Motor Temperature Estimation via Loss Coefficients
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Solution Overview
Problem
Existing temperature estimation apparatuses for motors face challenges in accurately estimating motor temperature due to variations in detection temperature caused by different placement positions of temperature detection devices and fluctuations in current passing through the motor, leading to inconsistent overheating alarms.
Innovation Solution
A temperature estimation apparatus that calculates motor loss and detection temperature, acquires coefficient values representing the relationship between heat generation, temperature variation, and detection device placement, and uses these values to estimate motor temperature, compensating for placement variations and current fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a temperature detection device is disposed in a vicinity of a winding wire to enhance cooling effect, then the cooling effect is improved, but the detection temperature varies due to different placement positions for each motor
Solution Approach 1:
The patent changes the measurement parameter from direct temperature detection to temperature estimation based on motor loss calculation. By calculating the loss (Ploss = R × I²) and using thermal models to estimate temperature, the system avoids the placement position sensitivity of direct temperature sensors while maintaining accurate temperature monitoring capability
Solution Approach 2:
The patent introduces motor loss calculation as an intermediary parameter between current measurement and temperature estimation. Instead of directly measuring temperature at the winding wire (which is sensitive to placement), the system measures current, calculates loss, and uses thermal models to estimate temperature, thereby eliminating placement position variability
2Temperature
If a temperature detection device is disposed in a vicinity of a winding wire, then the detection temperature decreases as the distance to coolant filling unit becomes shorter, but the timing for overheat protection alarm is delayed
Solution Approach 1:
The patent implements a feedback mechanism using motor loss calculation and thermal models to continuously estimate temperature and trigger alarms based on estimated temperature thresholds. This feedback loop provides consistent alarm timing based on actual motor temperature conditions rather than variable sensor placement, ensuring timely overheat protection
Solution Approach 2:
The patent performs preliminary temperature estimation through loss calculation before actual overheating occurs. By continuously monitoring motor loss and estimating temperature trends, the system can predict and prevent overheating conditions, enabling proactive alarm timing independent of sensor placement near coolant units
3Temperature
If a current is sequentially acquired in each sampling period to calculate motor loss, then the temperature can be estimated, but a variation of current increases the variation of estimated temperature
Solution Approach 1:
The patent uses dynamic thermal models that account for time-varying heat generation and dissipation. By using differential equations that model thermal mass and heat transfer coefficients, the system can filter out short-term current variations and provide smoothed, accurate temperature estimates that reflect actual thermal conditions rather than instantaneous electrical fluctuations
Solution Approach 2:
The patent applies thermal mass and heat transfer resistance as natural cushions against current variations. The thermal model incorporates thermal capacitance and resistance parameters that inherently smooth out rapid current changes, providing stable temperature estimates even when current varies significantly between sampling periods
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 accurate motor temperature estimation independent of detection device placement and current variations, ensuring timely overheating alarms and reliable temperature monitoring.
Implementation Method 1
a temperature detection device disposed in a motor
Implementation Method 2
a heat generation amount of the motor generated due to the loss
Data Source
AI summary
A coefficient value acquiring unit acquires values of coefficients C and K representing a relationship among a heat generation amount of a motor generated due to a loss Q1(t) of the motor, a temperature variation amount of the motor, and a placement position of a temperature detection device, using the loss Q1(t) of the motor, a detection temperature Td(t), and an ambient temperature Ta of the motor. The temperature estimating unit estimates a temperature Te(t) of the motor based on the values of the coefficients C and K, a preset reference value Cm of the coefficient C, a preset reference value Km of the coefficient K, the detection temperature Td(t), and the ambient temperature Ta of the motor.