Dual utility AC voltage line operated soft switching PWM DC-DC power converter with high frequency transformer link for arc welding equipment

This paper presents two new circuit topologies of DC busline series active snubber assisted soft switching PWM full-bridge DC-DC power converter acceptable for either utility AC 200 V-rms or AC 400 V-rms input voltage source. Proposed power converters are composed of a typical voltage source full-bridge high frequency PWM inverter using DC busline side series switching devices with the aid of a parallel capacitive lossless snubber. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutation operation and consequently the total turn-off switching losses can be significantly reduced. As a result, a high switching frequency for used IGBTs can be actually realized more than about 20 kHz. It is proved that the more the switching frequency of full-bridge inverter increases, the more soft switching PWM DC-DC power converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density as compared with the conventional hard switching PWM inverter type DC-DC converter. The effectiveness of this new converter topology is proved for low voltage and large current DC-DC power supplies as arc welding machine from a practical point of view.