A Novel DC Bias Suppression Strategy for Single-Phase Full-Bridge DC-DC Arc Welding Converter

Abstract

The high frequency transformer in single-phase full-bridge DC-DC converter is prone to saturation because of the asymmetry of circuit parameters. Transformer saturation will increase power consumption, accelerate the aging of winding insulation, and even damage power switches. In order to prevent this risk, a DC bias suppression strategy is presented in this article, and the main advantage of this strategy is that the problem of transformer saturation can be completely eliminated. In this article, firstly, the DC bias and saturation mechanism of single-phase full-bridge DC-DC converter are analyzed in detail, and the Maximum Integral Value of Volt-Second Product error (MIVVSPE) is derived. Secondly, aiming at the saturation problem of single-phase full bridge DC-DC converter, a new digital integral circuit is designed to evaluate the DC bias state of transformer, and a DC bias suppression strategy is constructed to suppress the saturation of transformer. Furthermore, different from the traditional current feedback control strategy, the DC bias suppression strategy based on volt-second product error integral can be triggered before the transformer enters the saturation state, and the transformer saturation can be completely suppressed. Finally, a 30 kW single-phase full-bridge DC-DC converter for arc welding is established in lab. The experimental results show that the new DC bias suppression strategy can effectively prevent the transformer from entering the saturation state and improve the operation stability of single-phase full-bridge DC-DC arc welding inverter.

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“…The second issue is related to the commutation of the converter components, which results in periodic voltage dips [5]. Finally, the third issue is the appearance of even-order harmonics in half-controlled rectifiers, which can result in asymmetry of the AC voltage (e.g., DC magnetic bias phenomenon in AC transformers) [6]. Furthermore, issues regarding PQ require careful study and monitoring of the impact of each disturbance type produced by PE converters [7].…”

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