A Utility AC 400V Grid-Connected DC Rail Side Active Edge Resonant ZVS-PWM DC-DC Converter using High-Frequency Transformer Parasitic Components

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 400 V-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 the newly proposed high frequency softswitching PWM inverter link DC-DC power converter circuits for utility AC 400V-rms input, all the active power switches in the full- bridge arms or half-bridge arm and DC buslines achieve ZCS turn- on 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.