Page 4 : Cores and Coils 蕊心與線圈

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原文: http://www.totallyamped.net/adams/page4.html

在探討其他更多的電路之前，讓我們來探討一下線圈。畢竟，在脈衝線圈馬達 (pulsed coil motor) 中，沒有線圈，就沒有“馬達”！ 而且 "簡而言之"，在討論線圈的設計時，也沒有 "簡而言之"。 Especially when we are talking about pulsed motors, and even more importantly when we are talking about open magnetic system pulsed motors. Throw into the mix different requirements, e.g low speed high torque, high speed low torque etc, and the party really gets cranking! Coils! who's got coils?

在討論 "Adams" 馬達時，最重要的是要瞭解 "Adams" 馬達 (and for that matter, a "Bedini" motor)與其他所謂的傳統脈衝馬達(而且隨處可見! - 想想你的電腦硬碟是怎樣轉動的?) 之間只有一個主要的差別，就是磁路(magnetic circuit)。在傳統的系統中，磁路或磁場(magnetic "circuit" or "field ")是封閉的。在某種意義上，它幾乎是短路的，只有轉子和定子之間的空氣間隙提供很小程度的磁絕緣，否則便是封閉磁系統。

The logic behind this has always been two fold. One is the assumption that, by bending the flux from the rear of the magnet or coil by way of metallic form work, (the side of the magnet not directly facing the coil and vice verse) to an area where it will be productive, this will increase overall torque. Which it definitely does (usually in well designed systems). But at a price!! (the reasons for which I will elaborate much later on.)

The other assumption is that by using a closed magnetic system, the imperfections in the system, such as sparking brushes (which are common in series wound motors used for most work tools), will not create undue RF interference, because the Closed Magnetic System allows the entire motor to be encased in an iron shroud without affecting its performance, and it is effectively encased in a "Faraday Cage". This is also a good thing for this very reason alone.

Imagine if every brush driven electric drill, saw, etc, were not effectively shielded to some degree by their inherent design. I know some cheap brands on the market, and they are not sufficiently shielded, but from my inspection of the goods, I dont think they will last long enough to be a persistent RF problem!

After many years of experimenting with "Adams" motors, I can say two things for certain. An Open Magnetic System acts and reacts differently to a Closed Magnetic System and "Adams" motors/generators are a challenge to design for a specific purpose, because, by their very nature, they are "Dynamic". Dynamic in the sense, that, by varying just one parameter of an operating motor, all other parameters change in response. As such, their behaviour is not "Linear" but instead conforms to a set of rules drawn from existing electrodynamic laws, but exhibit anomolous results just the same. The Anomolous Behaviour of Open Magnetic Systems is, I believe, an area of ElectroMagnetic Theory which needs some serious investigation, research and rethinking.

If you persist long enough with your "Adams" motors, I personally still doubt that you will ever achieve overunity (I'm quite skeptical in fact! - Please prove me wrong!), but you will definitely witness certain phenomena which are not covered in your average Technicians text book. And yes, I will discuss at great length, in another page, an anomoly which can be put to good use. Now lets talk cores and coils! Because thats where all the goodness happens!

在下面的 Fig 9，是兩種不同類型蕊心的示意圖。下面將參照 Fig 9 來說明這兩種不同類型蕊心的相關細節。.

在上面的 Fig 9 中，紅色的圖代表實心軟鐵心 (solid soft iron core)。 圖中還包括放大的前視圖。在圖的周圍有綠色的線。實心鐵心旁邊的藍色的圖代表平面軟鐵的堆疊或 "疊片(Laminating)" 長條製造的蕊心。 The green lines are representative of the fact, that when a magnet is constantly passing in front of the end of the cores, electric currents are set up within the cores themnselves. These currents are called Eddy Currents. They can be running in more than one direction at a time. They can run from one end of the core to the other, and they can run around the circumference of the iron material. According to accepted electrical theory, these Eddy Currents reduce the efficiency of the coil as both a transmitter and recevier of power via directed induction, by interfering with the preferred induction path. I agree.

