DC gain loss model and optimal choice of switching frequency and turns ratio for high gain, high power, phase modulated resonant transition converters

The Steady-State DC Gain Loss Model, Efficiency Model, and the Design Guidelines for High-Power, High-Gain, Low-Input Voltage DC–DC Converter

Abstract: The phase modulated full bridge resonant transition converter (PMRTC) is commonly used for high-gain, high-power applications, as PMRTC converters retain the qualitative nature of hard switched pulse-width modulation counterparts with additional damping ( $R_d$ ), where $R_d$ is load, transformer turns ratio and frequency dependent. The PMRTC converter enables operation at a higher switching frequency due to the soft-switching nature, thereby achieving better power density. For battery fed high-power, high-gain applications, PMRTC exhibits a significant drop in the dc gain due to $R_d$ and other nonidealities, limiting the maximum frequency of operation. Thus, computing this drop and analyzing the effects of switching frequency becomes necessary in achieving the required steady-state dc gain. From the analysis, it is observed that, for a choice of switching frequency above $f_{s\;{\rm critical}}$ , the required steady-state dc gain is not achieved for any turns ratio. Hence, to increase the switching frequency of operation of a PMRTC converter, a two-transformer configuration is adapted and with this configuration, the dc gain loss model, power loss, and efficiency model and small-signal model are established. The design guidelines on the choice of switching frequency and transformer turns ratio based on the proposed models is described. The proposed models with the presented design guidelines are validated in simulations and hardware prototype for a 1 kW PMRTC converter.

Fundamentals of Power Electronics

Abstract: Preface. 1. Introduction. I: Converters in Equilibrium. 2. Principles of Steady State Converter Analysis. 3. Steady-State Equivalent Circuit Modeling, Losses, and Efficiency. 4. Switch Realization. 5. The Discontinuous Conduction Mode. 6. Converter Circuits. II: Converter Dynamics and Control. 7. AC Equivalent Circuit Modeling. 8. Converter Transfer Functions. 9. Controller Design. 10. Input Filter Design. 11. AC and DC Equivalent Circuit Modeling of the Discontinuous Conduction Mode. 12. Current Programmed Control. III: Magnetics. 13. Basic Magnetics Theory. 14. Inductor Design. 15. Transformer Design. IV: Modern Rectifiers and Power System Harmonics. 16. Power and Harmonics in Nonsinusoidal Systems. 17. Line-Commutated Rectifiers. 18. Pulse-Width Modulated Rectifiers. V: Resonant Converters. 19. Resonant Conversion. 20. Soft Switching. Appendices: A. RMS Values of Commonly-Observed Converter Waveforms. B. Simulation of Converters. C. Middlebrook's Extra Element Theorem. D. Magnetics Design Tables. Index.

Novel zero-voltage-transition PWM converters

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. >

Design considerations for high-voltage high-power full-bridge zero-voltage-switched PWM converter

Abstract: A steady-state analysis is presented with complete characterization of the converter operation. A small-signal model of the converter is established. The design procedures based on the analysis are presented and the various losses in the circuit assessed. Critical design considerations for a high-power, high-voltage application are analyzed. The results of the analysis are verified using a high-voltage. 2 kW prototype. >

Small-signal analysis of the phase-shifted PWM converter

Abstract: The specific circuit effects in the phase-shifted PWM (PS-PWM) converter and their impact on the converter dynamics are analyzed. The small-signal model is derived incorporating the effects of phase-shift control and the utilization of transformer leakage inductance and power FET junction capacitances to achieve zero-voltage resonant switching. The differences in the dynamic characteristics of the PS-PWM converter and its PWM counterpart are explained. Model predictions are confirmed by experimental measurements. >

An Active Soft Switched Phase-Shifted Full-Bridge DC–DC Converter: Analysis, Modeling, Design, and Implementation

Abstract: A novel active soft switched phase-shifted full-bridge (PSFB) dc-dc converter is presented in this paper. An auxiliary circuit is added to the pulse width modulation counterpart to achieve the soft switching. The proposed circuit achieves soft switching for both main and auxiliary switches, without increasing the main device current/voltage rating. The auxiliary circuit is gated appropriately in order to achieve zero voltage switching for lagging leg. Tapping in the primary winding of power transformer is added for the purpose of commutation. The proposed circuit is capable of operating at elevated switching frequencies of several hundreds of kilohertz in a range of line and load variations. Steady-state analysis and evaluation of losses for the proposed circuit is presented. Analytical models valid for steady state and dynamic performance are proposed. A 350-W, 100-kHz active soft switched PSFB dc-dc converter prototype is implemented. The proposed analytical models are validated experimentally on 350-W prototype. Experimental results verifying steady state and dynamic models are presented.