Novel soft transition pushpull converter: Analysis, modeling, design and implementation

Abstract: This paper proposes an active soft-switching circuit for bridge converters aiming at improving the power conversion efficiency. The proposed circuit achieves loss-less switching for both main and auxiliary switches without increasing the main device current/voltage rating. It is capable of operating at elevated switching frequencies of several hundreds of kHz, at low and high power levels with a wide range of load variations. A winding coupled to the primary of power transformer ensures soft switching for the auxiliary switches during turn-on and turn-off. Phase Shifted Full Bridge (PSFB) topology is chosen to validate the design. Operation principle with analytical expressions for the proposed circuit are outlined. The proposed active soft switched PSFB DC-DC converter circuit is designed and implemented for 350 W, switching at 100 kHz. The simulation and experimental results are presented. Experimental results are used to validate the analysis.

Abstract: This paper proposes an active soft-switching circuit for bridge converters aiming to improve the power conversion efficiency. The proposed circuit achieves loss-less switching for both main and auxiliary switches without increasing the main switch current/voltage rating. A winding coupled to the primary of power transformer ensures ZCS for the auxiliary switches during their turn-off. A 350 W, 100 kHz phase shifted full bridge (PSFB) converter is built to validate the analysis and design. Theoretical loss calculations for proposed circuit is presented. The proposed circuit is compared with passive soft switched PSFB in terms of efficiency and loss in duty cycle. Keywords—Active soft switching, passive soft switching, ZVS, ZCS, PSFB.

Abstract: A class of zero voltage transition (ZVT) power converters is proposed in which both the transistor and the rectifier operate with zero voltage switching and are subjected to minimum voltage and current stresses. The boost ZVT-PWM converter is used as an example to illustrate the operation of these converters. A 300 kHz, 600 W ZVT-PWM boost, DC-DC converter, and a 100 kHz, 600 W power factor correction circuit using the ZVT-PWM technique and an insulated gate bipolar transistor (IGBT) device were breadboarded to show the operation of the proposed converters. It is shown that the circuit technology greatly improves the converter performance in terms of efficiency, switching noise, and circuit reliability. >

Abstract: The auxiliary resonant commutated pole (ARCP), a new power converter topology that fully achieves soft switching without increasing primary device voltage or current ratings, is discussed. The ARCP converter is capable of true pulse-width modulation (PWM) control of each phase. The power circuit relies on the addition of an auxiliary triggered resonant commutation circuit or snubber to commutate the inductive load current from a main diode to an active device, allowing a zero voltage turn-off of the main devices. The auxiliary devices operate in a zero current soft switching mode, thereby requiring minimal current turn-off capability. The operation and control of the ARCP converter are discussed. Its performance is analyzed, and a simulation is presented. It is shown that the ARCP converter is capable of operation at elevated switching frequencies (10-30 kHz), high power levels (200-1000 kW), and high conversion efficiencies. the auxiliary devices will typically account for a 20% increase in the total silicon area of a three-phase power converter. >

Abstract: A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400-800 V), high-power (2-10 kW) applications where IGBTs are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit.

Abstract: In designing conventional switching converters, the effort to increase operating frequency in order to reduce weight, size and cost of magnetic and filter elements is constantly hampered by higher switching stresses and switching losses. To overcome these obstacles, the concept of resonant switch was proposed. By incorporating additional Land C elements to shape device current and voltage waveforms, the desired zero-current switching property can be realized which enables converters to operate in the megahertz range.