Novel PM-Assisted Synchronous Reluctance Machines Using Asymmetrical Rotor Configuration

Abstract

This paper proposes a novel asymmetrical permanent magnet assisted synchronous reluctance machine (APMA-SynRM) with high cost performance, namely it has the advantages of high torque performance and low cost. This machine has an asymmetrical rotor configuration featured by low-cost ferrite and expensive NdFeB, and two kinds of material are placed asymmetrically on both sides of the 'U'-shaped barriers, which causes the magnet-axis-shift (MAS) effect. Consequently, the proposed APMA-SynRM improves the utilization of the reluctance torque and permanent magnet torque. The influences of permanent magnet volume ratio and hybrid permanent magnet on torque performance are further investigated, and the optimal topologies are designed through a multi-objective genetic algorithm. Moreover, the machine performance of APMA-SynRM is analyzed and compared with that of the conventional permanent magnet assisted synchronous reluctance machine (PMA-SynRM), which confirms that the proposed APMA-SynRM can reduce the cost of permanent magnets but still achieve similar torque and wider constant power speed range performance.