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.

To put this into context, the electrical speed of 4500Hz implies that a 2pole brushless motor would have reached a mind blowing speed of 270,000RPM.

The SC-120R servo drive accomplishes this under Field Oriented Control (FOC).

A Servosila SC-60R servo drive starts up a 61cc piston engine.

It takes 70A phase current at 6S input voltage to start up this engine reliably.

#Kudos to V.Rutkovski

In case you have not heard how a motor spinning 1500 times a second sounds like, here it is! A fearless support engineer recorded a follow-up demo using a Servosila SC-120R servo drive. This time no payload is attached to the motor to preserve the sound.

In this demo, a little 6-pole motor spins 1500 times a second, which is 90,000RPM, which is 4,500 electrical Hz, which is 270,000eRPM. This is achieved under Sensorless Field Oriented Control (FOC).

The rotor accumulates so much kinetic energy, that it then charges the servo drive's mighty DC-link capacitors from 10V to nearly 70V, while decelerating to a stop.

The clean 1500Hz tone produced by the spinning motor reminds of the video games from 90's.

Wishing you an exciting and prosperous 2026!

Happy New Year!

An interesting gyro-stabilized remotely-controlled weapon station (RCWS) on display at UMEX 2026 in Abu-Dhabi.

A 2-stroke 116cc piston engine is started up by a Servosila SC-60R servo drive.

#Kudos to V.Rutkovski