Sensorless field- oriented control for permanent magnet synchronous machines with an arbitrary injection scheme and direct angle calculation

In this paper a saliency based sensorless control method is proposed that does not rely on a certain form of injection. The underlying idea is that the saliency angle information can be obtained by comparing the real machine behavior with an isotropic machine model. The difference between the measured currents and the calculated model currents then provides the information of the rotor position. Moreover it is shown that the isotropic machine model, and thus the entire sensorless method, can be kept free of machine parameters by choosing an injection scheme with equal spacial distribution.