Wireless Power Coil Strand Segmentation for Temperature Control
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Solution Overview
Problem
Current methods for evaluating and controlling the temperature of wireless power coils in wireless charging systems are either costly, complex, or interfere with the electromagnetic field, leading to inaccurate temperature measurements and safety concerns due to excessive heating.
Innovation Solution
A coil unit with at least two strands, one for heating and one for wireless power transfer, where the heating strand receives a DC-current, allowing for independent control and monitoring of temperature through resistance measurements, minimizing static magnetic field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature-controlled chambers are used to evaluate temperature effects, then temperature control capability is improved, but cost and device complexity increase significantly
Solution Approach 1:
The power transfer coil itself is used to generate heat for temperature evaluation, eliminating the need for external temperature-controlled chambers. The coil's inherent electromagnetic properties are leveraged to create the thermal conditions needed for testing, making the system self-sufficient for temperature evaluation.
Solution Approach 2:
The temperature control and evaluation function is extracted from the complex external chamber system and integrated directly into the coil unit itself. By adding simple heating elements and temperature sensors to the coil assembly, the system achieves temperature control without requiring elaborate external equipment.
2Temperature
If heating elements are added to generate local heat, then temperature control capability is improved, but device complexity and cost increase
Solution Approach 1:
The heating elements are merged with the power transfer coil structure, using the same physical space and support infrastructure. The temperature sensors are also integrated into the coil assembly, combining multiple functions (power transfer, heating, temperature sensing) into a single unified unit rather than adding separate external components.
3Temperature
If existing power transfer coils are used as heating elements with DC current, then temperature control is achieved, but static magnetic field interference occurs
Solution Approach 1:
The coil structure is segmented into separate functional components: power transfer windings and heating elements. This segmentation allows the heating elements to carry DC current for temperature control while the power transfer windings handle AC currents for wireless power transfer, preventing static magnetic field interference with the power transfer function.
Solution Approach 2:
Dedicated heating elements act as intermediaries between the power supply and the coil structure. These separate heating components generate the necessary heat without creating static magnetic fields that would interfere with the power transfer coils, mediating the thermal control function independently of the electromagnetic power transfer system.
4Measurement precision
If multiple temperature sensors are placed at strategic locations, then temperature measurement accuracy is improved, but cost and device complexity increase
Solution Approach 1:
The power transfer coil's inherent electrical properties (resistance, inductance) are used as self-sensing mechanisms for temperature measurement. By monitoring changes in these electrical parameters, the system derives temperature information without requiring external temperature sensors, making the coil itself serve as both the power transfer medium and the temperature sensing element.
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 provides accurate and cost-effective temperature control and evaluation, ensuring safety and performance by minimizing interference with the electromagnetic field and allowing for controlled temperature testing of wireless power devices.
Implementation Method 1
the at least one strand used for heating is configured to receive a DC-current
Implementation Method 2
Operation of devices that comply with Qi relies on magnetic induction between planar coils
Implementation Method 3
The temperature coefficient of copper causes significant changes in the calculated losses
Data Source
Figure 1
Figure 2a~2b
Figure 3a
AI summary
A method of controlling and/or evaluating the temperature of a wireless power coil (105; 205; 305) in coil unit (100; 200; 300) is provided. The method comprises providing a coil unit (100; 200; 300) comprising a wireless power coil (105; 205; 305) comprising at least two strands (112, 114; 212, 214; 312, 314), wherein at least one strand (114; 214; 314) is used for heating and at least one strand (112; 212; 312) is used for wireless power transfer, and applying a DC-current to the least one strand (114; 214; 314) used for heating.