DC Voltage Regulation

Thread Starter


Joined Nov 25, 2007
Can someone explain how voltage is regulated in a permanent magnet generator? I understand how AC current is rectified to DC but I am at a loss as to how voltage is controlled, or adjusted with varying loads.

The specific application is the generator as used on most outboard motors. AC voltage is induced in a stator and then converted to 12 volts DC. The voltage is somehow maintained at nominally 14.5 volts up to the point of maximum current output. If the magnets are creating maximum power at a given RPM, what happens to the excess power that is not needed by the load on the system?


Joined Apr 20, 2004
I am not familiar with outboards, but all other alternator systems use a portion of the output that is rectified and fed back into the armature winding to make the magnetic field that actually does the generating. There is a residual magnetic field left in the armature structure that bootstraps the initial output.

This is different from the permanent magnet that was part of the flywheel in magneto ignition engines.