Open Circuit Rx Power Limiter for Wireless Power Transfer
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Solution Overview
Problem
Wireless power transfer systems face challenges in efficiently managing power delivery due to varying coupling coefficients between transmitter and receiver coils, leading to potential over-powering and heat generation, with existing solutions being costly, complex, or inefficient.
Innovation Solution
A wireless power transfer system that uses an electronic switch in series with the input voltage, controlled by a controller to maintain a constant DC output voltage, regardless of input voltage variations or load changes, employing PMOS or NMOS switches and voltage selector circuits to prevent excess power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-way communication between Tx and Rx is used to control power delivery, then power management is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the communication function from the power control system and replaces it with a passive electronic switch circuit on the receiver side. The controller opens or closes the electronic switch based on coupling conditions to limit power, eliminating the need for complex two-way communication while maintaining reliable power management.
Solution Approach 2:
The patent introduces an electronic switch as an intermediary component between the rectified voltage and the load. This switch acts as a mediator that passively limits power delivery under strong coupling conditions without requiring active communication protocols, thereby reducing system complexity while improving power control reliability.
2Reliability
If excess power is shunted on the receive-side to protect the receiver, then receiver protection is improved, but heat generation and energy waste increase
Solution Approach 1:
Instead of shunting excess power to ground (the conventional approach), the patent inverts the approach by using the electronic switch to block or limit power flow before it reaches the load. This prevents excess power from entering the system rather than dissipating it, thereby protecting the receiver without generating harmful heat or wasting energy.
3Reliability
If strong magnetic field is generated at transmit coil to ensure sufficient power delivery under worst-case coupling, then power delivery reliability is improved, but receive-side power becomes excessive under best-case coupling
Solution Approach 1:
The patent employs a dynamic electronic switch that automatically adjusts its state based on real-time coupling conditions. Under worst-case coupling, the switch remains closed to allow full power delivery. Under best-case coupling, the switch opens to limit power, thereby maintaining reliable power delivery across varying conditions while preventing excessive power reception.
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 solution effectively regulates output voltage across a wide range of input variations, preventing overheating and energy wastage, while ensuring reliable power delivery to loads.
Implementation Method 1
an AC magnetic field may be generated in the transmit coil, which may then induce an AC current in the receive coil
Implementation Method 2
the receive coil may be magnetically but wirelessly coupled to the transmitting coil and may wirelessly receive the power and generate an AC input voltage
Data Source
AI summary
A wireless power transfer system may wirelessly transmit and receive power. A transmitting coil may wirelessly transmit the power. A receiving coil may be magnetically but wirelessly coupled to the transmitting coil and may wirelessly receive the power and generate an AC input voltage. A rectifier may rectify the AC input voltage. A capacitance may filter the rectified AC input voltage. An electronic switch may be connected in series between the rectified AC input voltage and an output. A load may be connected to the output. A controller may open and close the electronic switch so as to cause the output to be at a constant DC voltage, notwithstanding variations in the load.