wye - Delta -> differences and stereotypes

Hi,

I notice that with every project id like to get an deeper understanding on all the technical aspects, thats why id like to understand why some motors are in wye or delta.
And by-the-way i got inspired and questioning by the following thread https://endless-sphere.com/forums/viewtopic.php?f=30&t=86152&start=25

Of course, you can do all this ina ingeneering and scientifical way, but my aim is to just ge a rule of thumb about what winding type to choose for what project.

I actually only want to collect the rough basic statements that can be made about these two types of windings.

Wye
- less amps at the start (at lower rpms)
- approx. 1.7X less KV as Delta - means lower end speed
- better suited for batteries which are not so strong (laptop cell zombies)
- Wye runs rather cool than Delta
- take wye if you want to have more torque at high-speed/rpm
- but therefore you get lamer starts
- with the weak cells of the past, Wye was still important


Delta
- more current at start and less at topspeed
- 1.7X higher top-speed than wye
- high currents at start, therefore high current-cells
- Delta runs rather warmer than wye (because of the start-currents in the lower-rpms)
- take Delta if you want burnout-starts, but accept less power at top-speeds
- most ebike and RC engines today are Delta because of high current cells
- The missing bite of Delta in the higher speeds can be compensated by "clever controllers", which in the end push more current, but the motor will get quite warm


Still open questions and assumptions about this:
- can one say that one of the types of windings is "more economical" with current (or is the higher current of the Delta at the start compensating with the higher current from wye to the topspeed?)
- does it make sense to choose Wye or Delta for the following reasons:
- I'll take wye because I do not care about burnout starts, but i want torque close to the top-speed, I live in a flat city!
- I take Delta because the most important are traffic-light-burnouts, or a lot of torque in dirt- tracks. I get my high top-speeds by gravity because I live in the Alps.

Would be fine if you give your knowledge and real experience on the subject.

greets and thansk in advance

Notger

Sorry, but almost none of what you posted above is incorrect...

The windings (and their power, torque & efficiency capabilities) remain the same - they are just terminated differently. The argument is the same as "slow wind" Vs. "fast wind" motors, where you have the same total amount of copper on the motor teeth.

There is also the usual confusion between battery and phase current. A BLDC speed controller is like a buck converter and phase current can be very different from battery current. This is why running in wye *for the same motor power* does not lessen the load on the batteries. Yes, you can have less load on the batteries or less motor heating using wye rather than delta, but only by reducing motor power and reducing performance of the vehicle.

I think industrial 3-phase induction motors produce confusion on this subject. They commonly used wye-delta switching at start-up, but the application is very different to a BLDC motor & controller, as the induction motor operates on a fixed voltage & unregulated current supply and at a (near) fixed speed. If you want to change the speed or reduce inrush current then the only thing you can do is change the winding resistance, which wye-delta achieves. Nowadays it's all different thanks to electronic Variable Speed Drives, which are the induction-motor equivalent of a BLDC controller.

notger said:

Wye
- less amps at the start (at lower rpms)
- approx. 1.7X less KV as Delta - means lower end speed
- better suited for batteries which are not so strong (laptop cell zombies)
- Wye runs rather cool than Delta
- take wye if you want to have more torque at high-speed/rpm
- but therefore you get lamer starts
- with the weak cells of the past, Wye was still important


Delta
- more current at start and less at topspeed
- 1.7X higher top-speed than wye
- high currents at start, therefore high current-cells
- Delta runs rather warmer than wye (because of the start-currents in the lower-rpms)
- take Delta if you want burnout-starts, but accept less power at top-speeds
- most ebike and RC engines today are Delta because of high current cells
- The missing bite of Delta in the higher speeds can be compensated by "clever controllers", which in the end push more current, but the motor will get quite warm


Still open questions and assumptions about this:
- can one say that one of the types of windings is "more economical" with current (or is the higher current of the Delta at the start compensating with the higher current from wye to the topspeed?)
- does it make sense to choose Wye or Delta for the following reasons:
- I'll take wye because I do not care about burnout starts, but i want torque close to the top-speed, I live in a flat city!
- I take Delta because the most important are traffic-light-burnouts, or a lot of torque in dirt- tracks. I get my high top-speeds by gravity because I live in the Alps
Notger

Click to expand...

A quick WYE vs delta primer...
1. Wye for the same voltage and amps will give you more torque than will delta. Delta requires more amps to generate the same amount of torque as WYE.
2. For the same volts WYE will be slower (less RPMs) than delta at any given throttle position.
3. Wye does better at lower RPM's than does delta mostly because it doesn't require as much current to generate torque.
4. Any BLDC motor is limited by how strong its magnets are and how strong of a magnetic field it can produce. You can't produce more torque than the motors magnets or magnetic fields are strong. WYE or delta is equally limited by those magnetic limits.
5. The same motor rewired for WYE or delta should run equally well assuming that the controllers eRPM isn't exceeded.
6. At no load, Delta at any RPM will require more current than WYE. In my tests at barely creeping along my motor in WYE used less than an amp and soon went up to 3 amps all the way to WOT. On delta, it took 3 amps just to get turning and soon jumped to 9 amps all the way to WOT. Holding the throttle steady and switching from WYE to delta or back always included an increase or decrease in current draw.
7. The windings for WYE or delta are exactly the same. It's how you terminate the winding ends that determines whether a motor is WYE or delta. Connect the three starts of three windings together and feed current into the ends of each winding and that is WYE. Think of the letter Y. Each leg is a winding. 3 winding ends connect together in the middle and there are three ends. Delta is just a triangle. The three sides of the triangle are the windings. So windings a,b,c...the end of a connects to the start of b, the end of b connects to the start of c and the end of c connects to the start of a.

