[Al_The_Man]

Are you looking at Field on the stator or rotor field (automotive style)?
As pointed out if you store the resultant rectified AC as DC, you will need an inverter to convert back to AC to drive the alternator as a motor.
Also If you have a rotor field (DC two brushes), when used as a motor you have the choice to make it run as an induction motor (no DC field) or by connecting DC to the rotor field when close to synchronism will make it a synchronous motor.
Al.

[gar]

070211-1058 EST USA

svenakela:

Your can build a 3 phase AC machine with the 3 phase coils on either the rotor or the stator. Generally these are the stator because this puts the high power dissipation near the outer surface of the machine.

With the 3 phase coils as stator the rotor can be either a permanent magnet, or a wound rotor with DC excitation. If it is a wound rotor, then there are two continuous slip rings.

A so called DC brushless motor is basically an AC alternator or synchronous motor with a permanent magnet rotor. Additionally there is position sensing circuitry.

Formulas: it is probably easiest to scale from an existing unit. If you want to double the voltage then double the turns. Obviously the fixed window area for copper will define wire size. The maximum flux density is most likely set by the saturation of the core material, but maybe by thermal considerations in some cases.

.

[pastera]

Are you looking at Field on the stator or rotor field (automotive style)?
As pointed out if you store the resultant rectified AC as DC, you will need an inverter to convert back to AC to drive the alternator as a motor.
Also If you have a rotor field (DC two brushes), when used as a motor you have the choice to make it run as an induction motor (no DC field) or by connecting DC to the rotor field when close to synchronism will make it a synchronous motor.
Al.

When back driving, you can use the coil inductance to pump the energy back into the batteries without a separate diode pack. That is why I mentioned a 2 quadrant drive (forward and braking) but I should have said regenerative.

I'm not sure wich configuration would be more efficient, (induction or shunt field) but it would be easy to test.

Aaron