Wireless Charging Transmitter Phase Error Correction
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Solution Overview
Problem
Existing wireless charging systems are inefficient and complex, requiring high-cost coil current measurement and LC phase detection hardware, and are slow to react to changes in resonant frequency, leading to suboptimal charging efficiency and increased electromagnetic interference.
Innovation Solution
A wireless charging transmitter that dynamically tracks and corrects the resonant frequency by measuring the capacitor voltage of a capacitor connected in series with the transmitter coil, using a phase-shift controlled full bridge inverter and a control circuit with an analog-to-digital converter, phase error detector, and pulse width modulation circuit to maintain optimal resonance operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless charging uses inductive coupling between transmitter and receiver coils, then wireless charging convenience is achieved, but charging efficiency is reduced compared to wired charging
Solution Approach 1:
The system dynamically adjusts the operating frequency to track the resonant frequency of the coupled coils. The controller continuously monitors the impedance of the transmitter coil and adjusts the inverter frequency accordingly, allowing the system to maintain optimal resonance conditions despite changes in coupling distance or load, thereby maximizing charging efficiency while preserving wireless convenience
Solution Approach 2:
The patent changes the operating parameter (frequency) dynamically to match the resonant frequency of the coil system. By sweeping through a frequency range and identifying the frequency that produces maximum current or minimum impedance, the system optimizes power transfer efficiency. This parameter adjustment compensates for the inherent losses in wireless inductive coupling
2Loss of energy
If prior resonance circuits are used to improve efficiency and maximize charging distance, then charging efficiency and distance improve, but the system becomes overly complex requiring high speed communication with receiver
Solution Approach 1:
The patent extracts and eliminates the need for complex bidirectional communication protocols and high-speed data exchange between transmitter and receiver. Instead, the transmitter independently determines resonance conditions by monitoring its own coil impedance and adjusting frequency accordingly, simplifying the system architecture while maintaining efficient resonance-based power transfer
Solution Approach 2:
The transmitter performs self-diagnosis and self-adjustment by monitoring its own electrical characteristics (impedance, current, voltage) to detect resonance conditions. The system serves itself by automatically tuning the operating frequency without requiring external feedback or complex communication with the receiver, thereby reducing system complexity
3Loss of energy
If prior resonance circuits with Schmitt trigger and LC phase detection are used, then resonant operation is achieved, but the system becomes expensive and slow to react to changes
Solution Approach 1:
The patent replaces complex mechanical/electronic measurement hardware (Schmitt triggers, LC phase detection circuits, high-speed comparators) with a microcontroller-based digital measurement system. The microcontroller samples voltage and current signals through ADCs and uses software algorithms to detect resonance conditions, providing both lower cost and faster response to frequency changes
Solution Approach 2:
The system uses inexpensive, readily available components: standard ADCs, microcontrollers, and basic voltage dividers replace expensive precision measurement hardware. The software-based resonance detection uses simple mathematical calculations rather than complex analog circuits, significantly reducing component costs while improving response speed
4Device complexity
If the wireless charging system does not track resonant frequency dynamically, then system simplicity is maintained, but charging efficiency decreases and electromagnetic interference increases
Solution Approach 1:
The system implements feedback by continuously monitoring the impedance of the transmitter coil and using this information to adjust the operating frequency. The controller measures the real and imaginary components of the coil impedance, calculates the phase angle, and adjusts the inverter frequency to maintain resonance, thereby achieving high efficiency without excessive complexity
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 solution enhances charging efficiency, reduces electromagnetic interference, and simplifies the system by dynamically adjusting the phase error, ensuring optimal resonance operation regardless of changes in coil orientation or load, while being more cost-effective and less complex.
Implementation Method 1
a phase-shift controlled full bridge inverter having an input for receiving a phase-shift signal, and first and second output terminals for providing an inverter output voltage; a capacitor having a first terminal coupled to the first output terminal of the phase-shift controlled inverter, and a second terminal; a coil having a first terminal coupled to the second terminal of the capacitor, and a second terminal coupled to the second terminal of the phase-shift controlled inverter
Implementation Method 2
The wireless charging transmitter tracks and dynamically corrects the phase error for resonance operation during a charging operation to provide the optimum charging frequency for receiver load
Implementation Method 3
In most wireless charging systems, inductive coupling between a transmitter coil and a receiver coil is used to transfer power
Data Source
AI summary
A wireless charging transmitter has a phase-shift controlled inverter, a capacitor, a transmitter coil, and a control circuit. The phase-shift controlled inverter has an input for receiving a phase-shift signal, and first and second output terminals for providing an inverter output voltage. The capacitor has a first terminal coupled to the first output terminal of the phase-shift controlled inverter, and a second terminal. The transmitter coil having a first terminal coupled to the second terminal of the capacitor, and a second terminal coupled to the second terminal of the phase-shift controlled inverter. The control circuit has an input coupled to the second terminal of the capacitor for sampling a capacitor voltage of the capacitor, and an output for providing the phase-shift signal corrected for the phase error. The control circuit determines the phase error of the capacitor voltage relative to a phase of an inverter output voltage to ensure the wireless charging transmitter operates in resonance.