Comparative Study of Dual- and Single-Rotor Radial-Flux Fractional-Slot PM Machines

Abstract

This paper presents a comparative analysis of electromagnetic performance of radial flux dual-rotor surface-mounted permanent magnet (SPM) machines with fractional slot non-overlapping windings, with reference to external- and internal-rotor SPM machines. All machines are optimised by genetic algorithm using finite element analysis under various design optimisation scenarios, together with the equivalent magnetic circuit analysis. In addition, the influence of air gap length, PM volume, machine inner bore radius, and pole number is investigated. The results have revealed that the dual rotor SPM machine has lower torque but higher overload capability than the single rotor SPM machines, as confirmed by experimental results.

Keywords

• Dual-rotor
• fractional slot
• permanent magnet machine
• segmented armature
• single rotor
• yokeless