Adding hall sensors to outrunners

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Thud
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Re: Adding hall sensors to outrunners

Post by Thud » Jan 30, 2011 9:53 am

Jeremy,
I can confirm your findings 100%.
I have also witnessed some other interesting issues in testing external Hall set up's
Here are my observations:

1) using the 17.14 deg. spacing can be finikey at times. It seems to work better on smaller motors.

2) On the big turnigys, in some positions the the adjustment becomes very sensitive & showes inconsistant performance under load.

3) Another thing that i found interesing is I can trigger the hall sensorer as far as .75" off the can.
(are ther potential benifits to a thicker flux ring?)

4) Once I made a 60deg hall spacing bracket It elliminated all weirdness on the 80mm motors. timing adjustments react as expected. & I can load the motor & not get the glitches that appeard previously.

once satisfied I designed a small universal motor mount for the turnigy motors.
This will snap into the motor's exiting mounting plate & be retained by the motor when attached to its mount.
The Halls will be on an ajustable bracket that bolts to the base unit. The whole unit is to be cast in some high temp urathane. I am awaiting some more silicone tooling rubber atm but here is a pic of the "base" Pattern for the mount:
60deg halls 003.jpg
60deg halls 006.jpg
60deg halls 007.jpg
This is my solution for a turn key Hall system applicable to the turnigy motors.
the Arc section will be aluminum cast in place.
input for design tweeks allways accepted.
get some......

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Re: Adding hall sensors to outrunners

Post by TylerDurden » Jan 30, 2011 10:57 am

That's sweet!

Perhaps a step file?... so the cnc crowd can machine various versions/materials. Might be faster/cheaper than castings?
Have a Nice Day,

TD

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Re: Adding hall sensors to outrunners

Post by Thud » Jan 30, 2011 11:35 am

Hi TD,

To clairfy. I will make rubber molds from the patterns & then cast the aluminum bits into a hi-temp plastic. De-mold time is in the 5-10 minute range & the mold itself shold last for thousands of parts.

Here is a look at the proccess.
http://www.youtube.com/watch?v=cL33dO8mQuQ

Since I need more than a couple of these I am investing the time to make a mold for each 1/2 of the assembly.
get some......

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Jan 30, 2011 11:52 am

That looks to be a brilliantly neat way of doing the job, better by far than the rather delicate PCB method. I've epoxied over the components and copper on the PCB now, and it'll probably do for the milling machine, but a fairly easy to fit system like yours looks to be a better bet for motors used on bikes.

Is the intention to also cast the Halls inside the movable urethane moulding? If so, then that would make for a pretty tough mounting method.

I'm not surprised at the sensors working so far away. The SS411A sensors change state at around +/- 60 or 70G, whereas the magnets are around 13,000G, so even a 1% leakage through the can is going to give around 130G, around double that needed to switch the Hall. I'd expect flux leakage through the can to be around a couple of percent or so, and doubt they'd be much real performance gain by trying to reduce it further.

Jeremy
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Re: Adding hall sensors to outrunners

Post by Thud » Jan 30, 2011 12:44 pm

Is the intention to also cast the Halls inside the movable urethane moulding?
That is correct. I don't have that assembly pictured yet.
Need to make the jig to hold hall alignment in that pc for"potting" them into position.

A pr. of 4-40 screws will adjust it on the base mount just like your PCB example.

easy-peasy.
get some......

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Re: Adding hall sensors to outrunners

Post by AussieJester » Jan 30, 2011 3:47 pm

Thanks for the information Jeremy ... theres a number of you fellas using these type
of motors on your mills now... ThudSTeR's new mounting setup is superb, hope too get my mits
on one or two in the near future :: wink :: Top job Thud ;-)

KiM

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Jan 30, 2011 4:15 pm

AussieJester wrote:Thanks for the information Jeremy ... theres a number of you fellas using these type
of motors on your mills now... ThudSTeR's new mounting setup is superb, hope too get my mits
on one or two in the near future :: wink :: Top job Thud ;-)

KiM
My milling machine has done a lot of work on that small Turnigy motor, and now looks like it'll do a lot more. I did a test cut at low speed on some fairly difficult stainless steel tonight and was mightily impressed by the low speed torque. Now it's got sensors it will cut at low speeds that were unthinkable when I was using the old sensored controller, although that's not the reason I made the switch.

I'm now even more convinced that fitting Halls is really the answer to getting these motors to work responsively.

