Magnetic Bearing Controller Temperature Drift Compensation
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Solution Overview
Problem
Conventional magnetic bearing devices face errors in magnetic levitation control due to temperature drift in position sensors, as differential amplification circuits fail to cancel out temperature drifts between two position detection units, leading to inaccuracies in supporting a target member using composite electromagnetic forces.
Innovation Solution
A magnetic bearing device with a controller that operates in two modes: one for acquiring temperature drift correlation information by controlling the target member's movement within a predetermined range and another for compensating the position sensor's input-output characteristic based on this information, ensuring accurate levitation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a differential amplification circuit is used to reduce temperature drift in position sensors, then temperature drift compensation is improved, but measurement precision deteriorates when the two position detection units have different temperature drifts
Solution Approach 1:
The system performs preliminary temperature drift characterization by moving the target member to multiple predetermined positions at a reference temperature to establish baseline sensor responses. This preliminary action creates a reference data set that is stored and later used to compensate for temperature drift during actual operation, allowing the system to distinguish between position changes and temperature-induced sensor drift.
Solution Approach 2:
The system changes the operational parameter of the position sensors by acquiring their input-output characteristics at different temperatures. By measuring sensor responses at multiple temperature points and establishing correlation information between temperature and sensor characteristics, the system dynamically adjusts for temperature drift through parameter-based compensation rather than relying on fixed differential amplification.
2Temperature
If two position detection units are arranged to face each other with a measurement target object interposed therebetween, then temperature drift reduction is attempted, but reliability deteriorates due to inability to cancel different temperature drifts
Solution Approach 1:
The system implements feedback by continuously monitoring the actual temperature of the position sensors and comparing it with reference temperature data. The controller uses this feedback to retrieve corresponding temperature drift correlation information and adjust the position detection results accordingly, creating a closed-loop system that actively compensates for temperature drift rather than passively relying on differential cancellation.
Solution Approach 2:
The system performs preliminary characterization of the position sensors' temperature drift behavior by moving the target member to predetermined positions at a reference temperature to establish baseline responses. This preliminary action creates a reference data set that is stored and later used to compensate for temperature drift during actual operation, enabling reliable magnetic levitation control across varying temperatures.
3Measurement precision
If temperature drift compensation is performed using correlation information between reference values and input-output characteristics, then measurement precision is improved, but device complexity increases due to additional control operations
Solution Approach 1:
The system performs preliminary temperature drift characterization by moving the target member to multiple predetermined positions at a reference temperature to establish baseline sensor responses. This preliminary action creates a reference data set that is stored in the controller's memory. During normal operation, the controller simply retrieves the appropriate reference data based on current temperature and applies compensation, avoiding the need for complex real-time calculations while maintaining high measurement precision.
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 solution effectively reduces errors in magnetic levitation control by accurately compensating for temperature drift in the position sensor, enhancing the operational efficiency of the fluid mechanical system.
Implementation Method 1
a position sensor (30) configured to output a detection signal having a signal level according to a position of the target member in a predetermined position detection direction
Implementation Method 2
a temperature compensation operation for compensating the input-output characteristic of the position sensor (30) in the magnetic levitation control operation, based on the temperature drift correlation information and the reference value (R) in the magnetic levitation control operation
Implementation Method 3
a magnetic bearing (20) including a plurality of electromagnets (51, 52) and configured to support a target member in a contactless manner using composite electromagnetic force (F) of the plurality of electromagnets (51, 52)
Data Source
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AI summary
A controller (40) performs, in a first mode, a first operation for controlling composite electromagnetic force (F) of electromagnets (51, 52) such that a target member moves within a predetermined moving range, and a second operation for acquiring temperature drift correlation information indicative of a correlation between a reference value (R) and an input-output characteristic of a position sensor (30), based on the reference value (R) and the input-output characteristic of the position sensor (30) in the first operation. The controller (40) performs, in a second mode, a third operation for controlling the composite electromagnetic force (F) of the electromagnets (51, 52) according to a signal level of a detection signal from the position sensor (30), and a fourth operation for compensating the input-output characteristic of the position sensor (30) in the third operation, based on the temperature drift correlation information and the reference value (R) in the third operation.