Wireless Power Transmitter Modulation Control
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Solution Overview
Problem
Wireless charging systems using electromagnetic induction or magnetic resonance face issues with output power control, leading to fluctuations in charging voltage due to pulse width modulation (PWM), resulting in ripple phenomena and potential instability in charging states.
Innovation Solution
A power transmitting unit is designed with a signal generator, power generation circuit, and control circuit to generate and modulate signals of specific frequency bands, allowing for real-time adjustment of modulation signal duty and frequency based on the charging state of the power receiving unit, thereby stabilizing the charging voltage and minimizing ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pulse width modulation (PWM) is used to control output power, then power level adjustment is achieved, but charging voltage fluctuates and ripple phenomena occur
Solution Approach 1:
The patent changes the parameters of the modulation signal (frequency and duty cycle) dynamically based on charging state. By adjusting these parameters in real-time, the system maintains stable charging voltage while controlling output power, resolving the contradiction between power adjustment capability and voltage stability.
Solution Approach 2:
The control circuit receives feedback information about the charging state from the power receiving unit and uses this feedback to adjust the modulation signal parameters. This closed-loop feedback mechanism ensures that output power control does not compromise charging voltage stability, as the system continuously adapts to maintain optimal charging conditions.
2Power
If modulation signal duty is decreased to increase output voltage, then power control is achieved, but ripple phenomenon increases
Solution Approach 1:
Instead of simply decreasing duty to increase voltage, the patent dynamically adjusts both frequency and duty cycle parameters based on charging state. This coordinated parameter adjustment allows voltage control while minimizing ripple by selecting optimal parameter combinations that avoid resonant frequencies and maintain stable power transfer.
3Productivity
If wireless charging power is increased, then charging efficiency is improved, but interference with other systems (e.g., NFC) increases
Solution Approach 1:
The patent dynamically adjusts the frequency and duty cycle parameters of the modulation signal based on charging state and detected interference levels. By changing these parameters, the system can operate at high power for efficient charging while avoiding frequency ranges that cause interference with NFC and other wireless systems, thus resolving the contradiction between charging efficiency and electromagnetic compatibility.
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 the efficiency of wireless charging, reduces the occurrence of unstable charging states, prevents initial charging failures, and minimizes interference with other systems like NFC, while maintaining optimal power transfer and reducing power loss.
Implementation Method 1
a battery of the power receiving unit may be charged by an electromagnetic resonance phenomenon between a transmit coil of the power transmitting unit and a receive coil of the power receiving unit
Implementation Method 2
a power transmitting unit may adjust a DC voltage supplied to a power amplifier to control an output power
Data Source
AI summary
A power transmitting unit is provided. The power transmitting unit includes a signal generator configured to generate a signal of a first frequency band for wireless charging, a power generation circuit configured to generate a modulation signal for modulating the signal of the first frequency band generated by the signal generator, and amplify a transmit power of the signal of the first frequency band based on voltage supplied from the outside of the power transmitting unit, a power transmission circuit configured to transmit the amplified transmit power to a power receiving unit via a first antenna, a second antenna configured to receive information about a charging state from the power receiving unit through a second frequency band, and a control circuit configured to control a duty and frequency of the modulation signal based on the charging state.