Passive Snubber Research Articles

Lossless passive snubber for double ended flyback converter with passive clamp circuit

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.

Improved passive snubbers suitable for single‐phase isolated full‐bridge boost power factor correction converter

In this study, two novel improved passive snubbers suitable for isolated full-bridge boost topology are proposed. The snubbers are composed of two capacitors, two inductors and four diodes. The voltage spike across the primary side of transformer is absorbed by one capacitor of the snubbers during a charging period, and by the other capacitor in the following charging period. The energy of capacitors can be transferred to the output side of the power factor correction (PFC) converter during one charging period by the resonance of the inductors and capacitors. Taking one improved snubber, for example the operational process of the original and the improved snubbers are analysed in a single-phase isolated full-bridge boost PFC converter. Furthermore, between the original and the improved snubbers, comparative analysis about the voltage and current stress, parameters limitation and the reliability are given. Finally, experimental study has been done on a laboratory-made single-phase PFC prototype, and the feasibility of the proposed method and the validity of the theoretical analysis are verified by the experimental results.

Family of Soft-Switching Single-Switch PWM Converters with Lossless Passive Snubber

To increase the power conversion density, decrease switching losses and electromagnetic interference (EMI), and provide safe operating area for a switch, applying snubber circuits which provide soft-switching conditions is inevitable. Among different types of snubber circuits, passive snubbers, due to their simplicity and robustness, are preferred. These snubber circuits can obtain soft-switching conditions without any additional switch. Thus, gate drive and control circuits remain simple. In this paper, a simple lossless passive snubber circuit which can be applied on isolated and nonisolated converters is introduced. The proposed snubber circuit provides zero-current-switching and zero-voltage-switching conditions at turn-on and turnoff instants, respectively. The proposed snubber is applied on a boost converter and analyzed. Also, in order to prove the effectiveness of the proposed snubber circuit from the converter efficiency and EMI viewpoints, a 200-W prototype boost converter is implemented, and experimental results are presented. Also, the simulation results of a soft-switched flyback converter with the proposed snubber cell are presented.

Novel Interleaved Bidirectional Snubberless Soft-Switching Current-Fed Full-Bridge Voltage Doubler for Fuel-Cell Vehicles

This paper presents a novel interleaved soft-switching bidirectional snubberless current-fed full-bridge voltage doubler (dc/dc converter) for an energy storage system in fuel cell electric vehicles. A novel secondary modulation technique is also proposed to clamp the voltage across the primary-side switches naturally with zero-current commutation. It, therefore, eliminates the necessity for an external active-clamped circuit or passive snubbers to absorb the switch turn-off voltage spike, a major challenge in current-fed converters. Zero-current switching of primary-side devices and zero-voltage switching of secondary-side devices are achieved, which significantly reduce switching losses. An interleaved design is adopted over a single cell to increase the power handling capacity obtaining merits of lower input current ripple, reduction of passive components' size, reduced device voltage and current ratings, reduced conduction losses due to current sharing, and better thermal distribution. Primary device voltage is clamped at rather low-reflected output voltage, which enables the use of low-voltage semiconductor devices having low on-state resistance. Considering input current is shared between interleaved cells, conduction loss of the primary side, a considerable part of total loss, is significantly reduced and higher efficiency can be achieved to obtain a compact and higher power density system. Steady-state operation, analysis, and design of the proposed topology have been presented. Simulation is conducted over software package PSIM 9.0.4 to verify the accuracy of the proposed analysis and design. A 500-W prototype has been built and tested in the laboratory to validate the converter performance.

Investigation and Implementation of a Passive Snubber with a Coupled-Inductor in a Single-Stage Full-Bridge Boost PFC Converter

In this paper, an improved passive snubber is investigated in a single-phase single-stage full-bridge boost power factor correction (PFC) converter, by which the voltage spike across primary side of the power transformer can be suppressed and the absorbed energy can be transferred to the output side. When compared with the basic passive snubber, the two single-inductors are replaced by a coupled-inductor in the improved snubber. As a result, synchronous resonances in the snubber can be achieved, which can avoid the unbalance of the voltage and current in the snubber. The operational principle of the improved passive snubber is analyzed in detail based on a single-phase PFC converter, and the design considerations of both the snubber and the coupled-inductor are given. Finally, a laboratory-made prototype is built, and the experimental results verify the feasibility of the proposed method and the validity of the theoretical analysis and design method.

