An aircraft power generation unit to generate direct current (DC) power includes a flux regulated permanent magnet generator (PMG) that includes first through fourth sets of windings and a control coil and a rectifier section that include first through fourth six pulse rectifiers and a common local output bus. The unit also includes an output bus configured to be connected to the load and an H-bridge circuit connected across the output bus and outputs connected to the control coil. A controller receives an input signal from at least one of the windings and selectively couples either the common local output bus and fourth rectifier to the output bus negative rail and one or more of the first, second and third six-pulse rectifiers to the output bus to provide a constant voltage to the load.