Originally Posted by greybeard  t, I did say a single phase motor, so three phase is not in the frame. And I should have emphasised that the reason for choosing the induction motor out of the scrap bin was that it is virtualy silent compared with any brushed motor I have. |
John, Going back to your original question, although there are VFD's out there for 1ph motors they are not very successfull unless the motor is Capacitor start-capacitor run, and even then they tend to drop out of run or will stall at low to medium rpm, especially with a load.
The brushed motors you mention must be Universal type, as a true DC permanent magnet motor is very quiet, apart from a bit of brush noise which should be negligable.
Al.