Author Topic: Zubbly Diary Repost PART #1 induction conversion process August 14, 2004, 09:  (Read 9043 times)

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Offline tomw

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This is a repost of a diary Zubbly originally posted on Fieldlines.com forum on August 14, 2004, 09:15:19 am.

I know he would want this archived for posterity so here goes:

Induction Conversion Process..

Hello everyone!


I promised a little while back that i would make a posting with more explanation on how to make the magnet cage, use round magnets, use existing winding and what the best windings are to use. also an explanation on how to design a complete winding if you wish to do so.


This post is rather long with many photos and diagrams, but i am sure you will have a good understanding of the process after viewing the all of the posts.


I have just completed another conversion from a 2 hp 4 pole 3 phase for my brother. So i shall use some of the photos from it.


The first part we will deal with is what motor to select for using existing windings, and how to modify them or not.


In Canada the most common industrial low voltage motors we use are 575 volt 3 phase, however 230/460 volt motors are quite common and the most common in the USA to my knowledge. These motors have from the factory 9 leads which allow you to use either a single circuit 460 volt connection or a double circuiut parallel 230 volt connection.


The most common winding that manufacturers use for this 1&2 circuit winding is of the Y connection. However, with a little operation to the winding and adding 3 more leads, you can have a 1&2 circuit alternator with both Y and Delta capability. This really gives you a lot more possibilities for cut in voltage and current carrying capability. You have to remove the lacing that is around the winding on the connection end, locate the internal "Y" point, brake the connection and add 3 more leads. The numbers which you give to these leads are as follows.


use #7 lead and trace to which wire from Y point has a circuit, call this lead #10

use #8 lead "   "     "     "     "       "                     call this lead #11

use #9 lead "   "     "     "     "       "                     call this lead #12


you now have a 12 lead motor which will correspond to the connections in this

diagram.




The most common winding being used today ( up to about 10 HP ) is a concentric winding, 4 pole, 36 stator slots, with a total of 6 groups of 3 coils per group, 18 coils in all. This winding having 2 coil groups per phase, produces 2 poles per coil group, and is connected in a consequent pole fashion.


Here is a lay out of the mentioned winding that corresponds to the connection diagram in the last photo.





another diagram showing the winding lay out with phase markings and showing the lamination set.





here is a diagram showing the lamination set layed out flat with one coil group installed





here is a picture of a completed winding i did on the 2 Hp showing the spans of the 12-10-8 winding. Note that only 3 leads have been brought out of this winding as it is designed to give cut in voltage of 14 volts using a 2 Delta connection at 200 rpm.





This is just the first part of a few posts into my diary that i hope you will enjoy.


zubbly


Sadly, the photos are not on the local server so I will try to remedy that.

Tom
Do NOT mistake me for any kind of "expert".

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24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

Offline tomw

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Zubbly Diary Repost PART #2 induction conversion process August 14, 2004
« Reply #1 on: March 02, 2012, 11:56:11 PM »
1
User Diaries REPOST/ PART #2 Induction conversion
 zubbly on August 14, 2004, 11:41:44 am »
 OK, here we are gonna deal with mainly the process of converting the rotor to a permanent magnet rotor. We will be using multiple magnets to form each pole and they will be held in place with what i call a magnet cage. I will refer to different diagrams of the rotor as well as the stator to get the point across as to how the process effects the rotor and also the stator.


first we have a look at how the magnets match with the stator winding we learned of in part #1.


here is a diagram showing how the magnet would normaly sit in position with the winding but without any skew. without a skew, the cogging force is very strong and makes start up very difficult.





here is how the magnetic pole pieces should sit with "skew" which will in most cases completely or nearly completely eliminate the cogging effect. Complete elimination can be acheived with a one piece magnet cut with a skew ( but i have never seen a magnet offered like this )





here is another diagram showing how all 4 magnet poles would line up with just one phase of the three phase winding




I will now explain best i can on how to construct your permanent magnet rotor. the methods i use works well for me and i have achieved excellent results using it. i chose to use round magnets for the simple reason it is easier to make a round hole that will be basically leak proof when you pour in the resin to bond all together. Yes, square or rectangular magnets would be a more effective magnet pole, but i have not put much effort into making this process simple with square magnets.


here is a diagram showing where to get the proper measurement for the width of the magnetic pole. the length of it is simply the length of the stator lamination set.




we will use the 2 hp i have just done for an example. it required a magnetic pole piece 3 7/8 inches long by 2 inches wide. i made the pole with 21 magnets per pole, total 84 magnets, 4 poles in all. i used 3 rows of 7 magnets, 1/2 inch round by 3/8 inch thick.


here is a pick of it





the length of the cage should be approx 1/2 - 3/4 inch longer on each end of the magnets. basically it overlapps somewhat onto the aluminum end rings of the rotor. the diamater of the cage should be approx 3/16-1/4 inch smaller than the original diamater of the rotor. it will end up just under the outer edge of the magnets. the actual thickness of the cage will be about 1/16 of an inch. the larger the cage and the longer the magnets, you may increase the thickness of the cage more. after you figure out the diamater and length of the cage, you will use a piece of platic pipe ( ABS, PVC ) for the inside diamater of the cage. turn down in a lathe the diamater of the pipe if you must and sand smooth. i then use a release agent all over the pipe, or you can use one layer of wax paper to cover the pipe. you then build up layers of fibre glass cloth approx one inch longer on each end more than what you will need and keep wrapping layers until the thickness is a little more than what you need. you then machine the layered pipe in a lathe until the fibre glass is at the diamater that you need. then cut to length between both ends of the cage and twist the cage off the pipe. you now have your cage ready to mark out for the mags and drilling.


