Glossary of Motor Terms
Position sensor
The position sensor is used to detect the rotational angle of the rotor. There are several principles employed: the major type used for a brushless DC motor is the Hall-effect element but a photo coupler is used, too.
Hall-element sensor
![](/-/media/www-nidec-com/technology/motor/glossary/item/position_sensor-01.jpg)
Photo coupler
Position (rotor angle) sensor using photo couplers
![](/-/media/www-nidec-com/technology/motor/glossary/item/position_sensor-02.jpg)