To directly address your WYE and delta lists...I'm going to assume no load always in my answers. Load is dynamic so that adds variables.

Wye
- less amps at the start (at lower rpms)
Always less amps, but also lower top RPM
- approx. 1.7X less KV as Delta - means lower end speed
yes...true
- better suited for batteries which are not so strong (laptop cell zombies)
Not true...build your battery pack to suit your current needs. The cell type is irrelevant. Use AAA batteries or watch batteries if you want...just be sure that the end pack build can deliver the voltage, current and capacity that you require. I use free/used laptop cells a good bit. They work fine, just means I need to use more of them to get the same discharge rates of an EV grade cell. Laptop cell or EV cell or tool cell are all fake distinctions. They will all work for whatever you want to use them for as long as you plan around that particular cells limitations.
- Wye runs rather cool than Delta
No...not really. Delta since it needs more current to generate the same amount of torque will probably run warmer while generating the same amount of torque since that also means a bump in current too over what WYE needs.
- take wye if you want to have more torque at high-speed/rpm
Torque is a factor of magnetic strength, not WYE vs delta. The same motor wired either way should have the same maximum torque.
- but therefore you get lamer starts
If you have the current delivery ability, delta or WYE will deliver the same amount of torque at zero RPM or any RPM assuming you are comparing their two power bands correctly. However, to get that maximum torque WYE will use less amps to do it. That means your battery charge will last longer running WYE than it will running in delta.
- with the weak cells of the past, Wye was still important
Wye is still important. It flat out uses less current than does delta to generate any amount of torque. Weak or strong cells is irrelevant.


Delta
- more current at start and less at topspeed
No...more current than WYE at all RPMs
- 1.7X higher top-speed than wye
Since the same motor wired in WYE will have 1.7X less Kv than that motor wired in delta, yes, there is a 1.7X increase or decrease in maximum motor RPM's for a given battery voltage.
- high currents at start, therefore high current-cells
Higher currents than WYE all the time, not just starts. Just build your entire battery pack out of whatever cells it is made from to handle the delta current load. The type of cell used or its specific limitations is irrelevant...just use what you have and plan your battery pack to take into account those limitations. 18650 cells commonly used in laptop battery packs are usually 2600mah and have 2 or 3C discharge rates. While a 31Q had a much higher discharge rate and a bit more capacity. Which ever cell you use, plan the battery pack to be enough cells to cover your current and capacity needs.
- Delta runs rather warmer than wye (because of the start-currents in the lower-rpms)
No...not quite...since delta draws more current all the time, it will run warmer than the same motor wired for WYE. It's not just at start up from zero RPM.
- take Delta if you want burnout-starts, but accept less power at top-speeds
No...not true. In WYE, I can gear for rubber burning, wheelie riding performance. Same can be done in delta. The motor can only produce as much torque as it's magnets and magnetic fields can produce. Delta or WYE doesn't change this. Since the motor in delta has a 1.7X higher Kv than it does in WYE, the motor will continue producing the same amount of torque up to a higher RPM than it would in WYE. BUT...it will use more current to do it.
- most ebike and RC engines today are Delta because of high current cells
No...not true. Outrunners are commonly wired in delta and inrunners are commonly wired in WYE...but not always. So when you say "RC", consider the type of BLDC motor to which you are referring. Outrunners are used extensively in drones, planes and helis while inrunners are mostly used in ground craft. In EV use, either motor type if it fits the needs of the EV will work. A lot of people are using hub motors on their EV's...that's an outrunner inside a shell with a crazy low Kv. Sometimes they are wired delta and other times they are wired WYE. I have a hub and it is wired WYE. My blue scooter runs a big block motor and it is wired WYE. It tops out at 50mph on level ground and I can accelerate faster than most cars while maxing out at less than 60 amps. I have smaller scooter running an outrunner wired delta. It draws similar amounts of current as the big block despite pushing less weight and being a smaller motor.
- The missing bite of Delta in the higher speeds can be compensated by "clever controllers", which in the end push more current, but the motor will get quite warm
So this this little bit of wording is a bit confusing since it's a mix of multiple concepts and implementations. A "clever controller" would be one that does FOC and feild weakening. Regardless of WYE or delta, it will run the motor a bit faster than it will run on a non-FOC controller and will cost you a little more current to do it. Can you get 1.7X via field weakening? No not likely, but .3X or so is doable. Any controller can push "more current". If your 2000 watt controller can only deliver 40 amps, then double the mosfets or use higher wattage mosfets and now it can deliver "more current". A semi smart controller with phase and battery current control can be set to say 20% of it's maximums and run a motor. Then change those settings to 100% and now it delivers more current to the motor.



Still open questions and assumptions about this:
- can one say that one of the types of windings is "more economical" with current (or is the higher current of the Delta at the start compensating with the higher current from wye to the topspeed?)
WYE is more economical...for the same amount of torque, wye requires less current than does delta. Ignoring the rest...already discussed.
- does it make sense to choose Wye or Delta for the following reasons:
- I'll take wye because I do not care about burnout starts, but i want torque close to the top-speed, I live in a flat city!
All ready talked about burn out starts...that's just gearing. Torque at higher motor RPM's is a matter of what you mean by "higher RPMs". As long as either wiring method is used on the same motor, both will generate the same amount of torque. WYE will start petering off sooner than delta, but if you took the same motor at 50% of full RPM in WYE or delta, they would produce the same amount of torque. Delta will continue applying that torque up to a higher RPM than will WYE, but the amount of torque will be the same.
- I take Delta because the most important are traffic-light-burnouts, or a lot of torque in dirt- tracks. I get my high top-speeds by gravity because I live in the Alps
Read everything else I wrote. Your conclusions are incorrect.

