Parallel Inverter Aircraft Engine Starting System
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Solution Overview
Problem
Conventional electrical starting systems for aeronautical engines are bulky, heavy, and costly due to the need for multiple high-power inverters and complex DC/DC converters, which complicates restarts in flight and ground starts, and increases weight and volume.
Innovation Solution
The system employs multiple parallel DC/AC converters with a DC/DC booster converter configuration that reduces mass and volume by dividing power delivery into sections, allowing for reduced power operation under critical conditions and using a filter to manage battery voltage, thereby minimizing equipment size and cost while maintaining high reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple high-power inverters and complex DC/DC converters are used to ensure high reliability for restart in flight and ground starts, then the reliability is improved, but the mass and volume of the system increase
Solution Approach 1:
The patent divides the single high-power inverter into multiple parallel inverters with lower individual power ratings. This segmentation allows the system to achieve the same total power capacity while using smaller, more manageable components that can be distributed throughout the aircraft, reducing the concentration of heavy equipment in one location and allowing for more flexible mounting options that can minimize overall system mass.
Solution Approach 2:
The patent designs the inverter system to serve multiple functions: it can operate with all inverters active for maximum power during ground starts, with reduced inverter operation during in-flight restarts, and can selectively power different motors (APU or propulsion motors) depending on operational requirements. This multi-functionality eliminates the need for separate dedicated systems for different operating conditions, reducing overall system mass.
2Reliability
If multiple high-power inverters and complex DC/DC converters are used to ensure high reliability for restart in flight and ground starts, then the reliability is improved, but the volume of the system increases
Solution Approach 1:
By segmenting the power conversion function across multiple parallel inverters, the system replaces a single large-volume inverter with multiple smaller units. These smaller inverters can be distributed throughout the aircraft structure, utilizing otherwise unused space and reducing the peak volume concentration in any single location, thereby reducing the overall system volume envelope.
Solution Approach 2:
The patent leverages the three-dimensional distribution of space within the aircraft by distributing inverters across different locations and levels rather than concentrating them in a single volume. This spatial distribution allows the system to achieve the required reliability through redundancy while minimizing the overall volume footprint by utilizing available space more efficiently throughout the aircraft structure.
3Reliability
If multiple high-power inverters and complex DC/DC converters are used to ensure high reliability for restart in flight and ground starts, then the reliability is improved, but the cost increases
Solution Approach 1:
The patent employs multiple parallel inverters with lower individual power ratings instead of a single high-power inverter. This segmentation allows the use of standardized, off-the-shelf inverter modules that are more readily available and less expensive to manufacture than custom high-power units. It also simplifies maintenance and replacement procedures, reducing lifecycle costs.
Solution Approach 2:
The inverter system is designed to perform multiple functions across different operational scenarios (ground starts, in-flight restarts, APU starting, propulsion motor starting), eliminating the need for separate dedicated systems for each function. This multi-functionality reduces the total number of components required, simplifies the bill of materials, and reduces both manufacturing and maintenance costs while maintaining high reliability.
4Reliability
If the system is configured to operate with reduced power under critical conditions using only one inverter, then the reliability under critical safety conditions is improved, but the power delivery capability is reduced
Solution Approach 1:
The patent implements a dynamic inverter configuration where the system can adapt its operational mode based on conditions. During normal operation, all inverters work in parallel to deliver maximum power. Under critical safety conditions or in-flight restart scenarios, the system dynamically reconfigures to operate with fewer inverters, selectively engaging only the necessary number of inverters to match the actual power requirements, thus maintaining high reliability while optimizing power delivery capability.
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 significantly reduces the mass and volume of the starting electrical system, enhances reliability through redundancy, and optimizes cost by eliminating the need for complex DC/DC converters, ensuring efficient and reliable engine starts from both power networks and batteries.
Implementation Method 1
said at least one motor is powered by only one of said two three-phase inverters so as to increase the reliability rate of the system under said critical safety conditions by a redundancy of the 1 out of 2 type
Implementation Method 2
said electronic protection device comprises a switch controlled in series on one of the two supply lines and a capacitor in parallel on these two supply lines on the side of said inverter
Data Source
AI summary
The invention relates to an electrical system for starting up an engine (18, 20, 22), including: an AC/DC rectifier (12), supplied with power by an AC power network (14) in order to generate a first DC voltage Vdc; a DC/AC conversion module (12) for generating, on the basis of said first DC voltage Vdc, an AC voltage for starting up the engine, comprising n phase k inverters arrange in parallel (k>1) and generating power at least two times less than a maximum power Pmax that is required to start up the engine. The two power supply lines of each inverter are connected to an electronic protection device that receives the first DC voltage Vdc, and the n outputs of each inverter generate the AC voltage for starting up the engine by means of n inductors in series.