Speed as Perturbation in Anisotropy Based Sensorless Control Methods

A simplified high-frequency model of the electric machine is usually assumed for designing sensorless control methods based on the magnetic anisotropy. This simplified model enables the derivation of simple but robust methods that are reliable up to the nearby of the rated speed. However, the estimation error increases with the speed due to the neglected terms in the model. The actual increase of the error depends on some key parameters such as the frequency of the carrier signal. In this study, a sensorless control method for PM synchronous machines is investigated considering the complete model. In this way the validity and limits of the simplified model are assessed. The aim is to lay the theoretical foundation for choosing the parameters or the structure estimation method for reducing the error.