Qi Power Receiver Mode Selection for Load-Modulated Communication
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Solution Overview
Problem
Existing wireless power transfer systems face challenges such as electromagnetic interference, acoustic noise, and communication errors due to load modulation, particularly in bidirectional communication scenarios, which affect compatibility and efficiency, especially with devices supporting different versions of the Qi Specification.
Innovation Solution
A power receiver and transmitter system that employs a communication mode selection mechanism based on load modulation of electromagnetic power transfer signals, using chip sequences to modulate data symbols, allowing flexible communication modes that adapt to device capabilities without requiring additional communication channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If load modulation is used for bidirectional communication in wireless power transfer, then communication functionality is improved, but electromagnetic interference and acoustic noise increase
Solution Approach 1:
The communication process is divided into separate phases: power transfer phase and communication phase. During the communication phase, load modulation is enabled for bidirectional communication, while during the power transfer phase, power is transferred with minimal communication interference. This temporal segmentation allows both functions to operate optimally without mutual interference.
Solution Approach 2:
The system alternates between power transfer intervals and communication intervals in a periodic manner. During communication intervals, load modulation is activated for data exchange, and during power transfer intervals, the system focuses on power delivery. This periodic switching reduces continuous electromagnetic interference while maintaining communication reliability.
2Loss of information
If load modulation is used for bidirectional communication in wireless power transfer, then communication functionality is improved, but acoustic noise increases
Solution Approach 1:
The communication operations are segmented into specific time windows separate from continuous power transfer. Load modulation is applied only during designated communication intervals, reducing the duration and intensity of acoustic noise generation while maintaining necessary bidirectional communication functionality.
Solution Approach 2:
Bidirectional communication using load modulation is performed periodically at scheduled intervals rather than continuously. This periodic action allows the system to maintain communication reliability while significantly reducing the overall acoustic noise exposure by limiting load modulation to necessary communication windows.
3Reliability
If separate communication functionality (Bluetooth, NFC) is added to wireless power transfer system, then communication reliability is improved, but device complexity increases
Solution Approach 1:
The communication functionality is merged with the existing power transfer infrastructure by utilizing load modulation of the power transfer signal itself. This eliminates the need for separate dedicated communication hardware (Bluetooth, NFC modules) while maintaining bidirectional communication capability, thereby reducing device complexity without sacrificing communication reliability.
Solution Approach 2:
The power transfer signal serves dual purposes: transferring power and carrying communication data through load modulation. This multi-functionality eliminates the need for separate communication channels and reduces overall system complexity while maintaining reliable bidirectional communication between transmitter and receiver.
4Reliability
If load modulation depth is increased to improve communication reliability, then communication reliability is improved, but electromagnetic interference and acoustic noise increase
Solution Approach 1:
The load modulation depth is dynamically adjusted based on communication conditions and phase. During communication intervals, sufficient modulation depth is applied for reliable data detection, while during power transfer intervals, modulation depth is minimized or eliminated. This dynamic adjustment maintains communication reliability while reducing overall electromagnetic interference.
5Reliability
If load modulation depth is increased to improve communication reliability, then communication reliability is improved, but acoustic noise increases
Solution Approach 1:
The load modulation depth is dynamically controlled to be high only during necessary communication intervals for reliable data transmission, and reduced or eliminated during power transfer intervals. This dynamic control maintains communication reliability while minimizing the generation of acoustic noise from mechanical elements.
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 communication reliability, reduces electromagnetic interference and acoustic noise, improves compatibility with legacy devices, and optimizes power transfer efficiency by dynamically selecting communication modes based on signal variations.
Implementation Method 1
an input circuit comprising a receiver coil arranged to extract power from the power transfer signal
Implementation Method 2
a transmitter arranged to transmit a set of data symbols to the power transmitter by load modulating the power transfer signal
Data Source
AI summary
A power transmitter (101) provides power to a power receiver (105) via an inductive power transfer signal which is also used by the power receiver (105) for communication by load modulation. The power receiver (105) comprises a transmitter (509) arranged to transmit symbols in accordance with a first or second communication mode where the first mode modulates data symbols by a chip sequence from a set of sequences and the second communication mode does not. The power receiver (105) may transmit data symbols requesting a power transfer signal variation using a chip sequence from the set. A detector (515) may detect if the variation occurs, and if so a selector (513) selects the first communication mode and otherwise it selects the second communication mode. The approach may allow selection of an appropriate communication mode without requiring data to be transmitted from the power transmitter. The approach may provide improved backwards compatibility.