EV Wireless Charging Coil Pad for Metal and Live Object Detection
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Solution Overview
Problem
Existing wireless power transfer systems for electric vehicles lack effective detection of both metal and living objects between charging pads, leading to safety hazards due to incomplete metal object detection and inadequate live object detection, resulting in low detection accuracy and increased system costs.
Innovation Solution
A combined metal object detection (MOD) and live object detection (LOD) system using a detection coil pad with a resonant circuit and signal processing, which changes inductance or capacitance values to differentiate between metal and living objects, eliminating blind spots with a four-layer coil structure and noise signal removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors such as thermal cameras, radar, pressure sensors are used to detect foreign objects, then detection capability is improved, but system cost increases
Solution Approach 1:
The detection coil pad serves multiple functions: it acts as both the transmitting pad for wireless power transfer and the detection coil for detecting metal and living objects. This multi-functionality eliminates the need for separate detection sensors, thereby reducing system cost while maintaining detection capability.
Solution Approach 2:
The transmitting pad automatically performs detection functions through its inherent electromagnetic field without requiring external detection devices. The system uses its own transmitting coil to detect the presence of metal objects and living objects, achieving self-service detection that reduces overall system complexity and cost.
2Area of stationary object
If additional coils are placed on the same layer to detect metal objects, then detection coverage is improved, but blind spots appear on the detection area
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of coils to a three-dimensional stacked configuration with detection coil pads positioned at different heights above the transmitting pad. This vertical dimensionality change eliminates blind spots by ensuring that objects at various positions are detected by at least one coil in the stacked arrangement.
Solution Approach 2:
The detection system is divided into multiple independent detection coil pads stacked vertically, each contributing to the overall detection coverage. This segmentation allows each coil to cover specific zones, and the combination of all coils provides complete coverage without blind spots.
3Measurement precision
If pressure sensors are used to detect objects, then object detection is improved, but false detection occurs for objects without influence on WPT system such as glass
Solution Approach 1:
The system monitors changes in electrical parameters (inductance, capacitance, resonant frequency) of the detection coil pad caused by the presence of objects. Different materials produce different parameter changes, allowing the system to distinguish between metal objects, living objects, and non-influential objects like glass, thereby eliminating false detections.
Solution Approach 2:
The system continuously monitors the electrical parameters of the detection coil pad and compares them against reference values. When parameter changes exceed predefined thresholds, the system identifies the presence of metal or living objects. This feedback mechanism enables reliable differentiation between various object types, preventing false alarms.
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 system accurately detects metal and living objects between charging pads, enhancing safety by preventing overheating and health threats, while reducing system costs through improved detection accuracy and eliminating blind spots.
Implementation Method 1
If a metal object such as a key or a coil falls on the charging pads, the metal object will get heated because of an eddy current generated in it
Implementation Method 2
a resonant circuit coupled to the detection coil pad. The resonant circuit may be configured such that the inductance or capacitance change causes a resonant condition of the resonant circuit to change
Implementation Method 3
the transmitting coil is excited by a high-frequency inverter. Then, a high-frequency AC magnetic field is generated and coupled with the receiving coil. Thus, power can be transferred to the EV via the magnetic coupling.
Data Source
AI summary
A combined metal object detection (MOD) and live object detection (LOD) system for a wireless power transfer (WPT) system in an electric vehicle (EV) charging application, and methods for use, are provided. The combined MOD and LOD system may comprise a transmitting pad, a detection coil pad coupled to the transmitting pad, and a receiving pad positioned adjacent to the transmitting pad. The transmitting pad, the detection coil pad, and the receiving pad may be configured such that, when a living object or a metal object appears between the transmitting pad and the receiving pad, an inductance or capacitance value change of the detection coil pad occurs.