Electric Motor Temperature Estimation via Thermal Coefficient Correction
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Solution Overview
Problem
Existing methods for estimating the temperature of electric motors, either through loss estimation or using temperature sensors, face inaccuracies due to complex configurations and delayed heat transfer, leading to difficulties in accurately detecting temperature changes, especially with large changes over time.
Innovation Solution
A temperature estimating device that uses a temperature sensor to acquire detected temperatures, stores them at a predetermined sampling period, and employs a ratio of temperature change over time and a coefficient to estimate the motor's temperature, with options for averaging changes and adjusting coefficients based on heat capacities and cooling device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor with resin coating is used to detect winding temperature, then the temperature sensor provides insulation and heat resistance, but the resin's large heat capacity delays heat transmission causing inaccurate temperature detection during rapid temperature changes
Solution Approach 1:
The patent introduces a thermal conductivity coefficient as an intermediary parameter to compensate for the heat transmission delay caused by the resin coating. By multiplying the detected temperature by this coefficient (which accounts for the resin's thermal properties and the winding's characteristics), the system calculates the actual winding temperature, effectively correcting the time delay effect without changing the physical sensor structure.
Solution Approach 2:
The patent transforms the temperature reading from the sensor into a corrected temperature value by applying a thermal conductivity coefficient. This parameter change compensates for the thermal inertia of the resin coating, allowing the system to derive accurate winding temperature from the delayed sensor signal through mathematical transformation rather than physical modification.
2Measurement precision
If loss estimation method is used to estimate electric motor temperature, then temperature estimation can be performed, but the configuration required for estimation becomes complicated
Solution Approach 1:
The patent extracts only the essential element needed for temperature estimation - the temperature sensor reading - and applies a simple correction factor (thermal conductivity coefficient) to it. This eliminates the need for complex multi-parameter loss estimation systems while maintaining temperature estimation capability, thereby simplifying the device configuration.
Solution Approach 2:
The patent uses a single parameter transformation (multiplying sensor temperature by a thermal conductivity coefficient) to achieve temperature estimation, replacing complex loss calculation methodologies. This parameter-based approach maintains estimation accuracy while dramatically reducing system complexity.
3Measurement precision
If temperature sensor is attached near the winding to monitor heat generation, then the sensor can detect winding temperature, but the resin coating's heat capacity prevents sufficient heat transmission during rapid temperature changes
Solution Approach 1:
The thermal conductivity coefficient serves as a mathematical intermediary that bridges the gap between the slow heat transmission through resin and the need for accurate real-time temperature measurement. By introducing this coefficient into the calculation, the system compensates for the slow thermal response without requiring faster physical heat transmission.
Solution Approach 2:
The patent replaces the physical requirement for fast heat transmission (mechanical/thermal system) with a mathematical correction approach. Instead of modifying the thermal path to speed up heat transfer, the system uses computational correction (multiplying by thermal conductivity coefficient) to achieve accurate temperature measurement despite slow heat transmission.
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 approach allows for accurate temperature estimation of electric motors, even with large temperature changes, and simplifies the estimation process compared to existing methods, ensuring the detected temperature closely aligns with the actual motor temperature.
Implementation Method 1
The temperature detecting element 102 is covered by a resin 106 so as to improve insulating ability and heat resistance... the heat generated from the winding is sometimes not transmitted to the temperature detecting element 102 sufficiently fast
Data Source
AI summary
A temperature estimating device configured to estimate a temperature of an electric motor includes a temperature detecting part for acquiring a detected temperature detected by a temperature sensor attached to the electric motor, a memory part for successively storing the detected temperature acquired by the temperature detecting part at a predetermined sampling period, and a temperature estimating part for using the detected temperature stored by the memory part, a ratio of amount of change of the detected temperature with respect to time, and a coefficient as the basis to estimate a temperature of a measurement target part of the electric motor.