Abstract—This paper presents a 3kW welding machine based on a half-bridge forward converter. It is known as the two transistor forward converter and has a primary power switch arrangement that is similar to its counterpart in the fly-back converter. This arrangement is particularly suitable for MOSFET transistor operation, as the energy recovery diodes D5 and D6 provide hard clamping of the switching devices to the supply line, preventing any overshoot during the fly-back operation. The voltage across the power switches will not exceed the supply voltage by more than two diode drops, and therefore voltage stress will be only half of what it would have been in the single-transistor, single-ended converter. In this system, the welding machine has been designed for one phase line input. This converter drives high frequency transformers with output ratings of 24V and 120A during welding process. The converter uses current mode PWM controller integrated circuit. SG1844 improves on the 100 KHz switching frequency with respect to size and weight, but the switching frequency is limited by the switch devices and transformer material. This control technique is able to ensure proper ignition with 78 V. The essential requirement for this welding machine power supply is to control the PWM wave form and adapt it for welding process. Current mode PWM controller can be achieved by using small values of the inductor and capacitor. The size and weight will be greatly reduced. They are reliable and flexible, offer good efficiency, fast response and control robustness. The unique load characteristics associated with arc plasma loads make this type of current mode PWM controlled converter well suited for arc striking. It also allows safe operation during the arc plasma state. The aim of this work was to design and build suitable power supply for a welding machine. This can be achieved by current mode switching power supply with a minimum number of external components.

 

Index Terms—half-bridge forward converter, welding machine, fly-back converter, arc plasma, current mode PWM controller

Cite: Yasar Birbir, "Arc Welding Machine with Half-Bridge Forward Converter," International Journal of Electronics and Electrical Engineering, Vol. 5, No. 2, pp. 106-109, April 2017. doi: 10.18178/ijeee.5.2.106-109