However it is also accepted electrical theory, that these eddy currents can be minimised by using laminated plates. Notice on the lower right of Fig 9 I have shown a blow up of the iron strips (which are all covered in an insulating film) and an area titled "Neutralising Area". Theory says that ordinarily large Eddy Currents which may be produced in solid cores, can be reduced by laminating, because by laminating you break up singular large eddy currents into numerous smaller ones, and also, these then counteract each others influence due to the oppositional fields they produce. Effectively they self cancel as indicated by the arrows facing in opposite directions in the area between the two plates. I also agree. Please Note, that the solid red circular iron core, could be made into a type of laminated core, by substituting a single large core, with muliple smaller diameter cores (e.g soft iron nails), packed into the same area.

From my agreement to the above two statements regarding eddy currents you might be thinking, AHAH, so I should use laminated cores for my coils then! Well lets just talk a little bit more about coils/cores and what makes one better than the other, depending on requirement.

First, what about air cored coils? They have no iron content at all! And do not suffer from eddy current problems!. So maybe I should use those. Well maybe, maybe not. You see, no matter which coil core you use, there will be an upside and a downside. See the Table Below for a quick rundown on the pros and cons of each sort.

所以，綜合上述的優缺點，使用那一種線圈蕊心來驅動馬達會有最佳的效率呢? 還有，那一種適合用來當獨立的發電機線圈呢? -- 答案揭曉 = 以上皆非! It's a trick question really because there's one (or more) core/s. I hadn't mentioned. But one in particular. Its a Hollow Iron Core, or much more specifically in a generalised sort of way (LOL!) Its a Hollow Iron Alloy Core. And the best thing is, the perfect piece of metal and core design are already easily available from any Hardware and Building Supplies. They are common and are manufactured by a number of companies all over the world. 你在說啥? when you look at Fig 10 below, so read beneath Fig 10 for a further explanation of these cores, for both energising and generating purposes.

上面 Fig 10 的是一般常見的壁錨 (masonry anchor，俗稱壁虎) 的相片，附帶有特製合金做的外鞘 (outer sheath)，雖然我不知道合金的成分，但是我知道這合金可以做什麼! I tried on numerous occasions to get details of the composition of the alloy, so I could get some specific cores custom made from it, but you'd think I was trying to extract a good tooth from a dentist! Stonewalled for no real known reason. But no matter, I didn't chase it too hard, and if you want to, you can chase up that information yourself. The ones I used were marketed as "Ramset" and I got them from Mitre10 Hardware (Australia). 我非常確定他們是依據國際標準規範來製造的，以符合一般建築業使用上的需求。我知道他們是某一類的合金，比軟鐵稍微輕一些，但具有較高的剛性。我猜測是鐵、錫、和鎳的混合物所製成的。 順帶一提，你不需要螺帽和螺栓! 但是這些東西可以用在其他地方，所以也別扔掉!

那麼，這種中空鐵合金和他們的外形有什麼特別之處呢? 好吧，我會發現這合金的獨特的磁性的特性和已經具有的外形，純粹是意外的發現。 Well actually I have to put a bit of "stubbornness" into the picture as well. 不論如何，這正是 "需要為發明之母 (necessity is the mother of invention)"。 I had decided during one set of experiments that I wanted to try a hollow iron core, based on the idea, that 90% plus of the induction from the core to the coils happened in the outermost region of the core, because changing magnetic fields would take the path of least resistance and follow the "skin" of the core. Much the same as electrons follow the skin of a conductor in greater numbers than the centre. 在我要做實驗的時候，和我想像中的中空鐵心有點像的東西，我可以找到就只有房屋修繕剩下的壁錨的外鞘。

Thank goodness for the luck of the Irish! Serendipity Rules! I used them initially as generator pickup cores and went WOW, thats Reeeeeally Freaky! I spent the next 10 months investigating every aspect of the cores with their precut shape. This particular core type will be referred to again later on and its unique qualities explained in greater detail. I will also explain in detail the previous "anomoly" I mentioned that can be used to advantage, but I will reserve that for much later down the track. For now I will stick to some conventional theory and concentrate on cores and coils. It's early days yet before we start exploring "anomolies".!

