The upcoming SC-120R servo drive has a maximum rated speed of 3kHz, which is the maximum electrical frequency it is designed to operate at. It turned out it can go way beyond that, to 4.5kHz and above.

In the lab, we've got an interesting little turbine motor with KV14000. This KV means that at 6V input the motor reaches 84000RPM. A well-known challenge with such motors is that their inductance is very small. This complicates sensorless control.

The motor has a current limit of 20A and has 6 poles.

So, we hooked the turbine to an SC-120R and easily reached 88000RPM or 4400Hz. We ran the demo at 9.5V input.

It was nice that the SC-120R had done a fully automatic system identification, and the entire demo "just worked right". The SC-120R operated at 85kHz PWM frequency.

At the end of the video, a step response test was ran, when the commanded speed was switched from -4500Hz to +4500Hz and back in a loop. The SC-120R remained in full control of the motor during the test.