Abstract: This paper has proposed a 48/36 multiplicity SRM for a direct-drive rotary table of turn-milling machine tools which requires high torque, minimum torque ripple in milling mode and a wide constant power speed range in turning mode. Generally, rotary tables have a rotor with a large outside diameter to improve their torque output capability, hence a SRM with multiplicity topology is appropriate for such applications. However the design of multiplicity SRMs is not methodical yet. Thus a design methodology of multiplicity SRMs based on theoretical and finite-element analysis has been established and a method of estimating the number of turns based on the supply voltage and the rated speed has been proposed. The static and dynamic characteristics of the proposed SRM are achieved by the finite-element method and a reasonable selection of the stator and rotor pole arc is fulfilled in compromise to satisfy the requirements of high torque, minimum torque ripple and a wide constant power speed range simultaneously. Besides, the dynamic simulation has validated the method of estimating the number of turns. Finally, flux linkage and torque static measurement have been carried out. The results show there a satisfactory agreement between the experimental measurement and finite element analysis results, thus validating the designed motor’s static performance.
