32 V-300 A/60 kHz edge resonant soft-switching PWM DC/DC converter with DC rail series switch-parallel capacitor snubber assisted by high-frequency transformer parasitic components

The conduction losses of the active switches can be lowered, which are connected to the primary side of extremely step-down high frequency transformer because of low voltage large current rectifier configuration. This paper presents two new circuit topologies of DC busline side active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200 V-rms or AC 400 V-rms input voltage source. One topology of proposed DC-DC converters is composed of a typical voltage source-fed full-bridge high frequency PWM inverter using DC busline side series power semiconductor 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 commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. It is proved that the more the switching frequency of full-bridge soft switching inverter increases, the more soft-switching PWM DC-DC converter with a high frequency transformer link has remarkable advantages for its efficiency and power density as compared with the conventional hard-switching PWM inverter type DC-DC converter. In this paper, another modified version topology of utility AC 200 V-rms grid-connected soft switching DC-DC converter mentioned above is also implemented and evaluated, which is more suitable for utility 400 V-rms grid power source. The effectiveness of these new DC-DC converters topologies is proved for low voltage and large current high efficiency DC-DC power supplies as TIG are welding machine from a practical point of view.