Motor Winding Temperature Estimation During Lock-State Torque Control
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Solution Overview
Problem
Existing motor control systems face challenges in accurately detecting the highest winding temperature during a motor lock state, leading to inadequate heat suppression and potential insulation degradation, as well as unnecessary torque restrictions due to sensor placement and heat transfer issues.
Innovation Solution
A method involving a motor control system with a winding temperature detection unit, cooling water temperature detection unit, and rotation detection unit, which estimates the maximum winding temperature using input electrical power and corrects it with an offset value based on detected temperatures, allowing for precise control of input electrical power to suppress heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor for acquiring coil temperature is arranged in a conventional position, then the sensor can detect temperature at that location, but it cannot detect the temperature of the winding phase generating the most heat during motor lock state
Solution Approach 1:
The patent introduces cooling water temperature as an intermediary parameter to indirectly assess winding temperature. By measuring the temperature of cooling water flowing through the motor and calculating temperature rise based on power input, the system infers winding temperature without requiring direct sensors in the windings. This resolves the contradiction by achieving accurate temperature assessment through a mediating measurement point.
Solution Approach 2:
The patent replaces direct thermal contact measurement (mechanical sensor placement in windings) with an electrical-power-based thermal calculation system. By using electrical power input data and cooling water temperature measurements to calculate estimated winding temperature, the system avoids the complexity of physically placing sensors in the windings while achieving accurate temperature detection.
2Temperature
If control is performed based on detected coil temperature, then heat generation can be suppressed, but unnecessary torque restrictions occur due to inaccurate temperature detection
Solution Approach 1:
The patent implements a feedback control system that continuously monitors cooling water temperature, calculates estimated winding temperature rise based on electrical power input, and adjusts torque commands accordingly. This closed-loop feedback ensures torque restrictions are applied only when actual temperature conditions warrant them, eliminating unnecessary restrictions while maintaining effective heat suppression.
Solution Approach 2:
The patent changes the control parameter from direct winding temperature measurement to estimated temperature calculation based on electrical power input and cooling water temperature. This parameter transformation allows for more accurate temperature assessment that reflects actual winding conditions, enabling precise torque control without unnecessary restrictions.
3Force
If electrical current concentration occurs in a specific phase during motor lock state, then torque can be generated, but heat generated by that winding increases excessively
Solution Approach 1:
The patent implements dynamic torque control that adjusts torque distribution among phases based on real-time temperature conditions. By continuously monitoring estimated winding temperature and dynamically modifying torque commands, the system allows current concentration when safe but redistributes current when temperature thresholds are approached, balancing torque generation with heat suppression.
Solution Approach 2:
The patent applies preliminary anti-action by predicting temperature rise based on electrical power input before excessive heat generation occurs. By calculating estimated temperature rise in advance and proactively adjusting torque commands, the system prevents current concentration from leading to dangerous temperature levels while still allowing beneficial current concentration for torque generation.
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 effectively reduces heat generation in motor windings during a motor lock state, minimizing torque restrictions and ensuring reliable motor operation while maintaining drivability.
Implementation Method 1
a winding temperature detection unit for detecting a temperature of the windings
Implementation Method 2
a cooling water temperature detection unit for detecting a temperature of cooling water
Implementation Method 3
The windings produce heat due to channeling the electrical current
Data Source
AI summary
A motor control method controls a motor having windings of a plurality of phases and a cooling water channel. The motor control calculates an estimated maximum temperature of the winding of the phase that reaches a highest temperature from among the windings of the plurality of phases based on the input electrical power when the motor is in a lock state. The motor control further calculates an offset value based on a detected temperature of the windings and a detected temperature of the cooling water, and corrects the estimated maximum temperature based on the temperature of the windings and the offset value. The motor control further controls the input electrical power according to the estimated maximum temperature.