How Can I Find/Build a "Tool" to Reverse E-Polarity in a Controlled Fashion?

For me, this isn't an area of expertise but it is an area of interest, so take my input accordingly.

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It seems to me you are describing a permanent magnet motor and you are looking for a controller. These should be readily available or could be home built based on 555 chips...

You just need to control how fast/how much current is flowing to your electromagnet from your 12V car battery. Easiest way to do this is with a POT... Not sure how much current you will need but it may be hard to find a POT with a high enough wattage rating.

I would get a digital potentiometer that you could control via a program such as LabView. With that being said, I'm not sure how you could get a readout of spead/torque with LabView, but you can do a million things with it so I'm sure you could find a way.

Highly inefficient control scheme to connect with LV!!

I would use PWM...

You really sound like someone trying to build an over unity machine.

But, assuming you are not "that guy":

You need a dynamometer to measure torque. You switch your electromagnets on and off using a simple proximity switch (like the $1.00 ones used in a home security system). You vary speed by varying the power to the e-mags (as someone stated, use a potentiometer).

Warning: This device may be used to drive a rotary device. This device will not generate energy in excess of input.

If proximity switches are quick enough, that would be a good choice. Otherwise, you may have to use a commutator or two and some clever adaptation to advance/retard the commutators relative to the rotor.

You need to point out how many magnetic poles you want to switch, each pole can be a plurality of coils. Perhaps some off the shelf electronics can be used if you fall within a standard configuration.

Brushed DC and universal motors use their brushes and multiple contacts along the circumference to act as contactors and swich energized poles.

In brushless DC motors, this is done using power transistors and control electronics, most often using magnetic sensors. In that case, the coils are stationary and the magnets rotate.

To add speed and power monitoring can be simple or complicated, depending on your needs. You got to walk before you can run...

Perhaps this is a dumb question, but:

What is E-Polarity?

Thank you for your interest! by "reverse e- polarity" I mean I desire to change the polarity of the magnets on the fixed axel side of the wheel. My model is a simple 8 electromagnets with 8 fixed magnets on the rotating wheel system. I anticipate wiring the nails in equal manner and running the wiring to one common electric source, the car battery. Changing the polarity in the electromagnets will cause the torgue to move the wheel.

As the discusion has pointed out, "self starting" and of course laws of thermodynamics are respectively a problem to overcome and a constraint to live with. Getting to a crawl before I walk has yet to be mastered. ;)

In the mean time, try Googleing "robotics" and/or "stepper motor driver".

Are you winding the electromagnets yourself or buying?

When you say 'wheel' do you mean some sort of vehicle wheel, or something more like The Wheel of Fortune?

You could use an optical tachometer to measure the speed but you will need some kind of dynamometer to measure the torque. You might be able to make something but it would probably be even more complicated than the motor.

Rhank you for your help!

I am making a model vehicle wheel. I am wrapping my own electromagnets.

I'm hardly crawling in this. I have a model wheel acquired from a hobby shop, two wood discs some store bought magnets, wire to wrap around long nails and am about ready to put it together. I am starting with 8 poles on each of the wheels. The outside wheel's 8 magnets are a chief "weak link" in that their magnetic fields are expected to dewindle exponentially with use. I'll be googling your suggestions.

Thanks again.

If you are using 8 magnets then I would make 9, 10 or 12 electromagnets. Otherwise you will have terrible cogging to overcome.

I thought of a way to make a dynamometer.

Get a bucket of oil on a lazy-susan and attach a torque wrench to the bottom of it. Next mount you motor with the axle vertical and a paddle wheel attached to it on an elevating platform so you can lower it into the bucket of oil.

Monitor the current and the torque wrench while slowly lowering the paddle wheel into the oil to get a graph. Repeat at various RPM.

For starting torque you can attach the torque wrench directly to the motor shaft.

Firstly, does this "Motor" have to be 100% "self-Starting" as I don't think it will, you will probably need to "help" it most times.....or put the magnets relatively close together, so that you can attract or repel from any position.....just one!

You need some form of commutator, maybe even a hall effect sensor or two, to decide where the next magnet is and to either "pull" or " push" according to your requirement at that point in time....

I would imagine that a PIC might be employed to do such things as logical decisions and speed control.......

Its all a lot of supposition on my part, so be (4)warned!!

Actually, self-starting shouldn't be a problem as long as the number of EM poles is different from the number of PM poles (exactly twice or half as many would also be bad) and, as you point out, at least 1 pole should be close enough to attract or repel at all times.

The best from a purely self-starting standpoint would be 9 EM poles for 8 PM poles but that would require 9 coil drivers and 18 commutation points per 1/4 revolution.

For simplicity sake I think 12 EM poles for 8 PM poles would be best as only 3 coil drivers and 6 commutation points per 1/4 rev would be required and should still have no trouble self-starting.

Now if you locate the poles in the 12 pole positions but leave 3 out (say the ones at 11, 12 and 1 o'clock) you could put some reed switches (you seem to be aiming for low tech) in the gap to detect the position of the rotor. Use the reed switches to control relays which will switch the polarity of the coils (EM poles) and around she goes!

As you said this is a demonstration, you could paint the magnets red and white to show their polarity and attach red and white lights to the EM's to show when they are attracting and repelling.

Later, if you get more ambitious, you can replace the reed switches and relays with hall effect and power transistors to increase the speed and decrease the noise.