here is a pic





for a four pole, 36 slot stator, you will want to skew the magnets by 10 degrees, or 1 stator slot. cut out a piece of cardboard the same diamater as the cage from a cerial box, use a protractor to mark 0 degrees, 10 degrees, 90 degrees, 180 degrees, and 270 degrees. then transfer the marks to one end of the cage. use a square and draw a line from the 10 degree mark to the other side of the cage. on that side of the cage, place the cardboard with the 0 degree mark on the 10 degree mark transfered from the other side. now mark out the 0,90,180 and 270 degree marks. now use a straight edge from one 0 mark on one side to the other 0 mark on the other side of the cage. do this with the rest of the angle marks. you now have the centre of the four poles marked out ready to be used to lay out the pattern of the magnets.


heres a pic





another pic with respect to the whole rotor




here is a simple to make aid for properly centering and drilling the holes in the magnet cage





the rotor must be turned down, and you must decide on the width and length of the mags. basically, you want to use the longest mags possible. as an example, i will use the 2 hp i just made. i used 3 rows of 1/2 wide mags to make the 2 inch wide pole piece. the two outside rows will be 2 inches apart on the outside with the third row in the middle of the other two. that leaves 1/4 inch between the 3 rows. but take note that they will be much closer together and almost touching where they sit on the turned down rotor. i suggest you draw to scale on a paper and make sure that all will fit before machining the rotor down.


there is another consideration you must take into account before machining the rotor. if you take one of your mags and sit it on the laminations of the stator right at the edge, you will see a very small gap that must be added to the total of the rotor material removal. 


here is a pic





the original measurement of the diamater of the rotor should be done with a micrometer.

we will assume a 4 inch rotor for calculations of how much to remove.


3/8 inch long magnet times 2 ( 2 sides of the rotor ) ---.75   inches

gap between magnet and laminations .o27 inch times 2  ---.054  inches

magnets not sitting square on rotor do too

improper drilling and other inconsistancies           ---.025

                                                         _

                                                  TOTAL  .829


                      rotor----4.000  inch

                      minus     .829

                             ____

    Turn rotor diamater too:   3.171  inch


here is a pic of the turned down rotor, magnet cage, and magnets ready to be installed.




sit the rotor on the inside of the cage and insert a couple of mags into the ends of each pole. the mags will be snug fit, and you will have to adjust the centering of the cage on the rotor so that the mags lay between the aluminum end rings and that the rotor is in the centre of the cage. be sure that each pole is of the opposite polarity to the next beside it and that all mags in each pole are of the same polarity. the magnet poles will be N,S,N,S..one little trick i do is to put all the mags together in the form of a bar without any of the packing spacers that they come with. i then use the bar to get a grip to push each magnet into place. i then slide the bar onto the next hole in the same row and at the same time push down and to the side to get the next one in. it takes a little practice, but you will get used to it quickley.


here is an end view of the rotor, cage, and mags installed showing the spacing of the mags on the rotor and where the cage sits in relation to the rotor and mags











you now have to block or "dam one end of the rotor so that fibre glass resin can be poured into the rotor with out leaking. if you do get a small leak, just keep pouring until the resin sets. try to only pour in one spot as this will let the resin rise from the bottom up and you will not have any air bubbles.


i just cut a ring from some plastic container lid and scotch tape it into place tight against the magnet cage and the aluminum end ring. this seals one end to keep the resin in and is easily removed once the resin is hard.


here are some pics















there you have it, a completed rotor ready to pump out some watts for ya  :)


hope you enjoyed this post on rotor construction. there will be one more post to cover a complete rewind process and how to determine the proper turns from a bare stator to using the existing winding to design the new one from.


zubbly

Again, a REPOST of one of Zubbly's Diaries packed with info.

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

Offline WooferHound

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Offline tomw

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Woof;
Quote
http://greenbits.com/User+Pages/zubbly
Yeah, and you know what is crazy?

I think I helped compile that or a PDF that contained it and I certainly knew about it.

Duh. :D


Thanks for the link. I still want to drag over some other posts of his. But these 3 documents are the real gems and I did it late ..


Tom (it is not Alshiemers but CRS)
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies

Offline WooferHound

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Just look in Zubbly's Project Journal on here.
I think that the Zubbly area should be open to post in so we can move a bunch of stuff in there.
----- W o o f e r h o u n d -----
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Offline tomw

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Just look in Zubbly's Project Journal on here.
I think that the Zubbly area should be open to post in so we can move a bunch of stuff in there.

Now it is just a redirect to greenbits.com.

Not sure how to get it to be a posting area?

Probably make a journal add that as a post in it that and make it writeable?

Tom
Do NOT mistake me for any kind of "expert".

( ͡° ͜ʖ ͡°)


24 Trina 310 watt modules, SMA SunnyBoy 7.7 KW Grid Tie inverter.

I thought that they were angels, but much to my surprise, We climbed aboard their starship and headed for the skies