Wireless Charging Coil Current Demodulation Without Sampling Resistor Error
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Solution Overview
Problem
Conventional ASK demodulation methods for wireless charging systems suffer from errors in signal sampling due to inconsistencies between the current signal flowing through sampling resistors and the actual coil current.
Innovation Solution
A method and circuit that directly samples the coil current signal of a wireless charging power transmitter, converting it into voltage signals, amplifying, detecting, and filtering these signals to achieve accurate demodulation through digital signal processing and algorithm decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ASK demodulation method using sampling resistors is used, then the circuit structure is simple, but signal sampling accuracy deteriorates due to inconsistency between sampling resistor current and actual coil current
Solution Approach 1:
The patent introduces an intermediary transformation process: the coil current signal is first converted to a voltage signal through a current-to-voltage conversion circuit, then sampled. This intermediary voltage signal accurately reflects the coil current while being easier to sample precisely, resolving the contradiction between sampling accuracy and circuit complexity.
Solution Approach 2:
The patent replaces the direct current sampling method with a voltage sampling method after current-to-voltage conversion. This substitution allows for more accurate sampling by converting the hard-to-measure current signal into an easier-to-measure voltage signal while maintaining fidelity to the original coil current.
2Measurement precision
If direct coil current sampling is implemented, then signal sampling accuracy is improved, but device complexity increases due to additional conversion and processing circuits
Solution Approach 1:
The patent designs the current-to-voltage conversion circuit to serve multiple functions: it converts coil current to voltage for accurate sampling, provides signal conditioning, and interfaces with subsequent amplification and filtering stages. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in overall device complexity.
3Measurement precision
If sampling resistor method is used, then ease of operation is maintained, but signal fidelity deteriorates due to signal loss and distortion
Solution Approach 1:
The patent performs preliminary current-to-voltage conversion before the sampling operation. This preliminary action transforms the coil current into a proportional voltage signal that can be sampled with high fidelity, preserving the original signal characteristics while enabling accurate measurement through subsequent simple voltage sampling operations.
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 proposed method and circuit accurately demodulate coil current signals, reducing sampling errors and enhancing signal capture efficiency.
Implementation Method 1
a transmitting terminal coil circuit signal sampling method applied to a wireless charging power transmitter... the current signal flowing through the coil of wireless charging power transmitter is formed from the modulation signal at the receiver coil by means of electromagnetic coupling
Implementation Method 2
the current signal flowing through the coil of wireless charging power transmitter is formed from the modulation signal at the receiver coil by means of electromagnetic coupling
Implementation Method 3
amplifying, detecting and filtering the sampled voltage signal SW1 and the voltage signal SW2
Data Source
AI summary
A coil current demodulation method and a circuit based on a wireless charging power transmitter are provided. The method includes the following steps: sampling transmitter coil current signal, carrying out signal processing on the sampled transmitter coil current signal, and completing coil current demodulation. By directly sampling the transmitter coil current signal, one may avoid the problem that the conventional ASK demodulation method has an error in signal sampling.