Comprehensive Analysis and Design of a Pulsating Signal Injection-based Position Observer for Sensorless Synchronous Motor Drives

The work focuses on a new mathematical formulation for the transfer function of a pulsating injection-based position observer, as the key point for its correct design. The proposed analysis exploits the modulation/demodulation control theory to derive the transfer function of the whole estimator in the Laplace domain. Magnetic iron saturation effects and cross–saturation between the dq-axes are taken into consideration in the observer design. To test the effectiveness of the new transfer function representation of the observer, it is used to synthesise two different regulators, namely by the direct synthesis and the internal model principle. An extensive experimental stage is included pointing to fully verify the accuracy of the proposed model and the theoretical considerations. A comparison with the existing mathematical model of the observer is also reported to show the improvement achievable in the position estimation by the proposed observer synthesis.