Wireless Power Transfer Load Modulation Using Spread Spectrum
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Solution Overview
Problem
Existing wireless power transfer systems face challenges such as electromagnetic interference, noise, and communication errors due to load modulation, particularly in scenarios involving multiple power receivers, which affect compatibility, reliability, and efficiency.
Innovation Solution
Implementing a power transmitter and receiver system that supports spread spectrum load modulation communication by switching between default and spread spectrum modulation schemes, using spreading chip sequences to reduce interference and improve communication reliability and compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If load modulation is used for communication from power receiver to power transmitter, then communication efficiency is improved, but electromagnetic interference and noise increase
Solution Approach 1:
The communication signal is segmented into multiple frequency components through spread spectrum modulation. By distributing the communication signal across a wide frequency range rather than concentrating it at a single frequency, the power spectral density is reduced, thereby minimizing electromagnetic interference while maintaining communication efficiency.
Solution Approach 2:
The modulation scheme is changed from conventional narrowband load modulation to spread spectrum load modulation. This parameter change in the communication method transforms the concentrated electromagnetic energy into distributed energy across multiple frequencies, reducing peak interference levels while preserving the communication function.
2Productivity
If load modulation is used for communication, then power transfer operation is efficient, but spurious oscillations and self-interference are introduced
Solution Approach 1:
The communication signal is divided into multiple frequency components through spread spectrum modulation. This segmentation distributes the modulation impact across the frequency spectrum, preventing concentrated spurious oscillations and reducing self-interference while maintaining the efficiency of power transfer operation.
Solution Approach 2:
The spread spectrum technique acts as an intermediary that mediates between the power transfer function and the communication function. By using a wideband modulation approach, it allows both power transfer and communication to occur simultaneously with reduced mutual interference, improving overall system reliability.
3Productivity
If load modulation is used, then communication between power transmitter and receiver is achieved, but acoustic noise is generated
Solution Approach 1:
The modulation frequency parameters are changed from low-frequency load modulation to high-frequency spread spectrum modulation. This parameter change moves the modulation energy away from audible frequency ranges, significantly reducing acoustic noise generation while preserving the communication capability between transmitter and receiver.
Solution Approach 2:
The communication signal is segmented across a wide frequency spectrum, distributing the energy that would otherwise concentrate at audible frequencies. This spectral segmentation reduces the amplitude of mechanical vibrations in the audible range, thereby reducing acoustic noise while maintaining communication effectiveness.
4Adaptability or versatility
If conventional load modulation is used, then compatibility with existing devices is maintained, but bit errors occur in noisy environments
Solution Approach 1:
The system dynamically adapts the modulation scheme based on environmental conditions. In noisy environments, it switches to spread spectrum load modulation which provides robustness against interference, while in quieter environments it can use conventional modulation to maintain compatibility. This dynamic adaptation resolves the contradiction between reliability and compatibility.
Solution Approach 2:
The modulation parameters are changed from conventional narrowband to spread spectrum wideband modulation. This parameter change in the communication method provides frequency diversity that combats narrowband interference and noise, reducing bit errors while the system maintains backward compatibility through optional implementation.
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
Enhances communication reliability, reduces interference, and allows for more compact designs by enabling multiple power transfers with improved compatibility and efficiency, particularly in Qi-compatible systems.
Implementation Method 1
power is inductively transferred from a transmitter coil in a power transmitter device to a receiver coil in the individual devices
Implementation Method 2
communication from the power receiver to the power transmitter is arranged to use load modulation of the power transfer signal
Data Source
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AI summary
A power transmitter (201) wirelessly provides power to a plurality of power receivers (207, 209) comprising a plurality of transmitter coils (203, 205) generating power transfer signals for the power receivers and a communicator (309) for communicating with the power receivers (207, 209) including receiving load modulation messages from the power receivers (207, 209). A power transfer controller (307) initializes a power transfer with a first power receiver (207) using a predetermined default modulation scheme including transmitting a communication capability message to the first power receiver (207) which includes a capability to support a spread spectrum load modulation communication scheme and indicating a set of spreading chip sequences. The power receiver responds with a spread spectrum modulation request message from the first power receiver (207) and both devices then switch to use the spread spectrum load modulation communication scheme with at least a first spreading chip sequence from the set of spreading chip sequences.