Power distribution systems
View Patent ↗The present invention relates to power distribution systems (e.g. a marine power distribution and propulsion system) that include first and second ac distribution busbars. The first ac distribution busbar will typically be a medium voltage busbar for the propulsion drive systems and the second ac distribution busbar will typically be a low voltage for ships services. A 12-pulse rectifier has its ac terminals electrically connected to the first ac distribution busbar. A multiple output generator has first and second galvanically-isolated stator windings. The first stator winding provides a six-phase ac output and is connected to the first ac distribution busbar. The second stator winding provides a three-phase ac output and is connected to the second ac distribution busbar. The six-phase ac output is phase shifted relative to the three-phase ac output to reduce the problematic coupling of harmonic distortion between the first and second ac distribution busbars.
1. A power distribution system comprising:
a first and second distribution busbars;
a multi-pulse rectifier having terminals electrically connected to the first and second distribution busbars; and
a multiple output generator having ID first and second subsidiary stator windings associated with a first stator winding and (ii) a second stator winding having a second multi-phase ac output;
wherein the first subsidiary stator winding provides a first phase group of a first multi-phase ac output with n phases, the first phase group being connected to the first distribution busbar;
wherein the second subsidiary stator winding provides a second phase group of the first multi-phase ac output with n phases, the second phase group being connected to the second distribution busbar; and
wherein the n phases of the first multi-phase ac output are symmetrically phase shifted relative to the multi-phases of the second ac output.
2. The power distribution system of claim 1 , wherein the first phase group of the n phases of the first multi-phase ac output is phase shifted by a predetermined positive angle relative to the n phases of the second ac output and the second phase group of the n phases of the first ac output is phase shifted by a predetermined negative angle relative to the multi-phases of the second ac output.
3. The power distribution system of claim 2 , wherein the predetermined positive angle and the predetermined negative angle have substantially the same magnitude.
4. The power distribution system of claim 1 , wherein the first ac output is a six-phase ac output and the second ac output is a three-phase output.
5. The power distribution system of claim 4 , wherein the multi-pulse rectifier is a 12-pulse rectifier.
6. The power distribution system of claim 1 , wherein three phases of the first ac output are phase shifted by a predetermined positive angle relative to the second ac output and three phases of the first ac output are phase shifted by a predetermined negative angle relative to the second ac output.
7. The power distribution system of claim 6 , wherein the predetermined positive angle is about +15 degrees and the predetermined negative angle is about −15 degrees.
8. The power distribution system of claim 1 , wherein the first ac output is a twelve-phase ac output and the second ac output is a three-phase ac output.
9. The power distribution system of claim 8 , wherein three phases of the first ac output are phase shifted by a first predetermined positive angle relative to the second ac output, three phases of the first output are phase shifted by a second predetermined positive angle relative of the second ac output, three phases of the first ac output are phase shifted by a first predetermined negative angle relative to the second ac output, and three phases of the first ac output are phase shifted by a second predetermined negative angle relative to the second ac output.
10. The power distribution system of claim 9 , wherein the first predetermined positive angle is about +22.5 degrees, the second predetermined angle is about +7.5 degrees, the first predetermined negative angle is about −7.5 degrees, and the second predetermined negative angle is about −22.5 degrees.
11. The power distribution system of claim 8 , wherein the multi-pulse is a 24-pulse rectifier.
12. The power distribution system of claim 1 , further comprising a capacitor bank connected to the second ac output.
13. The power distribution system of claim 1 , wherein the first distribution busbar carries an ac distribution voltage.
14. The power distribution system of claim 13 , wherein the multi-pulse rectifier is electrically connected between the first distribution busbar and an electrical load.
15. The power distribution system of claim 1 , wherein the first distribution busbar carries a dc distribution voltage and the multi-pulse rectifier is electrically connected between the first stator winding and the first distribution busbar to rectify the first ac output.