Replacing SPM by PMAREL machines in low-speed high-torque applications

The aim of this paper is to evaluate alternatives to Surface-mounted Permanent Magnet (SPM) machines in low-speed high-torque applications, such as elevator systems, grindstones and positioning systems, where the electrical motor is directly connected to the load. In particular, the potentiality of PM-Assisted Reluctance (PMAREL) machines is deeply investigated. The capability of an SPM motor (adopting either NdFeB or Ferrite magnets) is compared with those of PMAREL motors employing Ferrite magnets. Different solutions are considered, varying the number of slots and poles, taking into account both distributed and fractional-slot winding. The analysis highlights the satisfactory performance of the PMAREL motors with distributed winding. On the contrary, the configurations with fractional-slot winding exhibit worse torque quality, even though different results are found according to the machine periodicity.