Punx0r said:

The windings (and their power, torque & efficiency capabilities) remain the same - they are just terminated differently. The argument is the same as "slow wind" Vs. "fast wind" motors, where you have the same total amount of copper on the motor teeth.

Click to expand...

Clarifying this one point for those new to motors. He's referring to the Kv of the motor when he talks about slow/fast wind. You can take the same armature and stator and wind less turns on each tooth and get a motor with higher KV (fast wind) or wind more turns on each stator tooth and get a lower Kv (slow wind). As long as the amount of copper per stator tooth remains the same, the physics of the motor remain the same. It just spins faster or slower for any given voltage. So for this explanation, lets pretend you are using a single strand of 14 awg wire on this hypothetical motor. You wind each stator tooth with 10 turns and that gets you 200 Kv in WYE and 340 Kv in delta. Now you rewind the motor with 14 awg wire, but do 12 turns per stator tooth and now you get 240 Kv in WYE and 408 Kv in delta. IE: a fast wind vs a slow wind. The amount of copper used is still a single 14 awg strand.

Another topic here is if that motor has 10 turns of wire on it rather than 12, well there is now more unused space on the stator tooth with 10 turns vs 12 turns. Why not use a larger AWG wire? So rather than 14 AWG you wind those same 10 turns with 12 AWG or 10 AWG. THere's still the same number of turns per stator tooth so the Kv will remain the same, but now that motor can handle more current too. you can accomplish the same thing with many small strands of wire too. Lets say our motor was wound with 10 turns of 10 strands of 32 AWG wire and that totally fills the stator teeth. If you wanted to lower it's Kv, then that means more turns per stator tooth, but they are already full at 10 turns per tooth. As a result you have to use 8 strands of 32 AWG wire to make room for more turns per stator tooth. Since there is now less copper to conduct current, the motors current handling ability has decreased but it's KV has increased.

This is an Alien Power 12090 outrunner I have. It is wired delta right now. Look at all the empty space on those stator teeth. There's loads of room on them for making larger windings without changing the Kv of the motor and as a result make this motor capable of handling more current. Or...this motor could be rewound with the same number of strands but more turns and make it's Kv lower than it is now. Probably there's room to do both...add a few more strands and do a few more turns or make it handle more current and run at a lower Kv.



Compare that to this inrunner (Lighning Rods big block) I have. It already has a fairly low KV (64) and notice how the stator teeth are crammed full of windings. There's no room on those stator teeth to lower the Kv or make a slower wind without sacrificing some copper mass to make room for more windings per tooth. Less copper mass means the motor will handle less current.



There's lots of discussion on ES and elsewhere about winding motors. Feel free to read broadly. I've covered just the bare minimum on motor winding just now and ignored lots of other things.

ElectricGod said:

Your conclusions are incorrect.

Click to expand...

Luckily no conclusions, just assumptions, cause i just do not have any clue about that Topic.

Thanks to the Electric God for those enlightments,
really thanks man, lots of stuff is much clearer to me now.

Why did i actually came across that topic:
Im in the process of ordering Motors for a e-Trampa-Mountainboard, and a e-bike mid-drive-project.

Trough calculating reductions and desired top speed (-20% powerloss) i know the KV the motor should have.

So now i found a motor manufacturer wich opens up all those possibilities to me trough really amazing customization.

And i just want to find the best termination: Wye or Delta for my Projects.
So actually its not about the difference of one Motor terminated in Wye or Delta.

Its more about how does , ..a lets say: 100KV Delta Outrunner compare to a 100KV Wye Outrunner ?

greets and thanks

Gernot

I guess the best solution would be to order on 100KV Wye and on 100KV Delta and feel/experience the Difference In Reality worth a try , but to little Budget

Anyone here dare to make predictions how those Motors with same KV but different Termination "behave" ?

greets

Notger

For two identical sized motors terminated one wye and other delta too spin the same speed and rated equally there would have to be identical copper mass but wound in a different fashion to each other the delta would have more turns vs less for wye.

The winding gauge will be where the balancing act is performed so they have the same copper mass,phase resistance, and overall behaviour on the rotor.

They would run identical to eachother I'd think ?, both will use the same power and interact with the same amount of magnetic area, both will look different inside winding wise but end up identical by design in dimensions speed and torque.

Interests me this topic, increasing stock voltages of bldc inrunner motors and alike, What I found was the higher the voltage you climb the more leakage a motor encounters under heavy load past it's rated output shit can get heavy fast and meltdown.

A high voltage low pole count motor will typically have ultra thin laminates and a large gauge of wire wound from many thinner strands, But I have seen Ev motors with higher pole counts with large solid copper conductors these motors must have a lower switching frequency for skin effect not to be an issue with conductor choice.

It's possible to use a thermal trick of encapsulation on the end turns to get as much heat as possible out of the windings and into the laminations then into the case the heat sink off the motor.

Forced air needs to be just that a slow trickle of air can actual be worse sending end turn heat back into the stack and not pushed through and out of the vents with a cooling action, so any forced air needs to be fairly strong to be effectively increasing overload handling.

notger said:

ElectricGod said:

Your conclusions are incorrect.

Click to expand...

Luckily no conclusions, just assumptions, cause i just do not have any clue about that Topic.

Thanks to the Electric God for those enlightments,
really thanks man, lots of stuff is much clearer to me now.

Why did i actually came across that topic:
Im in the process of ordering Motors for a e-Trampa-Mountainboard, and a e-bike mid-drive-project.