Jeremy
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Re: Adding hall sensors to outrunners

Post by oatnet » Jan 30, 2011 4:43 pm

Thud wrote:Hi TD,

To clairfy. I will make rubber molds from the patterns & then cast the aluminum bits into a hi-temp plastic. De-mold time is in the 5-10 minute range & the mold itself shold last for thousands of parts.

Here is a look at the proccess.
http://www.youtube.com/watch?v=cL33dO8mQuQ

Since I need more than a couple of these I am investing the time to make a mold for each 1/2 of the assembly.
!!!! If you decide make these for sale, please sign me up for 3. :D

-JD
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Re: Adding hall sensors to outrunners

Post by katou » Jan 30, 2011 9:32 pm

I'm just checking in. Is this idiot proof yet? If so, let me have a crack at it, maybe you just need a better idiot.

Katou

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Re: Adding hall sensors to outrunners

Post by gtadmin » Jan 31, 2011 1:46 am

katou wrote:I'm just checking in. Is this idiot proof yet? If so, let me have a crack at it, maybe you just need a better idiot.

Katou
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Re: Adding hall sensors to outrunners

Post by olaf-lampe » Jan 31, 2011 3:38 am

Jeremy Harris wrote:Ysterday I had my first problem with fitting Hall sensors to an outrunner. So far I've done several low Kv wound, wye connected motors, with internal Hall sensors fitted in every fourth slot (so 120 degree spacing - these were 12 slot stator, 7 pole pair rotor, motors). All have worked very smoothly with masses of low speed torque.


You can just see the three Hall sensors set into slightly widened stator slots and glued in with epoxy.

Where exactly did you place the halls? Between the two Aa Bb Cc teeth? Would it help to place them 2 teeth further back ( or forth?) Would be 60 dgree difference


After a bit of playing around, I found that the roughness and cutting out problem was indeed caused by the Hall timing being out. This motor doesn't like running on internal sensors at the neutral position, as I needed to shift the timing by around 10 degrees from neutral (physical, ~ 70 degrees electrical) to find a point where the motor would run smoothly and accelerate cleanly .

Jeremy

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Jan 31, 2011 5:11 am

olaf-lampe wrote:Where exactly did you place the halls? Between the two Aa Bb Cc teeth? Would it help to place them 2 teeth further back ( or forth?) Would be 60 dgree difference
I can't see why it should make a difference as to which slot the Halls are in, as their placement is relative to the edges of the magnet passing any stator slot, isn't it?

In the past I've just picked any random set of three slots at 120 deg to each other and it's worked fine.

Jeremy
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Re: Adding hall sensors to outrunners

Post by olaf-lampe » Jan 31, 2011 5:39 am

Jeremy Harris wrote:
olaf-lampe wrote:Where exactly did you place the halls? Between the two Aa Bb Cc teeth? Would it help to place them 2 teeth further back ( or forth?) Would be 60 dgree difference
I can't see why it should make a difference as to which slot the Halls are in, as their placement is relative to the edges of the magnet passing any stator slot, isn't it?

In the past I've just picked any random set of three slots at 120 deg to each other and it's worked fine.

Jeremy
You're right Jeremy,
it isn't that important, but doesn't it make it easier to determine which hall corresponds to which phase?
For you it's not the first motor to mount halls on, so I guess you have a certain wiring-pattern, that always works?

-Olaf

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Re: Adding hall sensors to outrunners

Post by Burtie » Jan 31, 2011 6:12 am

I cant quite work this out :?

Assertions (please correct me if wrong), Assuming 14 magnet, 12 slot motor driven by a 6 step controller:

1) The hall sensors respond to the position of the 14 magnets on the can.
2) Consider the symmetry of the magnets around the can. If we rotate the hall group by 51.4 mech deg (360 electrical deg), we would expect everything to work the same.
3) going a bit further, If we rotate the hall group by any multiple of 60 electrical deg (then sort out the wiring), everything should still work the same. (Because we use a 6 state controller.)
4) However, if we rotate the hall group by 1 slot, that is 30 mech degrees = 210 electrical degrees

:?: Problem is that 210 is not a multiple of 60, so the timing must have changed by + or - 30 electrical degrees ??

Burtie

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Re: Adding hall sensors to outrunners

Post by gtadmin » Jan 31, 2011 6:37 am

One's moving 1/7 of 360, the other 1/12 (stuffed that twice :oops: ), so the second will almost always be out of step with what's required.

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Jan 31, 2011 7:04 am

Burtie wrote:I cant quite work this out :?

