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@johnpublicprofile6261

4 ай бұрын

What language? *Klingon* 😊

@jazzybeat28

4 ай бұрын

Distracting add. Do you really need to do this?

@jamarforsythe7262

4 ай бұрын

@@jazzybeat28 how about you pay them for the content they publish for free so that they don't ever need to do another ad. You act like you can't simply skip that part...

@zodiacfml

4 ай бұрын

@eat28 ads are fine if it is relevant to the topic or industry but this... it feels low like there is something wrong with Munro

@zodiacfml

4 ай бұрын

Lucid has a better video on hair pin motors, Munro should have watched that and just regurgitated what is in there. Skin Effect from what I remember is only significant frequencies. Electric motors don't have high frequencies, frequencies are just around the RPMs of the motor. The one huge advantage of hair pin also was not mentioned here

Another EXCELLENT video aimed at the ‘semi-geek’ for EV technology. Thank you for making understanding THE priority.

@sillystuff6247

4 ай бұрын

Paul Turnbull is one heckuva good teacher. No wasted words. Focuses on the important interesting facts & ideas.

@irri4662

4 ай бұрын

Indeed

@PaulTurnbull-EMfield

4 ай бұрын

@@sillystuff6247 Thank you!

@skippityblippity8656

4 ай бұрын

I heckin love soyence

As a former physics teacher I think you gave an excellent explanation of what is going on inside of an electric motor. I especially liked the way you explained back EMF 👍

@PaulTurnbull-EMfield

4 ай бұрын

Thank you!

I think this was one take. Impressive. Thank you for your service!

@MunroLive

4 ай бұрын

Thank you very much!

Twenty minutes well spent! Great video

@MunroLive

4 ай бұрын

Awesome, thank you!

The best explanation of skin effect I have ever heard. Thank you

@MunroLive

4 ай бұрын

You're so welcome!

2 things you don't mention about AC winding losses: first, the reduction to 1/3rd at skin depth, there is also a PHASE SHIFT in the current, being retarded about 60° at one skin depth, & this reduction in amplitude & phase shift continues as you move inward. But there is a second effect when a bunch of wires carrying current in the same direction are packed together. There is a loss which makes the resistance rise TO THE 4TH POWER OF THE FREQUENCY. This is because of the magnetic field in SURROUNDING conductors. Butterworth wrote about this in the 1930's as it applied to wound radio antennas, & showed that cheap radios, having antenna coils wound with thinner wire, actually performed better than the antennas in the expensive radios. I ran into this when working with Rockwell International making magnetic bubble memories in the 1980's, which have 2 quadrature driving coils (like 2-phase motor). Rockwell's coils used 1mm x 1mm square wire & had 3 times the loss of my 28-strand coils of the came cross-section. Another thing about bar-wound coils. Most of the stock for these are made from existing round wire, rolled square AFTER INSULATING & heat-treating. The copper is overworked & this raises resistivity. The wire needs to be brought to the same state in cold-working as round wire, but manufacturers selling square wire don't do that. Does Tesla have enough "pull" to get manufacturers to properly heat-treat wire BEFORE insulating?

@PaulTurnbull-EMfield

4 ай бұрын

This comment is a great example of what I love about the Munro Live community. Thanks for sharing this great information. You will be happy to learn that the copper wire suppliers have responded to the dramatic increase in square wire demand from auto manufacturers (not just Tesla) by producing new square wire products.

@nc3826

4 ай бұрын

Fascinating Comment.... Why not form the bar out of heat treated strands, by drawing the strands through a bar-shaped die? And if needed heat treat the entire bar again? And possibly with a lamination of the wires? The metallurgical nature of the copper does seem to be a relatively important factor that wasn't focused on in the post?

