Modular Multilevel Electrical System for Gas Turbine Voltage Conversion
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Solution Overview
Problem
Aerospace electrical systems face challenges in efficiently connecting electric machines to DC networks operating at different voltages, particularly due to the risks of arcing and corona at altitude, which necessitate the reduction of medium voltage systems while maintaining acceptable current ratings and power transfer efficiency between low- and high-pressure spools in gas turbine engines.
Innovation Solution
The implementation of a modular multilevel electrical system comprising ac-dc converter circuits and dc-dc converter circuits, configured to operate between different voltage levels, allowing for efficient power transfer and reduction of voltage differences across converter circuits, thereby minimizing losses and the number of systems operating at medium voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If medium voltage systems are used to maintain acceptable current ratings, then power transfer efficiency is improved, but the risk of arcing and corona at altitude increases
Solution Approach 1:
The patent divides the power conversion system into multiple converter circuits, each handling a portion of the total power. This segmentation allows the system to operate at lower voltage levels (reducing arcing and corona risks) while maintaining acceptable current ratings through parallel operation of multiple circuits. Each converter circuit processes a fraction of the total power, enabling safe operation below medium voltage thresholds while preserving overall system productivity.
2Reliability
If the number of systems operating at medium voltage is reduced, then the risk of arcing and corona is reduced, but the complexity of connecting electric machines to different voltage networks increases
Solution Approach 1:
The patent introduces converter circuits as intermediary devices between electric machines operating at different voltage levels. These converter circuits act as mediators that enable safe voltage transitions without requiring extensive medium voltage infrastructure. By using standardized converter circuits as intermediaries, the system reduces the number of medium voltage connections needed while managing the complexity through modular, repeatable connection patterns.
Solution Approach 2:
The converter circuits are designed to be universal and multi-functional, capable of operating in different configurations and connecting various electric machines to different voltage networks. This universality reduces the need for specialized medium voltage equipment, simplifying the overall system architecture while maintaining reliability by minimizing medium voltage exposure.
3Productivity
If converter circuits are used to transfer power between different voltage levels, then power transfer efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent segments the power conversion function into multiple standardized converter circuits, each handling a discrete portion of the power transfer. This segmentation improves power transfer efficiency by enabling optimized voltage conversion for each circuit while managing complexity through modular design. The segmented approach allows parallel operation of identical circuits, simplifying maintenance and replacement while achieving high overall efficiency.
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 enables efficient power transfer between electric machines connected to low- and high-pressure spools, reducing fuel consumption and operational risks while maintaining acceptable current ratings, thus improving the overall efficiency and reliability of aerospace electrical systems.
Implementation Method 1
a first set of N ac-dc converter circuits connected in a modular multilevel configuration, each ac-dc converter circuit having a respective index n=(1, . . . , N) and an ac interface for connection with a corresponding nth phase of the electric machine... a set of N dc-dc converter circuits each having a respective index n=(1, . . . , N) and being configured to convert dc power between a voltage V/N at a first dc interface and a voltage W at a second dc interface
Data Source
AI summary
Electrical systems for connecting rotary electric machines to dc networks operating at different voltages V and W where V>W are provided, along with gas turbine engine arrangements incorporating such systems.