I am thinking of building a sensorless mechanically timed (read: brushed) variable reluctance motor. The build would not be entirely homemade: I have found a three phase 4 wire stator already in a heavy aluminum frame and with bearings meant to run thousands of hours at over 12000 rpm. The donor frame and stator is in fact a truck alternator I bought at a repair shop for $10. My course of action would be to machine a rotor from a solid bar of mild steel (a local fab shop gets the stuff for less than a dollar per pound) and buy off the shelf brushes, which would go into a self made end plate. The original bearings would be kept as is. I already own a 9 inch metal lathe and a small milling machine.
The motor would be attached to a conventional steel frame mountain bike and fed with a 150 to 200 amp homemade controller and a group 31 lead acid battery. The battery in question weighs over 26 kg and is rated as 115 amp hours and a brief burst at 0 Celsius of about 600 amps. Where I live any bike that powerful, even electric must have a vin number, and be registered with the RMV/DMV, and pay a $40 biannual fee to get a state issued stamp. the rider must be over 16, wear a helmet and have a driver's license. I am legally qualified as a rider, have already legally owned and ridden a petrol powered scooter and am perfectly willing to wait in line at the RMV and pay $40.
If it matters I am over 190cm tall and weigh more than 90 kg, and frequently carry a heavy backpack that usually weighs between 10 and 20 kg loaded. The usual content is 2 multi semester textbooks, a notebook, and sometimes a lab manual and a 15 inch laptop computer.
Does anyone have any recommendations for a project like this. My main thought is due to the weight a lightweight motorcycle frame would be more suitable. In which case I would use two of the aforementioned batteries, wired in series for 24v 115ah.
It seems no one besides the long gone company lectra has ever built a bike with a reluctance motor. People have brought it up but advised to go with a large bldc motor. I would probably just buy a reluctance motor if they existed on the open market, but there seems to be only one company on earth that sells large reluctance motors. I got a quote of something like $3000 for a 2 hp motor and $2000 for its controller, not per shipment, per each. I know when a company doesn't want to deal with retail customers, and this is their not so subtle way of saying OEM only. most of their motors are OEM for commercial kitchen machinery. They also make the motor for an $800 vacuum cleaner.