Radial Direction Controller for Magnetic Bearing Stability
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Solution Overview
Problem
Existing radial direction controllers for magnetic bearing apparatuses struggle to adapt to changes in negative bearing stiffness due to varying mounting attitudes, leading to instability in levitation control, particularly when the shaft of devices like turbo-molecular pumps is mounted horizontally or vertically.
Innovation Solution
A radial direction controller system that includes a radial control circuit, a negative bearing stiffness elimination circuit, a current value command device, a DC component extraction device, a correction coefficient calculation device, and a coefficient multiplication device, which calculates and applies a correction coefficient to reflect changes in negative bearing stiffness, ensuring stable levitation across different mounting attitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed negative bearing stiffness elimination circuit is used, then the controller works correctly for a specific mounting attitude, but it cannot adapt to different mounting attitudes causing levitation control instability
Solution Approach 1:
The patent implements dynamic adaptation by detecting the actual mounting attitude of the device and automatically adjusting the negative bearing stiffness elimination circuit parameters accordingly. The controller transitions from a fixed configuration to a dynamic one that adapts to horizontal, vertical, or arbitrary mounting attitudes, resolving the contradiction between reliability for a specific attitude and adaptability to multiple attitudes.
Solution Approach 2:
The patent changes the parameters of the negative bearing stiffness elimination circuit based on the detected mounting attitude. By measuring the gravitational force direction and adjusting circuit parameters (such as feedback gain coefficients) according to the detected attitude, the system maintains stable levitation control across different mounting configurations, solving the contradiction between fixed parameter reliability and parameter adaptability.
2Reliability
If the negative bearing stiffness elimination circuit is designed for horizontal mounting, then it works correctly for horizontal installation, but it fails when the device is mounted vertically or at other attitudes
Solution Approach 1:
The patent creates a universal controller that can handle multiple mounting attitudes through a single design. By incorporating attitude detection and automatic parameter adjustment, the negative bearing stiffness elimination circuit becomes multi-functional, capable of operating correctly whether the device is mounted horizontally, vertically, or at any intermediate angle, thus achieving both control accuracy and mounting flexibility.
Solution Approach 2:
The patent employs feedback mechanisms where the actual mounting attitude is continuously detected and fed back to the controller. This feedback information is used to automatically adjust the elimination circuit parameters, ensuring that the controller maintains optimal performance across different mounting attitudes, thereby achieving both accuracy for specific attitudes and adaptability to various attitudes.
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 stabilizes levitation control by accounting for changes in negative bearing stiffness, preventing instability and ensuring reliable operation regardless of the mounting attitude of the rotating body.
Implementation Method 1
a magnetic bearing apparatus that supports a rotating body to be levitated by at least an electromagnet
Implementation Method 2
a negative bearing stiffness elimination circuit for eliminating negative bearing stiffness, which is negative position stiffness with increasing of the attractive force according to the amount that an electromagnet and the rotating body approach one another
Data Source
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AI summary
Provided is a radial direction controller capable of handling changes in negative bearing stiffness according to the mounting orientation. This radial direction controller (10A), which is a magnetic bearing device (1) that lifts and supports a rotating body (2) by electromagnets (4a, 5a), is equipped with: a radial control circuit (11) for controlling displacement of the axis (Ax) of the rotating body (2) in the radial direction; a negative bearing stiffness elimination circuit (12) that is connected in parallel with the radial control circuit (11) and outputs a signal pertaining to the negative bearing stiffness; converters (61, 62, 63, 64) that output current values for controlling the electromagnets (4a, 5a), based on the output signals from these circuits (11, 12) ; filters (76, 77, 78, 79) that extract the DC component from the current values; computing units (81, 82, 83, 84) that compute correction coefficients (C) based on the extracted DC components and the bias current (10) of the electromagnets (4a, 5a); and multiplication units (55, 56, 57, 58) that multiply the computed correction coefficients (C) with the signal output from the negative bearing stiffness elimination circuit (12).