Synchronous FET Rectifier for Low-Loss Wireless Power Reception

Solution Overview

Problem

Conventional wireless charging systems are inefficient due to the use of diode-based rectifiers, which consume a significant portion of the received power and have a large form factor, making them unsuitable for integration with devices and limiting their usability.

Innovation Solution

A wireless power receiver using a field effect transistor (FET) with a synchronous rectification method, where the FET operates as an open switch during the positive cycle of the AC waveform, minimizing power loss and allowing for a more compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If diode-based rectifiers are used in wireless power receivers, then rectification function is achieved, but power loss increases and device size increases

Engineering Contradiction:

Improvepower lossVSAvoidrectifier size

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent changes the operating parameters of the rectifier by using a synchronous switching mechanism controlled by the AC waveform phase. The switching elements are timed to conduct during specific phases of the AC cycle, optimizing the rectification process to reduce power loss while minimizing component size requirements.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional diode-based passive rectification with an active switching mechanism using transistors or thyristors that are electronically controlled. This substitution allows for more efficient power conversion by actively managing current flow timing, thereby reducing power losses and enabling compact design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If diode-based rectifiers are used in wireless power receivers, then rectification function is achieved, but charging efficiency decreases

Engineering Contradiction:

Improvecharging efficiencyVSAvoidpower loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent replaces traditional diode-based passive rectification with an active switching mechanism using transistors or thyristors that are electronically controlled. This substitution allows for more efficient power conversion by actively managing current flow timing, thereby reducing power losses and enabling compact design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs feedback control where the switching elements are timed based on the phase of the AC waveform. This feedback mechanism ensures optimal switching timing that maximizes power transfer efficiency and minimizes losses during the rectification process.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If diode-based rectifiers are used in wireless power receivers, then rectification function is achieved, but integration with devices becomes difficult

Engineering Contradiction:

Improveintegration easeVSAvoidrectifier size

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent changes the operating parameters of the rectifier by using a synchronous switching mechanism controlled by the AC waveform phase. The switching elements are timed to conduct during specific phases of the AC cycle, optimizing the rectification process to reduce power loss while minimizing component size requirements.

Inventive Principle:

Principle #35Parameter changes

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 FET-based synchronous rectification significantly reduces power loss and enables a more efficient transfer of power to the device, improving the charging efficiency and allowing for a smaller, more integrated charging solution.

Implementation Method 1

A wireless power receiver using a field effect transistor (FET) with a synchronous rectification method, where the FET operates as an open switch during the positive cycle of the AC waveform, minimizing power loss

Methodology Applied

Scientific EffectSynchronous rectification:

Data Source

PatentUS11777342B2Wireless power receiver with a transistor rectifier

Publication Date: 2023.10.03 ENERGOUS CORP

AI summary

Embodiments disclosed herein describe a wireless power receiver including a synchronous transistor rectifier using a Class-E or a Class-F amplifier. The wireless power receiver includes at least one radio frequency (RF) antenna configured to generate an alternating current (AC) waveform from received RF waves. The wireless power receiver further includes a power line configured to carry a first signal based on the AC current generated by the least one RF antenna, and a tap-line coupled to the power line, the tap-line being configured to carry a second signal. The second signal is based on the AC current generated by the least one RF antenna and distinct from the first signal. The wireless power receiver also includes a transistor coupled to at least the power line and the tap-line. The transistor is configured to provide a direct current (DC) waveform to a load based on the first and second signals.