Direct current voltage regulation of permanent magnet generator

An aircraft power generation unit to generate direct current (DC) power provided to a load, the unit comprising:

• permanent magnet generator (PMG) that includes first, second, third and fourth sets of windings, each of the winding sets including three windings;
• a rectifier section that includes:
• a first six-pulse rectifier connected to the first set of windings and having a first rectifier positive rail and a first rectifier negative rail and forming a first DC voltage (Vdc1) between the first rectifier positive rail and the first rectifier negative rail from voltage received from the first set of windings;
• a second six-pulse rectifier connected to the second set of windings and having a second rectifier positive rail and a second rectifier negative rail and forming a second DC voltage (Vdc2) between the second rectifier positive rail and the second rectifier negative rail from voltage received from the second set of windings;
• a third six-pulse rectifier connected to the third set of windings and having a third rectifier positive rail and a third rectifier negative rail and forming a third DC voltage (Vdc3) between the third rectifier positive rail and third rectifier negative rail from voltage received from the third set of windings;
• a fourth six-pulse rectifier connected to the fourth set of windings and having a fourth rectifier positive rail and a fourth rectifier negative rail and forming a fourth DC voltage (Vdc4) between the fourth rectifier positive rail and fourth rectifier negative rail from voltage received from the fourth set of windings;
• and
• a common local output bus;
• an output bus configured to be connected to the load and including a positive output bus rail and a negative output bus rail;
• and
• a controller that receives an input signal from at least one of the output sets and selectively couples either the common local output bus or fourth rectifier negative rail to the output bus negative rail and one or more of the first, second and third six-pulse rectifiers to the output bus positive rail to provide a constant voltage to the load, wherein the controller selectively couples the common local output bus and fourth rectifier negative rail to the output bus negative rail based on a speed of the PMG.