Brushless Motor For my EV

Discussion in 'The Projects Forum' started by GodF@ther, Apr 15, 2012.

  1. GodF@ther

    Thread Starter New Member

    Apr 15, 2012
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    Good Day to You all

    I Have a little problem;I was planing to build my own bl-dc motor for my Ev:p But Due to the high cost of thr Indudtrial BLDC i plained to make my own bldc from an Ac Motor Stator.
    Key features of the motor are
    -High initial torque
    -Great efficiency(so I am using A in runner based architecture)
    -High voltage operation of 48v

    For my initial start I got A Ac Motor Stator That is to be rewinded to work for my New Bldc;But I have no idea how to make the star connection winding over the stator...Its a 38 tooth based stator I think it kinda good for my bldc.

    Can any one please help me
     
  2. Experimentonomen

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    Feb 16, 2011
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    I believe this falls under the TOS "Automotive modifications" which is not allowed on this forum due to safety concerns.
     
  3. Kermit2

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    Feb 5, 2010
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    I believe it would actually be ELECTRIC MOTOR/GENERATOR modifications.

    The eagerness with which some members see 'forbidden' topics in innocent posts here confounds and confuses me. Human nature reduced to its most basic bad habit-condemnation without justification!

    Here ya go http://www.thebackshed.com/windmill/assembly1.asp
     
  4. shortbus

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    Sep 30, 2009
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    @ Godf@ther I was going to do the same thing, but instead of changing the original wiring connections I was going to totally rewire. The reason I gave up on the idea was the magnets for the rotor. You need the magnets to have a radius that matches the diameter of the rotor. The neo magnets are very dangerous to grind! The must be ground because they are too brittle and hard to do any other way. And a diamond grinding wheel is the only kind that will hold up to them.

    The neo magnets also have to be plated or e-poxy coated to keep them from rusting. In all just too much work for the outcome. Good luck if you go ahead with the project. And keep us informed on your progress.
     
  5. Kermit2

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    The solution is a magnet with a preformed center hole perforation designed for a screw to go through and secure them. You will need to place a soft steel "cap" on the magnet, drilled to match the perforation location and size, then secure the two together with epoxy AND a screw. The steel cap is what will be machined to the proper radius for clearing the stator, and the magnet need not be touched.

    see here for ideas http://www.kjmagnetics.com/products.asp?cat=173
     
  6. GodF@ther

    Thread Starter New Member

    Apr 15, 2012
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    @Shortbus @Kermit2 Thank you for the rotor based help;But can You help me to totally recoil the stator;I.e do help me rewind the rotor that is to be used to run at 48v dc
     
  7. Kermit2

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    Feb 5, 2010
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    That would require a physical presence. Did you not understand the information at the site I linked? You must use math and calculate the needed resistance of the coils, including the size of the wire, it's length and the number of turns. It is possible that the space available for winding the coils will either be to large or too small due to the fact the motor was originally designed and its size and shape optimized for a different voltage
     
  8. praondevou

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  9. shortbus

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    @Kermit2 - Wish I'd thought of that, before investing in my choice of a project

    @Godf@ther - I'm pretty sure (from my research) that the motor has to be rewound. An AC motor is base on a sinusoidal electric wave form an uses a winding for that type of wave. A BLDC motor uses a square wave for its windings and the sine wave winding doesn't match. A BLDC motor uses what are called "salient poles".

    How big and what type motor are you starting with? What horse power are you hoping to get out of it?
     
  10. GodF@ther

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    Apr 15, 2012
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    I might Opt to get about 2 to 3 Hp from this motor and after making my prototype i would make my own 20HP motor for sure.......
     
  11. GodF@ther

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    Apr 15, 2012
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    Please add up some suggestion
     
  12. shortbus

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    OK, hope you like to research - http://electrathonoftampabay.org/www/Documents/Motors/Brushless%20DC%20(BLDC)%20Motor%20Fundamentals.pdf

    http://web.mit.edu/scolton/www/SCThG.pdf

    http://www.instructables.com/id/Mak...otor/step13/Fabrication-notes-and-Conclusion/

    http://www.insightautomation.cc/resources/literature/Motorized Roller Primer.pdf

    http://www.instructables.com/id/How-to-build-a-hub-electric-bike-motor/

    http://www.flyelectric.ukgateway.net/motors.htm

    The motor you posted pictures of doesn't look like a good candidate for conversion. It looks to be a fractional HP single phase motor. With the "skewed" rotor segments it won't work good when machined for the magnets. If you've never rewound a stator before, you would be better off trying to make an "out-runner" style from a ceiling fan to start off with. Easier to wind the stator poles on that type motor. The last link has a lot of information on figuring the windings for that type motor.
     
