what are the wye and delta pathways - RC Groups
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Oct 15, 2017, 12:53 PM
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what are the wye and delta pathways


it LOOKS like with the delta termination there are two circuits that current will travel through, one of the two having more resistance than the other and current will flow through the two depending on their resistance, but the wye termination has one circuit. Therefore it seems the delta can magnetize more teeth than the wye at a specific time? it would seem that delta would be better at high torque since it can potentially magnetize more iron and be less likely to have it saturate.. what am I missing? I also heard foc programs will effect things differently.
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Oct 16, 2017, 06:54 AM
just look at it smokin'
z-matrix's Avatar
You can be sure that it does not change the motor efficiency if you switch to delta, AmpXturns will be the same, you will need sqrt(3) times current for a specific torque and have sqrt(3) times Kv.
Yes it is parallel, so the motor current goes to 2 strands at same time, even if you lose a delta winding, the motor would be able to run at speed with reduced torque so it has higher reliability than star because it does not have this feature.
You can also parallel windings (with same number of turns) of the same phases to get DeltaČ, Delta⁴, StarČ, Star⁴ for multiple Kv, this will give additional redundancy for wiring, even if you lose some wires, the motor will still be able to run.


Z
Oct 16, 2017, 10:33 AM
Registered User
Are less teeth energized at any given moment with wye? What of the possibility of a wye motor, since it has less potential teeth in operation at any moment, becoming more likely to saturate and therefore having a lower possible torque potential? With the fewer teeth fed high amps saturation would also increase hysterisis I think
Oct 16, 2017, 10:37 AM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by Hummina
Are less teeth energized at any given moment with wye? What of the possibility of a wye motor, since it has less potential teeth in operation at any moment, becoming more likely to saturate and therefore having a lower possible torque potential? With the fewer teeth fed high amps saturation would also increase hysterisis I think
Star and Delta are equivalent, but if your motor is not balanced, or you wind 1 more or less turns on a teeth then currents will circulate inside your Delta motor between phases, so go Star if you want to avoid this, otherwise Delta is good.


Z
Oct 16, 2017, 11:48 AM
Registered User
I've heard that but what of the one vs two circuits and the more teeth energized w delta? Maybe under extreme current delta would be less likely to saturate and would be better. If this isnt the case can anyone explain why?
Last edited by Hummina; Oct 16, 2017 at 11:58 AM.
Oct 17, 2017, 04:58 PM
Registered User
Hi,
dosnˋt matter for torque. As all magnetic circuite are closed . And as it can be fired by a sinwave electronic the phase has only a very short time when the wave is going to the zero line. If you want to fire as many statorteeth coils as can be ,you have to drive each coil by a saparate esc that fires all around . So there is allways only one coil that reach zero position and when the oo
Oct 17, 2017, 08:30 PM
Registered User
It doesn't matter for torque, everyone says so so I don't argue, but looking at the two circuits with the delta it seems obvious all teeth are magnetized through two separate paths, while wye only 2/3rds of the teeth are ever having current being put into them. If a motor could only have 8 teeth in operation vs 12 it would have less iron to utilize and more likely to saturate
Last edited by Hummina; Oct 17, 2017 at 09:06 PM.
Oct 20, 2017, 12:09 PM
Registered User
Am I right about the less teeth in operation w wye? Or wye not?
Oct 20, 2017, 06:33 PM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by Hummina
Am I right about the less teeth in operation w wye? Or wye not?
You don't believe it is equivalent?
Oct 26, 2017, 03:46 PM
Registered User
Equivalent in what way? I'm wondering about the electrical pathways of each and, from what it seems, wye would be electrifying 2\3rds the teeth while delta would electrify all. And I'm wondering how the winding is said to be almost equivalent (despite the stray voltages in the separate paths of delta) as more teeth electrified could mean less saturation and hysterisis
Oct 26, 2017, 05:06 PM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by Hummina
Equivalent in what way? I'm wondering about the electrical pathways of each and, from what it seems, wye would be electrifying 2\3rds the teeth while delta would electrify all. And I'm wondering how the winding is said to be almost equivalent (despite the stray voltages in the separate paths of delta) as more teeth electrified could mean less saturation and hysterisis
It is a bit more complicated than that, the stator is a transformer, the motor is a rotary transformer, its properties are affetced by mechanical parameters but it works both ways... A motor is a generator too.

I recently mentioned 180° commutation, that is what you are after if you want 33% more torque from your BLDC motor.
Standard 120° commutation uses the undriven phase to detect rotor position.
Motors with 3 hall sensors at 120° apart can be simply driven at 180°


Z
Oct 27, 2017, 11:43 AM
Registered User
But for starters, for that to make sense to me, it seems if u put current in a delta connected motor, all phases and teeth will have current. Looking at a visual representation delta shows current and wye would still have a leg without. This is assuming a circuit with one in phase wire and one out. Maybe they are only on for 120 degrees as u say and then when not pushing current they detect position and not in an unpowered leg. ? I dont have a pic handy but looking at the delta circuit as I say it seems all teeth would be electrified and wye would have two thirds teeth electrified based on the two pathways delta can take

Regardless, when u say with sensors commutation can be done for longer and produce more torque...wouldn't that equate to slighlt more peak and continuous power?
Last edited by Hummina; Oct 27, 2017 at 12:03 PM.
Oct 28, 2017, 11:40 AM
Jack
jackerbes's Avatar
Out of curiosity I took a brand new motor that was wound dLRK-Delta to a Kv of 750 and rewound it with a LRK-Wye wind that gave it a similar Kv (781 versus the original 750).

