50Hz 3-Phase 2-Pole Induction Motor Stalling Above 80Hz on VFD at 400Hz 415V

I want to run a 50hz 3phase 2 pole induction motor at 24000rpm. For that I'm using a vfd which is set to output 400hz at 415v. Problem is whenever i go above 80hz the motor stalls. I don't care about the torque right now. I just need 24000 rpm from this motor. Please suggest what might be wrong? 

I suspect that the motor you have is just not capable of spinning that fast. You need a motor that is rated to operate at the speed you desire. Alternatively, you could add gears to increase the speed of the output.

Thanks for the suggestion but gears make a hell lot of noise and maintenance is a big headache for me. This motor is a 2 pole motor and according to theory this motor will achieve 24000rpm at 400hz with reduced torque (1/8). There are a lot of videos on youtube of people doing this modification with their motors using vfd. By increasing the torque, i was able to get it 250hz. But after that motor stalls again. 

Is your VFD rated to run at 400 Hz?  Is it a Field Oriented Controller (FOC) of just a constant V/Hz type controller?  I suspect that torque losses in the motor are increasing so much that the induced field and resulting torque is not enough to keep up with them.  Or, the inductance of the stator is such that the current through the stator dwindles too much at the higher frequency to generate enough torque to overcome losses.  I think the latter would be the case if yours is a simple V/Hz type controller.  A FOC, when configured properly, will inherently compensate for the effect of inductance because it actively controls the magnetic field vector to be in the proper angle orientation to the induced stator field (which it has to estimate based on parameters of the motor and shaft angle (sensed or estimated).  My experience is mostly with driving permanent magnet AC (synchronous) motors so someone here with more experience driving induction motors may be able to provide a better answer.Best.  -JD