Segmented Magnetic Flux Pad for EV Charging
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Solution Overview
Problem
Conventional inductive power transfer (IPT) systems face challenges in maintaining efficient power transfer due to separation sensitivity, leading to reduced power at larger distances and potential overloading at closer separations, which complicates electric vehicle charging, especially with varying ground clearances and alignment requirements.
Innovation Solution
A magnetic flux pad design featuring two pole areas with magnetically permeable cores and flat, spiral wound coils that form a flux pipe, directing flux archedly beyond the pad with minimal leakage, and optionally including a vertical flux-sensitive coil for enhanced misalignment tolerance, allowing for efficient power transfer over a wider range of separations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional circular power pads are used for inductive power transfer, then power can be transferred at separations up to 100 mm, but the coupling factor becomes so small that it becomes impractical and power transfer efficiency drops significantly
Solution Approach 1:
The patent divides the conventional circular power pad into multiple rectangular modules arranged in a grid pattern. Each module contains its own windings and ferrite bars, creating segmented flux paths. This segmentation allows each module to independently contribute to power transfer, maintaining efficient coupling over larger separation distances without the rapid efficiency drop experienced by conventional circular pads.
Solution Approach 2:
The patent transitions from circular geometry to a rectangular modular arrangement, fundamentally changing the dimensional organization of the power transfer system. The rectangular modules are arranged in a grid that optimizes flux distribution across the separation distance, creating more efficient three-dimensional flux paths compared to the conventional circular configuration.
2Power
If the separation between power pads is reduced to increase power transfer, then more power can be transferred, but the components of the circuit become overloaded and the system must be shut down
Solution Approach 1:
By segmenting the power transfer system into multiple modular units, the patent distributes the power transfer load across several independent modules. Each module handles a portion of the total power, preventing any single component from becoming overloaded even when operating at high power levels, thus maintaining system reliability.
Solution Approach 2:
The patent employs dynamic control of the modular system, where individual modules can be independently adjusted or deactivated based on operating conditions. This dynamic capability allows the system to maintain stable operation across varying separation distances by optimizing the contribution of each module, preventing component overload while maximizing power transfer.
3Ease of operation
If the vehicle positioning is not precisely aligned with the charging pad, then ease of operation improves, but the coupling factor decreases and power transfer becomes impractical
Solution Approach 1:
The segmented modular design creates multiple flux paths distributed across the charging surface. When vehicle positioning is imperfect, flux can still couple effectively through adjacent modules, maintaining overall coupling efficiency. This redundancy of flux paths provides inherent tolerance to positioning errors without significant loss of power transfer capability.
Solution Approach 2:
The rectangular modular configuration creates a charging surface that is more universally effective across different positioning scenarios. The grid arrangement of modules ensures that regardless of the exact vehicle position, multiple modules can contribute to power transfer, making the system more forgiving of alignment variations compared to conventional circular pads.
4Length of stationary object
If the self inductance and mutual inductance are allowed to vary widely with separation, then the system can operate over a range of distances, but the circuit operates off-frequency putting extra stress on the power supply
Solution Approach 1:
The segmented modular structure creates more stable inductance characteristics across separation variations. Each module contributes consistently to the total inductance, reducing the wide variations in self and mutual inductance that occur with conventional designs. This stability reduces the need for frequent power supply adjustments and minimizes stress on the power supply system.
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 design achieves stable and efficient power transfer with reduced leakage flux, enabling effective charging of electric vehicles across a broader separation range without compromising reliability or safety, and can be used in various applications beyond pads, such as roadways.
Implementation Method 1
two coils magnetically associated with the core, whereby the flux enters the pad at one of the pole areas and exits the pad at the other pole area
Implementation Method 2
a magnetically permeable core, whereby the flux enters the pad at one of the pole areas and exits the pad at the other pole area
Data Source
Figure 1~2
Figure 3~4
Figure 4A~5A
AI summary
A magnetic flux pad for receiving or generating magnetic flux. The pad includes two pole areas (11, 12) associated with a magnetically permeable core (14). Coils (17) define the pole areas. The pad allows useable flux to be generated at a significant height above a surface of the pad.