Wireless Charging Pad Thermal Control Using Surface Feedback
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Solution Overview
Problem
Wireless charging systems face challenges in detecting and managing overheating during charging, particularly in complex mobile devices with limited heat dissipation capabilities, as they are unaware of the temperature or state of charge of the battery being charged, leading to inefficient charging duty cycles and potential thermal issues.
Innovation Solution
A multi-coil wireless charging system with temperature sensors on the charging surface that measure and estimate battery temperatures, allowing the system to reduce charging power or initiate a cool-down sequence when an overtemperature condition is detected, and selectively activate coils to optimize charging configurations based on device placement and temperature feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless charging power is increased to improve charging speed, then charging efficiency is improved, but thermal issues and overheating risks worsen
Solution Approach 1:
The system continuously monitors battery temperature and charging parameters, using this feedback to dynamically adjust charging power. When temperature exceeds thresholds, the system reduces or terminates charging power to prevent overheating, creating a closed-loop control system that balances charging speed with thermal safety.
Solution Approach 2:
The charging system transitions from static fixed-power charging to dynamic adaptive charging. The charging power is continuously adjusted based on real-time temperature measurements and battery state, allowing the system to optimize charging speed while preventing thermal runaway through responsive power modulation.
2Reliability
If temperature monitoring is implemented to improve safety, then thermal management capability is improved, but device complexity increases
Solution Approach 1:
The charging system performs self-monitoring and self-regulation of temperature. The controller automatically detects temperature conditions and adjusts charging parameters without requiring external intervention or complex additional control systems, allowing the system to manage its own thermal state through integrated sensing and control.
Solution Approach 2:
The controller integrates multiple functions including power management, temperature monitoring, and safety control into a single component. This multi-functional approach consolidates what could be separate complex subsystems into one unified controller, improving reliability while minimizing the increase in overall system complexity.
3Duration of action of moving object
If charging duty cycle is extended to improve charging completeness, then charge capacity is improved, but thermal accumulation worsens
Solution Approach 1:
The system employs periodic charging intervals with cooling periods in between. Instead of continuous charging, the system alternates between charging phases and cooling phases, allowing thermal dissipation during non-charging intervals. This periodic approach enables extended total charging duration while preventing excessive thermal accumulation through strategic charging pauses.
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
The system effectively manages thermal cooling by reducing charging power or terminating charging when overheating is detected, preventing damage to batteries and ensuring safe operation by correlating surface and internal temperatures, thus enhancing charging efficiency and safety.
Implementation Method 1
temperature sensors on the charging surface that measure and estimate battery temperatures
Implementation Method 2
Wireless charging systems have been deployed to enable certain types of devices to charge internal batteries without the use of a physical charging connection
Data Source
AI summary
A wireless charging device has a controller and at least one coil that is positioned near the surface of the charging device and configured to transmit an electromagnetic field and a first driver circuit configured to drive the transmitting coil. The controller is configured to cause the driver circuit to provide a charging current to the transmitting coil, decode a request for lower transmission power from a modulation of the charging current, reduce the amplitude of the charging current in accordance with the request for lower transmission power when a temperature measured at a surface of the charging device is less than a threshold temperature, and initiate a cool down sequence when the temperature measured at the surface of the charging device equals or exceeds the threshold temperature. In one example, the request for lower transmission power may be provided in an ASK-modulated signal superimposed on the charging current.