Wireless Charging Control Circuit for EMI Reduction
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Solution Overview
Problem
Wireless charging systems face challenges with electromagnetic interference (EMI) due to high-power output circuits, particularly in the frequency range of 110 kHz to 190 kHz, which affects charging efficiency and compliance with EMI regulation standards.
Innovation Solution
A wireless power transmitter design that includes a conductive coil, power transmission circuit, voltage source, and control circuit to monitor and adjust the transmission frequency and voltage level, using an inductor and switching module to control power variation within the available frequency range, maintaining a duty cycle of 50% to minimize EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power output is used for fast wireless charging, then charging speed is improved, but electromagnetic interference (EMI) noise increases
Solution Approach 1:
The patent applies dynamics by making the power transmission frequency adjustable rather than fixed. The control circuit dynamically changes the operating frequency within the 110-190 kHz range to optimize between charging speed and EMI reduction, allowing the system to adapt its transmission characteristics based on operational requirements
Solution Approach 2:
The patent changes the physical parameter of transmission frequency to resolve the contradiction. By varying the frequency within the available band and adjusting the duty cycle of the power transmission, the system can maintain effective power transfer while reducing peak EMI noise levels that occur at certain frequency points
2Reliability
If transmission frequency is changed to conform to EMI regulation, then EMI compliance is improved, but wireless charging efficiency decreases
Solution Approach 1:
The system dynamically adjusts the transmission frequency within the 110-190 kHz range rather than being constrained to a single fixed frequency. This allows the system to comply with EMI regulations by avoiding problematic frequency points while maintaining efficient power transfer at optimized frequencies within the permitted band
Solution Approach 2:
The patent employs periodic modulation of the power transmission through duty cycle control. By using periodic on-off cycles at the optimized frequency, the system achieves both EMI compliance through reduced peak emissions and maintains charging efficiency through sustained average power delivery
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
The solution effectively reduces EMI noise, maintains charging efficiency, and ensures compliance with EMI standards by dynamically adjusting power transmission within the specified frequency range, thereby enhancing the performance of wireless charging systems.
Implementation Method 1
A wireless power transmitter may transfer power to a wireless power receiver by at least one of inductive coupling based on electromagnetic induction produced by a wireless power signal
Implementation Method 2
monitor a frequency of a signal or electromagnetic waves radiated through the conductive coil
Implementation Method 3
electromagnetic resonance coupling based on electromagnetic resonance generated by a wireless power signal in a specific frequency
Data Source
AI summary
A method and electronic device for performing wireless charging are provided. The electronic device includes a housing, a conductive coil, a power transmission circuit electrically connected to the conductive coil, and configured to wirelessly transmit power to an outside of the housing through the conductive coil, a voltage source electrically connected to the power transmission circuit, and a control circuit electrically connected between the power transmission circuit and the voltage source. The control circuit is configured to change power radiated through the conductive coil, monitor a frequency of a signal and/or electromagnetic waves radiated through the conductive coil, and adjust a level of a voltage from the voltage source based on at least a part of a monitored result of the frequency.