Significant difference between results of AC losses from steady state AC and transient magnetic

Altair Forum User

Dear colleagues,

 

Recently I am investigating the AC losses of a coil region in a PMSM with different rotor speed / frequencies. I started with the application of Steady State AC, where I found that when the speed increases to 10,000 rpm, which corresponds to 833.3 Hz current frequency, the AC losses will increase by about 5 times. After that, I created a similar model in the application of Transent Magnetic, however, this models shows that when the rotor speed reaches 10,000, the AC losses will increase by about 25 times.

 

I am really surprised by the big difference between these two models. I assume that the Transient Magnetic model could take into account the additional AC losses resulting from higher-order harmonics, nevertheless, would they be that much more than the loss caused by the fundamental harmonic?

 

Did I miss something when change the application to Transient Magnetic?

 

Look forward to your suggestions!

 

Best regards,

Yang

lombard

Hello,

Sorry fo rhte delay in this answer. You should have same results for losses in AC and in transient magnetic analysis. I am surprised you can model PMSM in AC as normally when you have magnet you can not use the AC steady state magnetic module. Indeed, in this module we assume all quantities are varying sinusoidally, which is not the case of magnet where you have a DC component. Can you give us more detail on the device you are modeling, and which working point ?

For induction motor, in AC analysis, we do not take into account of the slot effect, as only the rotating flux due to the electric frequency is taken into account. Maybe this is what you are looking at. In this case only the transient analysis will give you the right value.

 

Regards

Patrick