Hybrid Vehicle Boost Converter Thermal Stress Control
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Solution Overview
Problem
Hybrid vehicle boost converters experience reduced load factor and thermal stress fractures due to temperature differences between switching elements and cooling materials, leading to potential element failure.
Innovation Solution
An onboard electronic device with a heat-generating element, a thermally distinct member between the element and coolant, temperature sensors for both element and coolant, and a controller to manage operation and limit temperature differences within predetermined ranges to mitigate thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the switching elements are joined by soldering to a substrate for cooling, then the heat resistance is improved, but thermal stresses cause fracture of the switching elements
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the operating temperature limit of switching elements based on coolant temperature. When coolant temperature is low, the element temperature limit is set lower to reduce thermal stress; when coolant temperature is high, the limit is raised. This resolves the contradiction by adapting the temperature parameter to balance heat dissipation needs against thermal stress-induced fracture risk.
Solution Approach 2:
The patent implements dynamics by making the element temperature limit variable rather than fixed. The control device continuously monitors coolant temperature and adjusts the permissible element temperature accordingly. This dynamic adjustment allows the system to optimize heat resistance performance while preventing thermal stress fractures that would occur with a static temperature limit.
2Productivity
If the element temperature is increased to improve output performance, then the productivity is improved, but the thermal stresses increase causing element fracture
Solution Approach 1:
The patent uses parameter changes to dynamically set the element temperature limit based on coolant temperature conditions. This allows the system to maximize output performance by raising the temperature limit when cooling is effective, while maintaining reliability by lowering the limit when coolant temperature is low and thermal stress risk is high. The parameter adjustment balances productivity and reliability adaptively.
3Temperature
If the coolant temperature is low to improve cooling efficiency, then the heat dissipation is improved, but the temperature difference between element and coolant increases causing thermal stress
Solution Approach 1:
The patent applies parameter changes by adjusting the element temperature limit in response to coolant temperature variations. When coolant temperature is low (improving cooling efficiency), the element temperature limit is reduced to maintain an acceptable temperature difference and prevent excessive thermal stress. This resolves the contradiction by adapting the operating temperature parameter to cooling conditions.
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
Reduces the probability of thermal stress-induced fractures by limiting the temperature increase range of heat-generating elements and maintaining consistent coolant-temperature differences, ensuring stable operation across varying coolant temperatures.
Implementation Method 1
a first element that generates heat
Implementation Method 2
a coolant that cools the first element
Implementation Method 3
a coolant that cools the first element
Implementation Method 4
a second member that is provided between the first element and the coolant cooling the first element, and differs in thermal expansion coefficient from the first element
Data Source
AI summary
An onboard electronic device includes: an element that generates heat; a member that is provided between the element and a coolant cooling the element, and differs in thermal expansion coefficient from the element; an element temperature sensor that detects the temperature of the element; a coolant temperature sensor that detects the temperature of the coolant; and a controller that controls operation of the element such that the temperature of the element allowed when the temperature of the coolant is a first temperature is lower than the temperature of the element allowed when the temperature of the coolant is a second temperature that is higher than the first temperature.