Inductor Air Gap Separator Thermal Expansion for Temperature Monitoring
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Solution Overview
Problem
Conventional power converter inductors in electrified vehicles face temperature management issues due to high current and voltage switching, leading to potential safety and durability concerns, and the use of thermistors for temperature monitoring adds complexity and cost.
Innovation Solution
A power system with an inductor core and a separator spanning the core's gap, made of material with a predefined thermal expansion coefficient, which changes size with temperature, allowing a controller to adjust power supply based on current ripple amplitude changes, eliminating the need for separate temperature measurement devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermistor or temperature measurement device is added to monitor inductor core temperature, then temperature monitoring capability is improved, but device complexity and cost increase
Solution Approach 1:
The inductor core itself serves as the temperature sensor through its inherent thermal expansion properties. The separator material expands or contracts with temperature changes, directly altering the air gap and inductance characteristics. This self-service approach eliminates the need for external thermistors or temperature measurement devices, resolving the contradiction between measurement capability and device complexity
Solution Approach 2:
The patent utilizes changes in physical parameters (thermal expansion coefficient) of the separator material to translate temperature variations into electrical parameter changes (inductance). By monitoring inductance changes caused by thermal expansion, the system achieves temperature monitoring without additional sensors, addressing both measurement precision and device complexity concerns
2Measurement precision
If a thermistor or temperature measurement device is added to monitor inductor core temperature, then temperature monitoring capability is improved, but manufacturing cost increases
Solution Approach 1:
The inductor core structure performs dual functions: magnetic energy storage and temperature sensing. The separator material's thermal expansion behavior provides intrinsic temperature monitoring capability, eliminating the need for separate thermistor components and reducing manufacturing costs while maintaining measurement precision
Solution Approach 2:
The separator material serves multiple functions simultaneously: maintaining air gap geometry and providing temperature sensing through thermal expansion. This multi-functionality reduces component count and manufacturing complexity, resolving the contradiction between measurement capability and manufacturing cost
3Measurement precision
If the separator material expands with temperature increase, then temperature monitoring sensitivity is improved, but inductance stability deteriorates
Solution Approach 1:
The patent intentionally utilizes parameter changes (thermal expansion coefficient) of the separator material to create a controlled relationship between temperature and inductance. By selecting materials with known expansion characteristics, the system achieves temperature monitoring sensitivity while maintaining predictable inductance behavior that can be compensated for in control algorithms
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 solution effectively monitors and manages inductor temperature without additional measurement components, improving safety, durability, and reducing costs by correlating inductance changes with temperature through current ripple amplitude, allowing for controlled power reduction or shutdown to prevent overheating.
Implementation Method 1
a separator spanning the gap and contacting the core... temperature driven change in size of the separator
Data Source
AI summary
A power system comprises a converter including an inductor core defining a gap, and a separator spanning the gap and contacting the core. The power system also includes a controller programmed to, responsive to a decrease in current ripple amplitude output by the converter to less than a first threshold, decrease power supplied by the converter. The first threshold is indicative of an inductance change through the core due to a temperature driven decrease in size of the separator.