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This paper presents a novel design concept for Synchronous Reluctance (SynRel) machines aimed at reducing the torque ripple. Two general sizing approaches based on the homothetic scaling principle are defined and compared. An in depth analysis on the torque ripple, for a wide range of scaled geometries, evaluated by finite element, has been carried out at different operating conditions. A further analysis is performed on 4 scaled geometries that have been optimized starting from 4 random rotor geometries. It is shown that the main rotor geometrical variables converge to similar values for all scaled machines. The accuracy of the proposed model is then validated by comparing the FE simulated torque ripple waveforms with the experimental data carried out, for a range of operating conditions, on a machine prototype. The outcome of this work is a fast and accurate scaling technique for the preliminary design of SynRel machines with reduced torque ripple. [ABSTRACT FROM AUTHOR]

This paper presents a direct power control strategy for a variable speed axial flux permanent magnet synchronous generator. The method consists on calculating the instantaneous power by measuring the machine currents and estimating the back electromotive force (back-emf). The real-time back-emf estimation is based on tracking the no-load voltage through off-line harmonic analysis, and the mechanical position and speed, obtained with an incremental encoder. A 3 kW laboratory prototype has been built to verify the performance of the proposed strategy. Experimental results are shown and discussed. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for the analytical computation of the slot leakage inductance of tooth-coil winding permanent magnet synchronous machines. Generalized equations for the slot leakage inductance of the whole phase are derived, suitable for several slot-pole combinations, and meant to be used during the machine design stage. For simplicity, self- and mutual-inductance components are formulated using the classical method with detailed permeance determination for both horizontal and vertical distribution of coil sides in the slots, considering a straight-line path for the flux leakage. Several slot-pole combinations were simulated by means of the finite element (FE) method in order to validate the analytical equations in both approaches, FE and analytical, showing adequate concordance. [ABSTRACT FROM AUTHOR]