Hello everyone,
I am simulating a four-pole induction machine in ideal no-load condition (slip s = 0) with a transient simulation in FLUX 2D. The supply frequency of the machine is fs = 50 Hz. The rotor rotates at synchronous speed, imposed in the mechanical set (ROTOR).
For the purposes of my analysis, I need to check the waveform of the magnetic flux density at some selected points on both the rotor and the stator core. I have been doing so using the sensors at different locations (teeth, yoke, etc).
Concerning the analyzed points in one period of the supply frequency T = 1/50 = 20 ms (let's assume in the stator and rotor teeth regions):
- In the stator teeth the fundamental frequency of the magnetic flux density B(t) is fs = 50 Hz + higher harmonics due to slotting effect, and this is very clear.
- In the rotor teeth, since s = 0 in ideal no-load condition, the fundamental rotor frequency is expected to be fr = s*fs = 0. So, I was expecting to see that B(t) was a DC component (rotor is magnetized) + higher harmonics due to slotting effect. However, B(t) has a fundamental frequency fr = 25 Hz. The reason is clear: B(t) is not displayed in the rotor coordinate system (which rotates at an electrical frequency of 25 Hz since I have a four pole machine), but in the stator coordinate system (fixed coordinate system). The same happens in case I export (on an Excel file) B(t) at the selected points in the domain.
From the physical point of view this is not correct.
I was wondering whether there may be a way to display/extract B(t) on the rotor referred to the actual rotor coordinate system (rotating system) in an attempt to overcome the issue mentioned above.
Thank you very much in advance.
Marco
