Next generation high efficiency high power dc-dc converter incorporating active switch and snubbing capacitor assisted full-bridge soft-switching PWM inverter with high frequency transformer for large current output

This paper presents a new circuit topology of dc busline switch-assisted full-bridge soft-switching PWM inverter type dc-dc power converter which is composed of typical voltage source H full-bridge type high frequency PWM inverter in addition to a single dc busline side power semiconductor switching device for PWM scheme and a capacitive lossless snubber. Under the newly-proposed high frequency inverter link dc-dc high power conditioning and processing circuit, all active power switches in the full-bridge arms and dc busline can achieve ZVS/ZVT turn-off commutation operation. On the other hand, although the conduction power loss of dc busline switch increases a little, the total turn-off switching losses of full-bridge type PWM inverter and dc busline switch with the single lossless capacitive snubber parallel with dc busline can be significantly decreased. As a result, the switching frequency of high frequency inverter power stage using IGBTs can be actually selected more than about 10kHz. The more the switching frequency of full-bridge inverter increases, the more newly-proposed soft-switching dc-dc power converter with a high frequency transformer link has remarkable advantage as for the power conversion efficiency and power density as compared with the conventional hard-switching inverter type dc-dc power converter. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies from a practical point of views.