Synchronous Rectifier FET Switching for Wireless Power Efficiency
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Solution Overview
Problem
Conventional half-bridge rectifiers in wireless power transmission systems suffer from inefficiency due to diode-based designs, resulting in significant forward voltage drops and heat dissipation, which reduce overall efficiency and reliability, especially at low voltage levels and high frequency switching.
Innovation Solution
The implementation of synchronous rectifier (SR) circuit topologies using switching FET transistors controlled by delay-locked loops, phase shifters, or wavelength links to minimize forward voltage drops and power losses, enabling efficient power transfer with reduced reverse recovery losses and voltage stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If diode-based half-bridge rectifiers are used, then the rectifier structure is simple, but the forward voltage drop is significant and power loss is high
Solution Approach 1:
The patent changes the fundamental operating parameters of the rectifier by replacing passive diodes with active FET switches that can be synchronously controlled. This transition from passive to active components enables dynamic parameter adjustment, resulting in significantly reduced forward voltage drops and power losses while maintaining structural simplicity through integrated control circuits.
Solution Approach 2:
The patent substitutes the mechanical/passive diode switching mechanism with an electronically controlled FET-based synchronous rectification system. This replacement eliminates the inherent forward voltage drop of diodes by using voltage-gated FET switches that can be precisely timed to conduct during optimal voltage conditions, thereby reducing power loss.
2Device complexity
If diode-based half-bridge rectifiers are used, then the rectifier structure is simple, but heat dissipation is significant
Solution Approach 1:
By transitioning from passive diodes to actively controlled FET switches, the patent dynamically adjusts conduction parameters to minimize resistive heating. The synchronous control ensures FETs conduct only when voltage differential is favorable, dramatically reducing I²R losses and heat generation while keeping the overall structure compact and simple.
Solution Approach 2:
The patent replaces the passive thermal-dissipating diode system with an active FET-based system that electronically controls current flow timing. This substitution reduces heat generation at the source by preventing current conduction during conditions that would cause excessive heating, thereby improving thermal performance without increasing structural complexity.
3Device complexity
If conventional rectifiers are used, then the circuit design is straightforward, but reverse recovery losses are high at high frequency switching
Solution Approach 1:
The patent replaces conventional diode rectification with synchronous FET switching that eliminates reverse recovery phenomena entirely. By using voltage-gated FETs controlled in synchronization with the input waveform, the system avoids the reverse recovery losses inherent in pn-junction diodes during high-frequency operation, achieving superior efficiency without complicating the circuit design.
Solution Approach 2:
The patent fundamentally changes the switching mechanism from passive diode recovery to active FET gate-controlled switching. This parameter change allows precise timing of conduction intervals, ensuring that switching transitions occur at optimal moments in the AC cycle, thereby eliminating reverse recovery losses and improving high-frequency performance while maintaining straightforward circuit implementation.
4Device complexity
If diode-based rectifiers are used, then the voltage drop is significant at low voltage levels, but the rectifier design is simple
Solution Approach 1:
The patent transforms the rectification approach from passive voltage-drop-prone diodes to active FET switches with synchronized gate control. This parameter change enables the system to maintain low on-resistance during conduction and actively manage voltage levels, ensuring that even at low input voltages, the voltage drop across the rectifier remains minimal, thereby preserving voltage efficiency without increasing design 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 SR circuit topologies significantly reduce power losses and heat dissipation, enhancing the efficiency and reliability of wireless power transfer by minimizing forward voltage drops and maintaining high conduction times, thus improving the overall power transfer efficiency.
Implementation Method 1
synchronous rectifier (SR) circuit topologies using switching FET transistors controlled by delay-locked loops, phase shifters, or wavelength links to minimize forward voltage drops and power losses
Implementation Method 2
controlled by delay-locked loops, phase shifters, or wavelength links to minimize forward voltage drops and power losses
Data Source
AI summary
Synchronous rectifiers for wireless power receivers are disclosed herein. An example receiver includes: an antenna configured to: (i) receive radio frequency (RF) power transmission waves and (ii) convert the received RF power transmissions waves into an alternating current. The receiver also includes a synchronous rectifier, coupled to the antenna, configured to synchronously rectify the alternating current into a direct current, wherein the synchronous rectifier includes: a first diode configured to receive a first portion of the alternating current that has a positive polarity, a second diode configured to receive a second portion of the alternating current that has a negative polarity, a first transistor coupled to the first diode, and a second transistor coupled to the second diode.