Assertions (please correct me if wrong), Assuming 14 magnet, 12 slot motor driven by a 6 step controller:

1) The hall sensors respond to the position of the 14 magnets on the can.
2) Consider the symmetry of the magnets around the can. If we rotate the hall group by 51.4 mech deg (360 electrical deg), we would expect everything to work the same.
3) going a bit further, If we rotate the hall group by any multiple of 60 electrical deg (then sort out the wiring), everything should still work the same. (Because we use a 6 state controller.)
4) However, if we rotate the hall group by 1 slot, that is 30 mech degrees = 210 electrical degrees

:?: Problem is that 210 is not a multiple of 60, so the timing must have changed by + or - 30 electrical degrees ??

Burtie
Glad it's not just me that finds the concept of 7 magnet pole pairs and 12 slots mildly confusing at times!

The Hall angular position datum is relative to the stator, as the Halls trigger commutation. The timing is relative to the magnet position. This means that the Hall sensors need to provide either 120 electrical degree or 60 electrical degree (relative to the stator) outputs. Because all slots are the same, in effect, the three Halls can be placed (at the correct angular spacing) relative to any of the 12 slots.

Timing variation is relative to the magnet pole passing position, so is angularly related to 360/7 per cycle, rather than 360/12 per cycle.

Jeremy
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Re: Adding hall sensors to outrunners

Post by gtadmin » Jan 31, 2011 7:09 am

Jeremy Harris wrote: Glad it's not just me that finds the concept of 7 magnet pole pairs and 12 slots mildly confusing at times!

The Hall angular position datum is relative to the stator, as the Halls trigger commutation. The timing is relative to the magnet position. This means that the Hall sensors need to provide either 120 electrical degree or 60 electrical degree (relative to the stator) outputs. Because all slots are the same, in effect, the three Halls can be placed (at the correct angular spacing) relative to any of the 12 slots.

Timing variation is relative to the magnet pole passing position, so is angularly related to 360/7 per cycle, rather than 360/12 per cycle.

Jeremy
Yes, that's what I meant, but much more eloquently expressed by Jeremy

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Jan 31, 2011 7:12 am

olaf-lampe wrote:You're right Jeremy,
it isn't that important, but doesn't it make it easier to determine which hall corresponds to which phase?
For you it's not the first motor to mount halls on, so I guess you have a certain wiring-pattern, that always works?

-Olaf
I always use a 'scope and a sensorless controller to find which wire is which, after I've wired up the motor. I don't bother to try and trace the windings and find out which Hall corresponds to which phase wire by inspection, as it's too much like hard work!

The technique I use is to power the motor with a sensorless controllers at a reasonable rpm, then I connect one scope channel to one of the motor phase wires and the other to Hall wires in turn (with them connected to pull-up resistors). It's then usually easy to see which Hall has edges that align with the phase switching point. By going through each phase in turn I can quickly determine which Hall corresponds with each phase. If I also note which direction the motor is turning, I can correctly label them so that I can then hook the motor up to rotate in either direction. My hack sensorless controller already has the three phase wires labelled, which makes life easier.

Jeremy
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Re: Adding hall sensors to outrunners

Post by olaf-lampe » Jan 31, 2011 9:44 am

OK ,
I just ordered a 2 channel scope. Always wanted one, but never had a real reason. I hope it'll arrive soon, time is running out...
-Olaf

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Re: Adding hall sensors to outrunners

Post by Burtie » Jan 31, 2011 10:37 am

Jeremy Harris wrote:

...The Hall angular position datum is relative to the stator, as the Halls trigger commutation. The timing is relative to the magnet position. This means that the Hall sensors need to provide either 120 electrical degree or 60 electrical degree (relative to the stator) outputs. Because all slots are the same, in effect, the three Halls can be placed (at the correct angular spacing) relative to any of the 12 slots.

Timing variation is relative to the magnet pole passing position, so is angularly related to 360/7 per cycle, rather than 360/12 per cycle.

Jeremy
Thanks for the explanation Jeremy and gtadmin.
I just had a feeling that the stator slots were not all exactly the same for a 14 mag DLRK motor, since half of them are between different phases and half are in the center of a phase.

For Aa we would have in-phase, but opposing stator poles either side of the slot.
For ab we would have stator poles which were 120 deg out of phase either side of the slot.

If this were the case, the rotational symmetry for the stator would be every two slots i.e. 360/6 =(60 mech deg).
So it might make a difference which slot you choose as your timing datum.
I wonder if this could explain why your most recent motor conversion did not run very well when you randomly chose the slots.

