The current from the stator is AC. Doesn't matter which way around the cables are for that. The RR rectifies it (ie turns it into DC) and regulates the voltage. Only in DC does positive/negative matter.
I've always found it weird why the 2 pin electrical plugs in North America have one pin larger than the other so a plug can only be inserted one way.
i've wondered that as well, so i looked it up. here is the yahoo answer that best explained it for me
One is the hot wire (black in the supply wiring) and the other is the return wire (white). This is called a polarized plug. If you had two prongs the same size, the plug could easily be switched where a chassis of an appliance, for example, could be hot and the other a return. This would set up a 120 volt between two appliances and touching them both at the same time could shock you.
For example, let's say you have a refrigerator plugged in one way and a gas stove (that runs on 120 volts for the timer and stuff) is plugged in the other way with no ground pin on the plugs. There would be a 120 volt potential between the chassis of the refrigerator and the stove. And, if you touched both of them at the same time, you would get shocked.
This may not be a problem with every type of electrical device. For example, I have an orbital sander that has a plug with both prongs the same size and no ground pin. That's because the device is double insulated from where you hold it. So, there is no need to have a polarized plug.
However, even though some devices don't need polarized plugs, manufacturers install them anyway for safety reasons.