Electric Motor Rotor Temperature Estimation for Speed-Adaptive Output Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric motor control systems for vehicles do not effectively consider rotation speed, leading to excessive output limitation at low speeds and inefficient operation, particularly due to the demagnetization of permanent magnets at high temperatures.
Innovation Solution
A control apparatus that estimates rotor temperature based on stator temperature, refrigerant temperature, and rotation speed, incorporating an electric power source cutoff time identification unit and a start-up temperature estimation unit to accurately control the electric motor's output and drive conditions, ensuring efficient operation across various speed ranges and preventing demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If output control is performed without considering rotation speed, then permanent magnets are protected from demagnetization at high speeds, but output is excessively limited at low speeds
Solution Approach 1:
The control apparatus dynamically adjusts output control strategies based on real-time rotation speed detection. At high speeds, conservative temperature control prevents demagnetization, while at low speeds, the system allows higher output levels, creating a dynamic, speed-adaptive control system that resolves the contradiction between protection and efficiency
Solution Approach 2:
The system changes the control parameters (output limits, temperature thresholds) based on the rotation speed parameter. By detecting rotation speed and adjusting control settings accordingly, the system optimizes both demagnetization prevention at high speeds and output efficiency at low speeds through parameter adaptation
2Reliability
If conservative output control is applied to prevent demagnetization, then permanent magnets are protected, but the electric motor cannot operate efficiently at low speeds
Solution Approach 1:
The control system transitions from static conservative control to dynamic adaptive control that responds to rotation speed conditions, allowing the motor to operate efficiently across different speed ranges while maintaining magnet protection where necessary
Solution Approach 2:
The system uses rotation speed feedback to adjust control strategies in real-time, enabling the motor to operate efficiently at low speeds without compromising magnet protection at high speeds through continuous monitoring and adaptive response
3Speed
If rotor temperature is not accurately estimated at startup, then control responsiveness is improved, but demagnetization risk increases
Solution Approach 1:
The control apparatus performs preliminary temperature estimation calculations during the startup phase using available sensor data and thermal models, establishing an initial temperature state before full operation begins. This preliminary action enables immediate appropriate control while maintaining accuracy
Solution Approach 2:
The system replaces direct physical temperature measurement of the rotor with a computational estimation model that uses stator temperature, rotation speed, and thermal characteristics to calculate rotor temperature, enabling accurate temperature knowledge without direct rotor sensing
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
The solution enables efficient operation of electric motors at both low and high speeds, increases torque output at low speeds, and effectively prevents demagnetization of permanent magnets, resulting in improved responsiveness and performance during vehicle startup.
Implementation Method 1
a rotor temperature estimation unit estimating a temperature of a rotor based on stator temperature information from a stator temperature identification unit for identifying a temperature of a stator, refrigerant temperature information from a refrigerant temperature identification unit for identifying a temperature of refrigerant used to cool the electric motor, and rotation speed information about the rotor from a rotation speed identification unit for identifying a rotation speed of the rotor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A control apparatus (60) includes: a rotor temperature estimation unit (62a) estimating a temperature of a rotor (14) based on stator temperature information from a first temperature sensor (17) for identifying a temperature of a stator (12), refrigerant temperature information from a second temperature sensor (25) for identifying a temperature of refrigerant used to cool an electric motor (10), and rotation speed information about the rotor (14) from a resolver (18) for identifying a rotation speed of the rotor (14); and an electric motor control unit (62d) controlling at least one of an output characteristic and a drive condition of the electric motor (10) based on the temperature of the rotor (14) estimated by the rotor temperature estimation unit (62a).