Comparison of Synchronous Motors With Different Permanent Magnet and Winding Types

Multipolar Ferrite-Assisted Synchronous Reluctance Machines: A General Design Approach

“…NOMENCLATURE fqk per-unit k-th step of the stator mmf distribution (differential value)  regular "rotor" pitch k rotor "slot" pitch F stator mmf (peak value) 0 power factor angle in case of "Natural Compensation" F q peak value of the q-axis stator mmf f qk per-unit k-th step of the stator mmf distribution (absolute value)  rib,k k-th magnetic rib mmf g airgap length I current vector amplitude (peak value) Iq0 characteristic current kCu slot filling factor k end end-winding factor k i specific iron loss k j specific Joule loss k j,block specific Joule loss (rectified pole model) kj+i sum of specific Joule and iron loss krib per-unit length of the k-th magnetic rib k sat coefficient that quantifies the magnetic saturation (d-axis) k sh shortening factor k t stator width factor ktip slot leakage inductance increase for tooth tip kw winding factor l active stack length l a rotor magnetic insulation (sum of l k ) lapu normalized rotor magnetic insulation (=la/(a/2)) Lbase base value for inductance normalization l k flux barrer length l m PM flux linkage L m,q magnetizing q-axis inductance Lq q-axis inductance Lq,pu normalized q-axis inductance L ,slot slot leakage inductance lt stator teeth length ly yoke height L zz,q q-axis zig-zag inductance m k k-th magnet mmf m k * equivalent mmf ferrite magnet + magnetic ribs n number of rotor flux barriers N number of conductors per slots n m mechanical speed n r number of rotor "slots" per pole pair pbk k-th magnet permeance pbk* equivalent permeance ferrite magnet + magnetic ribs pg airgap rotor teeth permeance p rib,k k-th magnetic rib permeance q slots/pole/phase r stator outer radius r' rotor radius  cu copper resistivity rk magnetic potential of the k-th rotor iron segment ermanent Magnet (PM) machines are the most performing electric actuators, in terms of torque density and efficiency, since the adoption of rare-earth magnets, which offer large energy products and ideal recoil characteristics over wide ranges of temperatures. However, the price volatility of these materials has been compelling designers of electric motors to test alternative solutions, using no PMs [1][2], a reduced amount of rare-earth PMs [3][4], or lower energy density PMs, such as hard ferrites [5][6][7][8][9][10][11][12][13].The mere substitution of high energy magnets with ferrite ones into standard Surface-mounted PM (SPM) and Interior PM (IPM) rotor configurations cannot lead to satisfactory designs [6][7], IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS since both SPM and IPM motors mainly rely on Nd-or Sm-based materials for their high performance [14][15]. A more effective way [8][9]…”

Design and analysis of a highly integrated 9-phase drivetrain for EV applications

“…Hence it is necessary to derive rotor designs with a larger amount of magnets to achieve a performance level equal to conventional NdFeB ones [22], [23], [24], [26]. This became a challenging part since neither the magnets nor the electrical steel sheets are characterized by high mechanical strengths.…”

“…Hard ferrites turned out to be a possible alternative, especially with the development from some manufacturers of high performance LantaniumCobalt-doped ferrites [7]. Depending on the application, rare earth magnets can be replaced by using an adequate motor topology based on ferrite magnets [8], [9], [10]. However a suchlike highspeed traction drive rotor design with ferrite magnets differes significantly in terms of the mechanical design and thus needs to be carefully investigated.…”

Characteristics Explorati on of NIiCuZn Nano-Composite coated Permanent Magnets

“…The main purpose of the rare earth free electric machines is to reach almost the same torque density as in commercially available neodymium PMSMs, without efficiency deterioration. Major part of these attempts is done for hybrid electric vehicle applications [20][21][22][23][24][25][26][27]. Common measures in order to increase the power density of PMSMs are high angular speeds [28], increase the number of pole pairs and increasing the tangential stress [29].…”