@andrewashmore8000

4 ай бұрын

wow super detailed insight. thanks

@wtmayhew

4 ай бұрын

Excellent comment. I was thinking Litz wire, which is multi strand woven wire with individually insulated strands. New England Wire Company has been manufacturing Litz wire in the US since at least 1920. The oldest reference I know dates from 1898, so knowledge of skin effect is not new. Historically, motors have not had to resort to exotic stator winding wire because AC current was at most a few hundred Hz frequency. Radio engineers started winding coils in receiving sets and transmitters with Litz wire to help prevent losses in the coils. Keeping the effective resistance of the coil low improves Q, the sharpness of resonance, and helps reject adjacent stations. If you want to find some litz wire, it is sometimes used in transformers of switch mode power supplies of mobile phone chargers, etc. If you disassemble a wireless Qi phone charger, the coupling coil is often made with Litz wire. If you read the Wikipedia article on Litz wire, the author mentions the antenna tuning coil of radio station WWVB, which operates at 60 KHz, has a 19 mm diameter conductor made of 6075 strands of #36 magnet wire. WWVB is the US time standard station which transmits signals to keep “atomic” wrist watches and wall clocks in sync with correct time. EV motors are directly coupled via a fixed ratio reduction gear set in the final drive without a multi ratio transmission. This means that EV motor rotors are turning many thousands of RPM at highway speed and hence need excitation currents which could be in the tens of KHz range. A washing machine motor designer can almost disregard skin effect because at 50 or 60 Hz, skin depth is 7.6 mm, which is more than the typical conductor cross section. At 10 KHz is cold worked copper, skin depth is about 0.3 mm.

@nathanieljames7462

4 ай бұрын

So there should be an annealling process between the forming and insulating processes, then? Thank for explaining the phase shifting relative to the skin effect. Didn't know that was a thing but makes sense that it is.

Great video and fantastic explanation of "skin effect"

@MunroLive

4 ай бұрын

Glad you liked it!

@matthewbeasley7765

3 ай бұрын

@@MunroLive Yep, one of the best explanations without diving into the math. I'd love to hear you delve into proximity effect ;-) I don't think proximity is as important in motor. I've never done motor design, just high frequency magnetics where proximity effect is huge.

Master class in science communication, Paul absolutely knocked it out of the park here. One of my favorite Munro Live videos I've seen. This looked like it was one take as well? Super impressive!

It is one thing to know, another to teach. Fantastic explanation for someone like myself who is not an engineer. Crystal clear!

Excellent video! Only someone who understands their subject very well can explain the engineering with the right amount of simplification. Many thanks. Can you do one comparing permanent magnet vs. induction motors in a similar style please?

@PaulTurnbull-EMfield

4 ай бұрын

Thank you, yes, I'm planning to do my next video comparing permanent magnet motors with induction motors. We see several examples of the two motor technologies appearing in the same car and understanding why can help us learn about how the vehicles are controlled.

@imconsequetau5275

4 ай бұрын

​@@PaulTurnbull-EMfield Please include reluctance motors vs simple PM since Tesla is using that.

Love the low tech flip chart. Very comfortable as a viewer.

@iandavies4853

4 ай бұрын

I didn’t. I’ve no need to see talking head, written chart is worse still, just project the data like PowerPoint. Munro Assoc is old school, not as bad as "After Hours", but old. Who is the audience? I appreciate it (enormously), but no money from me. PS. Content makes this one of the better vids I’ve seen, despite my niggle.

Great explanation. Wish you were my lecturer back in the day!

Very good video! I've worked on RFID coils, and at 100kHz and above you really start to see this effect. We investigated Litz wire, which is multiple stranded wire, but it didn't give us enough advantage to bother with the extra cost. Another issue is that if your cavity has too big of a cross-section, the inside of the cross-section is still affected by the magnetic field the same. This is probably why you see quite thin slots.

@scoutjonas

4 ай бұрын

Well the effect depends on conductor size. In a 70mm2 cable 2kHz will double the resistance... But in your thin antenna coil wire, 100khz might be correct.

@jamesvandamme7786

4 ай бұрын

Switching power supplies in the >100KW range use Litz wire in the active circuit. It looks like welding cable but the strands are insulated. You can get some that strips at soldering temperatures, but the good stuff you need to strip in hot acid.

