Wireless Charging Receiver Efficiency Optimization
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Solution Overview
Problem
Wearable electronics face battery life limitations due to small battery sizes and slow growth in battery energy density, necessitating frequent recharging or reduced functionality, and existing wireless charging techniques, like inductive coupling, are not optimized for maximum efficiency.
Innovation Solution
A device-to-device wireless charging system that includes a receiver with a rectifier circuit, a DC-DC converter, and an efficiency processor to dynamically track and control the duty cycle, maximizing end-to-end efficiency by adjusting impedance and minimizing switches, eliminating the need for a communication layer between the transmitter and receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If wireless charging through inductive coupling is used, then wireless charging capability is achieved, but end-to-end power efficiency is not maximized
Solution Approach 1:
The system dynamically adjusts the duty cycle of the DC-DC converter to track the maximum efficiency point, allowing the operating parameters to change in real-time based on load conditions and coupling variations, thereby maintaining optimal efficiency throughout the charging process
Solution Approach 2:
The efficiency processor continuously monitors input voltage and current signals, calculates efficiency values, and feeds this information back to control the converter's duty cycle, creating a closed-loop system that automatically optimizes power transfer efficiency
2Loss of energy
If a communication layer is added between transmitter and receiver to optimize charging, then charging efficiency can be improved, but device complexity increases
Solution Approach 1:
The receiver autonomously determines efficiency metrics and controls its own operating parameters through the efficiency processor and maximum efficiency tracker, eliminating the need for a communication layer between transmitter and receiver while maintaining optimal charging efficiency
Solution Approach 2:
The communication layer is completely removed from the system architecture, with the efficiency optimization function extracted and implemented locally within the receiver through the efficiency processor that measures and controls parameters unilaterally
3Use of energy by moving object
If multiple switches are used in the rectifier circuit to maintain near-square wave voltage, then voltage control is improved, but device complexity and power loss increase
Solution Approach 1:
Multiple switching functions are merged into a single switch in the rectifier circuit, which operates in conjunction with the resonant capacitor and inductor to achieve both voltage control and resonance, reducing component count and associated power losses while maintaining effective voltage regulation
Solution Approach 2:
The system transitions from a non-resonant rectifier topology to a resonant topology by adding a capacitor with specific capacitance value that resonates with the inductive element, fundamentally changing the operating parameters to achieve soft switching and reduced power loss
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 system achieves near-maximum efficiency in wireless charging by measuring variables only on the receiver side, allowing for efficient power transfer without a communication layer, thereby extending battery life and reducing power consumption in charging devices.
Implementation Method 1
wireless charging through inductive coupling
Implementation Method 2
a capacitance value selected to resonate with the inductance of the receiver coil
Data Source
AI summary
Described is a receiver for improving end-to-end efficiency in a device-to-device wireless charging system using resonant energy transfer through an inductive link. The receiver includes an efficiency controller which dynamically tracks a maximum efficiency point and controls an impedance between an inductive coupling of the receiver and a receiver rectifier circuit such that an impedance seen by the inductive coupling is an impedance which maximizes (or nearly maximizes) efficiency of the inductively coupled wireless power transfer operation.