Trough calculating reductions and desired top speed (-20% powerloss) i know the KV the motor should have.

So now i found a motor manufacturer wich opens up all those possibilities to me trough really amazing customization.

And i just want to find the best termination: Wye or Delta for my Projects.
So actually its not about the difference of one Motor terminated in Wye or Delta.

Its more about how does , ..a lets say: 100KV Delta Outrunner compare to a 100KV Wye Outrunner ?

greets and thanks

Gernot

Click to expand...

All else being equal, Y is typically slightly better than D, as there is some small amount of re-circulation current in D that wastes power. In reality your unlikely to notice though, as iirc the difference is something like 1% loss in efficiency.

So get Y if you can, but its not worth loosing sleep over if you cant.

As others have mentioned, the KV change doesn't actually change the motors performance characteristics, just the balance of volts/amps required to meet said performance. A 200kv motor will require 2x the current to produce the same torque as a 100kv motor, but will also produce 1/4 the heat at the same current as the 100kv motor (or equal heat at the same torque level - ergo same performance), so its simply a case of picking a motor kv best suited to your application (ie battery pack you'll be running, and current/voltage capability of your controller).

Just for clarity, in reality, the 100kv motor will actually produce slightly more torque per unit heat (ie higher net performance) due to lower end turn losses, but that difference is pretty much negligible. Exactly how much would vary depending on motor design, but i'd suspect its also in the range of ~1% or less.

A lot of what ElectricGod posted is incorrect.

Changing the motor termination from delta to wye and expecting it to produce the same torque at the same speed:

Does not reduce motor heating
Does not change efficiency of the motor
Does not make the motor "better" or "more economical"
Does not reduce the load on the battery
Does not affect the runtime of the battery

If you want to run in wye for reduced phase current then you *must* increase voltage by the same amount to deliver the same torque & power in order to overcome the greater winding resistance and back-EMF.

ElectricGod said:

At no load, Delta at any RPM will require more current than WYE. In my tests at barely creeping along my motor in WYE used less than an amp and soon went up to 3 amps all the way to WOT. On delta, it took 3 amps just to get turning and soon jumped to 9 amps all the way to WOT.

Click to expand...

Who cares if it's 3A or 3 x 1.73 = 5.2A (not sure why you measured 9A)? Current is not a measure of power, and the power absorbed in both cases would be the same. Phase current is also not a measure of battery current. You could produce hundreds of phase amps at low speed while drawing a handful of amps from the battery.

notger said:

ElectricGod said:

Your conclusions are incorrect.

Click to expand...

Luckily no conclusions, just assumptions, cause i just do not have any clue about that Topic.

Thanks to the Electric God for those enlightments,
really thanks man, lots of stuff is much clearer to me now.

So now i found a motor manufacturer wich opens up all those possibilities to me trough really amazing customization.
Gernot

Click to expand...

You're welcome!

Who have you found that you are getting your motors from?

Alien power makes good outrunners. Their motors are build stoutly and they use decent bearings and they come in a variety of Kv's. Turnigy motors while they may look the same as an Alien motor are not the same quality...smaller motor shafts, less precice bearings, etc. AstroFlight makes great inrunners, but they are expensive. The 3220 is a solid, very popular and compact AstroFlight motor. If you are looking for a rock bottom basic inrunner that's cheap and runs pretty well, look at the BOMA inrunners. There are a few variations...1300, 1500, 1600 and 2000 watt motors. You can find them on ebay and elsewhere. I own 2 1500 watt and a 2000 watt motor. I burned out the 2000 watt motor, but the 1500 watt motors are still good. I really abused that 2000 watt motor and was running it at 3500 watts when it died. LightningRods small block and big block motors are very strong, well built motors and do well in EV use. I own 2 big blocks. They are rated for 3000 watts, but that's really conservative. For EV use, I buy motors with halls in them or add halls such as with the 3220. There's lots of people running around on RC controllers, but I prefer not to. The Castle Creations 12S 160 amp controller is really solid and so are the Alien Power controllers. I own the biggest turnigy controller, but I wouldn't trust it half as much as a Castle or AP controller. For EV controllers, Kelly is a good choice. They have a really large product line. They will probably have a controller that will work for your purposes. Their tech support is great too. I own a couple Kelly controllers. They make good middle of the road controllers. Lyen sells on ES, but I wasn't impressed with his controllers. They tend to be older designs for a bit too much money. Never the less there are lots of people running his controllers out there. Grintech in Canada is a bunch of great folks. They have a very basic controller good for 2000 watts (2470-GR). It does regen and can be used with or without sensors. It's a very basic controller and can't be programmed at all, but it is sinusoidal. There are other cheap sinusoidal, basic controllers out there, but this one is built pretty well and it's fairly compact. I've just purchased an 18 fet controller from PowerVelocity on ES. Mine is modified to run at 150 volts. I took it apart and the build quality is reasonably good. I don't know what a "straight from the factory" controller looks like inside, but mine wasn't the best work I've seen. However, it is an inexpensive fully programmable controller that does FOC/feild weakening and other options for the same price as a similarly configured LYEN. I'll review it later once I've started bench testing it.

Punx0r said:

A lot of what ElectricGod posted is incorrect.

Changing the motor termination from delta to wye and expecting it to produce the same torque at the same speed:

Does not reduce motor heating
Does not change efficiency of the motor
Does not make the motor "better" or "more economical"
Does not reduce the load on the battery
Does not affect the runtime of the battery

If you want to run in wye for reduced phase current then you *must* increase voltage by the same amount to deliver the same torque & power in order to overcome the greater winding resistance and back-EMF.

