Low-Spool Integrated Rotor for Gearbox-Free Hybrid Engine Drive
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Solution Overview
Problem
Hybrid engine designs face increased weight and complexity due to additional motor connections, require extra cooling for permanent magnet synchronous motors (PMSM) to prevent demagnetization, and suffer from uncontrolled back EMF voltage issues leading to safety concerns.
Innovation Solution
Integrate an electric machine rotor into the low spool of the turbine engine, eliminating the need for a gearbox and incorporating a stator in a static or rotating reference frame, with power feeder cables and slip rings to power the stator, allowing for safe operation without magnets and minimal cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a permanent magnet synchronous motor (PMSM) is used in hybrid engine design, then motor function is achieved, but weight and complexity of the accessory gear box increase
Solution Approach 1:
The patent combines the motor rotor with the low spool shaft into a single integrated component. The rotor is mounted directly on the low spool shaft, eliminating the need for separate motor mounting structures and accessory gear boxes. This merging of the motor rotor with the existing shaft structure reduces overall device complexity while maintaining the hybrid power function.
Solution Approach 2:
The low spool shaft serves dual functions: it acts as both the mechanical shaft for the turbine engine and as the rotor for the permanent magnet synchronous motor. This multi-functionality eliminates the need for separate motor components and reduces the complexity of the accessory gear box while achieving both mechanical drive and electrical generation functions.
2Power
If a permanent magnet synchronous motor (PMSM) is used in hybrid engine design, then motor function is achieved, but weight of the thermal management system increases due to extra cooling requirements
Solution Approach 1:
The motor rotor is integrated with the low spool shaft, allowing shared thermal management resources. The cooling system can serve both the motor and the engine components simultaneously, reducing the need for separate cooling infrastructure and thereby reducing the weight of the thermal management system.
3Ease of operation
If PMSM is rotated, then motor operation is enabled, but uncontrolled back EMF voltage causes over voltage fault and high winding short circuit current
Solution Approach 1:
The control system continuously monitors the rotational speed of the low spool shaft and adjusts the switching of the power converter accordingly. This feedback mechanism allows the system to predict and manage back EMF generation, preventing over-voltage faults and controlling winding currents by synchronizing the power converter switching with the rotor position and speed.
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
Reduces weight and complexity, enables safe operation by eliminating back EMF voltage risks, and simplifies maintenance through modular design, while maintaining high temperature tolerance without additional cooling.
Implementation Method 1
The stator is configured to provide a magnetic field to rotate the rotor
Implementation Method 2
The PMSM cannot turn off the output due to back electromagnetic force (EMF) when the PMSM is rotated
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric machine (200) includes a rotor (204) and a stator (202). The rotor (204) is integrated into a fan drive gear system (201) in an engine. The stator (202) is configured to provide a magnetic field to rotate the rotor (204).