A generator system has two modes of operation, such as 120 VAC and 240/120
VAC. The generator system has a permanent magnet generator with two
independent sets of windings that each generate a three phase AC voltage.
One three phase AC voltage is coupled to a first cycloconverter and the
second three phase AC voltage is coupled to a second cycloconverter. Live
outputs of each cycloconverter are coupled to each other through a
switch, such as a relay, and netural outputs of each cycloconverter are
coupled to ground. A controller controls the cycloconverters to provide
the modes of operation. In the 120 VAC mode, the switch across the live
outputs of the first and second cycloconverters is closed, shorting the
live outputs of the first and second cycloconverters together so that the
live outputs are in parallel and the controller operates the first and
second cycloconverters so their output voltages are in phase with each
other. When in the 240/120 VAC mode, the switch across the live outputs
of the first and second cycloconverters is open so that the live outputs
are in series and the controller operates the first and second
cycloconverters so that their output voltages are 180 degrees out of
phase. The permanent magnet generator has rotor position sensors that are
used by a DC motor drive to drive the generator as a brushless DC motor
to start the engine of the generator system and also to develop cosine
wave information for use in controlling the cycloconverters.