Electric Power Steering Coil Temperature Estimation
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Solution Overview
Problem
Conventional electric power steering apparatuses face inaccuracies in coil temperature estimation due to the lack of consideration for heat transfer between phase coils and the control substrate, leading to potential errors in temperature measurement.
Innovation Solution
Incorporating a temperature sensor to detect the substrate temperature and a coil temperature estimating section that calculates coil temperatures based on heat transfer phenomena between phases and the control substrate, using frequency characteristics or differential equations to account for calorific values and substrate temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature estimation methods are used without considering heat transfer between phases and control substrate, then the estimation process is simple, but the temperature measurement accuracy deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring substrate temperature through temperature sensors and using this information to correct and refine coil temperature estimates. The estimated coil temperatures are fed back to update the thermal model parameters, creating a closed-loop system that improves measurement accuracy over time while managing system complexity through iterative refinement rather than requiring complete system redesign
Solution Approach 2:
The patent introduces thermal models and heat transfer coefficient calculations as intermediary elements between the physical heat transfer processes and the final temperature estimation. These mathematical models act as mediators that translate complex thermal interactions into usable temperature data, allowing accurate estimation without directly measuring every thermal parameter
2Measurement precision
If heat transfer phenomena between phases and control substrate are considered, then temperature estimation accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent replaces direct physical measurement of heat transfer parameters with mathematical modeling and calculation. Instead of using complex sensor arrays to directly measure heat flow between phases and substrate, the system uses thermal models that calculate heat transfer coefficients based on observable temperature data, substituting mechanical/physical measurement complexity with computational analysis
Solution Approach 2:
The patent dynamically adjusts thermal model parameters such as heat transfer coefficients based on operating conditions and measured temperature data. By changing parameters adaptively rather than using fixed values, the system maintains high estimation accuracy across varying operational states without requiring complex real-time measurement of every thermal parameter
3Measurement precision
If multiple temperature sensors are added to measure phase temperatures directly, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent uses thermal models as intermediary calculations to estimate phase temperatures based on substrate temperature measurements and heat transfer analysis. Instead of placing temperature sensors directly in each phase coil, the system uses the substrate temperature sensor readings combined with thermal modeling to derive phase temperatures, reducing sensor requirements while maintaining estimation accuracy
Solution Approach 2:
The patent creates a virtual thermal model that replicates the thermal behavior of the motor phases and substrate. This computational copy of the thermal system allows temperature estimation without requiring physical sensors in every location, as the model simulates temperature distribution based on measured data and thermal principles
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 more precise estimation of coil temperatures, reducing the risk of overheating and improving the safety and reliability of the electric power steering system.
Implementation Method 1
a temperature sensor that detects a substrate temperature of the control substrate
Implementation Method 2
a heat transfer phenomenon between the coil and a control substrate
Implementation Method 3
a heat transfer phenomenon between respective phases which is caused by a difference in temperature between coils of the respective phases
Data Source
AI summary
An electric power steering apparatus that enables more precise estimation of a coil temperature by considering a heat transfer phenomenon between a control substrate and a poly-phase coil in addition to a heat transfer phenomenon between respective phases of the coil. The apparatus includes a control substrate that controls a poly-phase motor, a temperature sensor that detects a substrate temperature of the control substrate and a coil temperature estimating section that estimates coil temperatures of respective phases of the poly-phase motor by a motor current of the phase and the substrate temperature based on a heat transfer phenomenon between the respective phases that is caused by a difference in temperature between coils of the respective phases and a heat transfer phenomenon between the coil and the control substrate.