  13. GodF@ther

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    Apr 15, 2012
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    Can any one please tell me how to wind a Y toplogy based 3 phase winding into my 36 tooth stator(INRUNNER)
     
  14. cork_ie

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    Oct 8, 2011
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    Whether you wire it STAR or DELTA is entirely dependant on the number of turns and the voltage you are using. You will still have 6 free ends , 2 from each phase , for a Y (STAR) configuration you will join one end of each phase together to form a neutral point.
    For the actual winding sequence you can use either lap (series) or wave (parallel) winding Google it and you will learn the differences.
    I would recommend you read the following Doc 10 times before you start to avoid weeks of frustration.
    http://www.indiastudychannel.com/attachments/Resources/127639-231211-AC_lap_single_full.doc
    Finally you should be able to pick up a 48V induction traction motor from a scrapped electric Fork Lift Truck. Most of the older generation were DC brush motors thyristor controlled but many of the more modern models are using AC induction motors.
    Good luck.
     
  15. GodF@ther

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    Apr 15, 2012
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    cork_ie :-> The type of winding that has been used in a bldc are like; a single teeth is been winded like a solenoid and they are connected externally to the other coils
     
  16. strantor

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  17. cork_ie

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    Oct 8, 2011
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    Yes I know the comparison referred to in the previous link doesn't exactly apply for the winding sequences as it applies to a polyphase AC motor. The principals however are exactly the same, apart from the winding sequences. Whether the coils are connected internally or externally isn't really your issue, you still end up with 3 Phases. I don't know if you are using synchronous or trapezoidal. If you start with 36 slots (teeth) then you will have 12 slots per phase and the winding sequence will depend on the number of poles you are using. I would try and use a ABCabcABC winding sequence for simplicity, use the calculators in the link given by Strantor above. In the end of the day a free end of each of the 3 separate phases needs to be joined together into a common neutral point. You will need to calculate the direction of the windings & (hence the direction of the magnetic fields) from "Fleming's lefthand rule" Have a look at tables 3 and 4 of this doc by Microchip on BLDC motors for phase sequences. It is a small file and also contains a lot of very useful info.
    http://ww1.microchip.com/downloads/en/AppNotes/00885a.pdf.
    Good luck in your project
     
    Last edited: May 5, 2012
  18. shortbus

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    Before you worry about the stator winding you need to decide on the number of magnets you will be using. The number of magnets will then determine how many of the 36 stator slots will get wound. The rotor like the stator has to have the poles (N and S) opposite each other. The links I have given you will give you many ideas about how to do it, if you read them.

    Like I said before, an in-runner made from an induction motor is not the easiest way for a first time rewind. A ceiling fan motor is a much easier one to do.

    Have you done the calculations on wire size yet? Have you worked out the magnets so the "air gap" is as small as possible? The air gap is where the real power is made in the motor, too large and it isn't efficient and too small it will rub.
     
  19. shortbus

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    @GodF@ther, you do know you can make a brush-less motor with no magnets at all, right? They are called "switched reluctance motors". The latest Prius uses this type of motor. And could be made from an induction motor, but has to be one without a skewed rotor. They take the same controller as the BLDC motor.
     
  20. wayneh

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    Sep 9, 2010
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    I've done a LOT of calculations in this area and it all comes down to choosing a wire gauge for your winding. There are tables of properties of copper wire available from the manufacturers, eg. Essex. From the properties (diameter, insulation thickness, etc.) you can calculate turns, length, resistance and so on, even inductance with the Wheeler formulae. Then, you have to allow for the fact that a human cannot wind perfectly. In a given volume, you'll get less turns and use more wire than the calculated ideal. For thin wire, I've seen an estimate of human winding efficiency versus machine. Can't recall the value.

    I shudder at the idea of this winding project. I've hand wound simple toroids and even that is a tedious chore.
     
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