Variable Magnetic Gear Ratio Electrical Machine for Gas Turbines
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Solution Overview
Problem
Existing electrical machines, particularly those with fixed gear ratios, are optimized for one operational condition, leading to reduced efficiency at high speeds and significant frequency losses, and require complex thermal management.
Innovation Solution
A gas turbine engine incorporating a permanent magnet electrical machine with a variable gear ratio achieved through modulation of the spatial magnetic field by an inter-pole component, allowing dynamic optimization for current operating conditions and reducing torque opposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed gear ratio is used in the electrical machine, then the machine can be optimized for one operational condition, but efficiency is significantly reduced at high speed operation
Solution Approach 1:
The patent applies magnetic gearing with a variable gear ratio that can be dynamically adjusted based on operating conditions. The magnetic gear ratio is varied by modulating the spatial magnetic field between the permanent magnet component and the stator, allowing the electrical machine to adapt to different speed and torque requirements, thereby resolving the contradiction between optimization for one condition and adaptability across multiple conditions.
Solution Approach 2:
The patent changes the magnetic gear ratio parameter dynamically by varying the modulation of the spatial magnetic field. This allows the electrical machine to operate efficiently across a wider speed range by adjusting the gear ratio to match current operating conditions, rather than being fixed at a single optimized point.
2Device complexity
If a fixed gear ratio is used in the electrical machine, then the structure is simpler, but frequency losses increase and thermal management becomes more difficult
Solution Approach 1:
The patent implements a dynamically variable magnetic gear ratio that adjusts based on operating conditions. This dynamic adjustment optimizes the frequency characteristics at different speeds, reducing frequency losses and associated thermal management challenges while maintaining a relatively simple permanent magnet electrical machine structure without mechanical gearboxes.
3Force
If the electrical machine is designed for high torque at low speed, then torque density is improved, but the machine size increases
Solution Approach 1:
The patent replaces traditional mechanical gearboxes with a magnetic gearing system. This substitution achieves high torque at low speeds through magnetic field interactions rather than mechanical gear multiplication, maintaining high torque density while keeping the machine compact without the bulk of mechanical transmission components.
Solution Approach 2:
The variable magnetic gear ratio allows the electrical machine to achieve high torque capability at low speeds when needed, while maintaining a compact size. By dynamically adjusting the gear ratio parameter, the machine can operate efficiently across different torque and speed requirements without requiring a larger physical size to accommodate fixed-ratio mechanical gearing.
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 electrical machine operates efficiently across a wider speed range with higher torque capability at lower speeds, minimizing power input requirements and thermal management challenges.
Implementation Method 1
The machine also includes a rotor which includes an annular array of permanent magnets, mounted to or preferably embedded in the surface of the rotor closer to the stator
Implementation Method 2
The gear ratio is varied by the movement of the inter-pole component modulating the spatial magnetic field between the permanent magnet component and the stator
Data Source
Figure 1~2
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Figure 5
AI summary
An electrical machine (30) comprising a moveable permanent magnet component (32) configured to generate a first magnetic field. A stator (44) comprising windings configured to excite a second magnetic field. A moveable inter-pole component (52) located between the permanent magnet component and the stator, the inter-pole component comprising an array of magnetic inter-pole pieces (54). The speed of movement of the inter-pole component is controlled to set a magnetic gear ratio between the first and second magnetic fields. Also a gas turbine engine, propulsor or thruster incorporating the electrical machine.