Efficiency Improvement of Permanent-magnet Synchronous Motor Drives for Household Appliances

This paper deals with some aspects of efficiency improvement of PMSMD (Permanent Magnet Synchronous Motor Drives). Particularly two aspects are focused: the control algorithm for the PMSMD, which allows to reduce the power losses of the electric drive without penalty on its dynamic performances and the optimization of an IPMSM (Interior Permanent Magnet Synchronous Motor) rotor configuration capable to increase the performances in terms of shaft torque production, limiting at the same time the rotor leakage flux. The loss minimization algorithm is here briefly analysed, a test bed for experimental validation is presented and the data are analysed. Experimental tests have been performed aiming to validate the actual implementation. The main results of these tests confirm that the dynamic performances of the drive are maintained, and enhancement up to 3.5% of the efficiency can be reached in comparison to the PMSM drive equipped with a more traditional control strategy. Moreover an IPMSM rotor design is proposed in order to improve more and more the PMSMD efficiency. As a matter of fact it allows a reduction in PM material quantity of about 25% compared to a tangential IPMSM one with the same dimension and weight, together with an increase of the motoring torque of about 50%. Some simulation carried out by using a FEM software and a comparative analysis with a traditional IPMSMs rotor configuration shows that a significant improvement of the PMSMD can be achieved with limited changes in the motor geometry and with the choice of a suited control algorithm