Autotransformer Phase-Offset Windings for Aeronautical Mass Reduction
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Solution Overview
Problem
Aeronautical autotransformers face challenges in reducing mass while maintaining efficiency, as existing solutions often require complex and expensive cooling systems to compensate for increased nominal power ratings, and existing autotransformers do not effectively minimize mass without impairing efficiency.
Innovation Solution
The autotransformer design optimizes mass by modifying its vector diagram to reduce winding lengths, achieving this through a magnetic core with interconnected limbs and additional windings that distribute power efficiently, allowing for phase-offset output voltages to minimize mass and volume while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the nominal power rating of the autotransformer is increased to reduce mass, then the mass is reduced, but complex and expensive cooling systems are required to compensate for the increased power rating
Solution Approach 1:
The patent changes the electrical parameters by introducing phase-offset outputs (37° or 40° offset) from the main three-phase network. This allows the autotransformer to operate with multiple pulse rectifiers (12-pulse or 18-pulse) that improve efficiency and reduce harmonics, enabling the system to achieve the required power transmission with lower nominal power ratings and thus reduced mass without requiring complex cooling systems
Solution Approach 2:
The patent segments the output into multiple three-phase networks (main network plus artificially recreated networks) with different phase offsets. This segmentation allows the use of multi-pulse rectifier configurations that improve overall system efficiency, reducing the thermal load and enabling mass reduction without proportionally increasing cooling system complexity
2Loss of energy
If additional outputs are added to create phase-offset networks, then the efficiency is improved and harmonics are reduced, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the autotransformer windings serve multiple functions: the same windings provide both the main three-phase output and the phase-offset outputs (37° or 40°) through intermediate points and additional terminals. This multi-functionality allows the generation of multiple pulse rectifier configurations without adding separate winding sets, thereby improving efficiency and reducing harmonics while avoiding excessive manufacturing complexity
3Device complexity
If the autotransformer uses a higher nominal power rating to simplify cooling, then the cooling system is simplified, but the mass increases
Solution Approach 1:
The patent changes the operational parameters by implementing phase-offset outputs that enable multi-pulse rectification. This improves the power factor and reduces harmonics, allowing the autotransformer to transmit the required power with a lower nominal power rating, thus reducing mass while maintaining acceptable thermal management without overly complex cooling systems
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 design reduces the autotransformer's mass by 10 to 15% and optimally distributes power, minimizing the apparent electric power rating and cross-sectional volume, thereby reducing the need for complex cooling systems.
Implementation Method 1
a first additional winding coupled magnetically to the third main winding... a second additional winding coupled magnetically to the first main winding... a third additional winding coupled magnetically to the second main winding
Data Source
AI summary
A voltage step-up autotransformer topology and an AC-to-DC converter including such an autotransformer are provided. The autotransformer is configured to take, at input, a three-phase AC current (for example 115 VAC with a constant frequency), and to output nine output voltages, which are supplied to an 18-pulse rectifier bridge assembly so as to supply a high DC voltage (for example +270 VDC/−270 VDC). These are particularly suitable for AC-to-DC converters in the aeronautical sector.