Motor Generator Vacuum Barrier for Stator Pressure
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Solution Overview
Problem
The integration of a motor/generator within a vacuum chamber in flywheel energy storage systems leads to issues such as stator component outgassing, increased cooling requirements, and electrical breakdown risks due to sub-ambient pressures and high voltages, necessitating specialized insulation and shielding designs.
Innovation Solution
A motor/generator design with a cylindrical vacuum chamber separating the rotor and stator assemblies, allowing the rotor to operate in a vacuum while the stator operates at atmospheric pressure, using a vacuum barrier made of impermeable materials and vents for air or coolant entry to manage pressure and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the motor/generator is placed within the vacuum chamber with the rotor, then aerodynamic drag is reduced, but stator components outgas into the vacuum chamber reducing service life of vacuum pumps
Solution Approach 1:
The motor/generator is segmented into two separate pressure environments: the rotor assembly operates in the vacuum chamber while the stator assembly operates in an atmospheric pressure environment. This segmentation allows each component to operate in its optimal pressure condition, eliminating outgassing issues from the stator while maintaining the vacuum for the rotor.
Solution Approach 2:
A vacuum barrier (impermeable cylindrical chamber) acts as an intermediary between the rotor and stator assemblies, separating the vacuum environment from the atmospheric environment. This barrier enables the stator to be cooled and supplied with air without compromising the vacuum integrity, while still allowing magnetic coupling between the rotor and stator.
2Device complexity
If the motor/generator is placed within the vacuum chamber, then integration is improved, but stator windings heat up requiring added cooling componentry
Solution Approach 1:
The motor/generator is divided into two pressure zones with the stator in atmospheric pressure and the rotor in vacuum. This allows the stator to access ambient air for natural convection cooling without requiring complex vacuum-compatible cooling systems, while maintaining integrated operation through magnetic coupling across the vacuum barrier.
3Quantity of substance
If sub-ambient pressures with voltages about 300 V are used, then energy storage density is improved, but electrical breakdown occurs governed by the Paschen curve
Solution Approach 1:
The high voltage electrical components (stator windings) are separated from the vacuum environment and placed in atmospheric pressure. This eliminates Paschen curve-related electrical breakdown risks in the high voltage regions while allowing the vacuum environment to be maintained for the rotor, enabling high energy storage density without compromising electrical safety.
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 configuration reduces outgassing, lowers cooling demands, and mitigates electrical breakdown risks, enhancing motor/generator performance and longevity by allowing stator windings to be cooled effectively and reducing the cost and maintenance needs of vacuum systems.
Implementation Method 1
a cylindrical vacuum barrier between the rotor assembly and the stator assembly that together with the motor generator housing partitions the motor/generator into an interior rotor volume and an exterior stator volume, enabling the rotor volume and stator volume to operate at different atmospheric pressures
Data Source
AI summary
The invention is a motor/generator that includes a motor/generator housing that encloses a rotor assembly, which rotates a shaft, and a stator assembly that remains stationary, and where the motor/generator is inside a vacuum chamber, which, during normal operation, is evacuated of gas and operates at a lower air pressure than atomospheric air pressure, and a cylindrical vacuum barrier between the rotor assembly and the stator assembly that together with the motor generator housing partitions the motor/generator into an interior rotor volume and an exterior stator volume, enabling the rotor volume and stator volume to operate at different atmospheric pressures.