A new welding machine which adopts zero voltage and zero current switching(ZVZCS) full bridge(FB) DC-DC converter is proposed. The proposed ZVZCS FB DC-DC converter uses auxiliary transformer to obtain ZCS for leading leg. It has capability of controlling load current even in short circuit condition and is suitable for arc welding machines. The power rating of the auxiliary transformer is about one 5th to one 10th of the main transformer. Experimental results for 10KW prototype are shown to verify the principle of operation.