Electrical gear and method for operating a subsea machinery rotating at high speed

Patent metadata

Field	Value
Publication number	US-9685897-B2
Application number	US-201214358082-A
Country	US
Kind code	B2
Filing date	Nov 14, 2012
Priority date	Nov 14, 2011
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

An electrical gear configured to supply electrical drive power to a machinery to be rotated at high speed, such as a subsea motor/pump or a subsea motor/compressor assembly, the electrical gear including a high input voltage AC-motor having a low pole number, the AC-motor drivingly connected to a medium output voltage AC-generator having inverted design, wherein in the AC-generator the field windings are supported on a rotor which is journalled for rotation inside an outer stator carrying a high number of magnet poles, the AC-motor is configured to run on high voltage alternating current at a first frequency, and the AC-generator is configured to deliver medium voltage alternating current at a second frequency, higher than said first frequency, to an AC-motor to be energized having a low pole number.

First claim

What is claimed is:

1. An electrical gear configured to supply electrical power to a subsea machinery to be rotated at high speed, the electrical gear comprising:
a high input voltage AC-motor having a low pole number; and
a medium output voltage AC-generator of inverted design,
wherein the high input voltage AC-motor is drivingly connected to the medium output voltage AC-generator,
wherein, in the medium output voltage AC-generator, field windings are supported on a rotor journaled for rotation inside an outer stator carrying a high number of magnet poles, and
wherein the high input voltage AC-motor is configured to run on high voltage alternating current at a first frequency, and the medium output voltage AC-generator is configured to deliver medium voltage alternating current at a second frequency, higher than the first frequency, to a motor to be energized, wherein the energized motor has a low pole number.

2. The electrical gear of claim 1 , wherein an electrical slip ring collector is configured to pick up the voltage generated in the field windings supported on the rotor of the medium output voltage AC-generator.

3. The electrical gear of claim 1 , wherein the high input voltage AC-motor, the medium output voltage AC-generator, and a medium input voltage AC-motor are arranged on a common geometrical axis of rotation.

4. The electrical gear of claim 1 , wherein the high input voltage AC-motor and the medium output voltage AC-generator are arranged within a common housing.

5. The electrical gear of claim 1 , wherein the high input voltage AC-motor ( 4 ), the medium output voltage AC-generator, and the energized motor are arranged within a common housing.

6. The electrical gear of claim 1 , wherein the high input voltage AC-motor, the medium output voltage AC-generator, the energized motor, and the rotating subsea machinery are arranged within a common housing.

7. The electrical gear of claim 4 , wherein the housing is a pressurized or a pressure-compensated subsea vessel.

8. The electrical gear of claim 1 , wherein:
the high input voltage AC-motor, the rotor of the medium output voltage AC-generator, and a rotor of the energized motor having inverted design are mechanically interconnected for co-rotation at the same rotational speed,
the rotors of the medium output voltage AC-generator and the energized motor are electrically interconnected, and
the rotor of the energized motor is journaled for rotation inside a journaling outer stator of the energized motor drivingly connected to the subsea machinery to be rotated via an output shaft, adding the rotational speed of the high input voltage AC-motor to the induced rotation of the journaling outer stator of the energized motor.

9. The electrical gear of claim 8 , wherein the high input voltage AC-motor, the medium output voltage AC-generator, and the energized motor are arranged within a common housing.

10. The electrical gear of claim 8 , wherein the high input voltage AC-motor, the medium output voltage AC-generator, the energized motor, and the rotating subsea machinery are arranged within a common housing.

11. The electrical gear of claim 9 , wherein the housing is a pressurized or a pressure-compensated subsea vessel.

12. The electrical gear of claim 1 , wherein the high input voltage AC-motor is further configured to run on alternating current at a high voltage above 10 kV at the first frequency of 10 or 60 Hz.

13. The electrical gear of claim 12 , wherein the medium output voltage AC-generator is configured to deliver alternating current at a voltage below 10 kV at the second frequency of 100-300 Hz or 360 Hz.

14. The electrical gear of claim 13 , wherein the energized motor delivers an output speed of 9,000 to 13,800 rpm.

15. A method of operating a subsea machinery at high rotational speed, the method comprising:
drivingly connecting a high input voltage AC-motor having a low pole number to a medium output voltage AC-generator having inverted design, wherein, in the medium output voltage AC-generator, field windings are supported on a rotor journaled for rotation inside an outer stator carrying a high number of magnet poles;
feeding high voltage alternating current at a first frequency to the high input voltage AC-motor;
retrieving medium voltage alternating current at a second frequency, higher than the first frequency, from the medium output voltage AC-generator; and
feeding the medium voltage alternating current at the second frequency from the medium output voltage AC-generator to a motor to be energized, wherein the energized motor has a low pole number.

16. The method of claim 15 , further comprising retrieving voltage at the second frequency from the rotor of the medium output voltage AC-generator by an electrical slip ring collector.

17. The method of claim 15 , further comprising arranging the high input voltage AC-motor, the medium output voltage AC-generator, and the energized motor on a common geometrical axis of rotation.

18. The method of claim 15 , further comprising:
mechanically and electrically connecting the rotor of the medium output voltage AC-generator with a journaling rotor of the energized motor having inverted design;
connecting the rotating subsea machinery with a journaling outer stator journaled for rotation about the journaling rotor of the energized motor; and
adding the rotational speed of the high input voltage AC-motor to the induced rotation of the journaling outer stator of the energized motor.

19. The method of claim 15 , further comprising arranging the high input voltage AC-motor, the medium output voltage AC-generator, the energized motor, and the rotating subsea machinery within a common housing, wherein the housing is a pressurized or a pressure-compensated vessel.

Assignees

• Vetco Gray Scandinavia As
• Tomter Ole Petter

Inventors

• Tomter Ole Petter

Classifications

• H02M5/32

  by dynamic converters · CPC title

• H02P23/0086

  specially adapted for high speeds, e.g. above nominal speed · CPC title

• H02P17/00

  Arrangements for controlling dynamo-electric gears (vector control H02P21/00) · CPC title

• H02P27/00 Primary

  Arrangements or methods for the control of AC motors characterised by the kind of supply voltage (of two or more motors H02P5/00; of synchronous motors with electronic commutators H02P6/00; of DC motors H02P7/00; of stepping motors H02P8/00) · CPC title

• H02K47/20 Primary

  Motor/generators · CPC title