Halling Up a RC heli motor?

[magudaman]

I got a new fancy helicopter motor in today and want to get some halls installed in it. Previously I have installed my hall between the lamination slots but this motor is much too tight between the slots for that to happen. So I am trying to plan out another way to set this motor up. Can I just get my spacing right and point the hall sensor down toward the magnets or am I going to get too much interference from the coils? I am hoping to do some testing tomorrow but if I can get some info that always helps!

I am using the Honeywell SS411A Sensors

 

[gwhy!1]

the sensors need to be in the path of the face of the magnets to enable reliable switching, so there are only 2 options if using the motor magnets these are in the slots or on the outside of the motor can.

 

[magudaman]

Arg! Well that is going to cause some trouble. The exterior route seems problematic from what I remember and additionally there seems to be very little magnetic field out there, a metal wrench barely even moves when place directly over the magnet. I think I may still try to place the hall directly above and as closely gap of the stators as possible. I can feel a ton of field there with the small wrench.

 

[gwhy!1]

the magic spacing of the sensors is the key to get them to work reliably if on the outside ( well this is what I have found ) use 60 mechanical with the center hall flipped this have worked for me 100% on the bigger motors.

 

[magudaman]

I'm still stuck on trying internal setup but am using 60 degree spacing between each hall as you had specified. The strange thing is immediately after connecting it to my kelly controller I get hall error lights. I can rotate the motor some and the error will go away. See edit at bottom. None of the 36 combos worked all gave the error light.

The motor is 8 magnet (4 pole pairs) and according to this guy 60 degree spacing should work for both 60 and 120 degree controllers:

http://mitrocketscience.blogspot.com/2011/08/hall-effect-sensor-placement-for.html

I am ready to go external but from the looks of this it doesn't look like it is going to be quite that simple. I guess I can try flipping that hall as you had suggested but reading through a couple other post going back and forth between 60 and 120 should have a similar effect:

http://endless-sphere.com/forums/viewtopic.php?t=957

hmm

EDIT: Actually it seems that error light actually comes on because all halls go low!

 

[magudaman]

Ok I improved my situation some. The halls were mounted writing facing down toward the tops of the magnet which didn't work . I have now moved them so that are facing writing towards the bell / parallel with the stators. I now have six rough combos so hopefully its just a mater of tuning the placement of the halls and then permanently mounting them. I need to hook up the scope and double check I'm not getting too much noise from the phases.

 

[johnrobholmes]

You gotta flip the middle sensor for 60* arrangement.

 

[magudaman]

Ok still running into issues. I confirmed the field is strong enough for external halls. I just started to design out the holder and will hopefully cut it sometime this week.