This paper presents two new circuit topologies of voltage source-fed soft-switching PWM inverter using a high frequency transformer parasitic inductive components with full-bridge or half-bridge configuration, which are more suitable for utility ac 400V-rms input mains. These circuits have each reverse conducting power semiconductor switching devices in series with high and low dc buslines, a single or two lossless snubbing capacitors in parallel with two dc buslines and additional diode components. Under die newly proposed high frequency soft-switching PWM inverter link dc-dc power converter circuits for utility ac 400V-rms input, all the active power switches in the fullbridge arms or half-bridge arm and dc buslines achieve ZCS turnon commutation operation and ZVS turn-off commutation operation, and consequently the total turn-off switching power losses can be significantly reduced. As a result, a high switching frequency for IGBTs used can be actually realized at a frequency band more than about 20 kHz. It is proved that the more the switching frequency of inverter increases, the more soft switching PWM dc-dc converters with a high frequency transformer have remarkable advantages for its power conversion efficiency and power density as compared with the conventional hard switching PWM full-bridge inverter type dc-dc converter. The practical effectiveness of these new converter topologies are confirmed for low voltage and large current dc power supplies as high performance arc welding machine from a practical point of view.