Query: Passive lossless snubber for double-ended flyback converter

Candidate papers:

abstract: Double ended flyback converter is one of the most popular topologies employed as a power supply or a power factor correction converter. Reducing switching losses at high switching frequencies is essential. In this study, a passive lossless snubber for double ended flyback converter is introduced. This snubber circuit provides soft switching condition for all semiconductor elements at turn on and turn off instants. Furthermore, the converter is controlled just like regular pulse width modulation converter. The proposed converter is analysed and the theoretical analysis is justified using experimental results.
author_names: Mehdi Mohammadi

Ehsan Adib

Hosein Farzanehfard
title: Passive lossless snubber for double ended flyback converter
year: 2015

abstract: Transformer leakage inductance in flyback converter results in high switch losses and stresses. For practical implementation of this converter snubber and clamp circuits are necessary. In this study a new passive lossless snubber and clamp circuit for double ended flyback converter is introduced. Operation of the new snubber is independent of load, and the converter duty cycle can be changed in a wide range. The proposed converter is analysed and experimental results are presented to justify the theoretical analysis.
author_names: Mehdi Mohammadi

Ehsan Adib

Hosein Farzanehfard
title: Lossless passive snubber for double ended flyback converter with passive clamp circuit
year: 2014

abstract: A double passive lossless snubber (DPLS) is applied to a pulse width modulation two switch flyback converter (TSFC) The DPLS, which has two capacitors, two inductors, and four diodes, has achieved zero voltage turn off and zero current (ZC) turn on for power switches without high voltage and current stresses; ZC turn on and ZC turn off for a rectifier diode without a reverse recovery problem. In this study, the steady state operating modes of TSFC DPLS are analysed and the proposed converter design procedure to operate in the continuous conduction mode is taken. To validate the theoretical analysis, a 240 W prototype TSFC DPLS under an 85 135 V rms input, 24 V DC output, and 300 kHz is implemented. Finally, by utilising the experimental results, the soft switching conditions under wide input voltage and output load ranges are discussed.
author_names: Karim Soltanzadeh

Mohammad Reza Yousefi
title: Analysis and design of two switch flyback converter with double passive lossless snubber
year: 2018

abstract: The flyback DC/DC converter traditionally finds use in low power applications (up to about 300 W) This contribution presents a high power flyback converter, utilizing a lossless quasi resonant snubber circuit and silicon carbide MOS FETs and diodes. The experimental 12 kW converter reaches a maximum efficiency of 97 while maintaining small dimensions and low weight. The maximum output parameters are 420 V, 30 A; the converter is fully controllable from zero voltage and current. In contrast to resonant converters, the presented converter keeps high efficiency even at decreased output voltages and currents, which makes it suitable for variable voltage/current applications.
author_names: Jan Martis

Pavel Vorel

P P Prochazka
title: 12 kW Flyback Converter with a Passive Quasi resonant Snubber
venue: 2019 International Conference on Electrical Drives Power Electronics (EDPE)
year: 2019

abstract: Hard switching flyback converters are widely used in the low power application but suffer from high electromagnetic emissions, current ripples, and low efficiency. To overcome these problems, a half bridge flyback converter with a new lossless passive snubber is proposed using an interleaved structure. All switches of the proposed converter turn on under zero current switching and turn off under zero voltage switching which decreases the switching losses and electromagnetic interference (EMI) Theoretical analysis of the proposed converter is presented and verified by the experimental results of a 200 W prototype. In addition to the 7% efficiency improvement, the proposed converter has lower EMI in comparison with its hard switching converter.
author_names: Navid Mohammadian

Mohammad Rouhollah Yazdani
title: Half bridge flyback converter with lossless passive snubber and interleaved technique
year: 2017

abstract: In this paper, a soft switching flyback inverter for AC module applications is proposed. Flyback inverter is used in many power conversion applications like AC module due to its simple circuit for implementation. The conventional flyback inverter has some major problems. One of them is voltage spikes across the converter switch originated from transformer leakage inductor. Other problems are high voltage stress and low efficiency owing to switching losses. Therefore, a dual switch flyback inverter providing soft switching condition using lossless passive snubber circuit is proposed. This circuit does not have any additional switch and thus, the control circuit is reliable and simple. Operating principles and control circuit of the proposed inverter are discussed. In order to justify the relevant theoretical analysis, simulation results are presented.
author_names: Ehsan Karimi

