# An Iterative Error Correction Procedure for Single Sheet Testers Using FEM 3D Model

## TL;DR

This paper introduces a method to improve the accuracy of BH and power loss curves for electric steels using a 3D FEM model and an iterative correction process.

## Contribution

The novel contribution is an iterative error correction procedure using a 3D FEM model and steepest descent algorithm for SST measurements.

## Key findings

- Root mean squared errors for BH curves were reduced from 1.85 A/m to 42.88 × 10−3 A/m.
- Power loss curve errors decreased from 44.5 × 10−4 W/kg to 7.28 × 10−4 W/kg.

## Abstract

Determination of single-valued BH curve and power loss curve of electric steels is an important parameter in the design of electrical machines and transformers. This paper proposes a correction procedure for the measurement of anhysteretic BH curve and power losses, based on the finite element model (FEM) and SST apparatus. A 3D finite element model (FEM) of the SST (Single Sheet Tester) was developed with respect to the IEC 60404-3 standard. The measurement results obtained with a standardized SST apparatus are fed to its FEM and used to iteratively correct initial BH and power loss curves, obtained using magnetic equivalent circuits theory. The proposed iterative correction procedure is based on the steepest descent algorithm, while the stopping criteria were based on the difference between simulated and measured global variables (power loss, induced voltage, and primary current). After correction, root mean squared errors were decreased from 1.85 A/m to 42.88 × 10−3 A/m for the BH curve, and from 44.5 × 10−4 W/kg to 7.28 × 10−4 W/kg for the power loss curve.