control methods for AC motor drives

On the other hand, if I actually tried this I would probably exceed the thermal limitations of the hamster.

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Tom, thanks for giving me a laugh and an education at the same time. Your wit puts a smile on my face at least once a week.
Paul C.

Dick can confirm or deny this, but I believe that modern field oriented control drive will try to maintain a constant rotor flux level and a constant 90 degree stator to rotor flux vector angle from 0 to base speed. Above that point I think the drive simply reduces the rotor flux vector length in order to reduce the back EMF for a given stator current level. I think you can do the same thing with the stator flux vector.

But what if you kept the stator and rotor flux vector lengths constant and decrease the vector angle? In this case back EMF would decrease along with torque and you can go faster, the typical action of operation above base speed. But now, let's increase the stator flux vector length by increasing the torque producing current component. This would increase the torque above base speed. But it would also increase motor heating. This would work right up until you hit the drive current limit or you magnetically saturate the stator.

The reason for this speech is that there is a way to overtorque an AC motor above base speed without necessarily violating any of the electronic drive constraints. You will just cook the motor before too long doing it.

Keith