Dual Loop Wireless Power Transmitter Current Control
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Solution Overview
Problem
Wireless power systems face challenges in maintaining a constant transmitter coil current due to varying load conditions, temperature drift, and dynamic changes in the charging environment, which can lead to inefficiencies and safety issues when using single feedback control loops.
Innovation Solution
Implementing a dual feedback loop architecture within the wireless power transmitter, where an outer loop adjusts the transmitter coil current based on feedback from the receiver and an inner loop continuously monitors and adjusts the coil current to maintain a quasi-constant value, using a current sensor and comparison elements to rapidly update control parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single feedback control loop is used to control transmitter coil current, then the system structure is simple, but the current control precision deteriorates under varying load conditions and temperature drift
Solution Approach 1:
The control system is segmented into two independent feedback loops: an outer loop that controls power delivery based on receiver feedback, and an inner loop that controls transmitter coil current based on current sensor feedback. Each loop operates independently to address different control objectives, resolving the contradiction between system simplicity and current control precision.
Solution Approach 2:
The patent implements dual feedback mechanisms: the outer loop uses feedback from the receiver about power delivery conditions, while the inner loop uses feedback from a current sensor about the actual coil current. This layered feedback approach enables precise current control while maintaining overall system simplicity.
2Ease of operation
If a single feedback control loop is used, then the system is easy to operate, but the response speed to temperature variations and load changes deteriorates
Solution Approach 1:
The control response is segmented into two stages: the outer loop handles slow-varying power delivery requirements, while the inner loop rapidly responds to fast-varying current deviations caused by temperature drift and load changes. This segmentation enables fast response without complicating overall system operation.
Solution Approach 2:
The inner current control loop operates continuously at a high update rate, providing continuous correction of coil current deviations. This continuous action ensures rapid response to temperature and load variations while the outer loop continuously adjusts power delivery, maintaining ease of operation.
3Adaptability or versatility
If the transmitter coil current is allowed to vary freely, then the system is more adaptable to different loading conditions, but the system efficiency and safety deteriorate due to current exceeding specified limits
Solution Approach 1:
The inner current control loop continuously monitors the actual coil current via a current sensor and compares it to the target current value. When deviations occur due to varying load conditions or temperature drift, the loop immediately adjusts the inverter output to maintain current within specified limits, ensuring both adaptability and reliability.
Solution Approach 2:
The control system dynamically adjusts the transmitter coil current based on real-time feedback from the inner loop. The system adapts to different loading conditions by allowing current variations within safe limits while the inner loop ensures current never exceeds specified thresholds, maintaining both versatility and safety.
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 dual loop control architecture provides more precise and stable control over the transmitter coil current, ensuring efficient and safe power transfer by separating voltage and current errors, allowing for faster response to temperature variations and maintaining coil current within specified limits, thus enhancing system efficiency and compliance with wireless charging specifications.
Implementation Method 1
A wireless power system employs a pair of inductive coils forming a loosely-coupled transformer to transfer power wirelessly
Implementation Method 2
The AC current in the transmit coil generates an oscillating magnetic field. The oscillating magnetic field induces an AC voltage into the tuned receiver coil
Data Source
AI summary
Methods and apparatus for providing closed loop current control in a wireless power transmitter. The method comprises adjusting a transmitter coil current generated by the wireless power transmitter based, at least in part, on first feedback reported by at least one wireless power receiver and second feedback based on a measurement of the transmitter coil current.