Abstract: From the perspective of engineering practicality and effectiveness, product level iron core models were designed and manufactured. Based on a physical model, the influence of harmonic phase difference on no-load loss was studied. When the phase difference is π, the performance of the iron core is the worst. The finite element simulation obtained the magnetic density distribution of the iron core under complex working conditions of harmonic and DC bias, and analyzed the reasons for the increase in no-load loss. Comparative experiments were conducted on the 0.20-0.27 mm oriented silicon steel iron core model under complex working conditions. The results showed that the additional loss of the 20SQGD070 iron core model was reduced by 31 % compared to the 27SQGD090 iron core model when the working magnetic density was 1.7 T and 10 % third harmonic was added. The additional losses of silicon steel core models with different thickness specifications under DC bias are comparable. Considering the service conditions of oriented silicon steel materials in transformers, suggestions for selecting oriented silicon steel materials under complex working conditions are proposed.

Key words: product level iron core model, DC bias, harmonic, finite element simulation