Design of a high speed interior claw synchronous reluctance machine

Abstract

Synchronous reluctance machine (SynRM) is one of the candidates of highspeed application drives. The rotor of this machine, as the most important and most challenging part of the design, has various tangential and radial ribs. Therefore, the quantity, thickness and length of the ribs are significant SynRM design parameters. If ribs' thickness is increased in order to enhance the mechanical robustness, its magnetic properties will be substantially deteriorated and vice versa. In this paper, by employing interior claws, a new rotor for SynRM is designed in a way that while increasing the mechanical robustness of the rotor for high speeds application, its magnetic characteristics enhanced, too. For this purpose, the proposed design method is applied on a two-flux barrier rotor of a 24 stator slot SynRM. The designed machine electromagnetic performance is evaluated by finite elements method (FEM) simulation and compared with other designs. Also, the mechanical strength of the proposed rotor with two alternative claws for the speeds up to 50krpm are evaluated and confirmed by structural FE analysis. At the end, the designed interior claw rotor is prototyped and tested. Prototyped SynRM magnetic characteristics that are extracted by experiment confirmed simulations results with acceptable accuracy. K E Y W O R D S flux barrier, flux carrier, interior claw, strain, yield stress List of Symbols and Abbreviations: k wq , Total width flux barrier to total flux carrier ratio; W bi , Width i-th flux barrier; C i , Width i-th flux carrier; N b , Number of flux barrier in the rotor per pole; N c , Number of flux carrier in the rotor per pole; P, Machine's pole pair number; I, Current (A); f qbi , Average mmf of each (i-th) flux barrier along with the q-axis; α 1 , Rotor slot pitch angle (mechanical); f q , q-axis component of the stator mmf (fundamental amplitude in per unit); n s , Machine's slot stator number; Δf qi , Differential average mmf over the each (i-th) barrier; D sh , Shaft diameter; α 2 , The end of final flux barrier angle (mechanical) to q-axis; N bi , i-th flux barrier; f dci , Average mmf of each (i-th) flux carrier along with the d-axis; f d , d-axis component of the stator mmf (fundamental amplitude in per unit); L d , d-axis inductance; L q , q-axis inductance; TR x , Thickness of tangential rib (mm); RR x , Thickness of radial rib (mm); T av , Average Torque (Nm); σ yield , Yield strength of core laminate; σ calc , Calculated maximum stress by FEM; W core , Width of core laminate; ΔT, Torque ripple; ω, Angular speed (mechanical); R so , Rotor slot opening (mm); F c , Centrifugal force over the each flux carrier; V, Velocity of rotor outer surface (m/s); m c , Mass of flux carrier; R c , Radius of center of gravity of flux carrier; S so , Stator slot opening (mm); D r , Rotor outer diameter; k, Factor of safety; n max , Maximum speed; n calc , Calculated speed by FEM; ξ, saliency ratio; SynRM, Synchronous Reluctance Machine; FEM, finite elements method; IM, induction machines; PMSM, permanent magnet synchr...