ElectricGod said:

At no load, Delta at any RPM will require more current than WYE. In my tests at barely creeping along my motor in WYE used less than an amp and soon went up to 3 amps all the way to WOT. On delta, it took 3 amps just to get turning and soon jumped to 9 amps all the way to WOT.

Click to expand...

Who cares if it's 3A or 3 x 1.73 = 5.2A (not sure why you measured 9A)? Current is not a measure of power, and the power absorbed in both cases would be the same. Phase current is also not a measure of battery current. You could produce hundreds of phase amps at low speed while drawing a handful of amps from the battery.

Click to expand...

Watch my videos...I posted several in my thread. I clearly show I have a watt meter inline with the battery and motor controller and I clearly state that in wye, I get X amps draw and in delta I get Y amps draw. All I have to do is switch from wye to delta and current jumps. Amps is a measure of current flow through a system. Volts is a measurement of voltage applied to a system. Watts is volts times amps. So if I am running at 48 or 82 volts like in my videos and that remains constant, BUT amps triple when I switch to delta, that also means watts consumed to do the exact same amount of work also goes up. In my case since I was just bench testing the motor under no load...the "work" was just turning the motor. So go ahead and say I'm wrong until you are blue in the face. You're not helping by offering criticism. How about offer actual help instead. If you noticed, I wrote loads of stuff to help out a noob. You on the other hand said he was wrong and then said I was wrong. LOL! I'm just going to posit that I was just a tiny bit more helpful in that one post than you have ever been in any post I have ever read in my thread or this one. Anyway, my observed results are that delta on the exact same motor at the exact same voltage at the exact same throttle position consumes significantly more current than does WYE. Even at WOT on WYE I still only pulled 3 amps. In Delta at nearly any throttle position I pulled more like 9 amps. So go ahead and say that wye and delta are going to use the same wattage, but I'm going to point out the observed facts and tell you that's not true.

Addressing these items specifically. I don't know what your educational background is, but mine is electrical engineering. I might, possibly know one or two things about electronics.

1. Does not reduce motor heating
More current as compared to less current in a given electrical system will create more heat than does less current. If you don't believe me, take a 1 megohm resistor and put it across a 3S LIPO pack...that's about .001 micro amps. Now replace that with a 1 ohm resistor. It probably started glowing red hot in a couple of seconds before it burned out because it has 11+ amps flowing through it. More current through a given electrical system is going to generate more heat. If a motor in WYE draws 3 battery amps and in delta it draws 9 battery amps, that is going to create more heat.)
2. Does not change efficiency of the motor
Efficiency...ugg...yes you are right when we are being technical about what efficiency in a BLDC motor really means. However in my example, I was referring to observed current used so how about not take what I said out of context.
3. Does not make the motor "better" or "more economical"
Observed results are 3 amps in WYE and 9 amps in delta while doing the same amount of work on the same voltage...I beg to differ with you on this.
4. Does not reduce the load on the battery
Ummm...3 amps vs 9 amps...that sounds like a 3X difference in load.
5. Does not affect the runtime of the battery
So lets do some basic math. I have a 24 ah battery pack. if I draw 3 amps from that battery pack how long will it take to run it down? This isn't even hard...8 hours. So now I draw 9 amps from that same battery pack...ummm...2.666 hours. That sure looks like a HUGE difference in battery run time. Specifically 1/3 as much run time.

and then this comment...and about phase current

"If you want to run in wye for reduced phase current then you *must* increase voltage by the same amount to deliver the same torque & power in order to overcome the greater winding resistance and back-EMF."

I was running at the exact same voltage and seeing 3X the battery current draw in delta over what I was seeing in WYE. These are the hard numbers that matter to the battery pack. Phase current can be whatever it wants to be, that has no impact on the hard numbers the battery pack sees. So, from a very practical perspective, a watt meter inline between the battery pack and the motor controller tells you exactly how much current the battery pack is seeing. In all of my examples I referred to battery current, not phase current. This guy is new at this stuff, why confuse him with the finer details when he doesn't understand the broad strokes? Again...not at all helpful. And onto phase winding resistance. Lets pretend our motor has 1ohm per winding. In WYE or delta you are always driving two windings at the same time. In WYE that's effectively (ish) 2 windings in series...so 2 ohms. In delta that's effectively 2 windings in parallel or .5 ohms. Hmmmm check that out! See my response to number 1 above...so delta does heat up the motor more. A motor phase is essentially a really high wattage, very low resistance resistor. So a 2 ohm resistor will have less current flowing through it than will a .5 ohm resistor. And yes I know motors don't typically have 1 ohm windings and that motor physics are a bit more complicated than this. I am making a practical and admittedly somewhat misleading example. For the noobs out there who are still struggling with WYE vs delta...good enough example. In either wye or delta...it's a really small amount of resistance, but delta ought to pull around 2X+ the battery current of WYE while doing the same amount of work. Oh and yes...I am aware of WYE and delta calculations in a circuit and I was deliberately NOT going there to keep things simple for the noobs.

ElectricGod said:

3. Does not make the motor "better" or "more economical"
Observed results are 3 amps in WYE and 9 amps in delta while doing the same amount of work on the same voltage...I beg to differ with you on this.

Click to expand...

Lets say for argument sake that in WYE efficiency is 85%, use any figure you like the argument is the same, then your data shows that at that operating point efficiency drops to ~ 28% in delta. Alarm bells ringing? Something seriously amiss, recirculating currents or inappropriate hall sensor placement for delta configuration comes to mind. You will find threads somewhere on ES where hall sensor placement had to be changed for successful wye/delta switching to work. There is no 3 orders of magnitude efficiency gain between wye/delta. Delta/wye switching all else being equal changes the power transfer function of the motor not the efficiency. With the advent of affordable FOC controllers a similar outcome can be achieved with field weakening albeit with a hit on efficiency.

kiwifiat said:

ElectricGod said:

3. Does not make the motor "better" or "more economical"
Observed results are 3 amps in WYE and 9 amps in delta while doing the same amount of work on the same voltage...I beg to differ with you on this.

