h a l f b a k e r ycarpe demi
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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.
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]
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Not sure I follow your point (d), but I
thought that most modern electric motors
are magnetless? |
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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. |
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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. |
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//As far as I know, all electric motors have permanent magnets//
So, not very far? |
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//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. |
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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. |
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pashute, you have perfectly described what is in the link.
Your idea is very good, but someone else got there first. |
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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. |
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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>> |
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In my case there is no metal nor magnet. Only coils attracting and repelling each other intermittently, controlled electronically. |
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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. |
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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. |
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Edit: pancake motors are not how I remembered them & are not applicable. |
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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. |
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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. |
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"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. |
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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. |
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What handwaving? Some people wrote that its baked. I showed that its not. Removed the additions (about 7 lines), so its a four liner. |
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I think its quite clear. Are we not to discuss any halfbaked ideas seriously? |
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Why do you want to modulate both stator and rotor coils? Surely one or the other. |
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