@InssiAjaton

4 ай бұрын

The talk about frequency where the effect becomes an issue is not quite so simple. Depending what you are doing, you mau have near, or not so near sinusoidal AC current. Among other wave forms, you would consider trapezoidal current and square wave. Of these, the square wave represents a broad range of harmonic frequencies. The faster the slope of rise (and fall) of the change, the higher frequencies appear. With modern semiconductors (Fiel Effect Transistors) you can have 50 kHz base frequency producing one MHz or more harmonic frequencies. That puts the project into a different class from the automotive motor windings of this presentation. I just have personal experience of having to abandon solid copper wire due to scorching heat at 50 kHz coil choke. Litz wire with over 200 insulated strands solved the issue. By the way, we prepare the ends by dipping into molten tin in a Solder Pot.

@ThisRandomUsername

4 ай бұрын

​@@InssiAjatonThanks for that, I completely missed the fact that the shape of the waves plays an important role, but it's obvious now. We did not need it because our RFID circuits used an LC tuned circuit with relatively little current flow, so we got a near perfect sine wave. Of course if you think about motors they often use trapezoidal waves, so much more harmonics as you say.

This was especially well presented, relevant, and interesting. More content from Paul would be awesome. Thank you for all your team's work.

@nc3826

4 ай бұрын

Yelp, great teachers make the complex seem simple .

Regarding the AC resistance, the wire wound is not to be looked at as single wires but as a large conductor that is the aggregate of many of the single conductors. As such the skin affect is there like the hairpin wound as a net affect of the many winding's. The magnetic domain is not bound by the enamel covering. Thus the high speed advantage is greatly reduced I think. Great video and content. Some of the best I have seen here.

@_Triple_S_

3 ай бұрын

I was thinking exactly the same while watching the video

@thinkmonkeyman

3 ай бұрын

You’re not taking into account the boundary conditions where the conductors meet the insulator.

@gregbailey45

3 ай бұрын

​@@thinkmonkeymanlooks like it gets awfully complicated awfully quickly!

Happy to finally see the comparison. Like most everything in life, there are tradeoffs. Great video.

Amazing explanation! I didn't even know I didn't know!

@nc3826

4 ай бұрын

“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.“

That was a very well presented subject and helped a lot with the understading of such an interesting matter !

after a short warm up period, the talking got pretty good!

Awesome video! Paul is clearly both very knowledgeable and very passionate, but he's also a natural educator.

Great video. Thank you for explaining the difference between the 2 concepts so even I can understand with my basic knowledge.

This channel is underrated, you guys rock! Thanks for making these videos. I support MunroLive :)

@MunroLive

2 ай бұрын

Much appreciated!

Excellent presentation! Thank you for taking the time to put this together.

I mean, with these videos why do I even need to go to University. Sooooo well explained and most importantly, VERY INTERESTING. Watched the whole video without realizing it was over.

@googacct

4 ай бұрын

Actually what he gives you is an explanation that would be adequate for a technician. The explanation is not sufficient for designing an efficient motor. And for most people that does mean going to college to get the proper training in math, physics and engineering.

@crissd8283

2 ай бұрын

​@@googacctThen after you get your degree, you get a job and the shop tells you, you don't need anything you learned in college. This is the way we build motors so just design them using our normal standard method. We don't need you t9 design anything revolutionary or cutting edge.

Now I will speak only in French to Sandy!!! Well done 👍

@f4c3l355

4 ай бұрын

"Le Audi électrique car est étron"

@gsbeak

4 ай бұрын

@@f4c3l355 étron means dog poop in French... By the way, Sandy has a good accent in French.

@jamesvandamme7786

4 ай бұрын

@@gsbeakHe should, being born a Canuck.

@gregbailey45

3 ай бұрын

​@f4c3l355 hahah!

@jamesvandamme7786

3 ай бұрын

@@f4c3l355 That name is even more clueless than the Chevy No Va.

Thanks for the explanation, Paul -- I learned something today! Cheers

Thanks. Skin effect. Reminds me of when our Electrical Tutor told us as young apprentices that we would laugh when he told us how the early Car Radios produced AC from DC. and proceeded to explain to us youngsters about, "The Vibrator", about 55 years ago.

16:09 a bundle of insulated strands doesn't make the skin effect disappear, it is just the same as a solid wire the same size. Insulated strands is only an advantage if they a woven in way so that they all both equal amount inside and outside of the bundle over the length and share the current better

Omg that was the funniest sponsor mention.Sandy is an engineer so he always looks happy to look at new things and disassemble them but when it was about money and business it's like someone sucked all the joy out of him lol

Very informative and practical accessible information. I think I learn more about batteries and electric motors here than I did in HS classes in a lot less time.

