You need a
3 phase induction motor. A 1-ph motor of any sort will not work, IMHO, due to the "trick" way it produces rotation. 3-ph I motors exist in fractional sizes down to 1/3HP, [new about $70] - old well pumps may be a good place to start looking for a salvaged 3-ph model. Your set up is similar to the methods used to create 3-ph from 1-ph to drive old machinery, using a motor to drive a 3-ph slave induction motor as a generator. In such setups, the 3-ph motor needs to be BIG. For experimental purposes it won't be necessary to rate the 3 ph motor against your drive motor- a 40W dc motor will easily spin up a 3hp 3-ph, as long as you don't expect it to make 2kw
To operate anything in your home at anywhere near your domestic voltage, you
must control the motor/generator speed. With variable demand, a series wound dc motor will be
useless, as at no-demand it could spin up the assembly to dangerous voltages. You need a
shunt-wound dc motor which you can speed regulate efficiently with a variable pot. on the field windings. [Such small shunt w. dc motors are used to start autos, motorcycles or lawntractors].
With this set up you will be lucky to get within 10% of poco volts and hertz and will need a tacho to set up the machine rpm. With these limitations, you can't use your juice to run anything electronic, so it's best use would probably be auxiliary power on domestic hot water, where you can make year round savings. I assume you will make a larger machine once you are au fait with the technical challenges, because the only 40W use will be 3 x 15W filament lamps. Best of luck!
