Magnetic Flux Bias Compensation Based on Voltage Injection Method With an Auxiliary DC/DC Converter

DC bias will make the transformer core saturated, causing local overheating and insulation materials aging. Therefore, it is of great significance to study the suppression of DC bias in transformers. In this article, a magnetic compensation scheme of DC bias based on a hybrid transformer (HT) integrated an auxiliary DC/DC converter is proposed. First, a compensation mechanism is established by designing a novel HT topology structure, which lays the magnetic circuit foundation of DC bias compensation. Second, the mathematical model of transformer DC bias is established, and the DC compensation amount of HT is derived. A transient simulation model of three-phase HT is established by the finite element model, and the situation of the DC bias before and after the compensation is analyzed. Finally, the platform of the DC bias compensation scheme is built. The full compensation experiment of DC bias is simulated by two parallel HT. The experimental results show the DC bias compensation effect is obvious, the distortion of excitation current, temperature rise, and flux density distribution drop obviously, which verifies the correctness of the scheme proposed in this article. It provides a reference for solving the problem of DC bias.

Automated summary

DC bias in transformers can lead to core saturation, local overheating, and aging of insulation materials. This article proposes a magnetic compensation scheme based on a hybrid transformer integrated with an auxiliary DC/DC converter to suppress DC bias. The compensation mechanism is established through a novel HT topology structure, the mathematical model of transformer DC bias is derived, and a transient simulation model is developed to analyze the situation before and after compensation. The experimental results demonstrate the effectiveness of the proposed scheme in compensating DC bias, providing a reference for addressing the issue.