Cogging Torque Reduction of 6/13 Hybrid Excited Flux Switching Machine with Rotor Step Skewing

Abstract

Hybrid excited flux switching machines (HEFSM) are appropriate candidates for hybrid electric vehicles (HEV) application owing to their high torque/power density, robust rotor structure as well as flux weakening capability by DC excitation windings. However they exhibit relatively high cogging torque due to their high air-gap flux density and their doubly salient structure which is a major problem of employing HEFSM in HEVs application; hence the cogging torque reduction is a required approach in HEFSM design. Due to the relatively simple rotor structure of HEFSM in comparison with stator structure, optimal rotor design techniques are much more preferable to reduce the cogging torque and torque ripple of flux switching machine. In this paper, the rotor step skewing method is employed to reduce cogging torque and torque ripple of 6/13 HEFSM. In order to evaluate the effectiveness of the employed method finite element analysis is employed.