Aircraft electrical system operating method

Patent metadata

Field	Value
Publication number	US-2016185462-A1
Application number	US-201414247708-A
Country	US
Kind code	A1
Filing date	Apr 8, 2014
Priority date	Apr 11, 2013
Publication date	Jun 30, 2016
Grant date	—

Abstract

A method of controlling an aircraft electrical system ( 40 ). The electrical system ( 40 ) comprises an alternating current electrical machine ( 56, 58 ) comprising a plurality of phases, each phase having a power rating, the electrical machine ( 56, 58 ) being configured to operate on failure of one or more phases. The method comprises: determining a power requirement; sensing a fault of one or more phases of the electrical machine ( 56, 58 ), and controlling the electrical machine ( 56, 58 ) to operate in a fault condition, in which the remaining phases of the electrical machine ( 56, 58 ) provide the electrical power requirement; and providing an overrating signal to a flight computer ( 66 ) of the aircraft ( 2 ) where the power provided by each phase exceeds the power rating of the respective phase.

First claim

1 . A method of controlling an aircraft electrical system, the electrical system comprising: an alternating current electrical machine comprising a plurality of electrical phases, each phase having a power rating, the electrical machine being configured to operate on failure of one or more phases; the method comprising:
determining a power requirement; sensing a fault of one or more phases of the electrical machine, and, where a fault is sensed: controlling the electrical machine to operate in a fault condition, in which the non-faulty phases of the electrical machine provide the electrical power requirement; and providing an overrating signal to a flight computer of the aircraft where the power provided by each phase exceeds the power rating of the respective phase.

2 . A method of controlling an aircraft electrical system according to claim 1 , wherein the alternating current electrical machine comprises an electrical motor, and the power comprises mechanical power provided by the electrical motor.

3 . A method of controlling an aircraft electrical system according to claim 2 , wherein the electrical motor is configured to drive an engine fluid pump, such as a fuel pump or oil pump.

4 . A method of controlling an aircraft electrical system according to claim 1 , wherein the alternating current electrical machine comprises an electrical generator, and the power comprises electrical power provided by the electrical generator.

5 . A method of controlling an aircraft electrical system according to claim 1 , wherein the fault is sensed on the basis of a measurement of any of current flow or voltage of each phase.

6 . A method according to claim 5 , wherein the fault is sensed using one or more of overcurrent protection, ground fault protection, unit protection and negative phase sequence protection.

7 . A method according to claim 5 , wherein the fault is sensed by one or more of a current transformer and a voltage transformer or digital equivalents

8 . A method of controlling an aircraft electrical system according to claim 1 , wherein where the power provided by each phase exceeds the power rating of the respective phase, the method comprises overrating the remaining phases until either a normal operation condition or a reversion condition is met.

9 . A method according to claim 8 , wherein if the normal operation condition is met, the method may comprise restoring the or each non-operational phase of the electrical machine.

10 . A method according to claim 8 , wherein if the reversion condition is met, the method comprises reducing the power provided by each remaining phase to the rated power, or below the rated power.

11 . A method according to any of claim 8 , wherein the reversion condition is met where a predetermined period of time has elapsed from the phases exceeding their rated power.

12 . A method according to claim 11 , wherein the predetermined period of time is calculated on the basis of a measured temperature of the electrical system or a part of the electrical system

13 . A method according to any of claim 8 , wherein the reversion condition is met where the electrical system or a part of the electrical system reaches a predetermined temperature.

14 . A method according to any of claim 8 , wherein the reversion condition is met where required power is less than the rated power of the remaining phases of the electrical machine.

15 . A method according to any of claim 8 , wherein the normal operation condition is met where each of the phases of the electrical machine is sensed to no longer have a fault.

16 . A method according to any of claim 8 , wherein the normal condition is met where the respective phase fault detection is found to have been erroneous.

17 . A method according to claim 16 , wherein the method comprises detecting that the fault occurred on a further electrical component.

18 . A method according to claim 17 , wherein where the fault is found to be on a further electrical component, the method comprises isolating the further faulty component, and subsequently operating the electrical machine in the normal condition.

19 . A method according to claim 3 , further comprising sensing relative oil and fuel pressures of fuel and oil systems of the aircraft engine, and operating the respective pumps to maintain a higher oil pressure relative to the fuel pressure.

20 . An electrical system for an aircraft, the system comprising: an alternating current electrical machine comprising a plurality of phases, each phase having a power rating, the electrical machine being configured to operate on failure of one or more phases, and a controller, the controller being configured to operate the electrical system in accordance with the method of the first aspect of the invention.

Assignees

• Rolls Royce Plc

Inventors

• Edwards Huw Llewellyn
• Vyas Parag

Classifications

• H02P29/028

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title

• B64D45/00

  Aircraft indicators or protectors not otherwise provided for · CPC title

• B64D41/00 Primary

  Power installations for auxiliary purposes · CPC title

• B64D2221/00

  Electric power distribution systems onboard aircraft · CPC title

• H02P29/0243 Primary

  the fault being a broken phase · CPC title