Analysis of ferrite based PMSM with field strengthening ability

Abstract

Abstract This thesis focuses on building a FI-PMSM equipped with ferrite magnets. This machine has flux barriers in the rotor design that make the inductance in direct axis greater than the quadrature axis, making the machine to operate primarily in the first quadrant. Further, when the machine enters field weakening operation, the usage of negative d axis current is lower compared to a conventional IPMSM. Theoretically, the working is well suited for a ferrite magnet as there is a lower risk for the magnet to be demagnetised. Firstly, an FI-PMSM was designed, similar to the one described in a reference paper, to gain a deeper understanding of the machine. As a second step, an IPMSM from a reference paper was selected as a benchmark machine, and the FI-PMSM was scaled to match the dimensions of this motor. After confirming that the machine operated well in its whole operating region, the magnets were replaced with ferrite magnets, and their performance was tested. Subsequently, different rotor designs were explored and tested for performance. After the theoretical design of the FI-PMSM equipped with ferrite magnets, it was compared with an FI-PMSM equipped with rare-earth magnets, as well as a conventional V-shape IPMSM using ferrite magnets. A comprehensive study was conducted on efficiency, performance, and demagnetization. It was observed that the risk of demagnetization was higher in the FI-PMSM compared to the V-shape IPMSM. Additionally, the V-shape IPMSM equipped with ferrite magnets was found to have similar torque performance to the FI-PMSM equipped with neodymium magnets. However, the FI-PMSM equipped with ferrite magnets demonstrated higher efficiency in the high-speed, low-torque region compared to the V-shape IPMSM.