Investigation of current harmonics using FEM on different rotor types of PMSMs

Current harmonics of the permanent magnet synchronous motors (PMSMs) varies with the shaft structures. These harmonics produce additional loses at both windings and the core of a PMSM and increase the temperature inside the machine. Such a temperature increase affects the machine parameters and the efficiency. Therefore, in order to obtain the optimum operating conditions of a PMSM, current harmonics should be analyzed. In the present study, two types of rotors for a PMSM have been simulated and evaluated with a current controlled voltage source inverter (VSI) by the help of a 3D finite element method. As a result of these simulations, motor current harmonics are examined by using the Hamming method at different modulation frequencies and the outputs of efficiencies, torques, powers and the induced voltages on windings are compared for these shaft structures. It has been proven that the current ripples and harmonics may be decreased to some extend by using a symmetrical structure among the proposed structures.