# B-H Curve Estimation and Air Gap Optimization for High-Performance Split Core

## TL;DR

This paper introduces a simple method to estimate the B-H curve for current transformer cores and optimizes air gaps to improve performance.

## Contribution

A straightforward B-H curve estimation method and air gap optimization for high-performance split-core current transformers.

## Key findings

- The proposed B-H curve estimation method achieved a 2.6% error compared to experimental results.
- Air gap performance deterioration is linked to surface roughness and validated through simulations and experiments.
- Design guidelines for core geometry and optimal air gap range are provided for high-performance CT cores.

## Abstract

The current transformer (CT)-based energy harvesting method has gained considerable attention for low-power devices. Accurate estimation of the B-H curve is essential to develop a high-performance CT, as it closely relates to the electromagnetic behavior of CT material. However, the existing estimation methods for the B-H curve face several drawbacks, which include process complexity and a high cost. This study presented an intuitive method to estimate the B-H curve based on the experimentally obtained resistance-voltage data. The performance of the CT core is obtained based on the estimated B-H curve, which exhibited an error of only 2.6% when compared to the experimental results for the most accurate case. Additionally, we analyzed split-core performance deterioration caused by the presence of an air gap. The air gap formation of the split core was closely related to the surface roughness, which significantly influenced core performance. The air gap range that minimizes the reduction in performance is predicted and validated through simulations and experiments. This research highlights a straightforward approach to obtaining the B-H curve of magnetic CT core material. We believe that this study provides the design guidelines needed to develop a high-performance CT core, including considerations for core geometry and the recommended air gap range.