Wireless Charging Rectifier Boosting Under Coil Misalignment
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Solution Overview
Problem
Wireless power transmission systems face inefficiencies when transmitter and receiver coils are not properly aligned, leading to insufficient power for internal circuits due to reduced rectified voltage, limiting spatial freedom and convenience.
Innovation Solution
A wireless power receiver with a switch control circuit and rectified voltage detection circuit that boosts the rectified voltage by turning on a transistor when it exceeds a turn-on voltage and limits the boost to prevent excessive voltage, using a combination of resistors, capacitors, and transistors to manage the rectified voltage within safe thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transmitter coil and receiver coil are not properly aligned, then the spatial freedom and convenience of the wireless charging system is improved, but the rectified voltage becomes insufficient to power the internal circuits
Solution Approach 1:
The patent applies dynamics by making the transistor's conduction state variable rather than fixed. The first transistor is controlled by a gate voltage that dynamically adjusts its conduction path based on the rectified voltage level, allowing the system to adapt to different alignment conditions between transmitter and receiver coils.
Solution Approach 2:
The patent changes the electrical parameters of the circuit by introducing controllable transistors that modify the conduction path based on voltage thresholds. The first transistor's conduction path is adjusted by the gate voltage to boost rectified voltage when coils are misaligned, while the second transistor's conductivity is modulated to prevent excessive voltage, thereby maintaining reliable power delivery across varying alignment conditions.
2Reliability
If the rectified voltage is boosted to power internal circuits with poor alignment, then the power delivery reliability is improved, but the voltage may exceed safe levels and damage components
Solution Approach 1:
The patent implements feedback control through the second transistor and its gate voltage control. The second transistor's conductivity is dynamically adjusted based on the rectified voltage level, creating a feedback mechanism that prevents the voltage from exceeding safe thresholds while allowing boosting when needed.
Solution Approach 2:
The system uses dynamic control of the second transistor's conductivity to adaptively limit the rectified voltage. When the rectified voltage exceeds a lower threshold, the second transistor's conductivity increases to lower the gate voltage and decrease the first transistor's conduction, thereby preventing overvoltage conditions.
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
Enables reliable power delivery to internal circuits even with poor coil alignment while preventing voltage from exceeding safe levels, ensuring efficient operation and device safety.
Implementation Method 1
a transmitter formed by a transmission coil Lp driven by time varying electric power from a power source 12 to form a time-varying electric field. The wireless power transmission system 10 includes a receiver formed by a receiver coil Ls in which the time-varying electric field induces an AC current
Implementation Method 2
a bridge rectifier having first and second inputs coupled to the first and second terminals of the receiver coil, the bridge rectifier having a first output coupled to ground and a second output coupled to a rectified voltage node at which a rectified voltage is produced
Data Source
AI summary
A wireless power receiver includes a rectifier with first and second inputs coupled to first and second terminals of a receiver coil, and having a first output coupled to ground and a second output at which a rectified voltage is produced. A first switch is coupled between the second input and ground, and is controlled by a first gate voltage generated at a first node. A second switch is coupled between the first node and ground, and is controlled by a second gate voltage. The first gate voltage closes the first switch to couple the second input to ground when the rectified voltage is less than a threshold voltage, boosting the rectified voltage. The second gate voltage closes the second switch to cause the second gate voltage to be pulled to ground when the rectified voltage is greater than the threshold voltage, limiting the boosting of the rectified voltage.