Temperature Estimation Control Using Thermal Time Constants
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Solution Overview
Problem
Existing temperature monitoring systems for devices, such as rotary electric machines, face challenges in accurately estimating temperatures due to response delays and thermal resistance issues, leading to reliability concerns and device enlargement, especially when sensors cannot be placed close to the temperature monitoring points.
Innovation Solution
A controller and control method that estimates temperatures using only the detection values and correction values of a temperature sensor, along with a thermal time constant, allowing for accurate temperature estimation even when the sensor is not directly attached to the monitoring point, thereby improving flexibility and reducing the need for additional sensors and complex calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the temperature sensor is attached close to the temperature monitoring point, then the temperature detection accuracy is improved, but the device structure becomes more complex and the sensor arrangement space is restricted
Solution Approach 1:
The patent introduces a thermal time constant as an intermediary parameter to bridge the gap between the sensor temperature and the actual temperature at the monitoring point. By using the thermal time constant to correct the sensor temperature, the system achieves accurate temperature monitoring without requiring the sensor to be physically close to the monitoring point, thus simplifying the device structure while maintaining measurement precision.
2Measurement precision
If multiple sensors and complex calculations are used for temperature estimation, then the temperature estimation accuracy is improved, but the device size increases and the cost increases
Solution Approach 1:
The patent extracts and utilizes only the essential elements for temperature estimation: the sensor temperature detection value and the thermal time constant. By removing unnecessary sensors and complex calculation processes, the system achieves accurate temperature estimation with a minimal configuration, thereby reducing device size and cost while maintaining estimation accuracy.
3Reliability
If the determination value for limiting output is set to a temperature lower than the heat resistant temperature, then the reliability is improved, but the device must be enlarged to provide the margin
Solution Approach 1:
The patent implements a feedback mechanism where the sensor temperature is continuously corrected using the thermal time constant to estimate the actual temperature at the monitoring point. This accurate real-time temperature feedback allows the system to set the determination value closer to the heat resistant temperature without compromising reliability, thereby eliminating the need for additional safety margins that would require device enlargement.
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 enables precise temperature estimation with reduced error, simplifies the device design, and enhances system reliability by eliminating the need for multiple sensors and complex calculations, while maintaining accuracy during transient and steady-state conditions.
Implementation Method 1
a response delay occurs in the temperature detection value... thermal resistance exists between the temperature monitoring point and the sensor part
Implementation Method 2
a thermal time constant from a temperature of the temperature estimation point set inside the temperature estimation object to the sensor temperature
Data Source
AI summary
To provide a controller and a control method which can estimate a temperature of the temperature estimation with good accuracy without depending on detection information of other sensors other than the temperature sensor, even if the temperature sensor is attached to a position away from the temperature estimation point. A controller is provided with a sensor temperature detector that detects a sensor temperature based on an output signal of a temperature sensor attached to a temperature estimation object; and a temperature estimator that calculates an estimated temperature of the temperature estimation point, based on the current detection value of sensor temperature or the current correction value of sensor temperature, the detection value of sensor temperature before the step time or the correction value of sensor temperature before the step time, and a thermal time constant.