Adaptive Negative ASK Modulation for Wireless Charging SNR Stability
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Solution Overview
Problem
Existing wireless charging systems face challenges in maintaining reliable communication and power transfer due to reduced signal-to-noise ratio (SNR) caused by decreased modulation depth, which can lead to disconnections and cessation of power transfer, particularly when modulation capacitors are decoupled from ground during non-communication periods.
Innovation Solution
Implementing adaptive negative amplitude shift keying (ASK) modulation, where a controller determines whether modulation capacitors should be coupled to ground based on voltage levels, ensuring a lower output voltage during active communication to enhance load modulation effects and improve SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If modulation capacitors are decoupled from ground during non-communication periods, then power transfer efficiency is improved, but modulation depth decreases and communication reliability deteriorates
Solution Approach 1:
The patent implements dynamic switching of modulation capacitors between coupled and decoupled states based on communication requirements. The controller selectively couples modulation capacitors to ground during non-communication periods to maintain lower voltage levels, then decouples them during active communication to achieve proper modulation depth, thereby adapting the system state to operational needs
Solution Approach 2:
The patent changes the voltage level parameter at the rectifier output by controlling the coupling state of modulation capacitors. By maintaining lower voltage levels during non-communication periods through capacitor coupling to ground, and adjusting voltage levels during communication periods, the system optimizes both power transfer efficiency and communication reliability through parameter modulation
2Reliability
If larger modulation capacitors are used to increase modulation depth, then communication signal quality improves, but device size and cost increase
Solution Approach 1:
Instead of using larger capacitors, the patent changes the operational parameters by dynamically controlling the coupling state of existing modulation capacitors. By coupling capacitors to ground during non-communication periods, the system maintains lower voltage levels that enable adequate modulation depth with standard capacitor values, avoiding the need for larger components
Solution Approach 2:
The system uses dynamic switching of capacitor connections to achieve variable modulation depth without changing physical capacitor size. The controller selectively couples and decouples modulation capacitors based on communication needs, enabling the same hardware to adapt its electrical characteristics for different operational states
3Stress or pressure
If modulation capacitors are decoupled from ground during non-communication periods, then voltage level increases, but load modulation effect decreases and communication quality deteriorates
Solution Approach 1:
The patent inverts the conventional approach by coupling modulation capacitors to ground during non-communication periods rather than decoupling them. This inverted strategy maintains lower voltage levels when communication is not active, which preserves the ability to generate sufficient load modulation effects when communication resumes, thereby improving communication quality
Solution Approach 2:
The system performs preliminary action by pre-coupling modulation capacitors to ground during non-communication periods, preparing the voltage conditions for optimal communication performance. This preliminary state ensures that when communication becomes active, the voltage levels and modulation characteristics are already optimized for reliable signal transmission
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
Enhances communication reliability and power transfer stability by maintaining a lower output voltage during non-communication periods, thereby increasing signal-to-noise ratio and preventing disconnections.
Implementation Method 1
a wireless charging receive coil that transduces, into an alternating current (AC) power signal, a magnetic field generated by a wireless charging transmit coil
Implementation Method 2
a rectifier that converts the AC signal received at an AC side of the rectifier into a direct current (DC) power signal
Data Source
AI summary
An example device includes a rectifier that converts an AC signal received at an AC side of the rectifier from a wireless charging receive coil into a DC power signal output at a DC side of the rectifier; a first capacitor connected to an upper rail of the AC side; a second capacitor connected to a lower rail of the AC side; a first switch between the first capacitor and a ground; a second switch between the second capacitor and the ground; and a controller configured to: toggle the first switch and the second switch to communicate with an external device; determine, based on a comparison of voltage levels measured at the computing device, whether to set the switches as open or closed when not communicating; and set, responsive to determining to set the switches as closed, the first switch and the second switch as closed when not communicating.