Wireless Charger Q-Factor Sensing With Continuous Resonant Excitation
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Solution Overview
Problem
Conventional wireless power chargers face challenges in accurately measuring the quality factor (Q-factor) due to instability and inaccuracy, which are exacerbated by the use of single excitation pulses, leading to unreliable foreign object detection and increased system complexity.
Innovation Solution
A method and apparatus that utilize a predetermined excitation pulse sequence, including continuous phase-shift excitation pulses, to stabilize the resonance circuit and measure the Q-factor with improved accuracy and reliability, utilizing software-based solutions without additional hardware, and employing MCU peripheral subsystems for excitation and sensing phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single excitation pulse is used to generate free resonance signal for Q-factor measurement, then the measurement process is simple and low power consumption, but the measurement accuracy and stability deteriorate
Solution Approach 1:
The patent applies periodic action by using multiple continuous excitation pulses instead of a single pulse. The excitation signal is applied continuously over multiple periods to build up sufficient resonance signal energy, allowing for accurate Q-factor measurement while maintaining system simplicity and low power consumption.
Solution Approach 2:
The patent implements continuity of useful action by applying continuous excitation pulses during the measurement phase. This continuous excitation ensures that the resonance circuit maintains steady-state oscillation, providing stable and accurate Q-factor measurements without requiring complex external hardware.
2Reliability
If external sensors and circuitry are used for foreign object detection, then detection capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent applies self-service by using the existing resonance circuit and controller to perform both power transmission and foreign object detection functions. The controller monitors the Q-factor changes of the resonance circuit to detect foreign objects, eliminating the need for separate external sensors and reducing system complexity while maintaining reliable detection capability.
Solution Approach 2:
The patent implements universality by making the resonance circuit serve multiple functions: power transmission during normal operation and foreign object detection during measurement phases. The same hardware components are used for both purposes, reducing overall system complexity while maintaining comprehensive functionality.
3Use of energy by moving object
If single pulse excitation is used for Q-factor measurement, then power consumption is low, but measurement stability and reliability worsen
Solution Approach 1:
The patent uses periodic action with multiple continuous excitation pulses to achieve stable Q-factor measurements. The periodic excitation allows the resonance circuit to reach steady-state oscillation, ensuring measurement reliability while keeping power consumption low by limiting excitation to specific measurement phases rather than continuous operation.
Solution Approach 2:
The patent applies preliminary action by performing Q-factor measurements at specific intervals during the charging process. The controller periodically interrupts power transmission to perform measurement phases, ensuring stable and reliable detection of foreign objects without continuously consuming additional power for measurements.
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 method achieves stable and accurate Q-factor measurement, enabling reliable detection of foreign objects by minimizing circuit saturation and reducing hardware requirements, thus enhancing the efficiency and cost-effectiveness of wireless power transmission systems.
Implementation Method 1
a first set of continuous excitation phase switching control signals to generate the output PWM signal to have alternating positive and negative pulses having a first pulse frequency... enabling the resonant tank circuit to generate a resonant decaying output voltage signal
Data Source
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AI summary
A method is provided for operating a wireless charger having a multi-switch inverter which supplies an output PWM signal to a resonant circuit in response to switching control signals, including a first set of continuous excitation phase switching control signals (which generate the output PWM signal to have alternating positive and negative pulses having a first pulse frequency) and a second set of free resonance signal sensing phase switching control signals (which enable the resonant tank circuit to generate a resonant decaying output voltage signal in the presence of a foreign object that is located near the wireless charger), where each continuous excitation phase switching control signal includes a plurality of positive or negative excitation pulses having the first pulse frequency, and where one or more quality factor parameters of the wireless charger are measured based on one or more electrical parameters of the resonant decaying output voltage signal.