DC power system for marine applications

Patent metadata

Field	Value
Publication number	US-9780643-B2
Application number	US-201514789111-A
Country	US
Kind code	B2
Filing date	Jul 1, 2015
Priority date	Sep 22, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A power system for a marine ship includes a plurality of protection zones, wherein at least two protection zones are coupled to each other via at least one bus-tie converter. Each of the protection zones includes a plurality of direct current (DC) buses and a plurality of power converters. The bus-tie converter includes at least two converter legs coupled by at least one inductor. Each converter leg includes a first branch connected with a snubber circuit by an intermediate switching device. The first branch includes two outer switching devices and at least one inner switching device connected between the two outer switching devices. The snubber circuit includes a combination of a diode, a resistor and a capacitor. A controller controls the operation of the plurality of power converters and the at least one bus-tie converter.

First claim

The invention claimed is:

1. A power system for a marine ship, comprising:
a plurality of protection zones, each protection zone including a plurality of direct current (DC) buses and a plurality of power converters;
a bus-tie converter to couple the at least two DC buses of two protection zones, the said bus-tie converter comprising:
at least two converter legs coupled by at least one inductor, each converter leg including:
a first branch having two outer switching devices and at least one inner switching device connected between the two outer switching devices;
a snubber circuit having a combination of a diode, a resistor and a capacitor, wherein the first branch and the snubber circuit are connected by an intermediate switching device; and

a controller to control the operation of the plurality of power converters and the at least one bus-tie converter.

2. The power system of claim 1 , wherein the intermediate switching device has an opposite polarity with respect to the outer switching devices and the inner switching device.

3. The power system of claim 1 , wherein the at least one inductor is connected between the two inner switching devices of the two protection zones.

4. The power system of claim 1 , wherein the at least two outer switching devices, the inner switching device and the intermediate switching device comprise controllable semiconductor switches.

5. The power system of claim 4 , wherein the controllable semiconductor switch comprises an insulated gate bipolar transistor, a metal oxide semiconductor field effect transistor, a field effect transistor, a gate turn-off thyristor, an insulated gate commutated thyristor, an injection enhanced gate transistor, a silicon carbide based switch, a gallium nitride based switch, a gallium arsenide based switch, or combinations thereof.

6. The power system of claim 1 , wherein the controller blocks power flow between a faulty protection zone and a non-faulty protection zone by controlling the bus-tie converter.

7. The power system of claim 1 , wherein the controller switches ON two outer switching devices and the intermediate switching device of each converter leg of the bus-tie converter during normal operation.

8. The power system of claim 7 , wherein the controller switches OFF two outer switching devices of each converter leg of the bus-tie converter when there is a fault on the at least one protection zone and facilitates a current between the intermediate switching devices and antiparallel diodes of outer switching devices of each converter legs.

9. The power system of claim 8 , wherein the controller switches ON inner switching devices after outer switching devices have been switched OFF and facilitates a circulating current between the inner switching devices.

10. The power system of claim 9 , wherein the controller switches OFF the intermediate switching devices after inner switching devices have been switched ON.

11. The power system of claim 1 , wherein each converter leg further includes a second branch connected across the snubber circuit, said second branch having a second diode connected in series with a damping resistor to dissipate a fault current after intermediate switching devices have been switched off.

12. A method of providing power to a marine ship comprising:
providing a plurality of protection zones, each protection zone including a plurality of direct current (DC) buses and a plurality of power converters;
connecting a bus-tie converter between the at least two DC buses of two protection zones, wherein connecting the bus-tie converter includes:
providing at least two converter legs coupled by at least one inductor, wherein providing each converter legs comprises:
forming a first branch by connecting at least one inner switching device between two outer switching devices;
forming a snubber circuit with a combination of a diode, a resistor and a capacitor; and
connecting an intermediate switching device between the first branch and the snubber circuit.

13. The method of claim 12 , wherein connecting the intermediate switching device comprises connecting the intermediate switching device in opposite polarity with respect to the outer switching devices and the inner switching devices.

14. The method of claim 12 comprises connecting the at least one inductor between the two inner switching devices of the two protection zones.

15. The method of claim 12 further comprises blocking power flow between a faulty protection zone and a non-faulty protection zone by controlling the bus-tie converter.

16. The method of claim 15 , wherein controlling the bus-tie converter comprises switching ON two outer switching devices and the intermediate switching device of each converter leg during normal operation.

17. The method of claim 16 comprising switching OFF two outer switching devices of each converter leg of the bus-tie converter when there is a fault on the at least one protection zone and facilitating a current between the intermediate switching devices and antiparallel diodes of outer switching devices of each converter legs.

18. The method of claim 17 comprising switching ON inner switching devices after outer switching devices have been switched OFF and facilitating a circulating current between the inner switching devices.

19. The method of claim 18 further comprising switching OFF the intermediate switching devices after inner switching devices have been switched ON.

20. The method of claim 12 , wherein providing each converter leg further comprises connecting a second branch in parallel with the snubber circuit, said second branch including a second diode connected in series with a damping resistor to dissipate a fault current after intermediate switching devices have been switched off.

Assignees

• Gen Electric

Inventors

• Dong Dong
• Raju Ravisekhar Nadimpalli

Classifications

• H02J2105/31

  for ships or vessels · CPC title

• B63J3/00

  Driving of auxiliaries (transmission elements per se F16) · CPC title

• H02J1/102

  being switching converters (H02J1/108, H02J1/12 take precedence) · CPC title

• B63H21/17

  by electric motor · CPC title

• H02M3/1582

  Buck-boost converters (H02M3/1584 takes precedence) · CPC title