I'm looking to measure the torque or slip angle on an AC induction (asynchronous) servo motor given the current induced in one of its phases. The servo and drive is yaskawa. Example data is shown above, the scale is in bit count from and ADC in a microcontroller. The picture shows a rapid movement.
I assume there isn't enough information given to calculate this? I've actually got access to two of the three phases in the servo motor sampled at 1000Hz.
My research so far has shown that torque can only be calculated if given the slip angle (or frequency?). However I've added a load to the servo and can see the average RMS current increase. This RMS value is taken for every 128 samples. Does this increase because the servo drive control loop increases the current to reduce the slip angle?
I've also found a rated motor-torque constant, does this apply for all motor speeds?
Thanks for your time!