Reflexive Field Containment Circuit for Dynamic WPT Stray Field Reduction
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Solution Overview
Problem
Dynamic inductive power transfer systems for electric vehicles face challenges with stray magnetic fields, high self-inductance, and complex control systems, which affect efficiency and safety, particularly in elongated-rail-transmitter-coil designs, and increase costs in segmented-transmitter-coil types.
Innovation Solution
A high-power reflexive field containment circuit topology with series charging impedance, including capacitors and inductors, is introduced to manage equivalent input voltage and current, allowing for higher output power and efficiency while reducing stray fields and system complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elongated-rail-transmitter-coil type is used, then system control simplicity is improved, but stray magnetic field generation increases
Solution Approach 1:
The transmitter coil is divided into multiple segments with independent control, allowing each segment to be activated only when needed. This segmentation reduces the overall area generating stray magnetic fields while maintaining system control simplicity through modular architecture.
Solution Approach 2:
Different segments of the transmitter coil can be activated based on the local position of the receiver coil. This local quality approach ensures that magnetic fields are generated only in the specific area where power transfer is needed, reducing overall stray field generation while maintaining simple control through position-based activation.
2Device complexity
If elongated-rail-transmitter-coil type is used, then fewer inverters are needed, but coil voltage exceeds insulation capability
Solution Approach 1:
The transmitter coil is segmented into multiple sections, each with its own inverter. This segmentation distributes the voltage stress across multiple lower-voltage inverters, preventing any single inverter from exceeding insulation capability while maintaining overall system efficiency.
Solution Approach 2:
The system dynamically activates only the coil segments currently needed for power transfer. This dynamic operation reduces the cumulative voltage stress on individual components and allows for better voltage management within insulation limits while maintaining simple control architecture.
3Object-generated harmful factors
If segmented-transmitter-coil type is used, then stray magnetic field is reduced, but system complexity increases
Solution Approach 1:
The transmitter coil is divided into manageable segments that can be independently controlled. This segmentation reduces stray magnetic fields by limiting active coil areas while the modular structure actually simplifies overall system management through standardized, reusable segments.
Solution Approach 2:
Each segmented coil unit is designed to be universal and interchangeable, capable of performing the same function in different positions. This universality reduces system complexity by using standardized components rather than unique custom-designed sections, while still achieving stray field reduction through selective activation.
4Reliability
If segmented-transmitter-coil type is used, then coupling coefficient is improved, but number of inverters increases
Solution Approach 1:
The transmitter coil is segmented to create multiple smaller, more manageable coil units. Each segment can achieve better coupling with the receiver coil due to reduced size and improved alignment, while the modular inverter architecture allows for efficient power distribution across segments.
Solution Approach 2:
Each coil segment is equipped with its own inverter that autonomously manages power transfer for that segment. This self-service approach improves coupling efficiency through localized control while the modular design allows segments to operate independently, reducing the need for complex centralized control and minimizing the total number of inverters needed.
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 proposed circuit achieves higher output power and efficiency, reduces stray magnetic fields, and simplifies system design, enabling more affordable and efficient dynamic wireless power transfer for electric vehicles.
Implementation Method 1
a first series charging capacitor, a parallel charging capacitor connected in parallel with the WPT charging pad circuit
Implementation Method 2
a series charging impedance connected in series between an output of the inverter and a connection between the WPT charging pad circuit and the parallel charging capacitor. The series charging impedance includes a second series charging capacitor and/or a series charging inductor
Implementation Method 3
The inductive power transfer type uses induced power with magnetically coupled coils
Data Source
AI summary
An apparatus for a high-power reflexive field containment circuit topology for dynamic wireless power transfer systems is disclosed. A wireless power transfer (“WPT”) charging apparatus includes an inverter configured to connect with a direct current (“DC”) source on an input side and one or more WPT charging branches. Each WPT charging branch includes a WPT charging pad circuit with a WPT charging pad connected in series with a first series charging capacitor, a parallel charging capacitor connected in parallel with the WPT charging pad circuit, and a series charging impedance connected in series between an output of the inverter and a connection between the WPT charging pad circuit and the parallel charging capacitor. The series charging impedance includes a second series charging capacitor and/or a series charging inductor.