Wireless Power Transmit Coil Current Sensing Circuit
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Solution Overview
Problem
Wireless power transmission systems face inefficiencies due to high transmitter power losses, particularly in monitoring and managing the current through the TX coil, which can represent up to 82% of losses, and challenges in setting a minimum operating frequency to avoid control inversion and electromotive interference.
Innovation Solution
A current sensing circuit and method for measuring and filtering the current through the transmit coil, combined with a processor-controlled system that adjusts the operating frequency based on zero-voltage switching deadtime to set a minimum operating frequency above the maximum deadtime, ensuring efficient power transfer and preventing control inversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transmitter operates at high power levels, then power transfer capability is improved, but power losses increase significantly
Solution Approach 1:
The patent implements a feedback mechanism where the transmitter monitors the current through the TX coil and adjusts its operation accordingly. The current sensing circuit provides real-time information about the coil current, enabling the transmitter to optimize power levels and reduce losses when full power is not needed, while maintaining the ability to deliver high power when required.
Solution Approach 2:
The patent changes operational parameters by dynamically adjusting the transmitter's power output based on monitored conditions. By varying the operating parameters (current, power level) according to actual load requirements and efficiency considerations, the system achieves optimal balance between power transfer capability and energy loss reduction.
2Loss of energy
If the operating frequency is reduced to improve efficiency, then power transfer efficiency is improved, but control inversion and electromotive interference occur
Solution Approach 1:
The patent applies dynamics by making the operating frequency adjustable rather than fixed. The system dynamically selects the operating frequency based on real-time conditions, allowing it to operate at lower frequencies for improved efficiency when appropriate, while automatically adjusting to higher frequencies when control inversion or interference risks arise. This dynamic frequency adjustment resolves the contradiction between efficiency and harmful effects.
3Reliability
If a minimum operating frequency is set to prevent control inversion, then system stability is improved, but operating flexibility is reduced
Solution Approach 1:
The patent implements a dynamic minimum operating frequency that adjusts based on operating conditions rather than using a fixed threshold. This allows the system to maintain stability by preventing control inversion when necessary, while preserving operating flexibility by allowing lower frequencies when conditions permit. The adaptive nature of the minimum frequency setting resolves the contradiction between stability and flexibility.
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 solution enables more efficient wireless power transfer by accurately monitoring and managing coil current, reducing power losses, and dynamically adjusting the operating frequency to maintain zero-voltage switching, thereby enhancing system efficiency and preventing control inversion.
Implementation Method 1
wireless power transfer involves a transmitter driving a transmit coil and a receiver with a receiver coil placed proximate to the transmit coil. The receiver coil receives the wireless power generated by the transmit coil
Implementation Method 2
a current sensing circuit is presented... receiving a signal from the switching node... amplifying the biased signal to provide a transmit coil current signal
Data Source
AI summary
A current sensing circuit and a minimum operating frequency for a wireless power transmission system is presented. A method of measuring current through a wireless power transmit coil, includes receiving a signal from a switching circuit into a sampling circuit; filtering the sampled signal from the sampling circuit; biasing the filtered sampled signal, wherein the biasing occurs only when the sampling circuit is active; and amplifying the biased signal to provide a transmit coil current signal. A method of measuring current through a wireless power transmit coil, includes receiving a signal from a switching circuit into a sampling circuit; filtering the sampled signal from the sampling circuit; biasing the filtered sampled signal, wherein the biasing occurs only when the sampling circuit is active; and amplifying the biased signal to provide a transmit coil current signal.