Click to expand...

Lets say for argument sake that in WYE efficiency is 85%, use any figure you like the argument is the same, then your data shows that at that operating point efficiency drops to ~ 28% in delta. Alarm bells ringing? Something seriously amiss, recirculating currents or inappropriate hall sensor placement for delta configuration comes to mind. You will find threads somewhere on ES where hall sensor placement had to be changed for successful wye/delta switching to work. There is no 3 orders of magnitude efficiency gain between wye/delta. Delta/wye switching all else being equal changes the power transfer function of the motor not the efficiency. With the advent of affordable FOC controllers a similar outcome can be achieved with field weakening albeit with a hit on efficiency.

Click to expand...

If you come across that thread where halls need to be switched too, post it here please. This is not something I have read about. Sure it could be possible. I have no ego to bruise not do I need to be right or to cover for my mistakes if any are made. If I'm wrong some how...so be it. I'll post my findings either way. Anyone that has attempted to figure out what phases go with what halls has seen that there are 2 forward and 2 reverse combinations that work and two of them draw extra current. This is true for wye or delta wired motors. It is possible that when switching from WYE to delta that I then get the inefficient hall phase combination. My assumption is that since the phases are the same that if I got it to work in WYE with the halls for the efficient combination that it is the same combination for delta. So...yeah find that thread. I certainly don't know everything.

KiwiFiat is right. Rolling a bike along a flat road and constant speed with constant wind requires a predictable power input. If changing from wye-delta gives you a change in power measurement that is extraordinary (you know the current change should be sq. root of 3 = ~1.7) the then this should be a red flag that causes you to check your experiment and your measurements.

All your assertions about reduced motor heating, load on the battery and longer run-time are all based on the faulty notion that delta uses 3x more power (and is 3x less efficient) to do the same work. Sanity check required.

The line current in a wye configuration is reduced, it has to be, because the line resistance is increased. If you make a winding effectively longer you can't stuff as much current down it before burning it up! The whole thing nicely balances out, exactly the same as slow wind/fast wind argument.

I don't doubt you're trying to be helpful, but confidently passing on bad or faulty information to people looking to learn is not helpful no matter how good your intentions.

In simple ("broad strokes" as you say), changing from delta to wye and expecting the motor to do the same job:

Increases voltage by 1.7 (decreased Kv by 1.7)
Decreases current by 1.7 (increased Kt by 1.7)

Everything else stays the same: efficiency, motor heating, motor power capacity (peak and constant), battery load, battery run-time.

If something seems to depart from that basic principle then something weird is going on and needs checking out.

Check out the rating plate on a dual voltage 3-phase induction motor if you like - you'll see the voltage and current change, but the speed, power, efficiency and power factor all stay the same. It's the same motor with the same windings made of the same amount of copper, just connected differently, no magic occurring!

Punx0r,

I reported my results based on what I was doing and what I knew and my assumptions. If there is something wrong, the below little bit of text is my first clue and it's not even from you. This is where offering suggestions rather than saying "you are wrong" is way more helpful. You never questioned my setup or asked about it or even mentioned anything about the possibility of a different hall set up in WYE vs delta. "You are wrong" is not helpful. Neither is refuting my results without actual reasons why my results are biased in some way. Imputing the watt meter is wrong or that I'm an idiot helps no one. All I did was look at the watt meter and read what it displayed. This was not a meter fault or user error reading the watt meter. It displays what it displays. What you claimed was how it should be and what I am seeing diverged completely. Next time around you decide to "help" someone, how about rather than criticize their results or them, instead explain why they are not doing the correct thing or explain why what they are saying is wrong. "You are wrong" is a statement of arrogance and not of help. IF...this is merely an incorrect hall placement, that's super easy to rearrange. So my intentions aside...stop criticizing me and actually offer help instead...like below. At least this comment wasn't critical, but rather gave me pause to think if there are other possibilities. You failed completely in this regard. I personally prefer to be partly wrong and not be a jerk than to be right and cram my superiority down everyone's throat like you did. If I find that what I posted earlier is incorrect, I'll be sure to post those corrections and say that I was wrong and here are the reasons why. Can you say you would do that? I doubt it.

From KiwiFiat: (a total noob as far as posts on ES are concerned) BTW...thanks for suggesting this. It didn't cross my mind that this was even a possible issue.
"inappropriate hall sensor placement for delta configuration comes to mind. You will find threads somewhere on ES where hall sensor placement had to be changed for successful wye/delta switching to work"

Taking 3x more current to get the motor turning doesn't sound right to me either. Something else must be going on.

Yes, in most cases you need to re-position the hall sensors when switching from delta to wye. If you used a sensorless controller, you would not have this issue. This could explain the 3x higher current. It would be great to test the motor delta vs. wye using a sensorless controller.

ElectricGod said:

kiwifiat said:

ElectricGod said:

3. Does not make the motor "better" or "more economical"
Observed results are 3 amps in WYE and 9 amps in delta while doing the same amount of work on the same voltage...I beg to differ with you on this.

Click to expand...

