Aircraft Generator Architecture Without Constant Speed Drive
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Solution Overview
Problem
Existing aircraft electrical power generators require complex and heavy constant speed drives (CSD) to maintain constant output frequency, which increases system complexity, mass, and maintenance costs, and may adversely affect efficiency and reliability.
Innovation Solution
A two-stage independent-speed variable-frequency generator system utilizing a wound rotor PM exciter and a rotating bi-directional AC/DC/AC electric power converter, which decouples the frequency of the rotor windings, allowing for independent speed operation and maintaining output frequency without a CSD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant speed drive (CSD) is used to maintain constant output frequency, then the output frequency stability is improved, but the system complexity, mass, and maintenance cost increase
Solution Approach 1:
The patent replaces the mechanical constant speed drive (CSD) system with an electrical control system. The variable-speed variable-frequency generator uses power electronic converters and control algorithms to maintain constant output frequency without mechanical speed regulation, thereby eliminating the complex mechanical CSD while achieving the same frequency stability objective.
Solution Approach 2:
The patent changes the operating parameters of the generator by allowing variable rotor speed while using power electronic conversion to maintain constant output frequency. This parameter change approach enables the system to operate at optimal speeds without being constrained by mechanical speed regulation equipment.
2Reliability
If a constant speed drive (CSD) is used to maintain constant output frequency, then the output frequency stability is improved, but the system mass increases
Solution Approach 1:
The patent replaces the heavy mechanical CSD system with lightweight power electronic converters and control systems. This substitution eliminates the need for mechanical speed regulation equipment while achieving the same frequency stability, thereby significantly reducing system mass.
3Reliability
If a 3-stage generator architecture is used with pre-exciter and main exciter, then the field excitation control is improved, but the device complexity and component quantity increase
Solution Approach 1:
The patent extracts and eliminates the redundant pre-exciter and main exciter stages from the generator architecture. By using a simplified single-stage design with direct field excitation control through power electronic converters, the system achieves the required excitation control without the complexity of multiple exciter stages.
Solution Approach 2:
The patent integrates multiple functions into a unified control system. The power electronic converters perform both excitation control and frequency regulation functions that were previously distributed across multiple separate components, thereby reducing component quantity while maintaining control capability.
4Device complexity
If variable-speed variable-frequency generator is used without CSD, then the system mass and complexity are reduced, but the output frequency varies with engine speed
Solution Approach 1:
The patent uses power electronic conversion systems to replace mechanical speed regulation, enabling the generator to operate at variable speeds while maintaining constant output frequency through electrical control rather than mechanical means.
Solution Approach 2:
The patent changes the control approach by using power electronic converters to independently control output frequency from rotor speed. This allows the system to decouple the relationship between engine speed and output frequency, maintaining frequency stability without mechanical speed regulation.
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
The proposed system reduces the number of components, mass, cost, and complexity, while enhancing reliability and efficiency by eliminating the need for a CSD and allowing for a compact exciter design.
Implementation Method 1
a wound rotor PM exciter (PME) that provides excitation to the rotor of a wound rotor asynchronous generator (WRAG)
Implementation Method 2
A rotating bi-directional AC/DC/AC electric power converter connects the rotor windings of the exciter and the generator
Data Source
AI summary
A system, apparatus, and/or method for an aircraft that provides a novel independent-speed variable-frequency generator for aviation power generation. The generator architecture utilizes a 2-stage generator architecture with a wound rotor PM exciter (PME) that provides excitation to the rotor of a generator. A rotating bi-directional AC/DC/AC electric power converter connects the rotor windings of the exciter and the generator.