Wireless Inductive Power Transmitter Frequency Control
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in matching resonance frequencies between power transmitters and receivers, leading to inefficiencies and complexities in power transfer, especially when dealing with legacy receivers and varying environmental conditions.
Innovation Solution
A power transmitter with a resonance circuit and frequency modification circuit that synchronizes the drive signal with the resonance frequency, allowing for adaptive matching and reduced intermodulation distortion by controlling the state change of capacitive and inductive impedances during fractional time intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If resonance frequency matching between transmitter and receiver is implemented, then power transfer efficiency is improved, but device complexity and measurement requirements increase
Solution Approach 1:
The transmitter automatically adjusts its resonance frequency to match the receiver's resonance frequency through self-measurement and self-adjustment mechanisms. The transmitter performs load modulation detection, measures the receiver's resonance frequency, and modifies its own resonance circuit parameters to achieve frequency matching without external intervention or complex coordination protocols.
Solution Approach 2:
The system implements a feedback loop where the transmitter continuously monitors the power transfer efficiency and receiver response, then adjusts its resonance frequency accordingly. The transmitter measures load modulation from the receiver, determines the optimal resonance frequency based on these measurements, and dynamically retunes its resonance circuit to maintain maximum power transfer efficiency.
2Adaptability or versatility
If adaptive frequency matching is implemented for legacy receivers, then compatibility and power transfer are improved, but intermodulation distortion increases
Solution Approach 1:
The transmitter employs periodic measurement cycles to detect receiver resonance frequency through load modulation. By periodically adjusting its operating frequency and measuring the receiver's response at different frequency points, the transmitter identifies the receiver's resonance frequency and locks onto it, enabling compatibility with legacy receivers while minimizing intermodulation distortion through controlled periodic tuning rather than continuous frequency sweeping.
3Measurement precision
If complex signal measurements are performed for frequency matching, then power transfer precision is improved, but communication overhead and system complexity increase
Solution Approach 1:
The load modulation mechanism serves multiple functions simultaneously: it enables the receiver to communicate its power requirements to the transmitter, allows the transmitter to measure the receiver's resonance frequency, and provides a basis for determining optimal power transfer parameters. By utilizing the same load modulation signal for both communication and frequency measurement, the system eliminates the need for separate measurement protocols and reduces communication overhead.
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 approach enhances power transfer efficiency, simplifies implementation, and improves communication by locking the operating frequency and resonance frequency together, reducing the need for complex signal measurements and supporting a range of power receivers.
Implementation Method 1
a resonance circuit for generating an inductive power signal
Implementation Method 2
a frequency modification circuit for controlling a resonance frequency of the resonance circuit
Data Source
AI summary
A wireless power transfer system includes a power receiver and a power transmitter providing power using an inductive power signal. The power transmitter includes a resonance circuit having capacitive and inductive impedances, and a driver configured to generate a drive signal for the resonance circuit. A frequency modification circuit is configured to control the resonance frequency of the resonance circuit by slowing a state change for the capacitive and/or inductive impedance for a fractional time interval of at least some cycles of the drive signal, The frequency modification circuit is configured to align at least one of a start time and an end time for the fractional time interval to transitions of a timing signal. In the power transmitter, the driver is configured to generate the timing signal to have transitions synchronized to the drive signal. The slowing may be by impeding current flow between the capacitive and inductive impedances.