Car alternator enhancement

[skenn]

Can anyone advise:
What is the relationship between rotor "turns", current, and output current ?. I know that inductance is proportional to turns squared, but what about mag' field strength.
Is there any way to "push" the field outwards towrds the stator, rather than a symmetrical field pattern.

 

[Heydave]

I am not sure but I think what is refered to by rotor "turns" current is the current fed to the rotor electromagnet through the slip rings. This establishes the magnetic field strength that stimulates the stator coils when the alternator is turning. The more current in the rotor, the more current output FOR A GIVEN RPM.
Also, the faster the alternator turns, the more output current for a fixed rotor current until the eddy currents in the stator cores increase and burn the whole thing up.
The cores of the stator coils serve to direct the field through the windings. Perhaps a better core material would improve efficiency but at what cost. As the RPM goes down, there is some point where the power in exceeds the power out. The rectification diodes also loose some power. If you really wanted efficiency, use a permanent magnet rotor and syncronous rectification of the stator coils. Regulation could be acheived through control of the rectification circuit. The switching FETs that do the syncronous rectification are more efficient than diodes. Expect to see this kind of thing in the future as cars shed their power wasting belts. The alternator will be integral to the flywheel and may even serve as the starter using the same FETs to make the alternator into a motor. Things like power steering and airconditioning will be electrically driven. In some hybrid concepts, there will be no output shaft at all to the primary motor. The wheels all use secondary electric motors that have better torque characteristics for vehicles than just about any other motor technology.

 

[skenn]

Not quite what I meant !. If the number of turns is increaded, and the current remains the same, how much will the output current increase. Inductance is proportional to turns squared Is the fields strength also proportional to turns squared, and is the o/p current proportional to the field strength ?.

BTW: I dont agree with using a synchronous rectifier to regulate, as the alternator is a current generator. What happens to the stator voltage when the rectifier is OFF !.