Aircraft Electrical System With Isolated AC DC Buses

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Solution Overview

Problem

Current electrical architectures in aircraft are inefficient due to the need for electrical synchronization of generators with varying frequencies, leading to increased fuel consumption as electrical loads grow with each new generation of aircraft.

Innovation Solution

The implementation of an electrical system with isolated AC and DC bus systems, including back-to-back AC-to-AC converters with a DC link, and switchable links between buses and loads, allowing for flexible power distribution between main and auxiliary generators without the need for synchronization, utilizing a controller to manage power sharing between generators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If electrical synchronization is used to connect generators with varying frequencies, then the electrical system can operate with conventional architectures, but the system efficiency decreases and fuel consumption increases

Engineering Contradiction:
Improvefuel consumptionVSAvoidflexibility in connectivity
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The electrical system is segmented into isolated AC and DC bus systems, allowing independent operation of generators without synchronization. The AC bus system handles AC loads while the DC bus system handles DC loads, and each can be fed by different generators operating at different frequencies, eliminating the need for electrical synchronization and improving overall system efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A back-to-back AC-to-AC convertor with a DC link acts as an intermediary between the AC and DC bus systems. This convertor enables flexible power transfer between buses without requiring the generators to be synchronized, allowing the system to adapt to varying generator frequencies while maintaining efficient power distribution

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If generators are electrically synchronized, then power distribution is simplified, but the system complexity increases due to synchronization requirements

Engineering Contradiction:
Improveelectrical system complexityVSAvoidpower supply redundancy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

By segmenting the electrical system into separate AC and DC bus systems with independent generator connections, the complexity of electrical synchronization is eliminated. Each bus system can be fed by generators operating independently, reducing the overall system complexity while maintaining reliability through redundant power paths

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs switchable links that can dynamically reconfigure power distribution paths between generators and buses. This dynamic reconfiguration capability allows the system to adapt to generator failures or varying operational conditions, enhancing reliability without requiring complex synchronization mechanisms

Inventive Principle:
Principle #15Dynamics

3Power

If electrical loads increase with new aircraft generations, then more electrical power is available, but fuel consumption increases significantly

Engineering Contradiction:
Improveelectrical powerVSAvoidfuel consumption
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The system changes the operational parameters of generators by allowing them to operate at different frequencies and connecting them to different bus systems. This enables more efficient power generation and distribution, meeting the increased electrical power demands of modern aircraft without proportionally increasing fuel consumption

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

This configuration enhances the overall efficiency of the electrical system by allowing flexible power connectivity, reducing fuel consumption, and providing redundancy in power supply, especially during generator failures or when the aircraft is on the ground.

Implementation Method 1

The electrical system may include a back to back AC-to-AC convertor having a DC link, wherein the DC bus connected to the DC link.

Methodology Applied
Scientific EffectElectrical energy conversion:

Data Source

PatentEP2727838B1An electrical system for an aircraft
Publication Date: 2021.03.17 ROLLS ROYCE PLC
  • EP2727838B1 patent drawingFigure 1~2
  • EP2727838B1 patent drawingFigure 3~4
  • EP2727838B1 patent drawingFigure 5

AI summary

The invention relates to an electrical system (310) for an aircraft, comprising: a first main generator (314a) connected to at least one load via a first bus; a second main generator (314b) connected to at least one load via a second bus; a first and a second auxiliary generator (316a,316b) associated with the first and second buses, the auxiliary generators being driven by a common prime mover (326).