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. >

Novel zero-voltage-transition PWM converters

The authors present an improved soft-switching full-bridge converter which is especially suitable for high-power application (e.g. more than 1 kW output) because of its inherently high efficiency. The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulse width modulation) full-bridge DC-DC converter substantially reduced the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors analyze the conditions for lossless transitions, discuss the effect of the added components on the operation of the converter, and present practical considerations and test results for a 1.5 kW converter with 100 kHz clock frequency. The converter has an efficiency above 95% at 60 V output, is free from voltage overshoots, and exhibits well-controlled transitions for all switch and rectifier voltages and currents. >

A novel soft-switching full-bridge DC/DC converter: Analysis, design considerations, and experimental results at 1.5 kW, 100 kHz

A new family of zero-current-transition (ZCT) pulse-width-modulated (PWM) converters are proposed. The new family of converters implements zero-current turn-off for power transistor(s) without increasing voltage/current stresses and operates at a fixed frequency. The proposed converters are deemed most suitable for high-power applications where the minority-carrier semiconductor devices (such as IGBTs, BJTs, and MCTs) are predominantly used as the power switches. Theoretical analysis is verified on a 100-kHz, 1-kW ZCT-PWM boost converter using an IGBT. >

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Novel zero-current-transition PWM converters

With the number of electric vehicles (EVs) on the rise, there is a need for an adequate charging infrastructure to serve these vehicles. The emerging extreme fast-charging (XFC) technology has the potential to provide a refueling experience similar to that of gasoline vehicles. In this article, we review the state-of-the-art EV charging infrastructure and focus on the XFC technology, which will be necessary to support the current and future EV refueling needs. We present the design considerations of the XFC stations and review the typical power electronics converter topologies suitable to deliver XFC. We consider the benefits of using the solid-state transformers (SSTs) in the XFC stations to replace the conventional line-frequency transformers and further provide a comprehensive review of the medium-voltage SST designs for the XFC application.

Extreme Fast Charging of Electric Vehicles: A Technology Overview

This paper presents an isolated on-board vehicular battery charger that utilizes silicon carbide (SiC) power devices to achieve high density and high efficiency for application in electric vehicles (EVs) and plug-in hybrid EVs (PHEVs). The proposed level 2 charger has a two-stage architecture where the first stage is a bridgeless boost ac-dc converter and the second stage is a phase-shifted full-bridge isolated dc-dc converter. The operation of both topologies is presented and the specific advantages gained through the use of SiC power devices are discussed. The design of power stage components, the packaging of the multichip power module, and the system-level packaging is presented with a primary focus on system density and a secondary focus on system efficiency. In this work, a hardware prototype is developed and a peak system efficiency of 95% is measured while operating both power stages with a switching frequency of 200 kHz. A maximum output power of 6.1 kW results in a volumetric power density of 5.0 kW/L and a gravimetric power density of 3.8 kW/kg when considering the volume and mass of the system including a case.

A High-Density, High-Efficiency, Isolated On-Board Vehicle Battery Charger Utilizing Silicon Carbide Power Devices

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. >

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

A recently proposed average current-mode control method is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. This control scheme is suitable for applications where the average inductor current needs to be controlled, as in power factor correction circuits and battery charger dischargers. The subharmonic oscillation, commonly found in peak current-mode control, also exists in this method. This subharmonic oscillation can be eliminated by properly choosing the proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >

Small-signal modeling of average current-mode control

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. >

https://u.dianyuan.com/bbs/u/25/1106037881.pdf

Small-signal analysis of the phase-shifted PWM converter

The authors present the analysis, design, and applications of a high-voltage, high-power, zero-voltage switched (ZVS), full-bridge (FB) pulse-width-modulated (PWM) converter with an active snubber in the secondary circuit. The nondissipative snubber completely eliminates the voltage overshoot and ringing across the rectifiers. The ringing of the parasitic capacitance of the rectifiers and the leakage inductance of the transformer are eliminated in a nondissipative manner, thus increasing the overall efficiency of the circuit. The active snubber employs only a high-voltage low-power MOSFET and a high-voltage capacitor. The control of the snubber switch is simple and utilizes the PWM signal to control the primary switches with a time delay. The authors also present the complete steady-state analysis of the ZVS-FB-PWM converter employing the active snubber. The analysis shows that the transformer secondary voltage is a function of the steady-state duty cycle and gives the equation to calculate the steady-state secondary voltage. The results of the analysis are in good agreement with the experimental results. >

High-voltage, high-power, ZVS, full-bridge PWM converter employing an active snubber

A recently proposed average current-mode control is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. By closing the current loop, a flat control-to-inductor current transfer function, up to half the switching frequency, can be achieved. This control scheme enables the converter to behave as an ideal current source. The subharmonic oscillation, as frequently reported in peak current-mode control, also exists in this control. This subharmonic oscillation can be eliminated by choosing a proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >

R.B. Ridley

Papers

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

Small-signal modeling of average current-mode control

Small-signal analysis of the phase-shifted PWM converter

High-voltage, high-power, ZVS, full-bridge PWM converter employing an active snubber

Small-signal modeling of average current-mode control