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

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.

MAW Productivity Development and Reduction of its Harmful Effect on Human Organisms

The article presents results of researches on manual arc welding efficiency development. It is proved that the arc welding inverter power source, compared with the diode rectifier, increases coefficient of transition of alloying elements into the weld joint; it also reduces the rate of alloying elements transition into slag and gaseous components and in addition reduces the harmful effects of welding on human organisms.

3-Phase 4-Wire VIENNA Rectifier Used in the Resistance Spot Welding Inverter Power Supply

Considering the distortion factor, the large power resistance spot welding (RSW) inverter power supplys actual power factor (PF) is very low. In this paper, the 3-phase 4-wire three-phase/switch/level (VIENNA) rectifier is proposed to realize the power factors correction (PFC). Firstly, an equivalent load model of the back-stage in the RSW inverter power supply is established, thus the real load of this PFC circuit can be archived. Then, the 3-phase 4-wire VIENNA rectifier PFC circuit is analyzed with the simulation software of Pspice. Finally, an experimental circuit power of 3kW is designed. Experimental results show that the PF of this system can be increased to 98.6% that demonstrates the practicability of the 3-phase 4-wire VIENNA rectifier in RSW inverter power supply.