Magnetic Bearing Sensor Sensitivity Estimation Without Extra Hardware
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Solution Overview
Problem
Determining the sensitivity of position sensors in magnetic bearings is challenging due to the difficulty in measuring radial and axial mechanical movements of the rotor, which is essential for adjusting the machine during commissioning.
Innovation Solution
A method that involves levitating the rotor in a magnetic bearing, applying a predetermined movement setpoint to reach an intermediate position, measuring control currents before and after the movement, determining the variation in control currents, and calculating the sensitivity of the sensor based on these measurements without requiring additional position measurement devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accurate comparator is used to measure the radial and axial mechanical movement of the rotor, then the sensitivity determination becomes more accurate, but the device complexity and measurement difficulty increase significantly
Solution Approach 1:
The magnetic bearing system uses its own control coils and control signals to determine sensor sensitivity. The method leverages the existing control currents and position measurements that the magnetic bearing system already generates during normal operation, eliminating the need for external measurement devices. The system essentially measures itself using its inherent components.
Solution Approach 2:
The invention introduces an intermediary approach by using the control coil currents as a mediator to indirectly determine the rotor position and sensor sensitivity. Instead of directly measuring mechanical movement with a comparator, the system uses the relationship between control currents and rotor position to infer sensitivity, making the measurement process feasible with existing components.
2Measurement precision
If additional position measurement devices are implemented to determine sensor sensitivity, then the measurement accuracy improves, but the device complexity and hardware requirements increase
Solution Approach 1:
The magnetic bearing system determines sensor sensitivity using only its own existing components - the control coils, power supply, and position sensors already present in the system. No additional measurement devices are required, as the system leverages its own operational parameters (control currents and position measurements) to calculate sensitivity.
Solution Approach 2:
The control coils in the magnetic bearing serve multiple functions: they provide magnetic levitation forces to hold the rotor, and simultaneously serve as measurement instruments to determine sensor sensitivity. By analyzing the control currents required to maintain rotor position at different sensor readings, the system uses the same components for both actuation and measurement purposes.
3Measurement precision
If the rotor mechanical movement is directly measured during commissioning, then the sensitivity calibration becomes more accurate, but the ease of operation during machine commissioning deteriorates
Solution Approach 1:
During commissioning, the system automatically determines sensor sensitivity using its own control signals and position measurements. The method requires no external measurement equipment or complex mechanical displacement measurements, making the commissioning process simpler and more straightforward while maintaining accurate sensitivity calibration.
Solution Approach 2:
The invention replaces the need for mechanical displacement measurement with an electrical measurement approach. Instead of mechanically moving the rotor and measuring the movement with a comparator, the system uses electrical measurements of control coil currents combined with position sensor readings to calculate sensitivity, simplifying the commissioning procedure.
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
Enables the determination of sensor sensitivity using existing machine elements, allowing for accurate adjustment of magnetic bearings without additional hardware, thereby improving the commissioning process.
Implementation Method 1
a magnetic-levitation magnetic bearing supporting a rotor in a stator
Implementation Method 2
at least one shaft provided with at least two radially opposite coils
Data Source
AI summary
A device for estimating the sensitivity of a position sensor for a magnetic bearing supporting a rotor, the sensor being capable of measuring the position of the rotor in relation to the magnetic bearing, the magnetic bearing including at least one shaft provided with at least two radially opposite coils. The device includes a control, a current-measuring component, a component for measuring the initial position of the rotor, a component for determining a variation in currents, a component for determining a movement of the rotor, and a component for determining the sensitivity of the sensor, configured to determine the sensitivity of the position sensor based on a movement setpoint and on the value of a movement of the rotor.