Systems and methods for providing an uninterruptible power supply to a ship-service bus of a marine vessel
A marine vessel power and propulsion system that provides a vessel-wide uninterruptible power supply is described. The power and propulsion system includes a propulsion system including a prime mover coupled to a motor/generator and a propulsion device. The motor/generator is configured to be driven by the prime mover and to generate alternating current (AC) electric power. The power and propulsion system also includes a ship-service electrical system including a generator set and a ship-service bus. The generator set is configured to generate ship-service electric power for distribution over the ship-service bus. The power and propulsion system also includes a bi-directional converter configured to couple the propulsion system to the ship-service electrical system and to convert AC electric power generated by the propulsion system to ship-service electric power for distribution over the ship-service electrical system.
1. A bi-directional converter configured to provide a ship-wide uninterruptible power supply (UPS), said bi-directional converter comprising:
a propulsion inverter electrically coupled to a motor/generator and an energy storage device and configured to convert AC ship-service electric power from a ship-service bus to DC electric power for recharging said energy storage device and at least one of:
convert direct current (DC) electric power from said energy storage device to alternating current (AC) electric power for powering said motor/generator, and
convert AC electric power generated by said motor/generator to DC electric power; and
a ship-service inverter electrically coupled to said propulsion inverter, said energy storage device, and a ship-service bus, said ship-service inverter configured to convert DC electric power from at least one of said propulsion inverter and said energy storage device to AC ship-service electric power.
2. A bi-directional converter in accordance with claim 1 , wherein said propulsion inverter is configured to operate in a first mode and a second mode, wherein the first mode comprises said motor/generator supplying said propulsion inverter with the AC electric power and the second mode comprises said propulsion inverter supplying said motor/generator with AC electric power.
3. A bi-directional converter in accordance with claim 2 , wherein the second mode further comprises said propulsion inverter receiving DC electric power from at least one of said energy storage device and said ship-service inverter.
4. A bi-directional converter in accordance with claim 2 , wherein said motor/generator is configured to be coupled to a ship propulsion device and a prime mover, wherein in the first mode said prime mover drives said motor/generator, generating AC electric power that is supplied to said propulsion inverter, and wherein in the second mode said motor/generator receives AC electric power via said propulsion inverter and drives said ship propulsion device.
5. A bi-directional converter in accordance with claim 1 , wherein said ship-service inverter is configured to provide the AC ship-service electric power to said ship-service bus for distribution over said ship-service bus.
6. A bi-directional converter in accordance with claim 1 , wherein said ship-service bus is a fixed frequency electrical bus configured to supply fixed-frequency AC power to electrical components within a vessel.
7. A bi-directional converter in accordance with claim 1 , wherein said propulsion inverter comprises a multi-level inverter, said multi-level inverter configured to permit high frequency operation of said motor/generator.
8. A bi-directional converter in accordance with claim 1 , wherein said ship-service inverter comprises a multi-level inverter.
9. A bi-directional converter in accordance with claim 1 , wherein said ship-service inverter is further configured to:
convert AC ship-service electric power from said ship-service bus to DC electric power; and
provide the DC electric power to said propulsion inverter, wherein said propulsion inverter is configured to convert the DC electric power to AC electric power for powering said motor/generator.
10. A bi-directional converter in accordance with claim 1 , wherein said propulsion inverter is configured to provide the DC electric power to at least one of said energy storage device for recharging said energy storage device and said ship-service inverter.
11. A bi-directional converter in accordance with claim 1 further comprising at least one of a DC bus and an energy storage converter for coupling said propulsion inverter to said ship-service inverter.
12. A bi-directional converter in accordance with claim 11 , wherein said energy storage converter comprises a DC to DC converter.