Research Of Technology Of Green Switch Power Based On UC3875

With the advancement in the electricity, switching supply has been widely in electricity, aerospace industry, communication etc, but the extensive of it will bring harmonic pollution and Electro Magnetic Interference (EMI), improving the power factor and reducing EMI are hot spots in power electronic field. Active Power Factor Correction (APFC) and the soft-switchingPulse-Width-Modulation (PWM) is proposed. And it makes without harmonic pollution, high PFC and low EMI as possible.Based on referring to lots of literature, the paper summarizes classification and APFC and the virtues and defects of various phase-shifted full-bridge zero-voltage zero-current switching (ZVZCS) topology. So the paper proposed a new green switching supply, it consists of forward stage and backward stage, of which the forward stage is Boost APFC circuit by One-Cycle Control (OCC) method, which has the advantage of simple circuit,constant switching frequency and easy high PFC etc. The backward stage is a ZVZCS phase-shifted converter by two diodes and a capacitor in the auxiliary circuit.The paper studies systemically Boost APFC circuit of the forward stage, it analyze the operation stage and design stage, and analyze applicability of the OCC in Boost APFC by the circuit model. The ZCS condition can be obtained by introducing an auxiliary circuit into the primary or secondary side. However, these converters introduce other questions too. The auxiliary circuit which consists of loss component or active switch costs the overall efficiency. Converter with tapped inductor or transformer makes the converter somewhat complex and the core loss is inevitable. Converter with snubber circuit seems a good choice and brings a duty cycle boost effect. However it increases the voltage stress of the secondary rectifier diodes. And the paper provides the analysis of the ZVZCS circuit, it give the operation principle, the small-signal model of backward stage. The ZVS range of leading-leg, ZCS range of lagging-leg and secondary voltage stress are analyzed. The results show that the converter achieves soft switching easier than conventional converters with fewer components in the auxiliary circuit and without increasing the secondary voltage stress.At last, introduces specially for the chip UC3875 which used in phase shifting control, the criterion for main parameter is deduced. And the research of simulation is verified by the MATLAB, and realizing the frequency of 100kHz. The properties of circuit are verified by a simulation circuit.