Magnet Temperature Estimation via Transmission Coolant
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Solution Overview
Problem
Existing methods for estimating the temperature of magnets in rotary electric machines are inaccurate due to the lack of consideration for the effect of lubricating oil scattered from the transmission, leading to deviations in estimated magnet temperatures.
Innovation Solution
A method that incorporates parameters related to the power transmitting mechanism, including losses and fluid dynamics, to accurately estimate magnet temperatures by accounting for the heat transferred from the lubricating oil to the rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnet temperature is estimated using conventional thermal models without considering lubricating oil effects, then the estimation method remains simple, but the estimation accuracy deteriorates significantly
Solution Approach 1:
The patent introduces a coolant temperature parameter as an intermediary that indirectly reflects the heat transfer from the power transmitting mechanism. Instead of directly measuring rotor temperature or installing sensors on rotating parts, the system uses the coolant temperature (which absorbs heat from the transmission) as a mediator to estimate the magnet temperature, thereby avoiding direct contact with rotating components while achieving accurate temperature estimation.
Solution Approach 2:
The patent replaces the mechanical sensor-based temperature detection system with a computational estimation system. Instead of using physical temperature sensors mounted on the rotor (which would require slip rings or rotary connectors), the system substitutes mechanical measurement with a thermal model that calculates magnet temperature based on operating parameters and coolant temperature, eliminating the need for complex mechanical detection infrastructure.
2Measurement precision
If temperature sensors are mounted on the rotor through slip rings or rotary connectors, then direct temperature detection is achieved, but the structural complexity and manufacturing cost increase
Solution Approach 1:
The patent uses coolant temperature as an intermediary parameter to indirectly detect rotor and magnet temperatures. The coolant serves as a thermal mediator that absorbs heat from the power transmitting mechanism and transfers it to the rotor area, allowing the system to infer rotor temperature without direct sensor contact with rotating parts.
Solution Approach 2:
The system utilizes the coolant that is already present in the power transmitting mechanism for dual purposes: lubrication/cooling of the transmission and as a thermal indicator for rotor temperature estimation. The coolant's temperature naturally reflects the thermal state of the system, eliminating the need for separate temperature sensing infrastructure on the rotor.
3Measurement precision
If conventional thermal models are used without lubricating oil parameters, then the model remains simple, but the estimated magnet temperature deviates significantly from actual temperature
Solution Approach 1:
The patent makes the coolant serve multiple functions: it acts as a lubricant for the power transmitting mechanism, a coolant for thermal management, and simultaneously as a thermal sensor that provides temperature information for estimating rotor and magnet temperatures. This multi-functionality allows the system to achieve accurate temperature estimation without adding separate sensing systems.
Solution Approach 2:
The coolant temperature acts as an intermediary parameter that bridges the thermal states of the power transmitting mechanism and the rotor. By measuring the coolant temperature and using it in the thermal model, the system can estimate magnet temperature without directly measuring temperatures in difficult-to-access rotating components.
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 minimizes deviations in estimated magnet temperatures, reduces the need for dysprosium in magnets, lowers manufacturing costs, and optimizes power management in electric vehicles by preventing unnecessary power save modes, thereby reducing fuel consumption and enhancing vehicle performance.
Implementation Method 1
the scattered lubricating oil is applied to the rotor of the rotary electric machine and transfers heat to the rotor, possibly changing, i.e., increasing or decreasing, the temperature of the rotor including the magnets thereof
Data Source
AI summary
A magnet temperature calculator estimates a magnet temperature of a rotary electric machine using at least parameters related to a transmission that is coupled to the rotary electric machine.