What are Shaft position and Speed sensing devices used in motors?



AC and DC tachometers are permanent magnet generators that produce a voltage proportional to speed.

The AC tachometer output frequency is also proportional to speed.

Tacho Meter - Motor Speed measuring device

Commutator (Rotor Angle)

Brushless dc motor require low resolution feedback derived from the motor magnets using hall effect sensor.

A hall effect based magnetic encoder generates a pulse train for speed and incremental position

hall effect sensor

Precision Shaft Angle

Optical encoders with precision pattern printed on a glass disk provided very high resolution shaft position and speed data.

Resolvers generate sine/cosine relative to position.They are the analog counterpart of the rotary encoder.

optical encoder