A high-performance electric motor without rare-earth magnets for automated ground vehicles

Abstract

With the world's increasing environmental concerns, sustainable energy solutions have received a lot of attention, particularly for electric vehicle (EV). The majority of electric vehicle motors now employ rare-earth elements, which are in short supply. Hence, the objective of this report is to investigate the use of non-rare-earth materials in achieving high-performance levels for AGV applications. This report had highlighted various types of electric motors used in low-speed AGV applications and focus on magnetic geared machines (MGM) that work on the concept of flux modulation. New MGM solutions using non-rare earth material were presented based on the analysis of different rare-earth magnet vernier machines that produce high torque density. The torque density, efficiency, and power factor were then used to evaluate the performance of the motors after they were simulated using JMAG software. The spoke-array PM vernier machine was discovered to have exhibited a high torque density suitable for the direct-drive application. Different gear ratios were used to evaluate the performance of the motor. However, due to the flux barrier effect, the torque performance was limited. To alleviate the flux barrier effect, another interesting option for direct drive use was the spoke-array vernier machine with an alternative flux bridge. The flux bridge may overcome the flux barrier effect discussed in this paper, resulting in an increased torque density. However, the torque performance was reduced to improve the power factor of the machine. Further efforts have been made to improve the torque performance and it was found that the double-spoke array Vernier machine exhibits the highest torque density among its counterparts.