Dual Electric Machine Starter-Generator for Turbine Engine Torque
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Solution Overview
Problem
Existing starter/generator systems for turbine engines face challenges in efficiently transitioning between starting and generating modes, with traditional starters becoming dead weight after engine startup and lacking efficient torque generation during starting.
Innovation Solution
A dual-mode starter/generator system with first and second electric machines, utilizing a magnetic shield and selective electrical communication between windings to induce rotation in both starting and generating modes, enabling efficient torque generation and continuous power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional starter is used to start the turbine engine, then the engine can be started, but the starter becomes dead weight after startup and reduces overall system efficiency
Solution Approach 1:
The electric machine is designed to perform multiple functions: it operates as a starter motor during engine startup and transitions to a generator during normal operation. This multi-functionality eliminates the need for a separate starter component, converting what would be dead weight into a productive power-generating asset throughout the entire operational cycle.
Solution Approach 2:
Instead of discarding the starter after use, the system recovers its value by converting it into a generator. The electric machine continues to serve the system by generating electrical power during engine operation, thereby recovering the weight and energy that would otherwise be wasted.
2Device complexity
If a single electric machine is used for starting, then the system is simpler, but torque generation during starting is insufficient
Solution Approach 1:
The starting function is divided between two electric machines operating in series: the first electric machine provides initial torque to overcome engine compression resistance, and the second electric machine receives mechanical energy from the rotating engine and converts it to electrical energy. This segmentation allows each machine to be optimized for its specific function while collectively providing sufficient starting torque.
Solution Approach 2:
The system merges the starting and generating functions into a unified dual-machine architecture where both machines share common magnetic shielding and control systems. This merging reduces overall complexity despite having two machines, as shared components eliminate the need for duplicate systems.
3Object-affected harmful factors
If magnetic shielding is added to protect against electromagnetic interference, then electromagnetic protection is improved, but system weight increases
Solution Approach 1:
The magnetic shielding structure serves dual purposes: it protects the electric machines from electromagnetic interference during both starting and generating modes, and it acts as a structural support framework for the entire assembly. This multi-functionality justifies the weight by providing both protective and structural benefits.
Solution Approach 2:
The magnetic shielding is constructed using composite materials that provide high magnetic permeability for effective EMI protection while maintaining low density. This reduces the weight penalty of the shielding by using materials that offer superior protection-to-weight ratios compared to traditional solid magnetic shields.
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 system effectively starts turbine engines with enhanced torque and transitions to a generating mode, providing continuous electrical power, reducing weight and operational efficiency during both phases.
Implementation Method 1
a first electric machine operable to convert a first mode of operation in which the first electric machine converts electrical energy to mechanical energy to rotate the drive shaft
Implementation Method 2
a second electric machine operable to convert a second mode of operation in which the second electric machine converts the mechanical energy to electrical energy to provide an electrical power output
Implementation Method 3
a magnetic shield disposed between the first electric machine and the second electric machine to block a magnetic flux
Data Source
Figure 1
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Figure 3
AI summary
A starter/generator system (10) that includes a first and second electric machine (52, 62). The first electric machine (52) has a first rotor (54) and a first stator (56) where the first rotor (54) is adapted to receive kinetic energy and the first stator (56) includes a first set of windings (58). The second electric machine (62) has a second rotor (64) rotatable and a second stator (66). The second stator (66) is fixed relative to the first stator (56) and the second stator (66) includes a second set of windings (68).