Milad Heidari

Ehsan Adib
title: Soft switching flyback inverter with lossless passive snubber for AC module applications
venue: 2017 8th Power Electronics, Drive Systems Technologies Conference (PEDSTC)
year: 2017

abstract: Discontinues output current of regular flyback converter will cause several problems such as large volume of output capacitor and also high output voltage noise. Interleaved structure can reduce output current ripple and process more power compared with single phase flyback converter. Normally, reducing the weight and size of a converter is an important goal while designing. An efficient way to reduce the size and weight of a converter and thus increasing power density is increasing switching frequency. However, in this way, switching losses increases. A half bridge interleaved flyback converter with clamp circuit is introduced and improved with a passive lossless snubber circuit. In this structure, the stored energy in parasitic elements is absorbed by passive snubber at turn off instant to provide soft switching condition for all semiconductor elements. The proposed snubber is load independent which is an important characteristic. In addition, a 500 W prototype converter is implemented which can improve the efficiency more than 6%
author_names: Mehdi Mohammadi

Ehsan Adib
title: Lossless passive snubber for half bridge interleaved flyback converter
year: 2014

abstract: Due to the simplicity of flyback converter topology, it is used in many power conversion applications. Although, the structure of the flyback converter is simple, it has two major drawbacks. One is transformer leakage inductor which creates voltage spikes at turn off instant for converter switch and another is high voltage stress. Also the output current is discontinues and large output filter is required. Due to the mentioned reasons, the flyback converter is not proper for high power applications. In this paper a soft switched interleaved flyback converter is introduced. The converter provides soft switching condition for all semiconductor elements. Also the output current observed is continues which decreases the volume of the capacitor. A 150W prototype converter is implemented to justify the theoretical analysis.
author_names: Mehdi Mohammadi

Ehsan Adib

Hosein Farzanehfard
title: A soft switched half bridge interleaved flyback converter with a modified lossless passive snubber
venue: 2014 22nd Iranian Conference on Electrical Engineering (ICEE)
year: 2014

abstract: A single stage bridgeless ac dc PFC converter using a lossless passive snubber and valley switching is proposed. The proposed converter is based on a two stage bridgeless boost flyback converter. In the proposed converter, the conduction losses are reduced by removing an input full bridge diode rectifier. The boost inductor is designed to be operated in the discontinuous conduction mode for achieving high power factor. In the flyback module, the couple inductor that provides input output electrical isolation for safety is designed to be operated in the critical conduction mode for low RMS current and low turn on switching loss by using valley switching operation. Because of the lossless snubber circuit, the voltage spike of switch is clamped, and the leakage inductor energy is recycled. The snubber capacitor is used as a dc bus capacitor, which is divided into two capacitors. In addition, some input power is directly conducted to the output, and the remaining power is stored in dc bus capacitor. So, low voltage rating capacitors can be used as the dc bus capacitor and power transfer efficiency is improved. The presented theoretical analysis is verified on an output 48 V and 60 Wexperimental prototype.
author_names: Sin-Woo Lee

Hyun-lark Do
title: Single Stage Bridgeless AC DC PFC Converter Using a Lossless Passive Snubber and Valley Switching
venue: IEEE Transactions on Industrial Electronics
year: 2016

abstract: To increase power conversion density, it is inevitably necessary to increase switching frequency. However, doing so has detrimental effects, including reduced efficiency and increased EMI under hard switching operation. To prevent the side effects of high switching frequencies, soft switching methods present advantages. In this paper, a lossless passive snubber circuit that operates based on the flyback converter is introduced. The proposed snubber circuit is not only able to produce ZVS and ZCS conditions for the converter switch, but also to produce soft switching conditions for the other semiconductor elements. The snubber circuit is applied to a flyback converter and the experimental results are presented to justify the theoretical analysis. The outcomes show that the proposed converter improved efficiency by over 3% compared with the hard switching flyback converter.
author_names: Mehdi Mohammadi

Martin Ordonez
title: Flyback lossless passive snubber
venue: 2015 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2015