HI, The inductance calculation via the flux method has errors due the calculation of this flux. The energy method is more exactly due the methodology used in FE method. Energy = (m/2)*L*I^2 m: number of phases L: inductance I: current RMS value! Steps on inductance determination: 1) aply set of current to produce a direct field (file: 00-36.fem) 2) calculate the energy in the gap. 3) Ld = Energy/((m/2)*I^2) 4) aply set of current to produce a quadrature field or rotate the rotor 180/(2p) (file: 45-36.fem) 5) calculate the energy in the gap. 6) Lq = Energy/((m/2)*I^2) the model attached: synchronous machine; S = 6 kVA; m = 3; V = 220 V; 2p = 4; nominal current (RMS value): I = 15.75 A; number of conductors/(slot&layer): 6. Bye. Ramon Bargallo Director U.E. d'Electricitat E.U.E.T.I.B. C/Urgell, 187 08036 Barcelona Tel.(34) 934137411 Fax.(34) 934137401 Ramon.Bargallo@xxxxxx -----Mensaje original----- De: raymondong66 <raymond.ong@xxxxxxxxxxxx> [mailto:raymond.ong@xxxxxxxxxxxx] Enviado el: domingo, 19 de enero de 2003 3:42 Para: femm@xxxxxxxxxxxxxxx Asunto: [femm] Inductance variation with rotor position in permanent magnet machine Hello: I am interested in calculating d axis inductance and q_axis inductance in permanet magnet rotating machine and their variation using finite element method. I am wondering whether anybody had done such calculation and I would like to hear from anyone on this subject. I have used commercial FE package and use transformation method of phase inductance to d and q axis inductance, stored energy method and flux linkage method and each of them provide different answer. Any opnion why these are so? Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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