Wireless Charging Circuit Abnormal State Protection
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Solution Overview
Problem
Wireless charging systems face hazards due to continuous increased current and overheating when the coil positions are mismatched or conductors intervene, leading to potential fires.
Innovation Solution
A wireless charging circuit with an abnormal state protection circuit that samples DC voltage and controls the power converter to limit current when the voltage exceeds a threshold, preventing overheating by entering a protection mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the wireless power transmitter continuously operates at resonant frequency to increase output power, then the power transmission efficiency is improved, but the current flowing through the coil continuously increases causing temperature rise and potential fire hazards
Solution Approach 1:
The patent implements a feedback mechanism where the control circuit continuously monitors the voltage at the resonant terminal and compares it with a reference voltage. When the monitored voltage exceeds the reference voltage (indicating abnormal state), the control circuit automatically adjusts the pulse width modulation signal to reduce the driving current, thereby preventing further temperature rise and potential fire hazards while maintaining safe power transmission levels.
Solution Approach 2:
The patent employs preliminary protective action by detecting voltage changes at the resonant terminal before they lead to dangerous temperature levels. The control circuit is designed to detect abnormal voltage conditions and preemptively reduce the output power and driving current, preventing the coil temperature from reaching critical levels that could cause fire hazards.
2Power
If the wireless power transmitter increases output power to meet receiver requests, then the power transmission capability is improved, but the plastic case may be melted due to excessive current and heat
Solution Approach 1:
The control circuit continuously monitors the voltage at the resonant terminal as an indicator of power transmission status. When the voltage exceeds the reference voltage, indicating that the system is approaching dangerous power levels, the control circuit automatically reduces the driving current through pulse width modulation, thereby preventing excessive heat generation that could melt the plastic case while maintaining optimal power transmission within safe limits.
3Productivity
If the coil placement is mismatched or conductor intervenes, then the wireless charging system continues to operate, but the receiver continuously requests increased power leading to abnormal current increase
Solution Approach 1:
The patent implements a feedback mechanism that monitors the voltage at the resonant terminal to detect abnormal operating conditions. When coil placement is mismatched or a conductor intervenes, the voltage at the resonant terminal will exceed the reference voltage. The control circuit detects this condition and automatically reduces the driving current, preventing the dangerous positive feedback loop where the receiver continuously requests more power, thereby maintaining system safety while allowing charging to continue at reduced power levels.
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
Prevents overheating and potential fires by limiting current flow through the resonant coil when abnormal states are detected, ensuring safe operation.
Implementation Method 1
Wireless charging technology is evolved from the wireless power transmission technology to use the magnetic resonant to transmit the electrical charge from charger to device to resonate coil and capacitor between the charge and device
Implementation Method 2
The DC sampling circuit is coupled to the resonant terminal of the resonant circuit, for sampling the DC component of a voltage of the resonant terminal of the resonant circuit to obtain a DC voltage
Data Source
AI summary
A wireless charging circuit and an abnormal state protection circuit thereof is provided in the present invention. The wireless charging circuit includes a power converter, a resonant circuit and an abnormal state protection circuit. The power converter receives an input voltage for outputting a PWM (pulse width modulation) signal. The input terminal of the resonant circuit receives the PWM signal. The common voltage terminal of the resonant circuit is coupled to a common voltage. The abnormal state protection circuit includes a DC sampling circuit and a control circuit. The DC sampling circuit is coupled to the resonant terminal of the resonant circuit for sampling the DC component of the voltage of the resonant terminal to obtain a DC voltage. The control circuit is coupled to the power converter and the DC sampling circuit for receiving the DC voltage. When the DC voltage is greater than a threshold voltage, the control circuit controls the power converter to reduce the current flowing through the resonant circuit.