Multi magnet motors

[dretceterini]

To the electronics experts: It seems to me that multi magnet motors work better, so why is it that motors with more then 3 poles seem no better than ones with 3 poles? In theory it seems to me that they should...

[[email protected].]

Stu,

Multi magnet motors are only an improvement when the parent material cannot be aligned into a radial pattern otherwise. This means all Cobalt magnets that I'm familiar with, but often not in ceramic motors, where the most popular magnets are already radial.

5 or 7 pole armatures do hit higher efficiencies than three pole armatures, but are much harder to balance (trust me, I have some recent experience on this one!). They also develop more torque but less rpm for a given wire size.

Most importantly, however, is the tendancy of a 5 or 7 pole to be much larger and heavier than a 3 pole motor. You, and a few other oldtimers, should remember how the Mabuchi 'tin cans' replaced the big Pittman and Ram motors in short order back in the mid 60's, not for being faster (they weren't!) but rather for handeling so much better.