If this were the problem, it may have shown when you looked at the Phase / Hall signal correlation during the setting up
with the sensorless controller.

I probably need to go and read some books on electrical machines...
:? :)
Last edited by Burtie on Jan 31, 2011 6:07 pm, edited 3 times in total.

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Re: Adding hall sensors to outrunners

Post by Burtie » Jan 31, 2011 3:37 pm

I did a bit of surfing and found this link:

http://groups.yahoo.com/group/lrk-torqu ... sage/12567

Here is a snip from the page, about half way down:

"
..From what I remember, on my distributed LRK motor, I put the sensors between the
two teeth that were wound with the same phase when in Delta and between teeth
from 2 different phases when in Wye...
..hope that helps

-ryan
"

This would seem to support the theory that there is a net 30 e degree phase shift between using 'same-phase' and 'different-phase' slots for hall placement.

ryan = (ES) Biff ??


Burtie

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Re: Adding hall sensors to outrunners

Post by Biff » Jan 31, 2011 6:15 pm

yep, thats me.

What you posted is correct, you put the hall sensor between teeth of the same phase if in delta. and make sure you put it between same direction wound pairs between teeth as well. So if you put it between the Aa pair, make sure you put the other two between Bb and Cc pairs rather than bB and cC pairs, otherwise you will get 60deree. That is just using my mental picture so I could be a little off on that, you also have to get the sensor in between the right pair of teeth for the direction you put in the sensor, otherwise it will be 180degrees out, if that is the case, leave it in the same place, but just flip the sensor over to the other side to get it to 0degrees. If you want to hook up in WYE, you put the sensor between teeth of different phases, that advances the timing by 30degrees, you will still have to figure out which hall sensor goes into which input, either by trial and error, or scope it out.

Now comes the complicated bit. If you angle the sensors a bit you can advance or retard the triggering, advancing is good, retarding is bad, you need to advance the timing as frequency increases to counteract the increased impedance due to inducance of the coil. In many peoples experiance, actually advancing the hall sensor 30 degrees by putting it in the position for WYE connected motors, but actually connecting the motor in delta, produces better power at high speed than if the hall sensor were in its 0degree advanced position.

That problem should be fixed by using a smart controller, or something like burtie's timing adjuster, which is designed to compensate for inductance (hence more advance as speed increases). Read about that here if there isn't a link already in this thread https://endless-sphere.com/forums/viewto ... =2&t=19054

I have always had an oscilloscope to help me place my hall sensors so I don't have any tips on proper positioning without using a scope.

To figure out what the phase angle between teeth is you use the magnet / tooth ratio, for LRK that is typically 7 magnets for each 6 teeth, so since there is an odd number of magnets, you get 180degrees electrical difference equally divided by 6 teeth, so therefore each adjacent tooth is 30degrees different.

-ryan

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Re: Adding hall sensors to outrunners

Post by Jeremy Harris » Feb 01, 2011 3:10 am

Thanks for that, Ryan, looks like I just got lucky with all the other motors I'd modded this way and unlucky with the 6374 I did at the weekend.

Jeremy
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Re: Adding hall sensors to outrunners

Post by olaf-lampe » Feb 01, 2011 3:39 am

Thanks Biff for the summary,
I can imagine how difficult it must be to find out the Aa or aA winding in an already wound HK motor.
Once you've found out where the first hall has to come, it automatically fulfills the 'Aa,Bb,Cc'-rule when the other halls were placed in a 120degree/4slots distance.
I'm glad, I mark my handwound stators with the winding-pattern. Makes it easier to follow the 'rules off hall placement'.

-Olaf

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Re: Adding hall sensors to outrunners

Post by Burtie » Feb 01, 2011 6:32 am

+1
Yes thanks Biff for all the very useful information. You have cleared up some thoughts that have been nagging me for a while.
olaf-lampe wrote: ..I can imagine how difficult it must be to find out the Aa or aA winding in an already wound HK motor.

-Olaf
I agree Olaf, this could be a bit of a problem.

One method I have used, is to energise a pair of phase wires with 2 or 3 DC amps, and then examine the field produced by each stator pole using a magnetic compass.

This is not the easiest thing to make sense of if the windings are terminated in delta, or wye, but it does give some useful clues.

Edit:
Update- Here is a practical demo using two sets of halls in adjacent sets of slots on an 80-100
https://endless-sphere.com/forums/viewto ... 85#p526585

Burtie
Last edited by Burtie on Jan 30, 2012 9:06 am, edited 1 time in total.

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