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Electric Motors Winding and Repair Electric Motors Winding and Repair Discussion


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Old 03-07-2021, 08:14 AM   #1 (permalink)
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Default Pyro 700 rewind for lower kv

Hi all, I am going to rewind a pyro 700 for approx 450kv. There are a couple ways to do this.
A delta with same wire as stock and add 2 turns for a total of 13.
The other option is to do a star with 8 turns per group and be a little lower at 430kv roughly. The copper increase will be significant with this.

What other options are there? What would you suggest?


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Old 03-08-2021, 01:56 PM   #2 (permalink)
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Hi apostolosnt,
I think its is courageously cool, and am very interested, that you are considering new winding ideas for your kontronics pyro 700. Can you tell me a little more about the setup as far as what type of drive you are using and if the setup is greater than 12s. What type of flying do you do? What was the exact oem model of you pyro when u first purchased it? Did you measure any of its motor parameters in stock form?

TIA,
Hubert

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Old 03-08-2021, 04:07 PM   #3 (permalink)
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Hi Hubert,
It's a hobby so yeh I am always interested in improving and learning and trying new things. This motor will go on a modified Logo 600SE which sports my own design and built carbon-Alu frame. It is 12S. Now I use a 5020 wye at 445kv with 1.9mm wire but i need to change the gearing.
I am more of an engineer than pilot! So my style is sport but I can do 3d moves just not really clean!
The pyro was a 700-52 and I recorded basic data stock. In the past I have rewound the same model for friends so I also have the data from two yy configurations.
I flew one of them on a tdr rigid and it was a very good motor.
From looking at how to wind D-Y, the wiring management will need care. Maybe I will do the three D to Y connections outside the motor case to allow better air flow inside but I will see what room there is once the wires are in.

Apostolos

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Old 03-20-2021, 04:41 PM   #4 (permalink)
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OK. So I had the time today to finish this motor as per 1Boho recommendation for a delta-wye wind.

First I wanted to show the state of the motor when I bought it used. For some reason the owner was putting a lot of oil trying to lubricate the bearing! The sheath had become like a sticky blob! Horrible



Of course it was all cleaned and new bearings put in place.
The wind was fairly easy with 1.20mm wire for the 7 turn detla and 4 turn stators.
Termination is a little complex here since there are three star points but it all fit inside the motor.
I was expecting this to be more complex since there were a lot of cross overs and the three internal star points. Here it is half way.







and here is the finished motor looking in at the termination side where things were tight!



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Old 03-20-2021, 04:47 PM   #5 (permalink)
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The most interesting part of course is the performance. There is a small problem with the rotor being unbalanced and so produces vibration and I will take it for proper balancing before I put it on heli but it is OK for the bench results.
Here is a full table of data of all the Pyuro 700 winds I have done and the data. What really stands out is the very low Io of this motor (no. 3 in the table).
Can't wait to get this balanced and on a heli! I expect very low temps and great performance on 12S. Let's see






Correction to the above table, stock Pyro is 1.06mm wire
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Old 03-21-2021, 12:34 AM   #6 (permalink)
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Congratulations! The slowest motor Looks great! and has more room for further optimization
Lower Kv with less turns is truly promising. Try to get the phase impendence comparisons with the other winds. Nevertheless If you have a plane propeller that will load them to a thousand watts u can make some real operational temperature comparisons between them if you still have a control motor for the test. You can measure can temperature with an IR and put the dmm's temperature probe on the windings. From here you can see how it will take a little fine tuning on sizing to get your Cu fill back. Winding is the best teacher you see in a real attempt that the wind is not that complicated. If it is a single wye to delta then u also have the parallel wyes and deltas for you next motors. For the HK 5020 Im working out the best mix of wire gauges to optimize the series connection and Cu fill.

Watching with great interest.

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Old 03-21-2021, 10:55 AM   #7 (permalink)
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Actually copper fill is not bad. Certainly better than stock. But I used 1.20 so it easy to use do. The same pattern can be done with 1.25 or 1.32mm.
There is enough empty space in the slots. Here is a close up. A good winder maybe even 1.40mm??




The other pyro 70-0 winds on the table were for friends so I can;t make more measurements, I just kept the baic info after finishing the motor.
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Old 03-21-2021, 04:01 PM   #8 (permalink)
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Took the time to balance this motor. I cannot believe the mass it took to get to a good point! I have never seen a rotor this badly unbalaced. Usually I start with some thick tape on the outside and when I find the spot I add the mass internally . I was at it for more than half hour untill I realised that it will take a lotmore than pieces of tape. So it was all done internally! Long process to remove the can and add/remove mass to get it right. The final vibration vector is almost 4 times smaller than the initial one. Very smooth at max RPM on 6S (~9600RPM).






