Axial Thermopile Rotor Temperature Detection in Electric Machines
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Solution Overview
Problem
Temperature measurement of rotating parts in electrical machines, such as electric motors and generators, is challenging due to the difficulty in implementing radial openings in compact designs and the issues of cost, contamination, and measurement inaccuracies caused by reflections and emissions in existing non-contact methods.
Innovation Solution
An arrangement with a thermopile infrared temperature sensor integrated into a slot of the stator, allowing for non-contact temperature detection with reduced complexity and cost, minimizing contamination risks, and eliminating the need for complex optics and additional structural space, while enabling continuous temperature monitoring and adjustment of operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radial opening is provided in the stator for temperature detection, then non-contact temperature measurement of the rotor is enabled, but the implementation becomes difficult due to windings and compact design constraints
Solution Approach 1:
The patent changes the detection direction from radial (perpendicular to rotor axis) to axial (parallel to rotor axis). By placing the infrared sensor in the axial direction at the end of the stator, the measurement path no longer intersects with the radial windings, eliminating the manufacturing difficulty while maintaining non-contact temperature detection capability.
2Measurement precision
If an external infrared temperature sensor with optics is used, then rotor temperature can be detected, but the distance between sensor and rotor surface requires complex optics increasing cost
Solution Approach 1:
By switching from radial to axial detection, the sensor can be positioned much closer to the rotor surface without requiring complex optical systems. The axial arrangement allows the infrared sensor to detect radiation from the rotor surface directly across a short air gap, eliminating the need for expensive lens systems.
3Measurement precision
If a radial opening channel is provided for temperature detection, then non-contact measurement is possible, but the channel becomes clogged with dirt particles over time falsifying measurements
Solution Approach 1:
The patent extracts the infrared sensor from the radial opening configuration and relocates it to the axial end of the stator. This removes the enclosed channel structure that trapped dirt particles, allowing the sensor to operate in a cleaner environment while maintaining its ability to detect rotor temperature non-contactly.
4Measurement precision
If cooling air bores are designed radially to the rotor, then temperature detection is improved, but this is not feasible in medium-sized and small electrical machines due to space constraints
Solution Approach 1:
The patent transitions from radial to axial detection geometry, which eliminates the need for additional radial space for cooling bores and temperature detection. The axial arrangement fits within the existing end-structure of the stator, making it suitable for compact medium-sized and small electrical machines without increasing overall machine volume.
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 provides reliable, cost-effective, and accurate temperature detection for rotor monitoring, preventing thermal overloading and demagnetization, optimizing performance, and reducing the need for oversizing, thereby enhancing operational efficiency and energy savings.
Implementation Method 1
A thermopile is an interconnection (usually in the form of a column or a layered system) with (usually) several thermocouples, which are measured by means of the Seebeck effect as a function of a captured thermal radiation and a substrate or reference point temperature
Implementation Method 2
the heat radiation of the rotor and thus its surface temperature can be detected
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method and arrangement having an electric machine, comprising a stator (4) and a rotor (1) and an infrared temperature sensor, wherein the detection field of the infrared temperature sensor is directed at an outer surface of the rotor (1). The infrared temperature sensor is a thermopile (6) for radiometrically contactlessly detecting a temperature of the rotor (1), the thermopile being arranged in a slot of the stator (4) and being compatible with standard slot-sealing-wedge components of the electric machine with regard to assembly, and thus enables the operational monitoring of the thermal state of an electric machine in a novel manner, such that adapted power states can be achieved.