Magnetic Characterization of Unsymmetrical Coil Pairs Using Archimedean Spirals for Wider Misalignment Tolerance in IPT Systems
Bibliographic record
Abstract
Resonant inductive power transfer (RIPT) is gaining popularity for wireless charging applications of future electric transportation. A fundamental challenge of implementing an RIPT system for wireless power transfer is the coupling variation between the primary and secondary coils, due to misalignment, while parking the car over the primary coil. Thus, it is desirable to have a coil pair, which is least sensitive to misalignments, to ensure efficient power transfer over a wide operating area, and to enable ease of use. The operating area of a coil pair is limited by the existence of a magnetic null in its coupling profile. For circular charging pads, employing a symmetrical Archimedean spiral, a magnetic null occurs at a misalignment distance equal to approximately 40% of the pad diameter (or about 70% of the coil diameter), irrespective of the air gap. In this paper, five diverse unsymmetrical coil pairs have been investigated, to find the coil pair least sensitive to misalignments. For unsymmetrical coil pairs, the position of the magnetic null shifts with the change in separation between the coils. By operating the primary and secondary pads at a distinct separation, the null position can be shifted further away from the center of the coils. This, in turn, increases the effective area, over which a given amount of power can be transferred to the load. After investigating the unsymmetrical coil pairs, it was found that the outer radius of the secondary coil should be kept equal to the outer radius of the primary coil, and inner radius of the secondary coil should be maintained greater than the inner radius of the primary coil, to obtain the best coupling profile.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".