Polyphase Motor Stator Segmentation for Gas Turbine Fuel Reliability

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Solution Overview

Problem

Conventional fuel systems for gas turbine engines are inefficient due to high power demands, excess fuel recirculation, and increased complexity and weight from redundant electrical components, which are required for fault tolerance, leading to issues like lacquering and potential blockages, and the need for multiple power electronics units.

Innovation Solution

A fuel system with polyphase motors having concentrated windings with electrically isolated stator sets, allowing for reduced weight and complexity while maintaining redundancy, as each motor can operate with a 50% reduction in power without losing thrust control, and a single power electronics unit can provide power to both motors, minimizing overall weight and space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional fuel systems use a single electrical motor to drive fuel pumps, then device complexity is reduced, but reliability decreases because one electrical failure can result in inability to supply sufficient fuel

Engineering Contradiction:
Improvenumber of electrical motorsVSAvoidfuel supply reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the electrical motor into two electrically isolated sets of polyphase stator windings that can operate independently. Each winding set can drive the common rotor separately, allowing the system to segment the power supply function while maintaining a single motor physical structure. This segmentation enables continued operation with one winding set if the other fails, thus improving reliability without increasing overall device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent incorporates redundant electrical windings before failure can occur. By providing two electrically isolated sets of stator windings in advance, the system cushions against potential electrical failures. This prior cushioning ensures that if one winding set fails, the other is already in place to maintain fuel supply, preventing catastrophic failure and ensuring continuous operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If redundant electrical motors are provided for fault tolerance, then reliability is improved, but weight and complexity increase

Engineering Contradiction:
Improvefuel supply reliabilityVSAvoidmotor weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges two redundant motor functions into a single physical motor structure. By combining two sets of stator windings around one common rotor, the system achieves the reliability of redundant motors without the weight and space of two separate motors. The merged structure shares common components (rotor, housing, cooling system) while maintaining electrical isolation between the two winding sets, thus improving reliability without proportionally increasing weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single electrical motor is designed to perform multiple functions through its two independent winding sets. Each winding set can independently drive the fuel pumps, providing multi-functionality within a single device. This universality allows the motor to serve as both a primary and backup power source simultaneously, eliminating the need for separate redundant motors and reducing overall system weight.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If excess fuel is pumped at all times, then fuel flow requirements are met, but power consumption increases and fuel temperature rises causing lacquering

Engineering Contradiction:
Improvefuel flow availabilityVSAvoidpump power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs variable speed electric motors that can dynamically adjust their rotational speed to match the actual fuel flow requirements of the engine. Instead of pumping excess fuel at constant high speed, the motors vary their speed according to demand, reducing power consumption when full fuel flow is not needed. This dynamic adjustment prevents unnecessary energy use and reduces fuel heating that would cause lacquering.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameters of the fuel pumps by using variable speed motors that can adjust rotational speed, flow rate, and pressure according to engine demands. By changing these parameters dynamically rather than maintaining constant high values, the system meets fuel flow requirements while minimizing power consumption and preventing fuel temperature rise that leads to lacquering and blockages.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution ensures sufficient fuel flow for full engine power operation even with a single electrical fault, reduces weight and mechanical complexity, and minimizes the number of power electronics units required, enhancing reliability and efficiency.

Implementation Method 1

each motor comprises at least first and second electrically isolated sets of polyphase stator windings, the first and second stator windings of each electrical motor being configured to drive a common rotor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3012438B1Gas turbine engine fuel system
Publication Date: 2018.09.12 ROLLS ROYCE PLC
  • EP3012438B1 patent drawingFigure 1~3
  • EP3012438B1 patent drawingFigure 4~5
  • EP3012438B1 patent drawingFigure 6~7

AI summary

A fuel system for a gas turbine engine (10), the gas turbine engine (10) comprising a combustor (18) having a pilot fuel injector (54) and a main fuel injector (58), the fuel system comprising: first and second variable flow fuel pumps (150, 152) configured to provide metered fuel flow to the pilot injector (54), and the main injector (58) respectively; first and second variable speed electric motors (154, 156) configured to drive respective first and second fuel pumps (150, 152); wherein each of the electric motors (154, 156) comprises a polyphase motor (154, 156) comprising a stator (410) having concentrated windings (412).