Wireless Charger Q-Factor Measurement via Resonant Tank Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the quality factor (Q-factor) in wireless chargers with complex resonant tank circuits are challenging due to multiple poles, making it difficult to detect the presence of foreign objects and prevent overheating or damage.
Innovation Solution
A method involving an inverter, filter, and resonant tank circuit, where specific switch configurations and current pulses are used to isolate the resonant tank circuit during the Q-factor determination phase, simplifying the resonance network and allowing for accurate Q-factor measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex resonant tank circuit is used to meet EMC requirements, then electromagnetic compatibility is improved, but the system has multiple poles making Q-factor determination difficult
Solution Approach 1:
The patent segments the resonant tank circuit into multiple independent resonant circuits, each with a single pole. This segmentation allows the Q-factor to be determined for each individual circuit separately, avoiding the complexity of measuring multiple poles simultaneously while maintaining EMC compliance through the combined operation of all segments.
2Difficulty of detecting and measuring
If a series LC resonant circuit is used, then Q-factor determination is simple, but the system cannot meet EMC requirements for automotive applications
Solution Approach 1:
The patent changes the circuit configuration parameter from a single series LC circuit to multiple parallel resonant circuits. This parameter change enables the system to meet EMC requirements through frequency filtering while maintaining simple Q-factor measurement capability for each individual resonant circuit.
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
Enables effective detection of foreign objects by simplifying the resonance network, reducing complexity and improving the accuracy of Q-factor determination in wireless chargers with complex resonant tank circuits.
Implementation Method 1
The resonant tank circuit connects to the filter and receives the filtered signal, and provides wireless power to a receiver
Implementation Method 2
The inverter receives a supply voltage and generates a PWM signal by switching first, second, third, and fourth switches of the inverter
Data Source
AI summary
A method for determining a quality factor of a wireless charger is disclosed. The wireless charger includes an inverter, a filter, and a resonant tank circuit. The inverter receives a supply voltage and generates a PWM signal at a first node and a second node. The filter connects to the first and second nodes of the inverter to receive the PWM signal, and generates a filtered signal at a first terminal and a second terminal of a capacitor. The resonant tank circuit connects to the first and second terminals of the capacitor of the filter to receive the filtered signal, and provides wireless power at an inductor coil to a receiver. The method includes: issuing a current pulse to the resonant tank circuit; and in a Q-factor determination phase of the wireless charger, connecting the resonant tank circuit and only the capacitor of the filter in a resonance network.