You can read all the details on that here:

LRK Wind on DAT-750 - It's a good one! - https://www.rcgroups.com/forums/show...postcount=1409

Here is the full throttle test on the LRK-Wye rewind:

GP 10 X 4.5 SF = 5,744 RPM, 11.58V, 10.00A, 116W
full throttle temp rise 74F to 92F in 38 seconds
estimated thrust = 688 grams

And for comparison, the numbers for the stock factory dLRK-Delta wind are:

GP 10 x 4.5 SF = 5,338 RPM, 11.02V, 19.12A, 211W
full throttle temp rise 75F to 81F in 15 seconds
estimated thrust = 600 grams

So the Wye terminated LRK wind give me an 8% increase in full throttle RPM, a 48% reduction in current draw, and a 15% increase in thrust.

You can spend all the time you want agonizing over the images and the current draw and details like that but it is not until you actually rewind and compare the data from static testing or actual use that you can really decide which is the better wind.

And don't forget, other details like the percentage of magnet coverage and the termination can all have an effect on the testing results so that opens the door to having to explore and play with a number of details.

In the test I did, the motor had 95% or more magnet coverage and the best choice for an LRK wind would have been a coverage down around 75% or 80% or so. So as much better as that re-wind looked, it could probably be made even better with a different magnet arrangement that gave wider gaps between the magnets.

So if that is interesting to you, read on in that thread as that motor was praised, bedeviled, ridiculed, burned up due to a shorted winding, re-wound again and in further testing it good even better!

So anyone that is trying to convince me that a Delta wind is better than a Wye wind, for any reason, is going to have to do it both ways and prove it with the numbers.

Jack
Last edited by jackerbes; Oct 28, 2017 at 06:44 PM.
Oct 28, 2017, 02:10 PM
Registered User
haha I'm slow to do anything out of the theoretical but I'll be doing some extremely solid, nitpickingly exact comparisons of wye vs delta under heavy load soon trust me. waiting for new/new motors to show.

your comparison has different kv, and the wye killed it anyway somehow in what we can see. the temp test I find so vague with my infrared thermometer but I'll throw that in too(and I'll be able to open the motor and get right to the windings for my sample and I'll make it a standard test) I wonder what the resistances of the phases are most as that should I believe tell exactly what a lot of your results point to and I can get very accurate results there.

But thats not my argument! tell me...looking at the simple diagrams of delta and wye...you can see there are two pathways for the delta to go vs the wye and therefore, assuming that these two pathways are taken by delta, which makes sense, and the wye is only able to follow the single path, ...we now have the delta with all teeth electrified while the wye has only 2/3rds. tell me if you see this and tell me if this is true or why it isn't.
and please Z-matrix tell me how commutating at 180 degrees works with sensors and compared to the 120 degrees as I've heard of sensors being slightly more efficient at the slowest speeds and also good for avoiding cogging but I've never heard of them being able to produce more torque. 33 percent more torque is huge.
Oct 28, 2017, 03:47 PM
just look at it smokin'
z-matrix's Avatar
Quote:
Originally Posted by Hummina
haha I'm slow to do anything out of the theoretical but I'll be doing some extremely solid, nitpickingly exact comparisons of wye vs delta under heavy load soon trust me. waiting for new/new motors to show.

your comparison has different kv, and the wye killed it anyway somehow in what we can see. the temp test I find so vague with my infrared thermometer but I'll throw that in too(and I'll be able to open the motor and get right to the windings for my sample and I'll make it a standard test) I wonder what the resistances of the phases are most as that should I believe tell exactly what a lot of your results point to and I can get very accurate results there.

But thats not my argument! tell me...looking at the simple diagrams of delta and wye...you can see there are two pathways for the delta to go vs the wye and therefore, assuming that these two pathways are taken by delta, which makes sense, and the wye is only able to follow the single path, ...we now have the delta with all teeth electrified while the wye has only 2/3rds. tell me if you see this and tell me if this is true or why it isn't.
and please Z-matrix tell me how commutating at 180 degrees works with sensors and compared to the 120 degrees as I've heard of sensors being slightly more efficient at the slowest speeds and also good for avoiding cogging but I've never heard of them being able to produce more torque. 33 percent more torque is huge.
I would suggest epoxy mounting a PT100 platinum RTD like this PT106051 between the motor windings to measure (and limit) motor temperature.
honeywell PT100 information

I can't really help in getting a 180° commutating controller at the moment, busy building prototypes and gathering funds...
maybe you can make one yourself?

researchgate 180-Degree_Commutation_System_of_Permanent_Magnet_Brus hless_DC_Motor_Drive_Based_on_Speed_and_Current_Co ntrol


Z
Last edited by z-matrix; Oct 29, 2017 at 03:29 AM.


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