Magnetic Bearing Sensor Drift Compensation
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Solution Overview
Problem
Magnetic bearing devices face challenges in accurately controlling shaft positions due to temperature-induced drift in displacement sensor outputs, especially when there is limited space for temperature sensors and installing them increases manufacturing costs.
Innovation Solution
A magnetic bearing device that compensates for temperature-induced changes in displacement sensor outputs using reference values detected from the system, such as rotational speed, temperature, and refrigerant pressure, without requiring a temperature sensor near the displacement sensor, by applying a transformation law with adjustable parameters based on these values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are installed near the displacement sensors to compensate for drift, then measurement precision is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent uses readily available reference values (temperature, rotational speed, vibration) as intermediary parameters to indirectly compensate for displacement sensor drift. Instead of directly measuring sensor temperature with additional sensors, the system uses these reference values to detect changes in operating conditions and apply corresponding compensation to the displacement measurements, thereby avoiding the need for additional temperature sensors near the displacement sensors.
Solution Approach 2:
The system uses its own existing sensors and operational data (temperature sensors already present in the system, rotational speed measurements, vibration data) to compensate for displacement sensor drift. The system serves itself by utilizing its own operational characteristics and existing measurement capabilities to correct measurement errors, eliminating the need for external or additional dedicated temperature compensation sensors.
2Measurement precision
If temperature sensors are installed near the displacement sensors to compensate for drift, then measurement precision is improved, but manufacturing costs increase
Solution Approach 1:
The patent makes existing system components serve multiple functions. Temperature sensors originally intended for general temperature monitoring are also used for compensating displacement sensor drift. Similarly, rotational speed and vibration measurements, while serving their primary control functions, are also utilized as reference values for drift compensation. This multi-functionality eliminates the need for additional dedicated temperature compensation sensors, thereby reducing manufacturing costs.
Solution Approach 2:
The system compensates for displacement sensor drift using its own existing operational data and sensors. By utilizing temperature, rotational speed, and vibration measurements that are already being collected for other control purposes, the system avoids the need for additional manufacturing expenses associated with installing dedicated temperature compensation sensors near the displacement sensors.
3Device complexity
If reference values are used to compensate for temperature-induced drift without additional temperature sensors, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent employs reference values (temperature, rotational speed, vibration) as intermediary indicators that correlate with the operating conditions affecting displacement sensor drift. These reference values serve as proxies for direct temperature measurement, allowing the system to infer and compensate for drift effects without needing additional temperature sensors. The transformation law mathematically relates these intermediary reference values to the expected drift, maintaining measurement precision while simplifying the sensor configuration.
Solution Approach 2:
The system changes the parameters used for drift compensation from direct temperature measurements to a combination of reference values including temperature, rotational speed, and vibration. By transforming the compensation approach to use these alternative parameters and applying a transformation law, the system achieves accurate drift compensation while avoiding the need for additional temperature sensors, thus maintaining measurement precision with reduced device complexity.
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 enables accurate compensation for temperature-related drift in displacement sensor outputs, improving shaft position control without the need for additional temperature sensors, thus reducing manufacturing costs and maintaining system accuracy.
Implementation Method 1
a displacement sensor (31, 32) configured to output an output signal in accordance with a displacement of the shaft (5)
Implementation Method 2
a magnetic bearing (21, 22) including a plurality of electromagnets (51 to 54) configured to apply electromagnetic force to a shaft (5)
Data Source
AI summary
A magnetic bearing device includes a magnetic bearing including a plurality of electromagnets, a displacement sensor configured to output an output signal in accordance with a displacement of a shaft, and a controller configured to control the electromagnets. The controller compensates for a change in levels of the output signal, the change occurring in accordance with a change in ambient temperature around the displacement sensor, based on one or more reference values correlating with the change in levels of the output signal. The one or more reference values are detected for use in controlling the rotary electric machine, a fluid machine system including the rotary electric machine, or an apparatus including the fluid machine system.