Design of Hybrid Excited Asymmetric-Stator-Pole Doubly Salient Machine

Abstract

Doubly salient permanent magnet machine (DSPMM) enjoys the advantages of high torque density, simple rotor structure, high reliability, etc. However, the air-gap flux density is difficult to regulate due to that the air-gap magnetic field is produced only by permanent magnets (PMs). Thus, this paper proposes a hybrid excited asymmetric-stator-pole doubly salient machine (HE-ASPDSM) and its air-gap flux density can be regulated easily by controlling the excitation current of field winding. The topologies and operation principle of the HE-ASPDSM are studied firstly based on modern winding theory and two-dimension finite element analysis (2D FEA). Then, the comparison of no-load flux linkage, back electric magnetomotive force (EMF) and air-gap flux density of different topologies is made. Besides, the expression and harmonic components of airgap flux density are also derived based on mathematical analysis. And then, the influence of key design parameters on the cogging torque, flux regulation ability, electromagnetic torque, losses and efficiency is investigated in details. Finally, the analysis of main performance indexes is performed based on the proposed 12/7 (stator/rotor poles) HE-ASPDSM. It indicates that the proposed 12/7 HE-ASPDSM has strong air-gap flux regulation ability.