Synthesis of dimensionless indexes for IPM machine in variable speed operations

Interior permanent magnet (IPM) electric machine is not a pure PM machine but a mixture of permanent magnet and synchronous reluctance electric machines. As a mixed electric machine, an IPM machine has two components to consider based on many parameters. Synthesis of new dimensionless indexes based on machine parameters is proposed. It is to shown that the new pair of dimensionless indexes, chi and xi can be defined and better used for IPM machine design. Different from published work, not only can chi and xi determine the IPM torque and speed capabilities but also directly relate to Constant Power Speed Ratio (CPSR). Derivation of the new pair of dimensionless indexes is presented along with the application of the new dimensionless indexes in an example IPM design.