance fluctuates to a certain extent. Hence, there is a coherence between the measured inductance and the rotor angular position. By using a special measurement sequence, the influence of the induced voltage due to the rotor velocity can be eliminated. Furthermore it is shown how to integrate the new method in usual control concepts. The practical realization on a digital signal processing system points out the usefulness of the proposed method.