Bi-Linear Electrodynamic Motor Balancing via Magnetic Displacement Sensing
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Solution Overview
Problem
Bilinear electrodynamic motors in cryogenic machines used in spacecraft face challenges in balancing moving masses, leading to residual vibrations that degrade performance, particularly due to mechanical and magnetic parameter tolerances and environmental factors like vibrations and thermal conditions, which existing solutions like force sensors and accelerometers fail to adequately address.
Innovation Solution
The method employs magnetic sensors, such as Hall effect sensors, to measure displacement of moving masses independently of the motor environment, constructing an excitation signal as a Fourier series to minimize harmonic errors, allowing for optimal balancing and reduced residual vibrations without intrusive sensors or modifications to mechanical and thermal interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If force sensors or accelerometers are used to measure vibrations for balancing, then vibration measurement capability is improved, but measurement precision deteriorates due to mechanical environment interference and thermal conditions
Solution Approach 1:
The patent introduces magnetic sensors as an intermediary measurement tool that detects the position of magnetized moving masses through magnetic field interactions rather than direct mechanical contact. This intermediary approach allows vibration measurement without being affected by mechanical environment interference, thermal conditions, or mass coupling issues that plague force sensors and accelerometers.
Solution Approach 2:
The patent replaces mechanical measurement systems (force sensors, accelerometers) with a magnetic field-based measurement system. By substituting mechanical contact and force measurement with magnetic field detection, the system eliminates the harmful effects of mechanical environment interference while maintaining the ability to measure vibrations for balancing control.
2Measurement precision
If magnetic sensors are used to measure moving mass displacement, then measurement precision is improved, but device complexity increases due to additional sensor integration
Solution Approach 1:
The patent makes the magnetic sensors serve multiple functions: they detect the position of moving masses for vibration measurement, provide feedback for balancing control, and can potentially serve as part of the actuation system. This multi-functionality reduces overall device complexity despite adding magnetic sensors, as they replace or supplement multiple separate measurement and control components.
Solution Approach 2:
The patent combines the measurement and control functions into an integrated system where magnetic sensors provide displacement information that directly feeds into the balancing control algorithm. The sensor integration is merged with the existing control architecture, eliminating the need for separate mechanical measurement interfaces and reducing overall system complexity.
3Reliability
If redundant force sensors are implemented for reliability, then system reliability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent uses magnetic sensors that can be easily replicated and positioned at multiple locations without complex mechanical mounting requirements. The magnetic field detection capability allows for simple sensor copies to be placed throughout the system, providing redundant measurement points without the mechanical layout complexity associated with redundant force sensors.
4Stability of the object's composition
If the compressor is rigidly fixed to the satellite structure, then mechanical stability is improved, but harmful vibrations propagate to other equipment
Solution Approach 1:
The patent implements a feedback control system using magnetic sensors to continuously monitor the position and vibration of moving masses. The measured vibration information feeds back to the control algorithm, which adjusts the excitation signals to minimize vibrations. This active feedback control reduces harmful vibration propagation to other satellite equipment while maintaining the rigid mechanical connection needed for thermal management.
Solution Approach 2:
The patent changes the operational parameters of the moving masses through adaptive control, adjusting their motion characteristics to minimize vibration generation. By dynamically modifying the excitation parameters based on real-time magnetic sensor measurements, the system reduces harmful vibrations while maintaining mechanical stability for thermal dissipation.
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 approach enables effective balancing of moving masses at any time, including during the satellite mission, reducing minimum residual vibrations and allowing for easy system redundancy, without affecting the motor's operation or requiring complex integration, and is suitable for the harsh space environment.
Implementation Method 1
magnetic sensors, such as Hall effect sensors, to measure displacement of moving masses independently of the motor environment
Implementation Method 2
The operating principle of a bilinear electrodynamic motor is based on the generation by induction coils of cyclic magnetic forces which come to animate with a rectilinear movement the magnetized mobile masses
Implementation Method 3
This approach enables effective balancing of moving masses at any time, including during the satellite mission, reducing minimum residual vibrations
Data Source
Figure 1
AI summary
The invention relates to a method for balancing the movement of magnetised mobile masses (10, 20) in a bi-linear electrodynamic motor that comprises two mobile masses (0, 20) moving in opposite directions parallel to the axis (x-x) of the motor, characterised in that said method comprises the following steps: providing at least one first magnetic sensor (12) and at least one second magnetic sensor (22) capable of respectively supplying a first electric signal (s