@nc3826

4 ай бұрын

It's easier to concentrate here, since they have such nicer toys.

What's the scrap rate difference? Reliability? Durability? Nice explanation by the way. Another way of explaining is that AC current prefers traveling along the outside edge of the wire while DC travels throughout the entire wire evenly so having more wires increases the ability to carry more AC current efficiently.

@abraxastulammo9940

4 ай бұрын

VW seems to have big production problems with their new APP550 motor. I wonder how many bars they put into one slot. Edit: Seems to be a stack of eight, too.

@dusselElite

4 ай бұрын

​​@@abraxastulammo9940They are also using 8. kzread.info/dash/bejne/gaOD16enY5qel8Y.htmlsi=PHGK3tC8vzFtc_1y&t=955

@PaulTurnbull-EMfield

4 ай бұрын

In my experience bar wound motors are more challenging to launch, but once the process is fully debugged it tends to be more repeatable and reliable than the stranded wound process.

@nc3826

4 ай бұрын

​@@PaulTurnbull-EMfield What do you think about the Ghent University research project on "Semi-Stranded Windings"' Revised: 25 January 2023? Which seems to combine the advantages of both designs? What's the chance do you think it has to make it out of the lab and into production?

@PaulTurnbull-EMfield

4 ай бұрын

@@nc3826 Thanks for highlighting this very promising research. The paper very nicely illustrates the point that I was trying to make with my sketches. It's also nice that the paper isn't behind a paywall and is freely available. Thanks.

Great video and wonderful educational content. I’d like to see more of these videos Sandy!

THANKS PAUL 🤗 AND THE MUNRO TEAM , for explaining this in layperson’s terms 🤔💚💚💚

Motors are confusing, and it's hard to find good info on the _whys_ of the differences in design. This video was an unusually good explanation of the physics and the corresponding effect on design choices. A fine example of someone who really understands their field. Much appreciated. I too look forward to clarification of when induction is chosen and PM vs electromagnets. Later on you might get to aluminium/iron motors maybe?

Amazing detail! Yes, I wanted you to tell me that one is better for the city and one is better for the highway earlier, but I wouldn’t understood it if I didn’t have the full explanation. Thank you

I appreciated this explanation and seeing the difference of the windings. Thank you!

*In a world where many things are “dumbed down” thank you for a decent explanation*

Intresting how nomenclature can vary a bit in different parts of the same field. I work at a shop that repairs electric motors for industrial applications. We generally call them mush wound and formed coils instead of stranded/bar wound. I also found it interesting to see some of the design considerations that go into the manufacturer side vs the repair side. From a repair standpoint stranded is much quicker for us to rewind. A half dozen different adjustable mandrel heads is sufficient for our winders to spin off a full set of coils ready to be stuffed into the slots in an hour. Those few heads work for most motors. Bar wound you need more spcalized jigs that are much more specific to that coil design. Worth it if your only working on a few types of motors or are specialized in making coils but not worth it for one off, bespoke repairs. We normally have to order in new preformed coils from a company that specializes in making them. That greatly impacts repair turn around. Stranded we can start putting in new windings as soon as the stator is striped and cleaned out, bar wound and your looking at at least a week to get the coils ordered, formed, and shiped to us and that's on an expedited schedule. Stranded windings we've had some where we could have the motor back to the customer in a day for an emergency repair.

When I first learned about skin effect, I figured stranded wire would be better for EV motors. But also, thank you for explaining WHY the skin effect happens. This was ultimately very informative and I really appreciate it! Love this channel!

Great educational video. Make more of them please.

I am always so thankful I found this channel. Such GREAT content!!!

Paul is setting a new _bar_ @ munro ... A very motor-vating presentation.

@nc3826

4 ай бұрын

;)

I guess the broader context here is optimizing for specific speed rangers. Many industrial applications want a very high and constant speed so stranded is optimal. Vehicle applications with variable low to moderate speeds (attached to a fixed ratio gearbox) are slow enough that different bar designs can pay off.

