Inductive Charging Feedback Mechanism for Battery Safety
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Solution Overview
Problem
Lithium-ion batteries pose challenges in inductive charging due to their inability to absorb overcharge, requiring precise voltage and current control to avoid premature failure, and existing inductive charging systems lack efficient mechanisms for monitoring charge state without increasing device complexity, size, and weight.
Innovation Solution
An inductive charging system with a feedback mechanism that adjusts the frequency of the primary coil's power based on reflected impedance, incorporating over-voltage and over-current detectors to protect the battery and optimize charging, allowing for nonlinear charging profiles with a simple circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant current is applied to a fully charged Li-Ion battery, then the battery may be overcharged, but the charging process becomes simple and straightforward
Solution Approach 1:
The patent implements a feedback mechanism where the charger monitors battery voltage and current during charging. When the battery reaches maximum voltage (4.2V), the charger automatically switches from constant current mode to constant voltage mode, preventing overcharge. The system continuously adjusts charging parameters based on real-time battery state feedback.
Solution Approach 2:
The charging system dynamically transitions between two distinct charging modes: constant current mode for the initial charging phase and constant voltage mode for the final charging phase. This dynamic adaptation allows the charger to optimize charging efficiency while preventing overcharge, resolving the contradiction between simplicity and safety.
2Measurement precision
If complex circuitry is added to monitor battery charge state in inductive charging, then charging precision improves, but device size and weight increase
Solution Approach 1:
The patent uses the magnetic coupling between primary and secondary coils as an intermediary communication channel. The charger modulates the magnetic field to encode charging status information, which the battery pack detects through the same inductive coupling mechanism. This eliminates the need for separate communication hardware, maintaining measurement precision while minimizing device weight.
Solution Approach 2:
The inductive coupling system serves multiple functions simultaneously: power transfer and bidirectional communication. The same magnetic field used for energy transmission also carries charging status information, eliminating the need for dedicated monitoring circuitry in the portable device and reducing overall system weight.
3Ease of operation
If inductive charging is used for Li-Ion batteries, then charging convenience improves, but precise voltage and current control becomes difficult
Solution Approach 1:
The system employs real-time feedback from the battery pack to the charger through magnetic coupling. The battery pack communicates its charge state, voltage, and current requirements by modulating the magnetic field, allowing the charger to precisely control charging parameters despite the wireless interface.
Solution Approach 2:
The patent replaces direct electrical connection with magnetic field coupling for both power transfer and information exchange. This substitution maintains charging convenience by eliminating physical connectors while achieving precise control through field-based communication and monitoring.
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 prevents overcharge and ensures full charging of lithium-ion batteries while maintaining a lightweight and cost-effective design, suitable for portable devices by using a feedback mechanism to adjust power delivery and protect the battery from harmful conditions.
Implementation Method 1
a primary coil for inductively supplying charging power and a secondary coil for inductively receiving the charging power
Implementation Method 2
the feedback mechanism includes a subcircuit for varying the reflected impedance of the secondary circuit
Data Source
AI summary
An inductive charging system for recharging a battery. The system includes a charger circuit and a secondary circuit. The secondary circuit includes a feedback mechanism to provide feedback to the charger circuit through the inductive coupling of the primary coil and the secondary coil. The charger circuit includes a frequency control mechanism for controlling the frequency of the power applied to the primary coil at least partly in response to the feedback from the feedback mechanism.