Now the interesting part: After balancing Io dropped to 1.39Amps and kv up to 425!
It makes sense though since the very bad vibration absorbs energy from the system. Has anyone else experienced this?
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Old 03-21-2021, 08:41 PM   #9 (permalink)
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Pretty

Absolutely of course bad vibrations rob power in many ways. Multiple layer winds shifted 30 degrees forward of the base wind then 30 degrees backwards help mitigate stator modal vibrations which rob efficiency and generate noise. The winds are more complicated and require more planning for fit and terminations. They create a interval slot like distribution of the phase windings where teeth share coils from different phases. The execution of single coil winding system helps. What you end up with is a 6 channel delta or wye motor. With the single coil wound and terminated 180 degree hi lo configurations winders could easily terminated right at the coil with female bullets and provide a high current parallel delta single layer with more equally matched lines paths from the inverter. Extreme builders can shave away the unnecessary parts of the carrier and run heavy phase wire in parallel paths. This would also accommodate large dual flexible cables to the inverter for each phase. This way the motor is more flexible and can be driven several different ways. It can be run with one inverter two matched inverters, but it can also be driven six phase or in an open ended configuration. However the delta can be finished under most OEM hoods the same way forming what I call the kings crown with six solder points. This is soldered to the wye ends and you only be left with the six starts on the wye to form 2 conductor "UVW" motor terminals which can be pulled to one notch to exit traditionally shown on the hobby forums. Very easy. BTW What bearings did you use in replacing the factories?[/CENTER]

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Old 06-01-2021, 10:58 AM   #10 (permalink)
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So the pyro with the D-Y winding using 1.2mm on all turns has been on the heli for a couple months and I flew it for maybe 25-30 flights. I never got around to making a motor stall bench to test under controlled conditions. The motor bogs on hard manouvers and does not feel it has a lot of power. Not sure why that is. The overall setup is well optimized with the ESC being in a good PWM range and the amps absorbed are not over the top for the ESC.
The second trial in this is now to use the motor with a standard Wye, near the same kv and see how it performs and then to wind it D-Y again with 1.15mm on the D and 1.5mm on the Y to potentially handle the currents better.

The Wye winding with 1.5mm was more difficult than I expected. The wire I have is quite stiff and not easy to work with and doing a continuous Wye scheme needed some good planning of the sequence of winding. Threading with stiff wire is no fun so it took some thinking!
Here is the result (not the pretiest wind but it works well ).


Some basic data: kv 420 RPM/V, Io = 1.2 A @ 23.4V.
There is good space for air flow in the stator so I expect this to run cool as well.


This is on my heli now and I will be running this for maybe two months to see how it performs before I change it (again )



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Old 06-02-2021, 10:04 AM   #11 (permalink)
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There's no reason to expect it to run better if you have the wye and delta connected in parallel. The zero order circulating currents will increase copper loss. If anything a better optimization of copper cross section and wire diameters should yield better results. Truly stalling the motor requires more esc than you likely have. You need to do parallel delta and wye winds for the lowest resistance. When you do this the ratios change. Read thoroughly Dr. Dorells works in that regard. This is also why Davids crown and single coil winding facilitate a Y - D better. Try a 1.15 ratio. For easy comparison with a standard wind use a load like a prop that pulls 1 kw and run it for set amount of time observe any differences in operational temperature thrust per amperage delivery etc. For real comparisons you need a control. The heli test environment isn't a truly controlled one even though u may draw some good conclusions there..

Regards
Hubert
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Old 06-03-2021, 12:04 PM   #12 (permalink)
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I am not doing a Y-Δ. This is a simple Wye that I am trying now and then I will re-do the Δ-Υ with different wires to see if there is a limiting factor in the Y side wire cross section. In earlier posts you had mentioned that it should not affect things but I am just wondering if it does.
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Old 06-03-2021, 12:23 PM   #13 (permalink)
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A wye motor with open ended coil ends feed the delta motor terminals. The right wind is wye-delta....not delta to wye. If you set the ratios correctly there should not be any issues. I suggest again that you review Dr Dorell's work. I also suggest that you take measurements an gather all the parameters of each contestant so you can run them through calculators to make further comparisons. If you move too fast things will get confusing.

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Old 06-04-2021, 02:07 PM   #14 (permalink)
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Hi apostolosnt,

If I were you id take some phase resistance measurements of your machines. Of your rewound motors you Y-D has the least copper cross section in the slot. Take time to get that closer to the other winds. If you take the time to gather the phase resistance date then you can compare in a virtually controlled environment for fair comparisons.

Rm = volts/amps To measure it you can use the 4 wire method. U need to measure Kv , Idle current , and phase resistance.
Anyone that wont post these constants doesn't really want you to have a look at their motors for comparison in calculators.

Regards
Hubert
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