Advanced high frequency transformer linked soft switching PWM DC-DC power converter with utility AC dual voltage modes for low voltage and large current applications

This paper presents two new circuit topologies of dc bus line 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. One of proposed power converters is composed of a typical voltage source full-bridge high frequency PWM inverter using dc bus line 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 bus line 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.