Wireless Power Transfer Timing for EMI and Noise Control
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Solution Overview
Problem
Existing wireless power transfer systems face issues such as electromagnetic interference, acoustic noise, and inefficient power transfer due to periodic power interruptions for communication, especially at higher power levels, which can affect both the power transmitter and receiver devices and other nearby electrical equipment.
Innovation Solution
A power transmitter system that employs a repeating time frame with power transfer and communication intervals, utilizing a transition controller to adjust power levels between these intervals, with a factor of at least two times difference, and an adapter to dynamically adapt the transition properties based on the power level operating point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power transfer is interrupted periodically for communication, then communication quality is improved, but electromagnetic interference and acoustic noise increase
Solution Approach 1:
The patent applies periodic action by implementing a repeating time frame structure that alternates between power transfer time intervals and communication time intervals. This periodic switching enables communication during dedicated intervals while managing electromagnetic interference through controlled power level transitions rather than complete interruptions
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the power level of the drive signal during transitions between power transfer and communication intervals. The adapter modifies transition properties (such as transition duration and timing) based on the power level operating point, changing parameters to reduce electromagnetic interference and acoustic noise while maintaining communication quality
2Loss of energy
If power level transitions are made faster, then power efficiency is improved, but electromagnetic interference increases
Solution Approach 1:
The patent applies dynamics by making the transition characteristics adaptive rather than fixed. The adapter dynamically adjusts transition properties based on the power level operating point, allowing the system to optimize the balance between power efficiency and electromagnetic interference reduction for different operating conditions
Solution Approach 2:
The patent employs parameter changes by modifying transition duration and timing parameters based on the power level operating point. At higher power levels, longer transition intervals are used to reduce electromagnetic interference, while at lower power levels, faster transitions improve power efficiency
3Loss of energy
If power transfer is maintained at high levels during communication intervals, then power efficiency is improved, but communication quality deteriorates due to interference
Solution Approach 1:
The patent applies periodic action by implementing distinct communication time intervals where power transfer is reduced or suspended. This periodic structure dedicates specific time slots to communication, ensuring communication quality while managing power efficiency through the overall repeating time frame structure
Solution Approach 2:
The patent employs parameter changes by adjusting the power level of the drive signal during communication intervals based on the power level operating point. The adapter modifies these power level parameters to achieve an optimal balance between maintaining power efficiency and ensuring communication quality
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 reduces electromagnetic interference and acoustic noise, improves efficiency, and allows faster switching with less power loss, providing a balanced trade-off between conflicting requirements like electromagnetic interference and power efficiency.
Implementation Method 1
wireless power transfer system in which power is inductively transferred from a transmitter coil in a power transmitter device to a receiver coil in the individual devices
Implementation Method 2
a communication coil arranged to generate a communication carrier signal during communication time intervals
Data Source
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AI summary
A power transmitter (101) wirelessly provides power to a power receiver (105) via a power transfer signal. A driver (201) generates the power transfer signal to employ a repeating time frame comprising a power transfer time interval and a communication time interval. A communication unit (205) and power transfer coil (103) communicate with the power receiver (105) using modulation of the communication carrier signal during communication time intervals. A transition controller (209) controls the drive signal to perform a power level transition between a higher power level during a power transfer time interval and a lower power level of a communication time interval closest to the power transfer time interval. The power transmitter further includes an adapter (211) which adapts a property of the power level transition in dependence on a power level operating point for the power transfer. For example, faster transition may be performed at lower power transfer levels than at higher power transfer levels.