I am using FEMM to see how the losses in a motor change when different soft magnetic materials are used for the stator/rotor laminations. My simulation showed that the no-load losses (hysteresis, eddy current losses) were 3-4 orders of magnitude lower than the resistive losses. This result surprised me quite a bit since I've heard no-load losses make up such a significant portion of losses in transformers, for instance.
The two materials I am comparing are M27 Silicon iron and metglas 2605. The metglas alloy had ~40% lower no-load losses in the stator than the M27 steel laminations. I'm surprised as to why these losses, for both materials, made up such a small portion of the total stator losses.
I have very little experience with power engineering or motors, and want to know whether no-load losses in motors are supposed to be small compared to the winding/resistive losses. I should note that I have not input any boundary conditions to account for the skin effect.
Iron loss for, induction machine, consist of Hysteresis loss,and eddy current loss(at constant flux density(v/f=constant) Wi =Wh+We= Af+B(f)(f) OR Wi/f=A+Bf, where f is frequency of supply voltage, and A and B are constants). the constant A depends on the area of hysteresis loop, obtained on B/H curve of core material used(higher the area, more is the loss), constant B depends stamping thickness,and flux linking to stamping(Hence thinner the stamping, less would be eddy current loss as eddy current in stamping, reduceses.)
Wi/f=Af+B is strait line equation y=mx+c, hence running induction motor at no load,at different supply frequency,then subtract friction windage loss, from consumed watt at no load,the value would be Wi for given motor.Plot f to Wi/f graph slop would be A, and intesection on y axis is B value for the given motor, thus can saperate the Wh and We from Wi, and can do the study of Wh for the core material used and, We(eddy current loss)for stamping shape and thickness.
copper loss is a winding loss,depend on winding resistance(Wc=(I)(I)R),I the current,R the resistance of winding)
Thank you for your help. I want to know the following though: how does the magnitude of iron losses compare to those of winding losses in an induction machine in general? I am doing my simulation on a three-phase machine at 60 Hz supply frequency (10 Hz slip frequency) and inputing a current of 10*sqrt(2) A.Given these conditions, does it seem reasonable to you for the iron losses to be nearly 3-4 orders of magnitude smaller than the resistive losses?
If you are familiar with FEMM, I used mo_blockintegral() method over the area of the stator to compute the lamination/iron losses(Wi) and resistive losses. I am also not certain whether these resistive losses are referring to the winding losses Wc or to something else. I've attached a brief summary of the results.
Copper loss is resistive loss, in induction motor, as mechanical load increases, slip increases(S),rotor voltage(SE2), and hence rotor current increase, which reflect on primary(stator)to increase stator current, or can say as torque increase, more current will draw by motor(primary).Hence with almost same iron loss, the negligible copper loss at no load, has increased to 15to 20 times at full load, From your result the stator resistive and rotor resistive loss can be called as, stator and rotor copper loss. Result may be for full load, motor ratings. .
- Badges
- Science topic
- Similar topics
- Engineering
- Electrical Engineering