Solenoid Coil Unit Structure for Misalignment-Robust Power Transfer
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Solution Overview
Problem
Current contactless power transfer devices face challenges in achieving a high coupling coefficient, robustness against misalignment, and weight reduction, particularly for dynamic power transfer applications like electric vehicles, where conventional solenoid coil units are either too heavy or inefficient.
Innovation Solution
A solenoid coil unit design featuring a rod-shaped core with a length twice the gap and a center portion length-to-width ratio of 2 or more, optionally with additional plate-like magnetic pole portions, to enhance coupling coefficient and robustness while minimizing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional solenoid coil unit with a flat ferrite core is used, then the coupling coefficient is slightly lower but the tolerance for misalignment is large, but the weight is too heavy for practical electric vehicle applications
Solution Approach 1:
The flat ferrite core is segmented into an H-shaped core with two separate magnetic poles, allowing the coil to be positioned only in the center region where magnetic flux is most effective. This segmentation reduces the total ferrite material required while maintaining strong magnetic coupling between transmitter and receiver units.
Solution Approach 2:
The coil is extracted from surrounding ferrite material and positioned only in the optimal magnetic flux region between the two H-shaped magnetic poles. This extraction eliminates unnecessary ferrite weight while preserving the essential magnetic coupling function.
2Length of stationary object
If the gap between power-transmitting and power-receiving coil units is increased to accommodate electric vehicle applications, then the coupling coefficient significantly decreases, but increasing coil size to compensate results in increased weight
Solution Approach 1:
The design transitions from a planar coil configuration to a three-dimensional solenoid structure with the coil wound around the H-shaped core. This dimensional change creates a more concentrated and directed magnetic field that maintains coupling efficiency over larger gaps between transmitter and receiver units.
Solution Approach 2:
The invention combines ferrite magnetic material with a solenoid coil configuration to create a composite structure that generates a focused magnetic field. This composite design enhances magnetic flux density and coupling coefficient while maintaining a compact form factor suitable for larger gap applications.
3Weight of moving object
If an H-shaped ferrite core is used to reduce weight, then the weight is reduced but the coupling coefficient might be significantly reduced depending on misalignment direction and amount
Solution Approach 1:
The H-shaped core concentrates magnetic flux in specific local regions between its two poles, creating areas of high magnetic density where the coil is positioned. This local concentration of magnetic quality maintains coupling efficiency even when misalignment occurs, as the focused flux paths are more resilient to positional variations.
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 solenoid coil unit achieves a high coupling coefficient and robustness against misalignment while reducing weight, improving power transfer efficiency and practicality for dynamic applications, such as electric vehicles.
Implementation Method 1
a contactless power transfer device that transmits power from a power transmitting side to a power receiving side by magnetic field coupling
Implementation Method 2
a rod-shaped core around which the solenoid coil is wound and having a length longer than the length of the solenoid coil in the center axis direction
Data Source
AI summary
A solenoid coil unit is provided with a solenoid coil that is to be arranged in parallel with another solenoid coil with a predetermined gap in a separation direction orthogonal to a center axis direction; and a rod-shaped core around which the solenoid coil is wound and having a length longer than the length of the solenoid coil in the center axis direction. The rod-shaped core has a center portion around which the solenoid coil is wound and end portions located at both ends of the rod-shaped core and extending from both ends of the solenoid coil, the ratio of the length to the width of the center portion is 2 or more, and the length of the solenoid coil in the center axis direction is approximately twice the gap.