Lets say for argument sake that in WYE efficiency is 85%, use any figure you like the argument is the same, then your data shows that at that operating point efficiency drops to ~ 28% in delta. Alarm bells ringing? Something seriously amiss, recirculating currents or inappropriate hall sensor placement for delta configuration comes to mind. You will find threads somewhere on ES where hall sensor placement had to be changed for successful wye/delta switching to work. There is no 3 orders of magnitude efficiency gain between wye/delta. Delta/wye switching all else being equal changes the power transfer function of the motor not the efficiency. With the advent of affordable FOC controllers a similar outcome can be achieved with field weakening albeit with a hit on efficiency.

Click to expand...

If you come across that thread where halls need to be switched too, post it here please. This is not something I have read about. Sure it could be possible. I have no ego to bruise not do I need to be right or to cover for my mistakes if any are made. If I'm wrong some how...so be it. I'll post my findings either way. Anyone that has attempted to figure out what phases go with what halls has seen that there are 2 forward and 2 reverse combinations that work and two of them draw extra current. This is true for wye or delta wired motors. It is possible that when switching from WYE to delta that I then get the inefficient hall phase combination. My assumption is that since the phases are the same that if I got it to work in WYE with the halls for the efficient combination that it is the same combination for delta. So...yeah find that thread. I certainly don't know everything.

Click to expand...

The issue comes up in this thread https://endless-sphere.com/forums/viewtopic.php?f=30&t=15686 and others. ES does have a search function. BTW post count is no guide to education,experience, or knowledge.

I agree. The only person I've seen on this forum made a deal out of post count is EG.

EG, your reasoning is quite a piece of work. You wouldn't accept you might be wrong before (and attacked me, questioned by attitude & competence and waved around your EE qualification), now you're having to climb down, you're butt-hurt and still I'm wrong - it's my fault somehow for not informing you in just the right way.

I am not an expert in these matters (or claimed to be, although you clearly inferred that I was claiming so). I'm not familiar with your setup and I did not consider that your hall sensors might need moving. I tip my cap to KiwiFiat and Fetcher here.

All I saw was you making a fundamental error in clear contravention of basic theory and flagged it up. I didn't know how exactly you'd gone wrong or how to fix it (I'm neither that clever nor a mind-reader). You might prefer me to have just kept quiet (not that I could have known that) and let you carry on oblivious, but this is a public forum, so uncorrected or unchallenged mistakes have the potential to mislead current and future readers. Remember that you resisted any discussion of your claims about wye-delta switching in your project thread as Off-Topic and so this thread was created because I wouldn't leave it alone. Without this thread you'd probably have ended up running the motor with grossly miss-timed halls, excessive phase current and possibly have burned it up as a result. Don't shoot the messenger?

Punx0r said:

I agree. The only person I've seen on this forum made a deal out of post count is EG.

EG, your reasoning is quite a piece of work. You wouldn't accept you might be wrong before (and attacked me, questioned by attitude & competence and waved around your EE qualification), now you're having to climb down, you're butt-hurt and still I'm wrong - it's my fault somehow for not informing you in just the right way.

I am not an expert in these matters (or claimed to be, although you clearly inferred that I was claiming so). I'm not familiar with your setup and I did not consider that your hall sensors might need moving. I tip my cap to KiwiFiat and Fetcher here.

All I saw was you making a fundamental error in clear contravention of basic theory and flagged it up. I didn't know how exactly you'd gone wrong or how to fix it (I'm neither that clever nor a mind-reader). You might prefer me to have just kept quiet (not that I could have known that) and let you carry on oblivious, but this is a public forum, so uncorrected or unchallenged mistakes have the potential to mislead current and future readers. Remember that you resisted any discussion of your claims about wye-delta switching in your project thread as Off-Topic and so this thread was created because I wouldn't leave it alone. Without this thread you'd probably have ended up running the motor with grossly miss-timed halls, excessive phase current and possibly have burned it up as a result. Don't shoot the messenger?

Click to expand...

You're not helping. Your ego has been bruised and now your mad. LOL..get over it already. Read into what I wrote how ever you want. I don't care. No ego here...just stating what I was observing and how it didn''t match with what you were saying. If you can't handle that, that's on you. Your comments about being wrong are not helpful and now you're imputing things about me that are not there either. I posted based on my OBSERVED RESULTS. If I find out that I had an incorrect phase/hall combination that is causing the increased current draw, I will post it here. I really don't care that I may have made mistake. That's part of the learning experience. Edison when asked how he felt about failing to make a light bulb 200 times replied that he didn't fail, that instead he had LEARNED 200 ways to NOT make a light bulb. LOL...I'm not the expert on everything and have never said that I am. If anything, I pointed out that I'm not an idiot...aka EE degree. Anyway, it will probably be this weekend once I get things set up again to try out new hall/phase configurations without the relay. I have loads of 5.5mm bullets so I am going to solder them together to make up three 3-way bullet connections so that I can use them for WYE and delta. Since all 6 phase ends are exterior and separate and have 5.5mm bullets on them, it will be fairly easy to eliminate the relay and connect together the phase ends in any way that I can imagine. My goal will be to connect in wye first without the relay and see if I get the 3 amp load again. Then I will reconfigure in delta and mess with the hall combinations until I get 3 amps load again...if that happens...well I will post those new results here and that will be that. No ego, no need to be right, no need to hide some mistake. LOL...just the facts...just the observed facts...whatever they are. I could care less if I made a mistake or was misinformed...LOL...that's part of the learning experience...one way to not make a WYE/delta switch over.

Since KiwiFiat posted the possibility of hall/phase mismatch first. I hope that you are right and thanks for the tip in the right direction. I did not consider the possibility that switching to delta may also include changing the hall combination too. I hadn't read it anywhere and did search the ES threads before ever doing this experiment. I have no problem being wrong, but if I post results that don't match what others have seen or expect, I want to know why and you may have given me that reason. More to come. Thanks again for the idea.

