Effects of Rotor Flux Barrier Design on Torque Ripple and High Speed Performance of Synchronous Reluctance Machines

摘要

Synchronous reluctance machines (SynRMs) suffer from high torque ripple, low power factor and poor high speed performance due to their singly excited nature. To overcome these challenges, rotor geometries are optimized to get a low torque ripple and ferrite magnets are inserted in the flux barriers to get a higher power factor and a better high speed performance. This study aims to compare the torque ripple, power factor and high speed performance of machines with different rotor designs that have the same q-axis iron-to-air ratio and flux barrier shape but various spatial iron and air distribution. Only the SynRMs without permanent magnets (PMs) are considered, since PMs can be added to all the designs to further enhance their performances. Firstly, rotor geometries with selected iron and air distributions are individually designed in terms of low torque ripple by using finite element analysis (FEA) models. Then, the torque-speed and power-speed characteristics of the selected designs are compared. It has been shown that the iron and air distributions influence the machine high speed characteristics much more than their maximum torque outputs. Designs with around 20% more power output at maximum speed can be realized only by changing the iron and air distribution within layers. This is a very useful finding in the process of designing SynRMs with a long extended speed range with or without PMs.