Comparison of permanent magnet synchronous motor and synchronous reluctance motor based on their torque per unit volume

The paper deals with comparative analysis and equivalence determination of the brushless synchronous motors based on their torque per unit volume in power range from 1 kW to 2.5 kW. Novel designs of external-rotor surface-mounted permanent magnet synchronous motors and external-rotor synchronous reluctance motor are analyzed in the comparative study. Two types of the permanent magnets are analyzed with the use in surface-mounted permanent magnet synchronous motor: ferrite magnets and neodymium magnets. The optimal designs of studied motors are found for correct comparison with the help of synthesized analytical relationships between torque per unit volume and main dimensions of the motor magnetic circuit (also known as metamodels). The calculation of studied motor torque is based on the results obtained with numerical calculations of the motor magnetic field. Comparative analysis shows that permanent magnets do not significantly reduce dimensions of the motor in comparison with studied synchronous reluctance motor in the considered power range.