How to control the output voltage for the different types of the dc generator?
The voltage of a permanent-magnet generator must be controlled by controlling the generator speed. The voltage sent to loads could be controlled by sending the voltage first to a voltage regulator or converter. The voltage of a separately-excited DC generator can be controlled by controlling generator speed, by using a variable field supply, or by a combination of both. A self-excited dc generator can be controlled by generator speed or by a rheostat or electronic circuit that reduces the field current. A combination could also be used.