Dear All,
I have read in the Generalized Theory of Electric Machines book by P.S. Bimbhara that the speed voltage in the rotor d-axis winding of Kron's primitive machine model is dependent on the rotor q-axis flux, but it does not exactly appear as the mutual inductance. There is defined a term named rotational or motional inductance which is known to be different from the transformer mutual coupling (However, Professor Bimbhara mentions that the difference is not of practical importance). Could somebody please kindly explain where this difference merges from?
Thanks a lot in advance.
Electric current follow low resistance path, similarly magnetic flux follow low reluctance path. Flux produced by field will mainly follow direct axis path (low reluctance path due to smaller air gap) and will only be responsible to produce EMF/TORQUE, when the salient pole machine work as Alternator/Synchronous motor. The quadrature axis (high reluctance path due to larger air gap) flux can considered only as leakage flux( not useful flux). Using slip test method, you can find Xd and Xq (Xd=Vmin/Imax, and Xq=Vmax/Imin) of given machine. Happy to hear the name of my Ph D, partner at IIT Roorkee.
Kron's primitive machine model, represent change in Xd and Xq offered by the machine in working. In working the direct axis flux will enhance and leakage flux will reduced, but not with considerable effect in salient pole machine, which will not be the case, with round rotor..
Dear Professor
Thanks a lot for your response. I should however remind that by the Kron's machine, I did not mean the model related to any specific machine, as the synchronous machine you described. I wanted to know why in the relations for Vdr and Vqr expressed in Bimbhara's book, the speed voltage terms (does having wr and not have the time derivatime (p) term) have an approximation if they are expressed by the mutual inductances. Professor Bimbhara says that they are motional inductances and are only equal to mutual inductances as an approximation.
Better talk, with Bimbhara, at Elect. Engg. Deptt. 'Thaper Institue of Technology, Patalia., Punjab., India. or will get contact phone, as may around '70.
Thanks a lot. Do you have his telephone number or email address?
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