1,071 research outputs found
A Unified Design Theory for Class-E Resonant DC–DC Converter Topologies
Resonant and quasi-resonant dc-dc converters have been introduced to increase the operating frequency of switching power converters, with advantages in terms of performance, cost, and/or size. In this paper, we focus on class-E resonant topologies, and we show that about twenty different architectures proposed in the last three decades can be reduced to two basic topologies, allowing the extension to all these resonant converters of an exact and straightforward design procedure that has been recently proposed. This represents an important breakthrough with respect to the state of the art, where class-E circuit analysis is always based on strong simplifying assumptions, and the final circuit design is achieved by means of numerical simulations. The potentialities of the proposed exact methodology are highlighted by realistic circuit-level simulations, where the desired waveforms are obtained in one single step without the need of a time-consuming iterative trial-and-error process
A unified analysis of PWM converters in discontinuous modes
Three discontinuous operating modes of PWM (pulsewidth modulated) converters are considered: the discontinuous inductor current mode (DICM), the discontinuous capacitor voltage mode (DCVM), and a previously unidentified mode called the discontinuous quasi-resonant mode (DQRM). DC and small-signal AC analyses are applicable to all basic PWM converter topologies. Any particular topology is taken into account via its DC conversion ratio in the continuous conduction mode. The small-signal model is of the same order as the state-space averaged model for the continuous mode, and it offers improved predictions of the low-frequency dynamics of PWM converters in the discontinuous modes. It is shown that converters in discontinuous modes exhibit lossless damping similar to the effect of the current-mode programming
Optimal PWM control of switched-capacitor DC/DC power converters via model transformation and enhancing control techniques
Abstract—This paper presents an efficient and effective method
for an optimal pulse width modulated (PWM) control of
switched-capacitor DC/DC power converters. Optimal switching
instants are determined based on minimizing the output ripple
magnitude, the output leakage voltage and the sensitivity of the
output load voltage with respect to both the input voltage and the
load resistance. This optimal PWM control strategy has several
advantages over conventional PWM control strategies: 1) It does
not involve a linearization, so a large signal analysis is performed.
2) It guarantees the optimality. The problem is solved via both the
model transformation and the optimal enhancing control
techniques. A practical example of the PWM control of a
switched-capacitor DC/DC power converter is presented
Unified analysis of switched-capacitor resonant converters
Author name used in this publication: Y. P. Benny YeungAuthor name used in this publication: K. W. E. ChengAuthor name used in this publication: S. L. HoAuthor name used in this publication: K. K. Law2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
IMPROVEMENT STUDY ON SOFT-SWITCHED QUASI-RESONANT DC/DC BOOST CONVERTER
This report describes a novel soft-switched quasi-resonant DC/DC boost converter.
Recently, remarkable efforts have been made in soft-switched quasi-resonant DC/DC
converters to reduce losses and improve power efficiency. This project presents a new
technique and it had improved the performance of the most recent study on soft-switched
quasi-resonant DC/DC boost converter, which is presented in Ba-Thunya and Prasad's
study [1]. The proposed converter employs an active snubber circuit with an auxiliary
switch in series with a clamp capacitor to reduce powerlosses in Ba-Thunya and Prasad's
original an active snubber circuit with an auxiliary switch and a clamp diode to reduce
power losses in Ba-Thunya and Prasad's original converter. The energy from the snubber
inductor after the auxiliary switch turn-off is returned to the input or delivered to the
output via the active snubber circuit, thus the voltage stress onthe main switch is reduced
and switching losses are minimized. Furthermore, the proposed converter reduces the
reverse-recovery-related losses of the boost rectifier by controlling the di/dt rate of the
rectifier current with the snubber inductor. This report describes the principle of
operation of the new soft-switched quasi-resonant DC/DC boost converter. The
feasibility study of the proposed converter is investigated using PSPICE program
Modeling and control of a high power soft-switched bi-directional DC/DC converter for fuel cell applications
This work presents a new high power, bi-directional, isolated dc-dc converter for a fuel cell energy management system that will be fitted into a test vehicle being built by Ford Motor Company. The work includes two parts. The first part is to propose a new topology and analyze the principles of the circuits operation. Design guidelines with detailed circuit simulations are presented to verify the feasibility of the new circuit topology. Based on the conceptual understanding of the converter, the mathematical model is also derived to design a control system that achieves soft start up and meets the performance requirements. The second part is to fabricate a 1.6 kW prototype converter in the laboratory. Using the prototype, the steady state performance of the open loop system was tested to verify the analysis and simulation results. A dual half-bridge topology is presented to implement the required power rating using the minimum number of devices. Unified zero-voltage-switching (ZVS) is achieved in either direction of power flow to eliminate switching losses for all devices, increase the efficiency of the system and reduce the electromagnetic interference (EMI). Compared to the other soft-switched dc-dc converters, neither a voltage-clamping circuit nor extra switching devices and resonant components are required in the proposed circuit for soft-switching implementation. All these new features allow efficient power conversion and compact packaging. Different start-up schemes are proposed to successfully limit the in-rush current when the converter is started in the boost mode of operation. The full control system including the start-up scheme is developed and verified using simulation results based upon the average model. A 1.6 kW prototype of the converter has been built and successfully tested under full power. The experimental results of the converter\u27s steady-state operation confirm the simulation analysis
A review on power electronics technologies for electric mobility
Concerns about greenhouse gas emissions are a key topic addressed by modern societies worldwide. As a contribution to mitigate such effects caused by the transportation sector, the full adoption of electric mobility is increasingly being seen as the main alternative to conventional internal combustion engine (ICE) vehicles, which is supported by positive industry indicators, despite some identified hurdles. For such objective, power electronics technologies play an essential role and can be contextualized in different purposes to support the full adoption of electric mobility, including on-board and off-board battery charging systems, inductive wireless charging systems, unified traction and charging systems, new topologies with innovative operation modes for supporting the electrical power grid, and innovative solutions for electrified railways. Embracing all of these aspects, this paper presents a review on power electronics technologies for electric mobility where some of the main technologies and power electronics topologies are presented and explained. In order to address a broad scope of technologies, this paper covers road vehicles, lightweight vehicles and railway vehicles, among other electric vehicles.This work has been supported by FCT – Fundação para a Ciência e Tecnologia with-in the Project Scope:
UID/CEC/00319/2020. This work has been supported by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017, and by the FCT Project new ERA4GRIDs PTDC/EEI-EEE/30283/2017. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by FCT
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