現在你會注意到，在上面 Fig 10 中的其中兩個外鞘，有一段纏繞著膠帶，註記著 "Area of maximum Magnetic influence in an open Magnetic system"。 I have to assume somewhere along the line that you've made your rotor, and you are mounting your coil in front of the rotor. In an open magnetic system, the bloch wall of the magnetic interaction will shift from the magnets own center to a point between its own center and the centre of the influenced body. That is, the coil core. See Fig 11 below. The bloch wall is the neutral point in a magnet and always lies at the centre of the magnet unless influenced by another magnetic/reactive body.

在上面的 Fig 11 中，有兩個中空合金鐵心，上面繞的線圈是一樣的。當它們接近磁鐵時，會它們自己變成磁鐵，並且形成它們自己的 bloch wall。 This induced bloch wall wants to establish itself near the centre of the core, with its own South pole facing the North pole of the magnet, and its own North pole facing away from the magnet . Coil A has a long core and is wound in what is known as Heel End Slug Configuration. Coil B is on the same hollow core material, but it has been cut down to the same length as the coil winding. A standard practice in most cases.

比較 Coil A 和 Coil B，各有那些優缺點呢?

嗯，這就得看你的需求囉。假如你用 Coil B 當做驅動線圈，會稍微好一些，可以傳遞稍微大一點的可用轉矩，因為它的 inductive reactance 較低 (因為它的 core material 較少)。但是假如你要做發電機的拾取線圈，那麼 Coil A 遠為更佳。因為 Coil A 的鐵心的 bloch wall 延伸到超出線圈繞線區以外的地方，而 Coil B 的 bloch wall 最多只延伸到線圈繞線區的一半。 In both instances the bloch wall tries to extend towards the middle of the core as normal.. But because the core in Coil A is long, then more of the coil is exposed to the "same magnetic polarity" of the induced magnetism of the core. The voltage produced by Coil A will be significantly higher than Coil B though the maximum current availability will be almost the same into a given low impedance load. The higher voltage stems from 2 influences. The greater amount of coil windings appearing on the "same side of the induced bloch wall" in Coil A, and the greater inductive reactance caused by the extra metal in Coil A which is not present in Coil B.

Now what about those core shapes? Whats so special?. Fig 12 below shows the sheaths exposed for analysis. See below Fig 12 for explanation.

還記得渦流嗎? 功率變壓器和電感 (inductor) 設計者的剋星! An analysis of the pre-formed shapes of these cores, reveals that they have their own built in Eddy Current Suppression. The slotting and cut out areas form "skin paths" for counter running eddy currents to cancel each other out. Neat Hey! Its like using laminates, but without the hassle of bundling the plates together. And if you're winding your coils directly onto the sheaths (with a paper insulation wrapped onto the sheath first), their round shape makes winding easy. In fact the nut and bolt that you shouldn't have thrown away can be used as part of the jig you create to wind your coils!

On top of that, the alloy itself has high permeability, low magnetic retention, resists oxidation, and is cheap and easy to source. The hollow alloy core is more efficient than a solid core or laminated core in translating magnetic induction in the core to useful electrical output from the coil. It has the advantage of a solid core, in that it produces a high permeability environment for maximum induction, creates a strong magnetic field not prone to distortion, yet it offers considerably less magnetic drag and a higher electron yield per unit of core mass than a soft iron solid core or laminated core.

Summary: The hollow alloy core achieves this superior translation through 3 main causes. 1.) The "skin effect" which concentrates the magnetic flux into a region which is very close to the actual coil windings. 2.) The actual core material has superior magnetic coercian and induction properties to that of soft iron alone. 3.) The core structure minimizes rampant Eddy Currents, thus maximising positive induction potential. This makes it suitable for use with high torque motor designs, and also for generator designs**

POSTNOTE----- December 4, 2007 *---------------------------------------------------------------------------------*

Now I must say, that I like/d using these Hollow Alloy Cores, but they are not the holy grail of cores, and have operating parameter limitations as do all cores. What I particularly liked about using them, was the learning curve that came from observing their performance as pick-up coils. Below is an update of this page which is an extract from Overunity.com and concerns a question and statement made by another forum member aimed at this subject. The question and answer will be relevant (hopefully) to your own expectations and hence designs.

