Study On DC And AC Dual-Input Inverter Welding Power Supply

At present, there is no one kind of welding machine could be used in the circumstance of power grid failure or no power grid such as field, ships and so on. For this situation, this study developed an AC and DC dual-input inverter welding machine. This welding machine can work separately in two different input voltages:AC220V and DC24V, and can get desired welding effect to meet different conditions of welding work. Even though the output voltages are equal or very close, but because of the two are quite different input voltages, we could not use the same inverter topology when the input voltage is different, it can only choose different topology. Based on the characteristics of the input voltage, full-bridge inverter topology is used when input voltage AC220V and push-pull inverter topology is used when selected to input voltage DC24V. Full-bridge inverter topology is mature and reliable suited for high power applications, and push-pull inverter topology with characteristics of high-voltage utilization, low conduction losses, is perfect suitable for low voltage and high current output applications. In this paper, the author makes a reasonable modification on the push-pull inverter circuit to reduce the losses of the circuit to adapt the input voltage of DC24V which is a significant low input voltage for high power circuit. In the view of the requirements of small size and light weight of this welding machine, there is a reasonable integration of the two inverter topologies in this paper, so the two topologies could share one high-frequency power transformer and one output rectification filter circuit. Consequently simplify the design of this welding machine.In addition, this paper designed PWM signal generating circuit, the current regulation and negative feedback circuit, over-current protection circuit over temperature protection circuit, and under-voltage protection circuit typical of DC24V input inverter welding power supply, these circuits are all based on the PWM control chip SG3525. The waveform of PWM control signal is good; the feedback signal processing speed is fast, protection signal very sensitive, these circuits provide this welding machine excellent control and protection to ensure reliable welding work.With the characteristics of little splash, deep bath, beautiful welding seam, stable welding current, arcing fast and reliable performance, this welding machine achieved the expected effect.