@scoutjonas

4 ай бұрын

Weight and motor size is not so important in the industry. It's not the rpms that are important, it's the current frequency. In cars it varies between 0 and 600Hz, but in industrial motors it is fixed at 50 or 60 hz.

@iandavies4853

4 ай бұрын

Esp with Plaid motor passing 20,000 rpm, still having flat power curve. There’s some magic. To think Porsche started with 2-speed gearbox, Jeep still wanting multi speed transmission, same for many legacy semi-trailers.

Thank you, excellent video! Paul's presentation is very clear, I'm looking forward to more videos with him hosting.

50 years later, I finally understand the skin effect! Wouldn't hollow bars save on wasted copper?

The slot fill difference isn't just due to the number of strands and thus the space taken by insulation - rectangular cross-sections of bar windings nicely pack into a rectangular slot, compared to round cross-sections of "stranded" windings... plus the small round wires are not neatly organized into an ideal packing pattern.

Félicitations pour votre français, cher ami ! Merci pour la qualité de vos vidéos. Salutations de 🇨🇵

These are really good videos, the deep dives are just super valuable!

That was a most intriguing expose' on winding vs. hairpin. And you managed to avoid any mention of 'inductance' throughout.

Good job new Paul!

I've been working with electricity for quite a few years.... And every so often I learn something new that reminds me how little I know about it😅

I think I've got it! Very well done/explained, thanks!! Hi Sandy!

This is a great simple explanation of these 2 different type of motor. Lucid uses 8 bar design together with other patent technology to achieve by far the industry leading efficiency.

Congratulations on a fantastic presentation. So well explained in one take! Wow

Wow, just wow. I never thought I would understand physics that easily. You just triggered multiple "Aha"-moments for me. Thank you

Most interesting; I shall have to come back to this when I’m ready for the design stage.

Thanks, this helps me understand back-EMF a lot better than I did before.

Brilliant Video Sir explaining the skin effect. This is why AC transformers use very thin laminations in their construction and why high end loudspeaker cable uses very fine and many conductor strands. So in an ideal world, the windings of an electric motor would be made from "hairpins" constructed from hair thick copper copper strands with enough ductile strength and elasticity to form the hairpins. So extrapolating that idea into a manufacturable component would mean having fine threads with a thick copper wrap, which would allow the manufacture of a bar like construction, with less resistance than the current wire wound. That would maximise the benefits of both. Example: 1mm copper sheet, encasing 1000 strand copper core ( length to be determined by the need to form, say 20% longer). This would allow the outer casing to be press machined to the hairpin and the part trimmed after forming. This would give the best of both worlds. 🙂

Outstanding clarity. Thanks, Paul

Excellent video. Thanks for precise explanation of the difference between wire wound and hair pin stator design

Thanks for teaching us! I just thought all electric motors are extremely efficient and it's the PWM / voltage that was the main driver for differences/sizing. Didn't realize the windings contribute so much. It would be great to see the spec sheet comparisons for two similar motors to understand the real-world effect of the decision, versus and illustrative line. Thanks again, great stuff!!

Real education! Thanks

What a great video and a superb teacher, thank you!

Thank you for explaining this!

Not only CEMF is an issue with AC cutternt/resistance but inreasing Frequency as well.... Good presentation! @ the end of the day nobody gives a hoot as long as the car starts and the lights come on...!

This is a great video. Brought the concepts of these motors to a very understandable level.

I remember being introduced to Skin effect at collage when we had a radar dish donated to us and I questioned why the conductors were all pipes. The maths followed when I went to University... fun times.

Something in this video really hit me. In contrast with modern infographics and animation video, that chartboard and physicals examples maybe your tone and gesture make me feel calm emgage and enjoy watching.

Excellent presentation Paul. Thanks!

Thank you for the video, I did not know about the inverse relationship between the thickness of the hairpin bars and the improve frequency of the motor.

This is so amazing. Absolutely increible! I cant thank you enough.

