ADA4571 for PMSM motorcontrol sine commutation

Hello,

i have an ADA4571 GMR-Sensor with a 30 pole Magnetring (Off-Shaft integartion). The sensor works very well and the estimated angle is very accurate, but my question is, can i obtain a 360° mechanical angle with this build? I know that the ADA4571 is only for 0-180° degrees with the atan2 function, but in the datasheet is described, that you can use this sensor for motorcontrol and positioning. Actually i get a very nice angle between 0 and 180°degrees but for my commutation algorithm i need also the range of 180° up to 360° is it possible with a software trick or something else?

Thanx for your help!

  • Hi,

    Unfortunately this is a limitation of these sensors for commutation purposes. Where they can be useful in motor control or positioning is in situations where additional 'crude' information is available to distinguish between the 180 degree segments. This could be something like a simple index marker, Hall elements, or a crude back emf estimation on one motor phase. You might argue that if you have Hall elements then there is no need for the ADA4571. However, in many cases, performing the entire control algorithm with Hall elements does not give the performance requirement required in terms of torque ripple or speed/position controllability. In such a situation, the Hall elements can be used to distinguish between the 180 degree segments and the ADA4571 can be used as a replacement for an incremental optical encoder, for cost, robustness, bandwidth or other reasons.

    Hope this helps.

  • hi.... Any solution to measure angle in between 0 to 360C at 1k RPM ??

  • This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin