the hall effect book came, just what I needed, but a lot more than I needed too.
Yah, solid cores and pulsed DC, what's the normal problem with that? eddy currents? Just wondering what I should look for. I do have an oscilloscope to watch what the voltage does, and eddy currents would just heat the cores and limit the speed. (I did a lot of primitive motor stuff when young but then jumped on into radio electronics and never got into more advanced motor technology)
I think it would be called salient poles, except it's not the usual way of doing it. I have taken the basic idea that I came across, and thought up my own configuration of applying it that seemed most practical to build. The coils are just like solenoid coils with steel cores, the PM's are about twice the dia of the coil cores, with maximum magnet size of 3/4" dia. in order to keep the drive pulse short. That was the basic guideline. I used 13, 1/2" dia x 1" long PM's in a 1" thick nonconductive flat rotor disc, matched by two sets of 12 solenoid coils with 3/8" cores inserted in nonconductive stator discs. (anything conductive in the mounting substance would make eddy current drag) One method used by someone else was a drum type rotor and the solenoid coils mounted on a housing for the stator, but that requires the PM's to be cemented in very securely to prevent them from flying out at high speed, something I wanted to avoid. I've been told that using conventional motor design criteria this would appear to be a very inefficient motor, but actual practice proves it's performance to be in the other extreme. (apparently something going on that conventional motor design criteria does not take into account) For me it's still in the "I don't know for sure" realm.
it's very self starting, with that small not so perfect one I made last winter it self started when I got 2 poles installed. With 13 rotor poles reacting against the 12 stator poles with 1/8" per pole separation. it should start itself very strongly, like a normal DC brush motor. lot of magnetic forces going on in there, and applying the timed pulse unbalances it. But when accurately built the rotor will spin freely as if there's nothing there when no power is applied. (my current one is almost that good, just barely noticeable cogging due to slight inaccuracy in coil mounting) If it were made with the same number of poles on both sides the cogging would be so powerful you would not be able to turn the motor shaft with anything short of a long handled wrench. Just holding them I can feel how strongly one of those magnets tries to line up with a steel rod, 26 of those all at the same time would take a whole lot of force to move them. Fully unbalancing the force, I should have a very strong motor. We'll see when i find some more time to play with it.
Right now I'm preparing to go fetch a cousin and his camper he just bought, from Columbus Ohio, his job is ending the end of next week. As of now it looks like we'll be driving our car up there, working for a couple days up there, swapping the work for a '98 ford explorer, and using that to pull the camper back. (a slight bit cheaper than driving my old truck both ways, plus we end up with another vehicle to keep or sell) Along with it we've decided to run up to Michigan and pick up an old milling machine (or 2 perhaps) that are in need of some repair and a salvage company is trying to sell for not a whole lot. But I gotta put a hitch on the car, build a trailer to haul lumber up, (and the machines back) pull some cedar trees outa the woods and saw the lumber, plus make enough extra cash (sell some trees) to buy the machines.