Inductive Power Transfer Receiver Detection via Inrush Current
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Solution Overview
Problem
Inductive power transfer (IPT) systems face challenges in controlling transmitter power, detecting and identifying receivers, and managing parasitic loads without adding complexity or bulk, leading to inefficient power transfer and potential transmitter or receiver failure.
Innovation Solution
The methods involve using the power transfer componentry for detection and identification, employing inrush current detection, frequency sweep detection, inrush current removal, frequency vary detection, and voltage vary detection to accurately identify receivers and manage parasitic loads, minimizing additional componentry and noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional componentry is added for detection and identification, then receiver detection accuracy is improved, but device complexity and bulk increase
Solution Approach 1:
The patent applies multi-functionality by enabling the power transfer componentry to serve dual purposes: both transferring power and detecting/identifying receivers. The transmitting coil generates a time-varying magnetic field that induces current in receivers, and the same system measures the induced current characteristics to detect presence and identify compatibility. This eliminates the need for separate detection sensors, proximity sensors, or communication modules, thereby reducing device complexity and bulk while maintaining accurate receiver detection.
2Measurement precision
If power transfer is reduced or interrupted for detection, then receiver identification accuracy is improved, but productivity decreases
Solution Approach 1:
The patent implements continuous power transfer during detection by measuring the induced current in receivers while the magnetic field remains active. The system continuously monitors current characteristics (amplitude, phase, frequency response) during normal operation to detect receiver presence and identify compatibility without interrupting or reducing power transfer. This allows simultaneous power delivery and receiver identification, eliminating detection interruptions and maintaining high productivity.
3Device complexity
If steady-state current is used for detection, then detection simplicity is improved, but measurement precision deteriorates due to false results from unloaded receivers
Solution Approach 1:
The patent employs periodic action by applying a time-varying magnetic field at specific frequencies to induce alternating current in receivers. The system measures current characteristics during these periodic cycles, analyzing amplitude, phase, and frequency response variations. This periodic measurement approach distinguishes between loaded and unloaded receivers by detecting differences in current waveform characteristics, thereby achieving accurate detection without the false results that plague steady-state methods.
4Ease of operation
If manual power switching is implemented, then control over transmitter power is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring induced current characteristics and using this information to automatically control transmitter operation. The system detects receiver presence through current measurements and automatically adjusts power transfer accordingly, switching off or reducing power when no receiver is detected or when compatibility issues are identified. This automated feedback loop eliminates the need for manual power switching while maintaining user control through intelligent, adaptive 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
These methods enable accurate detection and identification of receivers with minimal additional componentry, reducing power transfer interruptions and ensuring compatibility, thus enhancing the efficiency and reliability of IPT systems.
Implementation Method 1
a primary side or transmitter generates a time-varying magnetic field with a transmitting coil or coils. This magnetic field induces an alternating current in a suitable receiving coil
Implementation Method 2
the transmitter coils or the receiver coils may be connected with capacitors to create a resonant circuit, which can increase power throughput and efficiency at the corresponding resonant frequency
Data Source
AI summary
A method for detecting the presence of a receiver in an inductively coupled power transfer system having a transmitter and receiver. The method includes switching on a transmitter converter at a first frequency, measuring the inrush current and determining whether there is a receiver present. In another method, the inrush current is measured for a range of transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the inrush current is measured when there is a change in voltage in the transmitter, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter voltages, and the variation in current is used to determine where there is a receiver present.