Sensorless Wide Speed Range Position Estimation Method for Permanent Magnet Synchronous Machines

Flux linkage based sensorless position estimation methods for permanent magnet synchronous machines (PMSM) use integrators to obtain the flux linkage signal. However, these integrators can cause steady-state errors (offsets) in the estimated flux linkage signals. In this paper, a new method to eliminate these offsets will be presented. The offsets in the reconstructed flux linkage signals are identified by means of a geometry-based least squares method, allowing them to be compensated using a feedback loop. This new method can be applied in situations when the rotor movement is severely confined and includes speed reversal. This is of particular interest for PMSM-based linear actuators and other applications with small stroke.