LF Distance Estimation for EV Wireless Charging Alignment
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Solution Overview
Problem
Existing fine positioning methods for electric vehicle (EV) wireless power transfer (WPT) face challenges such as inability to specify the center point of the secondary device relative to the primary device, low data transmission rates, and lack of information on the antenna arrangement of the primary device, leading to difficulties in aligning the secondary device with the primary device.
Innovation Solution
A distance estimation method using low-frequency (LF) signals that aligns the center of the secondary device with the center of the primary device by compensating for the interval between transmitters and receivers based on time differences of LF signals, without requiring information on the antenna arrangement of the primary device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If WLAN data transmission is used to share antenna arrangement information, then fine positioning information can be obtained, but data transmission rate is low and real-time positioning cannot be achieved
Solution Approach 1:
The patent introduces LF signals as an intermediary medium to transmit positioning-related information between the EV device and supply device. Instead of relying on WLAN to share antenna arrangement data, the system uses LF signal transmission characteristics (time differences, signal strengths) to indirectly convey positioning information, thereby avoiding the bandwidth limitations of WLAN while still achieving accurate fine positioning.
2Adaptability or versatility
If antenna arrangement information of primary device is not available, then system compatibility is improved, but fine positioning cannot be performed
Solution Approach 1:
The patent enables the EV device to autonomously determine its position without requiring advance knowledge of the primary device's antenna arrangement. By using LF signals transmitted from the EV's own transmitters and received by the primary device's receivers, the system self-generates the necessary positioning data through time difference and signal strength measurements, eliminating the need for pre-shared antenna arrangement information while maintaining positioning accuracy.
Solution Approach 2:
The system uses feedback from LF signal transmission and reception to dynamically adjust positioning calculations. The primary device receives LF signals from multiple transmitters in the EV device and returns response information containing timing and signal strength data. This feedback loop allows the EV device to iteratively refine its position estimate without needing prior knowledge of the primary device's antenna configuration, thus achieving both compatibility and precision.
3Adaptability or versatility
If LF signals are used for fine positioning, then alignment can be achieved without antenna arrangement information, but positioning time increases due to signal processing
Solution Approach 1:
The patent performs preliminary actions by having the EV device transmit LF signals from multiple transmitters simultaneously or in rapid sequence before the positioning calculation is needed. The primary device receives and processes these signals in advance, storing the timing and signal strength information for subsequent positioning computations. This preliminary signal transmission and data collection reduces the actual positioning time when alignment is required.
Solution Approach 2:
The system maintains continuous LF signal transmission and reception during the approach phase, allowing the EV device to continuously update its position estimate as it moves toward the primary device. This continuous action eliminates the need for time-consuming single-shot measurements and enables real-time tracking and adjustment, reducing overall positioning time while maintaining accuracy without antenna arrangement information.
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 effectively estimates the distance and direction of the secondary device from the primary device, enabling accurate fine positioning for EV WPT even in environments where antenna location information is not available, thus improving alignment efficiency and user convenience.
Implementation Method 1
transmitting a first low-frequency (LF) signal to a first receiver and a second receiver of a primary device
Implementation Method 2
compensating for an interval between a first transmitter and a second transmitter on the first straight line or the second straight line based on a time difference of LF signals of the first transmitter and the second transmitter arriving at the primary device
Data Source
AI summary
A method for estimating distance using low frequency (LF) signals when performing fine positioning for electric vehicle (EV) wireless power transfer (WPT) includes steps of: restricting a position of a first transmitter of an EV to a point on a first straight line extending towards a center of a primary device of a power supply device; restricting a position of a second transmitter of the EV to a point on a second straight line extending towards the center of the primary device; compensating, on the first straight line or the second straight line, for the distance between the first transmitter and the second transmitter based on the time difference of LF signals arriving at the primary device; and calculating the positions of the first and second transmitters such that first and second distances from starting points on the first and second straight lines to the first and transmitters, respectively.