10:58 This is how I understand AC vs DC resistance - DC uses the entire cross-section of the conductor while AC uses the outer layer of the conductor thus "cramming" the charge into a smaller volume hence more resistance. The reason for the "cramming" is magnetic field being changed to the opposite direction the back emf is like walking through a wave of water pushing against the new polarity forcing it to the outside of the conductor, almost like moving in deep water vs moving through shallow water adding resistance to that smaller volume in the conductor (smaller volume of the conductor for the charge + opposing "wave" = resistance). Yes I'm aware it's a very convoluted explanation it's just a way to visualize it in my head. Although I think people will go for your explanation.

You are a great speaker, thanks for the quality information and insight you gave us!

Excellent Explaination ! Thanks !

Thank you for the depth

Keep these vids coming !!!❤

What a knowledable guy, and what an interesting topic. Fantastic video guys!

Loved this! Thanks, Paul!

I learn something new today! Thank you for the great video! ⚡️

This is a great explanation of electric motors for cars. It's absolutely amazing that century old technology is almost as good as the present day. As mentioned in other comments, I am asking for a comparison between permanent magnet and induction motors.

VERY GOOD explanation! AWESOME!

Excellent explanation! Much appreciated, thank you!

Insightful video. Thank you!

@MunroLive

4 ай бұрын

Glad it was helpful!

Electromagnetic theory and motor design was my favourite subject. In the real world, outside cars, it's basically induction motors and VFDsthese days. I do work on a a pair of large DC Wound Rotor Motors, 383KW. We measure and replace brushes periodically. We are considering a new AC system with very wide stators and rotors that eliminate the need for gearboxes. I fear that these will prove less reliable than our old ABB monsters in our tropical environment. Excellent presentation. Thanks.

@joeabad5908

4 ай бұрын

You will be surprised and love the New reliable AC motors with VFD..

@yuglesstube

4 ай бұрын

@@joeabad5908 Thanks for your reply. What about their applicability in hot and humid conditions? ThesenoldbDC machines are amazingly reliable. Can these new systems equal that, in your opinion?

@imconsequetau5275

4 ай бұрын

The AC motors are just as reliable, if not better, but without the carbon brush replacement downtime. However, the VFD electronics reliability will depend greatly on the choices made by each manufacturer. Besides knowing their MTBF, you should look closely at how well the PCB surfaces are passivated after soldering and whether every connector is water-tight and pre-filled with silicone grease. I _personally_ prefer air-tight electronics enclosures ever since my one encounter with an air-cooled super-minicomputer contaminated with conductive metal dust. (*shudder*) The 500 Amp DC super minicomputer power connector that I serviced had gold plated copper stud, nut, and multilayer PCB interface. I re-torqued the gold plated PCB nut 6 months into service, 500 Amps live. No joke.

@yuglesstube

4 ай бұрын

@imconsequetau5275 That's interesting. One of our guys.forgot to replace a brush in the rack. It was connected to the frame and when switched on, it basically blew up leaving a black mark that's still there today.

10:02 The AC "resistance" (actually, impedance) is so high in "bar" or "hairpin" windings that the motor driver (VFD) does not need significant modifications of voltage output or current capacity. Also, since the DC resistance is far lower, the I²R loss is proportionately lower, thus increasing _range._ When you factor in Tesla's use of the reluctance PM rotor core, the efficiency is first class.

Great explanation! Very informative!

Thank you very much for another greatly insightful presentation of the current tech in motors used in BEV's

Nice primer. This part really is the heart of the subject.

Great explanation, thanks Paul. Thanks Sandy, your channel is invaluable.

I have been rewinding motors since the early 70s, Bar wound, winding have been around very long time, going way back to the beginning of electric motors. The only difference being is that bar wound were mainly (95%) we're in the winding of rotors and armatures. Not the stairs, however they were still used in states as well in very large equipment.

Thanks. So well explained I understood.

Fantastic video with clear and well spoken explanation! And no filler words whatsoever! Excellent. Please have the younger presenters at Munro Live watch and learn from the older guys (who speak so much better)! Thanks.

Excellent! Thanks for the great explanation.

Thanks for making these amazing educational videos

Good information, answered many of my questions about motors. Only feedback is get rid of the yums.

Awesome explanation of the difference between bar and wire wound motors - fascinating!....

No one on earth better than Munro!

Great video I have a better understanding!!

Very well explained, thank you for your efforts.