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Perma-Magnetless Electric Motor

Computer controlled electro-magnets run motor
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[edited: made shorter, changed name after many misunderstood] Motor with only electromagnets on both stator and rotor.

Small low-power embedded computer, controls circuitry of electro-magnet coils in both stator and rotator wheels.

pashute, Oct 19 2007

Nothing to do with hamster wheels. http://en.wikipedia...Squirrel_cage_motor
[AbsintheWithoutLeave, Oct 19 2007]

Brushless dc electric motor http://en.wikipedia...s_DC_electric_motor
some use rotating permanent magnets and an electronically switched set of windings. [Ling, Oct 19 2007]

Wound rotor type http://en.wikipedia...ed_electric_machine
[Ling, Oct 21 2007]

Raser - new tech motor http://www.rasertec..._demonstration.html
seems they may have hit the nail [pashute, Oct 22 2007]

[link]






       Not sure I follow your point (d), but I thought that most modern electric motors are magnetless?
MaxwellBuchanan, Oct 19 2007
  

       Old car starter motors had no permanent magnets, but the stator coils were fixed and always had the current flowing in the same direction, so they are not quite the same as this. It's a good idea, but I would be a little surprised if this didn't already exist.
Srimech, Oct 19 2007
  

       As far as I know, all electric motors have permanent magnets. They rely on physics. Here I want a digitally controlled motor. E.g. The stator can have image markings showing its position, and the chip accordingly decides which coils should work, and at what current.
pashute, Oct 19 2007
  

       //As far as I know, all electric motors have permanent magnets//
So, not very far?
AbsintheWithoutLeave, Oct 19 2007
  

       //As far as I know, all electric motors have permanent magnets//, as AWOL said, not very far then? Most motors are magnetless; coils generate fields on both the rotor and the stator.   

       Magnetless motors use a variety of control systems. Have you heard of stepper motors, for example? In these, the coils are switched stepwise, to turn the motor by a precise amount (eg, 1 fraction of a turn, or certain number of turns). These are very common.
MaxwellBuchanan, Oct 19 2007
  

       pashute, you have perfectly described what is in the link.
Your idea is very good, but someone else got there first.
Ling, Oct 19 2007
  

       Nope ling! No Way! Brushless motors have permanent magnets! Here's a quote from the link you gave: <<In a BLDC motor, the electromagnets do not move; instead, the permanent magnets rotate and the armature remains static>> My motor has NO PERMANENT MAGNETS.
pashute, Oct 21 2007
  

       And Maxwell, the stepper motors work by magnetic attraction to the metal gear (which is similar to having a permanent magnet). Quote from wikipedia: <<Closely related in design to three-phase AC synchronous motors are stepper motors, where an internal rotor containing permanent magnets or a large iron core with salient poles is controlled by a set of external magnets that are switched electronically>>   

       In my case there is no metal nor magnet. Only coils attracting and repelling each other intermittently, controlled electronically.
pashute, Oct 21 2007
  

       OK, I didn't realise you meant no permanent magnets, but I can add a few more links that you might want to check out.   

       The wound rotor link is a rather complex solution, but the second is for a pancake type motor, some versions of which are called printed circuit board motors since the rotor can be a disc with radial conductors: but these come with commutators.   

       Edit: pancake motors are not how I remembered them & are not applicable.
Ling, Oct 21 2007
  

       I don't see how using electro-magnets will improve the functionality, I can't think when you would want to turn them off. I can see how the weight will be reduced but you will be using more power as you have to power 2 sets of magnets.
marklar, Oct 21 2007
  

       1. Permanent magnets are not used in larger motors because of their low energy density.
2. Air-core coils are not used in motors because adding an iron core increases the magnetic field greatly - as much as two orders of magnitude with the same amperage. That's so much more than the weight penalty that the weight isn't even a consideration. Particularly in the stator, which is, well, static.
3. in section (d) you've invented a solenoid; that's pretty 'baked' and it's not going to share many design or drive linkage characteristics with a rotational motor, leaving you without much design synergy in having them together. It will probably end up being a rotary motor twice as long as need be for the power required, but has massive amounts of end-play in the shaft.
lurch, Oct 21 2007
  

       "No metal" was my typo. Of course there is the metal of the wiring, and iron core for coils is not part of the discussion. I meant no "permanent" stator parts, but rather a digitally controlled stator (i.e. both parts are electromagnets). You wont be needing "double the power" since the magnetic power is not lost, just the opposite: you are fully controlling the use of power, so that none is ever wasted (when the coils are out of range, or when induction is causing interference). This is definitely not a solenoid, and I'm sorry to say, but a Doubly fed motor, with wound rotors, still has nothing to do with a permanent stator which does still exist in the motor.   

       The sad point is that I have probably found something similar (albeit perhaps not digitally controlled, so still my invention holds). See link on Raser.
pashute, Oct 22 2007
  

       What handwaving? Some people wrote that its baked. I showed that its not. Removed the additions (about 7 lines), so its a four liner.   

       I think its quite clear. Are we not to discuss any halfbaked ideas seriously?
pashute, Oct 22 2007
  

       Too clever, by half.
4whom, Oct 22 2007
  

       Why do you want to modulate both stator and rotor coils? Surely one or the other.
Texticle, Oct 22 2007
  
      
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