Enhanced AC servomotors include battery-free absolute encoders
17 March 2025 
Nidec Instruments has announced a new range of high-accuracy AC servomotors with battery-free magnetic absolute encoders, as well as other enhancements including higher peak and cogging torques, top speeds and levels of ingress protection.
The new S-Flag Dynamic Motion MB series motors have evolved from the earlier S-Flag models, which Nidec originally developed for its use in its own transfer robots. These motors were later enhanced for general-purpose industrial applications, and were further improved and released as the S-Flag Ⅱ motors in 2019.
Nidec says that in some markets and applications there is an increasing demand for absolute encoders that can remember the locations of devices, even after they have been switched off. So far, the conventional method for achieving this has been to connect a backup battery to the encoder. However, with a growing requirement to reduce the need for battery maintenance, Nidec has has now adopted battery-less encoders with a resolution of 23 bits, that can withstand harsh production environments.
The new motors’ rated peak torque levels have been increased from 300% to 350%, while their cogging torque has been reduced from a ratio of 3% to 1.5% to enable more precise movements. The maximum rotating speed has been raised from 6,000 rpm to 7,000 rpm, while their water- and dust-resistance have been improved from IP65 to IP67. The motors’ short-length designs – ideal for use in robots – meet CE and UL safety requirements.
Nidec’s S-Flag AC servomotors will continue to be available.
