Investigation of core loss characteristics of 3% SiFe using the laser scribing method

Abstract

The core loss of 3% SiFe is strongly dependent on silicon content, impurities, permeability, and domain structure of the SiFe. Domain refining has proved to be a very good method for the reduction of core loss in high-permeability grain-oriented SiFe, and laser scribing is well known as an effective and industrially important method of domain refinement. In this work, magnetic domain refinement was carried out using a pulsed and Q-switched Nd : YAG laser, and the core losses were measured and analysed to find the optimal parameters of the laser treatment. The laser beam was focused with a spot size of 0.2 mm and pulse energy of 15 -30 mJ and the lines were scribed with a period of ~5 mm. The core loss was improved by up to 18% in 3% SiFe using this method, and the loss was relatively insensitive to the optical energy of the Q-switched pulse. 1 Introduction In the field of metal processing lasers have been very useful tools for the processing or heat treatment of many materials, such as silicon, ceramics, magnetic materials, and thin films. Among these applications, laser scribing, in particular, has been paid a lot of attention as a very powerful method for improving the electrical characteristics of silicon steel (SiFe) [1 -5]. SiFe is used as an important material for motors and transformer cores. Since 65% of electrical energy is consumed by motors, SiFe can be said to be one of the main factors in electrical energy consumption. The efficiency of a motor is known to be about 86% [6] and most energy loss is caused by heat radiation (I 2 R) and core loss. It is expected that the efficiency of a motor can be increased to 93% by reducing the core loss, which will, in turn, contribute greatly to energy savings.In this work we try to decrease the core loss by directing a laser beam on the surface of SiFe. Generally, laser processing of materials has many advantages over mechanical methods: easy automation of the process, no frictional wear of processing tools, and it is free from pollution caused by direct contact of mechanical tools with materials. Also, no mechanical damage occurs when handling hard and fragile materials like SiFe, silicon, and ceramics. If we use a laser in pulsed mode, the laser pulse energy and corresponding heat transfer can be localized to a very small region. Therefore the distortion and shrink of the target object caused by heat can be avoided [7,8].Laser scribing, in particular, is expected to enhance the quality of processing substantially because it provides much higher controllability and reproducibility than the conventional method where stress is

Investigation of Laser Scribing Technics for Reducing Core Loss of Grain-Oriented Silicon Steels

“…Considering experimental conditions, the pulse energy's scope was set to 0.5-3.3mJ. And the scribing velocity and the scribing spacing's scopes were set to 50-200mm/s and 1-4mm separately, according to the existed research literatures [6][7][8][9]. Each factor…”

Parameter Optimization of Laser Scribing Technics of 30Q130 Grain-Oriented Silicon Steel Based on Genetic Neural Network

“…The factors and their scopes were chosen based on the existing literatures. It was pointed out that the four factors scribing direction, scribing spacing, pulse energy and scanning velocity have significant effects on core loss reduction [8].It was also proved that scribing along the perpendicular direction of rolling would be more likely to get a greater reduction of core loss than other directions [9]. Hence, scribing direction was not discussed and all scribing operations were along the perpendicular direction, and the factors such as scribing velocity (V), pulse energy (P) and scanning spacing (L) were identified as the process parameters.…”

The effects of CO2 laser and thulium-doped fibre laser scribing on magnetic domains structure, coercivity, and nanohardness of Fe-3.2Si grain-oriented electrical steel sheets

“…The laser scribing technique is based on a rapid laser-induced increase of temperature on the sheet surface causing residual stresses during subsequent cooling that refines the magnetic domains. The mechanisms responsible for the improvement of soft magnetic properties include magnetic domain structure refinement, stress relaxation, and inhibition of domain-wall movement [10]. The industrially used laser scribing systems have been widely optimized for several other materials and applications, e.g.…”