基于移相全桥与自适应辅助电流的快速脉冲焊接电源研究

The high-frequency inverter power supply is an major trend in the development of modern industrial arc welding power supply. In this article, a phase-shifted full-bridge topology based on the principle of adaptive enhancement of the auxiliary current is proposed for a 26kW fast-frequency pulsed silicon carbide (SiC) welding power supply. It only adds an auxiliary transformer, an inductor, and a capacitor compared to a conventional phase-shifted full-bridge (PSFB), which can realize zero-voltage switching (ZVS) operation of all switches over the entire load range. The lower leakage inductance of the transformer, in comparison to the conventional PSFB, minimizes duty cycle loss and diode oscillations. Furthermore, the reduction in circulating current conduction loss enhances efficiency and reduces switching noise due to hard switching under light loads. This advantage that allows using SiC half-bridge modules with higher switching frequencies at high power. Based on the equivalent model of auxiliary transformer and high-frequency transformer, the steady-state operating principle of this topology is analyzed, the effects of transformer leakage inductance and auxiliary inductance on ZVS are analyzed in detail, and the precautions for the design of the welding power supply are discussed. The performance of the proposed topology, which is based on the SiC half-bridge modules, is verified in prototypes with a switching frequency of 100kHz, an output current of 650A, and a 26kW class specification.