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.
Highlights
With the rapid development of power electronic technology, high efficiency low voltage and high current arc welding inverter have been widely used in industrial production [1,2]
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
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
Summary
With the rapid development of power electronic technology, high efficiency low voltage and high current arc welding inverter have been widely used in industrial production [1,2]. The essence of the software optimization method is a closed-loop optimization control strategy, where the control variable is the duty cycle of the full-bridge drive pulse, and the feedback variable is the primary current of the transformer. When the transformer enters the saturation state, a large current pulse will be generated in the primary current, and, if the current pulse exceeds the reference current, the DC bias suppression strategy will be triggered. This method belongs to passive suppression method.
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