Hybrid Aircraft Electrical Architecture with Variable and Constant Frequency Generators
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Solution Overview
Problem
Aircraft electrical systems using variable frequency generators face challenges such as increased size, weight, and complexity due to torsional oscillating loads and the need for complex motor controls to convert variable frequency power to constant frequency power, which is required by many components.
Innovation Solution
An electrical generation system combining a variable frequency generator and a constant frequency generator, both driven by a single rotating member through a single gearbox, eliminating the need for motor controllers by providing both variable and constant frequency power directly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If variable frequency generators are used, then generator size and weight are reduced, but torsional oscillating loads increase and complexity increases due to need for motor controllers
Solution Approach 1:
The electrical generation system is segmented into two independent generator channels: a constant frequency generator channel and a variable frequency generator channel. Each channel operates independently with its own generator, eliminating the need for complex motor controllers to convert variable frequency power. This segmentation allows the system to capture the weight benefits of variable frequency generators while maintaining the simplicity and reliability of constant frequency generators for components requiring stable frequency.
2Power
If variable frequency generators are used, then power transfer capability is limited, but constant frequency generators provide reliable power transfer
Solution Approach 1:
The system merges the advantages of both constant frequency and variable frequency generators into a single hybrid electrical generation system. The constant frequency generator provides reliable no-break power transfer capability, while the variable frequency generator contributes efficient power generation. Both generators share a common control system and can operate simultaneously or independently, combining their strengths to achieve both high power transfer capability and reliability.
3Reliability
If constant frequency generators are used, then power transfer reliability is maintained, but system weight and size increase
Solution Approach 1:
The hybrid system applies local quality by providing different frequency types to different components based on their specific requirements. Components that require stable frequency receive constant frequency power from the constant frequency generator, while components that can tolerate variable frequency receive power from the variable frequency generator. This localized approach optimizes the overall system weight by eliminating the need for all components to be served by heavy constant frequency generators, while maintaining reliability where needed.
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 hybrid system reduces the complexity and weight of aircraft electrical systems by eliminating the need for motor controllers and providing a balanced power solution, enhancing power transfer capabilities and system efficiency.
Implementation Method 1
a variable frequency generator (28) operating in combination with a constant frequency generator (26), which generators are driven by a single rotating member (27) through a single gearbox (129)
Implementation Method 2
a variable frequency generator (28) operating in combination with a constant frequency generator (26), which generators are driven by a single rotating member (27) through a single gearbox (129)
Data Source
Figure 1
AI summary
An electrical generation system utilizes a variable frequency generator (68) operating in combination with a constant frequency generator (26). Also disclosed are an aircraft electrical system, and a gas turbine engine incorporating the above electrical generation system.