LF Vehicle Position Sensing for Wireless Charging Coil Alignment
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Solution Overview
Problem
Conventional methods for aligning primary and secondary coils in magnetic resonance wireless power transfer systems are prone to user intervention errors, leading to inefficiencies and reduced stability due to coil misalignment, which affects power transfer efficiency and reliability.
Innovation Solution
A method using low-frequency (LF) sensors to accurately measure and adjust the position of a vehicle's secondary coil relative to a ground assembly's primary coil by transmitting LF signals, estimating the vehicle's position, and adjusting transmission strength based on measured and estimated positions, as well as an acceleration flag, to optimize alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional alignment techniques (rear camera or bump-based movable charging pad) are used, then the system can achieve basic alignment functionality, but user intervention is required which leads to alignment errors and reduced power transfer efficiency
Solution Approach 1:
The system performs self-alignment by automatically detecting vehicle position using LF sensors and adjusting the charging pad position or vehicle guidance without requiring user intervention. The control unit processes LF signal data and autonomously achieves optimal coil alignment, eliminating manual operation errors while maintaining high alignment accuracy
Solution Approach 2:
The patent replaces manual mechanical alignment methods (camera-based visual alignment or physical bump guidance) with electromagnetic field-based LF sensor detection. The LF signals penetrate the vehicle body to detect position internally, providing more accurate and reliable alignment data compared to external visual or mechanical methods
2Device complexity
If manual alignment methods are used, then the system structure remains simple, but alignment deviation occurs leading to excessive system performance deterioration
Solution Approach 1:
The patent introduces LF sensors as an intermediary detection mechanism between the vehicle and charging pad. These sensors emit low-frequency electromagnetic signals that penetrate the vehicle body to detect internal position, providing accurate alignment data without adding complex external alignment infrastructure or significantly increasing system complexity
Solution Approach 2:
The system changes the detection parameter from visual/optical (camera-based) or mechanical (bump-based) to electromagnetic field penetration (LF signals). This parameter change enables detection through the vehicle body, providing more accurate position information while maintaining relatively simple system architecture
3Speed
If LF signal transmission strength is high, then detection range is improved, but saturation of LF receive antennas occurs reducing measurement accuracy
Solution Approach 1:
The system dynamically adjusts the LF transmit signal strength based on detected vehicle position and antenna saturation status. When saturation is detected, the transmit power is reduced; when position detection is clear, power is increased. This dynamic adjustment maintains optimal detection range while preventing saturation-induced measurement errors
Solution Approach 2:
The system implements feedback control by monitoring the output signals from LF receive antennas for saturation conditions. When saturation is detected, the control unit adjusts the transmit power level accordingly, creating a closed-loop system that maintains measurement precision while ensuring reliable detection response
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 accuracy of coil alignment, thereby maximizing wireless charging efficiency and improving the stability and reliability of the power transfer system.
Implementation Method 1
transmitting low frequency (LF) signals to initiate alignment with the GA
Implementation Method 2
receiving information regarding a position of the vehicle measured by LF receive antennas of the GA
Data Source
AI summary
A method for measuring a position, is performed by a vehicle assembly (VA) for alignment between a ground assembly (GA) and the VA. The method includes transmitting low frequency (LF) signals to initiate alignment with the GA and estimating a position of a vehicle using at least one sensor mounted on the vehicle. Information regarding the estimated position of the vehicle is provided to the GA and information regarding a position of the vehicle measured by LF receive antennas of the GA and an acceleration flag calculated by the GA is received. Accordingly, a transmission strength of the LF signals transmitted by the VA is adjusted based on the information regarding the position of the vehicle measured by the LF receive antennas and the acceleration flag.