Inductive Position Sensor With Integrated Microbolometer
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Solution Overview
Problem
Existing sensors for detecting rotational properties in electric machines, such as resolvers, require significant space, are costly, and lack redundancy, while temperature measurement methods like bolometric sensors are difficult to integrate and provide inaccurate rotor temperature data due to limited accessibility and unknown emissivity.
Innovation Solution
An inductive position sensor system comprising a coil arrangement with receiver coils and a microbolometer element, where the microbolometer determines absolute temperature and encodes temperature information into signals, eliminating the need for additional signal lines and allowing for accurate rotor temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resolvers are used to detect rotational properties, then measurement reliability is improved, but device complexity and installation space increase
Solution Approach 1:
The patent replaces the mechanical resolver system with an inductive sensor system that uses electromagnetic coupling between a transmitter coil and receiver coils. The encoder wheel with conductive and non-conductive segments modulates the magnetic field, eliminating the need for complex mechanical resolvers while achieving similar measurement reliability through simpler electromagnetic principles
Solution Approach 2:
The patent extracts the temperature sensing function from the rotational position sensing system by integrating a separate microbolometer element. This allows independent temperature measurement without interfering with the position detection function, resolving the contradiction by separating measurement functions
2Reliability
If resolvers are used to detect rotational properties, then measurement reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses inexpensive planar coils printed on circuit boards instead of expensive resolver assemblies. The encoder wheel can be manufactured as a simple plastic component with conductive paint or foil patterns, dramatically reducing manufacturing costs while maintaining functional reliability
Solution Approach 2:
The patent changes the measurement approach from mechanical angle detection to electromagnetic induction with an encoder wheel. This parameter change allows the use of cheaper materials and manufacturing processes while achieving comparable measurement reliability through different physical principles
3Measurement precision
If bolometric sensors are used for temperature measurement, then temperature detection capability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent makes the encoder wheel multi-functional by integrating both position encoding (conductive/non-conductive segments) and temperature sensing (microbolometer element) into a single component. This universal design improves ease of manufacture by eliminating the need for separate temperature sensors and their associated mounting and wiring
Solution Approach 2:
The patent merges the position detection and temperature measurement functions into a single integrated system. The encoder wheel serves dual purposes: its conductive segments modulate magnetic fields for position detection, while the integrated microbolometer element measures temperature, simplifying the overall manufacturing process
4Reliability
If redundant receiver coil systems are installed on resolvers, then reliability is improved, but installation space increases
Solution Approach 1:
The patent uses dynamic signal processing to achieve redundancy without additional physical sensors. The evaluation unit can process signals from a single receiver coil system to determine both position and temperature, using temporal and spectral analysis to ensure measurement reliability without requiring redundant hardware
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 provides a compact, cost-effective solution for determining rotational properties and temperature, enhancing the accuracy and reliability of electric machine performance monitoring without external magnetic field influence and additional signal lines.
Implementation Method 1
An excitation coil and several receiver coils are mounted annularly around a stator. The excitation coil is supplied with an alternating voltage signal, which permeates the entire assembly with an alternating electromagnetic field.
Implementation Method 2
Far-infrared sensors based on the bolometric principle are also well-known for contactless temperature measurement. These sensors detect the integrated spectrally emitted power of an object.
Implementation Method 3
Depending on the angle of rotation, a sinusoidally amplitude-modulated voltage can be induced in a first receiver coil, while a cosine-amplitude-modulated voltage is induced in a second receiver coil.
Data Source
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AI summary
The invention relates to an inductive position sensor (124), in particular for sensing at least one rotation property of an element (114) which rotates about at least one axis of rotation (112), comprising: at least one circuit carrier (132); at least one coil assembly (134), which is arranged on the circuit carrier (132), the coil assembly (134) comprising at least one excitation coil (136) and at least two receiving coils (138); at least one application-specific integrated circuit (ASIC) (140), which is arranged on the circuit carrier (132) and is designed to provide an excitation signal (158) for the excitation coil (136), the application-specific integrated circuit (140) being designed to process signals (162, 164) produced by the receiving coils (138) and to provide the same as output signals (172, 174); characterized in that the inductive position sensor (124) has at least one microbolometer element (148), which is arranged on the circuit carrier (132).