Asynchronous machine incorrect speed plot
3 views (last 30 days)
I have made a simple model for an Induction Motor. I've used its constants (stator's and rotor's impedance and resistance etc) that I've found at its datasheet. I was expecting to find its Nominal Speed (around 4400 rpm with 2 pairs of poles at 150Hz), but instead I find this strange plot. At the beginning, it seems like the speed is indeed around 4400, but it starts decreasing until it hits 0 and I cant understand why.
During the simulation shown at the photo I was using Rotor Type: Squirrel Cage, Reference Frame: Rotor and Mechanical Power (at "Load Flow") = 6000W
Steps that didn't solve the problem:
-Change the voltage between 51V, 51*sqrt(2)V and 51*sqrt(2)/sqrt(3)V
-Change the slip between 0.0267, 0 and 1
-Change the reference frame between Rotor, Stationary and Synchronous
-Add an input at Tm
-Change the solver information between ode15, ode23 and ode45
Graham Dudgeon on 27 Apr 2021
The speed reduces as you have a friction factor of 0.05479 on your motor shaft that is not compensated for by an input torque. Connect a constant block to 'Tm' and set the value to -150*2*pi*(1-0.0267)*0.05479/2.