Question from sanmankl

@HopToad

..............

I've been doing some adam motor setups previously and today, after winding a new coil onto an anchor boot sleeve (1 layer of #23 wire to a 3/8" sleeve), the current draw to start up was high and it remains high. Killed my TIP122 in the process. Everything is running hot! Too high current draw.

So, my question is what's the windings for your coil? I'd tried 4 layer and it's still high. My guess is multi-layer windings to at least 5 ohms?

My answer :

@sanmankl

Sorry to hear to you're having the dreaded burn-out problems! You've actually highlighted the need for me to expand on the information regarding this sort of core. After all, I gave plenty of good reasons why I liked and used it, but like all other core types, it has its limitations which must be taken into account and a downside when limitations are exceeded!

Firstly the 3/8 " diameter hollow core (you didn't specify length, but no matter), will be a very low impedance core which will saturate very quickly. That in itself is not really an issue, but if you are using the cores for drive coils, the characteristics for the drive coil will be closer to an air core, than a solid core in terms of impedance. This will mean using lighter gauge wire and more windings to achieve a higher resistance/impedance if you don't want to suffer more burn-outs. Also you could go to a slightly higher diameter sleeve as well, e.g, 1/2 inch (10mm ID, 12 MM OD), and it will help to increase impedance.

If you are only using one coil, then indeed you will need to wind many more turns of the same gauge, but it will probably be more practical to wind more turns with a lighter gauge. BTW I've never bought wire on the basis of gauge, because imperial and metric gauges are different and I can never remember either of them. DOH! So I always look for and refer to the wire diameter. e.g: .63mm .4mm .32mm etc.

The more coils that you use in series, as drivers, the higher the total inductive reactance will be. In my experiments with these particular cores, I used no less than 2 coils in series, and up to 8 coils in some setups, because they are very low impedence cores. But not as low as air cores, and therefore not requiring anywhere near the number of turns as an air core. In other words, they are a good compromise between air cores and solid or laminated cores, in terms of the number of coil winds required to achieve a given inductance and hence inductive reactance.

Your problems with using this core type may partly lie in the diameter and mass of your rotor. (I don't know anything about your rotor). The smaller the diameter, the higher the speed and the larger the diameter the lower the speed, generally speaking of course! High speed means high frequency, which means higher inductive reactance, which means less current.

My Rotor consisted of eight x (10mm x 6 mm) Neo Magnets arranged in North South Configuration in very tight proximity to each other. I used the Dual Pole not the Mono Pole arrangement, to allow for more experiment parameters. Its Diameter is 65 mm, its made from high temperature resistant epoxy resin and fine lathed to the thickness of the rotor magnets. I used a planar rotor assembly with a precison Hard Drive bearing and brass rotor axle.

My drive cores were (8mm ID, 10mm OD) x 45 mm Length). The coils consisted of .3mm transformer wire x 250 turns. The length of coil turning on core was 15 mm. Coils wound in heel end style. Approx diameter of coils (on core) 20 mm. DC Resistance less than 1 ohm. Drive circuit consisted of Flip Flop MOSFET circuit based on page 3, figs 7+ 8 combined with precision optical switching as shown in fig 28 on page 9. Optimum duty cycle 20%.

At 12.6V rotor speed approximated 8,000 RPM with 2 coils at 400ma; 6000 RPM with 4 Coils at 120 ma; and 4500 RPM with 8 coils at 30ma. (BTW all the above numbers are from memory - it's nearly 6 years ago now since I played with these motors!) If your rotor is a larger diameter, these sorts of speeds will not be reached, and therefore frequency will be lower and impedance will be lower, and current will be greater.

@sanmankl

The real benefit with these cores lies in their use as pick-up coils rather than as drivers, but they will still be suitable as drivers if you bear in mind that they are inherently low impedence, and you may need to compensate by increasing total coil impedance by methods just discussed.....

I hope this info helps you.

Cheers from the Toad who Hops

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