In my WYE/delta thread, once I figure this out, I will give step by step instructions so that there is at least one place ES that has it all in a single place with out having to read post after post after post and then possibly miss something in the process. My final set up, if there is a problem with it right now will get corrected and I will post the correct way to do this on that thread and here too.

ElectricGod said:

You're not helping. Your ego has been bruised and now your mad. LOL..get over it already. Read into what I wrote how ever you want. I don't care. No ego here...just stating what I was observing and how it didn''t match with what you were saying. If you can't handle that, that's on you.

Click to expand...

Yeah, OK. You called me a "FUDder" for stating basic electrical theory, reminded us you'd been an EE for 20 years and weren't "some wet behind the ears kid", then when you were proved wrong claimed I was wrong for being mean about it, when I'd actually been quite polite. Arguing on the internet is sad, but I'm not going refuse to defend myself.

Seems this thread is about done...

Punx0r said:

ElectricGod said:

You're not helping. Your ego has been bruised and now your mad. LOL..get over it already. Read into what I wrote how ever you want. I don't care. No ego here...just stating what I was observing and how it didn''t match with what you were saying. If you can't handle that, that's on you.

Click to expand...

Yeah, OK. You called me a "FUDder" for stating basic electrical theory, reminded us you'd been an EE for 20 years and weren't "some wet behind the ears kid", then when you were proved wrong claimed I was wrong for being mean about it, when I'd actually been quite polite. Arguing on the internet is sad, but I'm not going refuse to defend myself.

Seems this thread is about done...

Click to expand...

For anyone who doesn't know what FUD is...
Fear, Uncertainty and Disillusionment

Anyone who who says to me "your wrong or you can't do that or that's a bad idea" and yet has no insights to offer...just "your wrong and you can't do that"...well they are a FUDder in my book.

Anyway, this is still all about your ego...let it go man and move on. Thanks for NOT being helpful at all. Cheers! I do really hope that this thread in your mind is done so that you will stop the FUD.

I'm still going to post my results based on the clue that I may have hall/phase issues. I personally want to figure this out...if there really is an issue.

Let's not cry over who said what and put what where, apologies have been made errors admitted, we all try our best to add valid information to the site for others it's not always correct we are human now let's shake hands or beg to differ EG has added a fair amount of good information on here so correct him is fine but to discredit him and attack him is childish it doesn't belong on this forum were all adults let's act like it.

Hall position is calculated by the controller normally 120°or 60° programable or self learn, The halls are situated in between phases for even number pole counts like the big block rather than in the centre of a phase for an uneven pole count, the circuit board with the halls floats in between the phases so if they are off just a fraction it will retard or advanced a phase, when switching to delta it maybe exaggerating this effect with increased hysteresis in the laminations from the added inductivity creating a larger emf

Switching between the two on the fly with relays is a bad idea the rating under load means you need three heavy duty 100amp winch relays really, and the larger motors tend to have a lot of momentum and decent weight to give the magnets enough force for nasty as hell reverse spikes with lots of potency, when the relays trigger too the sparking action created can cause more damage too, the caps take a lot of shit filtering this crap out.

I've seen bldc generators use a loaf of bread shaped magnet so when spun it creates a sineasoidal wave form rather than flat magnets creating a square or trapiz shape, just thought I'd chuck that one in for free.

I am no expert on Wye / Delta. However the problem for me right now concerning this thread is that there is some useful information mixed in with personal attacks. Do I remove mocking and contentious statements while leaving the contested technical info in that post? Do I remove an entire post because there is one sentence that is OT?

OT personal contention would likely be moved to the "toxic" section, rather than deleted, and yet...is it really so hard to argue and counter-argue the technical info in a civil manner?

It's amazing the consistency with which those who pull out their education and experience card are wrong on this forum. From what I've seen it's exactly 100%, since those who know what they are talking about such as Punx0r and others don't need that crutch to support their arguments.

The same stator, magnets, and amount of copper means it's the same motor regardless of how it's wound or terminated. That means identical performance limits and efficiency with the only requirement being a different (but equal) combination of current and voltage to achieve the identical result. If these aren't changed in the correct proportion for the comparison, then you get an apples and oranges result.

Apples and oranges results can be useful if you're locked into a specific controller or voltage, but no overall conclusions can be drawn about winding counts or how they are terminated. Even with nothing changed (identical controller and settings, same battery pack and SOC, same gearing and wheel, etc), the differences in results when comparing Delta vs WYE can be misleading, because a controller typically behaves differently driving the same motor due to driving current into a different resistance and inductance.

A perfect example of this is one of the very few who still utilize Delta/WYE switching. Recumpence builds extreme power ebikes. He switches to the slower speed termination for more tame riding, with smoother takeoffs and lower speed. This flies in the face of the idea that the lower Kv termination has more torque, which would make launches more brutal. This is because the controller behaves very differently.

The bottom line is that the stator steel and magnetic circuit design of a motor set it's rpm and torque (power) limits. The amount of total copper fit onto the stator is a big factor in efficiency, but how many turns on the stator teeth and how the ends are terminated determines only the voltage and current combination to get to the same optimum.

Applause
Thanks too John cr for a very well worded basic explination.

That's why when doing a rewind some try to squeeze a little more copper in and tweek the wind to get a slightly higher rated power and manipulate the voltage, current, kv to the design needs. If there's room for more copper then there's room for more performance be it as a slower wind with more turns for a high voltage motor if the laminations are upto the job or added phase meat for higher current handling it's all a juggling act but thumbs up to John cr.