Wireless Charging ASK Circuit Layout to Prevent Rectifier Interference
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Solution Overview
Problem
Conventional wireless power transfer systems experience interference and inefficiencies during in-band communications due to oscillating currents generated by capacitor-switch networks, leading to potential shutdowns and data loss when the receiver is not coupled to loads or is lightly loaded.
Innovation Solution
The solution involves connecting capacitor-switch networks in parallel with the resonant capacitor instead of between the inputs of the rectifier, and using a controller circuit to adjust impedance coupled to the receiver coil for ASK modulation, reducing oscillating currents and improving communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If capacitor-switch networks are connected between inputs of the rectifier for in-band communications, then impedance modulation for ASK is achieved, but oscillating currents interfere with the rectifier causing shutdowns and data loss
Solution Approach 1:
The patent divides the capacitor-switch network into two separate functional blocks: one connected between rectifier inputs for power processing, and another connected in parallel with the resonant capacitor for communication. This segmentation allows each block to perform its specific function without interfering with the other, eliminating the oscillating current interference while maintaining both power transfer and communication capabilities
Solution Approach 2:
The patent introduces a coupling inductor as an intermediary element between the receiver coil and the capacitor-switch networks. This inductor acts as a mediator that allows the capacitor-switch networks to be connected in parallel with the resonant capacitor without directly affecting the rectifier inputs, thereby enabling impedance modulation for communication while preventing oscillating currents from interfering with the rectifier operation
2Reliability
If receiver is not coupled to loads or is lightly loaded, then power transfer continues, but oscillating currents become large enough to change rectifier current direction causing shutdown
Solution Approach 1:
By segmenting the capacitor-switch networks into separate blocks with distinct connection points, the patent ensures that the communication-related oscillating currents are isolated from the rectifier inputs. This prevents the harmful oscillating currents from changing the rectifier current direction and causing shutdowns, thereby maintaining reliable power transfer even under light or no-load conditions
Solution Approach 2:
The patent extracts the communication function from the power processing path by connecting the communication-related capacitor-switch networks in parallel with the resonant capacitor rather than between the rectifier inputs. This extraction removes the source of harmful oscillating currents from the rectifier circuit, preventing reliability issues during light or no-load operation
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 configuration reduces interference with the rectifier, enhances the reliability of wireless power transfer by minimizing unintended shutdowns and data loss, and improves the overall efficiency of in-band communications.
Implementation Method 1
The primary side transmitter is coupled to the secondary side receiver through a magnetic coupling. The magnetic coupling may be implemented as a loosely coupled transformer having a primary side coil formed in the primary side transmitter and a secondary side coil formed in the secondary side receiver.
Implementation Method 2
a resonant circuit with the receiver coil. When the capacitor-switch networks are turned on, an oscillating current between the inputs of the rectifier may be generated due to the LC tank properties of the resonant circuit.
Implementation Method 3
a rectifier configured to convert an alternating current voltage into a direct current voltage for a load coupled to the apparatus
Implementation Method 4
The first switch and the second switch are configured to adjust an impedance coupled to the receiver coil, where the impedance is associated with an Amplitude Shift Keying (ASK) modulation used by the apparatus.
Data Source
AI summary
An apparatus for wireless power reception includes a receiver coil and a rectifier having a first input and a second input, the first input coupled to a first terminal of a receiver coil, the second input coupled to a second terminal of the receiver coil through a resonant capacitor. The apparatus further includes a first capacitor and a first switch network connected in series between the first input and ground and a second capacitor and a second switch network connected in series between the second input and ground, each of the first switch network and the second switch network including at least a plurality of field-effect transistors (FETs) connected in parallel, wherein the first switch network and the second switch network configured to adjust an impedance coupled to the receiver coil, the impedance associated with an Amplitude Shift Keying (ASK) modulation used by the apparatus.