Rectifying-and-modulating circuit for wireless power receiver
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Solution Overview
Problem
Conventional wireless power receivers have high costs and large area occupancy due to external modulating capacitors and decreased power conversion efficiency due to the use of full-bridge rectifiers with diodes, which can be improved by replacing diodes with NMOSFETs and integrating a rectifier control unit.
Innovation Solution
A wireless power receiver with a rectifying-and-modulating circuit that includes a series connection of switches and a control unit, allowing for synchronous operation of N-channel metal oxide semiconductor field effect transistors (NMOSFETs) to constitute a full-bridge rectifier, eliminating the need for external modulating capacitors and enhancing power conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external modulating capacitors are used in the conventional wireless power receiver, then the modulating function can be achieved, but the area occupancy and cost increase
Solution Approach 1:
The patent merges the modulating capacitor function with the integrated circuit by using the body diodes of the NMOSFETs as rectifying elements and the gate-source capacitance of the NMOSFETs as modulating capacitors. This integration eliminates the need for external modulating capacitors, thereby reducing area occupancy while maintaining the modulating function.
Solution Approach 2:
The NMOSFETs in the patent serve multiple functions: they act as switches for rectification, their body diodes provide rectifying capability, and their gate-source capacitance provides modulating capacitance. This multi-functionality eliminates the need for separate external components, reducing both area and cost.
2Reliability
If diodes are used in the full-bridge rectifier, then the rectifying function is achieved, but the power conversion efficiency decreases
Solution Approach 1:
The patent changes the key parameter of the rectifying element from diode to NMOSFET. The NMOSFET has lower on-resistance compared to diode forward voltage drop, resulting in lower conduction losses and improved power conversion efficiency while maintaining the rectifying function.
3Loss of energy
If NMOSFETs are used to replace diodes in the full-bridge rectifier, then power conversion efficiency is improved, but device complexity increases due to additional control requirements
Solution Approach 1:
The patent combines the rectifier control unit with the modulating unit into a single integrated control structure. The control signals for rectification and modulation are generated and managed within the same integrated circuit, simplifying the overall control architecture despite the use of NMOSFETs.
Solution Approach 2:
The NMOSFETs utilize their own intrinsic properties (body diodes and gate-source capacitance) to perform rectification and modulation functions, reducing the need for external control circuitry and simplifying the overall device complexity.
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 reduces the cost and area occupancy of the wireless power receiver while improving power conversion efficiency by integrating the rectifying-and-modulating circuit into a single chip and synchronizing NMOSFETs to efficiently rectify and modulate the induced current.
Implementation Method 1
The power receiving circuit 11 is used to wirelessly receive power transmitted from the wireless power transmitter so as to generate an induced current
Data Source
AI summary
A wireless power receiver includes a power receiving circuit wirelessly receiving power transmitted from a wireless power transmitter so as to generate an induced current, and a rectifying-and-modulating circuit including first to eighth switches and a control unit. The control unit is operable to control operation of each of the first to eighth switches between conduction and non-conduction. Accordingly, the first to fourth switches cooperatively constitute a full-bridge rectifier for rectifying the induced current generated by the power receiving circuit, and each of the fifth to eighth switches is operable to switch synchronously with a respective one of the first to fourth switches or to became non-conducting, thereby changing an amplitude of the induced current.