Motion Setup in Maxwell transient simulation

- January 25, 2019 at 4:59 pm
  
  AmirKrz
  Subscriber
  
  Hello everybody
  
  I'm simulating a 2 pole conventional induction motor connected to 220V 50Hz single phase source with Maxwell 2D transient tool .
  
  I want the simulation to include mechanical transient as well. So in the motion setup window, I set the "Initial Angular Velocity" equal to zero and change the "Load Torque" from [if(speed<152.11, -0.0232804*speed, -538.647/speed)] to 1.6 Nm (as I get from RMxprt simulation). "Moment of Inertia" and "Damping" is calculated by Maxwell .like attached photo.
  
  After simulation is completed I get Speed-Time graph that is attached.
  
  obviously it can be observed that the rotor speed reaches the synchronous speed while it is impossible in case of induction motor. It was expected the speed peaks at around 2900 rpm according to Rmxprt simulation.
  
  So what is the problem?
  
  and what is this [ if(speed<152.11, -0.0232804*speed, -538.647/speed) ] mean? (that is substituted to "Load Torque" field by Maxwell)
  
  Thank you so much
- January 31, 2019 at 5:20 pm
  
  Dennis Steward
  Ansys Employee
  
  Hi AmirKrz,
  
  Try entering -1.6Nm for the load torque. Maxwell expects a negative value here.
  
  The conditional expression that RMxprt adds for the load is such that the load is smaller at lower speeds so that the motor can start, and then it increases linearly with speed up to the operating point that RMxprt computed.
  
  If you divide -538.647 by the rated speed (in rad/s) computed by RMxprt, I'll bet that the result is close to -1.6Nm
  
  Take Care,
  
  Dennis