Intelligent Photovoltaic Maximum Power Point Tracking Controller for Energy Enhancement in Renewable Energy System

Photovoltaic (PV) system is one of the promising renewable energy technologies. Although the energy conversion efficiency of the system is still low, but it has the advantage that the operating cost is free, very low maintenance and pollution-free. Maximum power point tracking (MPPT) is a significant part of PV systems. This paper presents a novel intelligent MPPT controller for PV systems. For the MPPT algorithm, an optimized fuzzy logic controller (FLC) using the Hopfield neural network is proposed. It utilizes an automatically tuned FLC membership function instead of the trial-and-error approach. The MPPT algorithm is implemented in a new variant of coupled inductor soft switching boost converter with high voltage gain to increase the converter output from the PV panel. The applied switching technique, which includes passive and active regenerative snubber circuits, reduces the insulated gate bipolar transistor switching losses. The proposed MPPT algorithm is implemented using the dSPACE DS1104 platform software on a DS1104 board controller. The prototype MPPT controller is tested using an agilent solar array simulator together with a 3 kW real PV panel. Experimental test results show that the proposed boost converter produces higher output voltages and gives better efficiency (90%) than the conventional boost converter with an RCD snubber, which gives 81% efficiency. The prototype MPPT controller is also found to be capable of tracking power from the 3 kW PV array about 2.4 times more than that without using the MPPT controller.

A Design of Cascaded Multilevel Inverter Snubber Circuit

The high frequency induction heating power supply has received increasing attention from researchers, multilevel converter is a high voltage large power application areas of research focus and core, it solves the problem of the multilevel inverter output voltage waveform adjustment, avoids the problem of two times reversing that the load voltage in the commutation during the dead period occurred. An effective way to improve efficiency is to keep the power device of low voltage stress and less switching loss. A passive lossless snubber circuit is designed for inhibiting the reverse recovery current of diode and improving the turn-on condition of powers switch. The operation process of snubber circuit is analyzed and the parameter design method is given. The results of simulation have verified the validity of design methods and the conclusions given by theoretically analyzing in this paper.

Improvement of Power-Conversion Efficiency of a DC–DC Boost Converter Using a Passive Snubber Circuit

This paper proposes a method of improving the power-conversion efficiency of a direct-current-direct-current boost converter. The proposed method uses a passive snubber circuit, which consists of two inductors, a capacitor, and a diode, to reduce switching loss. The proposed boost converter was built and tested on 42-, 47-, and 55-in edge-lit light-emitting-diode (LED) backlight units (BLUs). The power-conversion efficiency for an input voltage of 24 V was measured as 96%, 95.1%, and 93.7% for the 42-, 47-, and 55-in edge-lit LED BLUs, respectively; these values were 2.3%, 2.2%, and 2% higher than those of the conventional boost converters in the corresponding BLUs. The proposed boost converter ensured reliable operation and high-power efficiency under a ±10% variation of input voltage and a ±20% variation of the passive snubber component values.

Novel Passive Snubber Suitable for Three-Phase Single-Stage PFC Based on an Isolated Full-Bridge Boost Topology

In this paper a novel passive snubber is proposed, which can suppress the voltage spike across the bridge leg of the isolated full-bridge boost topology. The snubber is composed of capacitors, inductors and diodes. Two capacitors connected in series are used to absorb the voltage spike and the energy of each capacitor can be transferred to the load during one switching cycle by the resonance of the inductors and capacitors. The operational principle of the passive snubber is analyzed in detail based on a three-phase power factor correction (PFC) converter, and the design considerations of both the converter and the snubber are given. Finally, a 3kW laboratory-made prototype is built. The experimental results verify the theoretical analysis and evaluations. They also prove the validity and feasibility of the proposed methods.

A Passive Lossless Snubber Applied to the AC–DC Interleaved Boost Converter

High switching frequency operation of static power converters is often required to reduce size, weight, and electromagnetic interference levels, at the cost of increased switching losses and reduced efficiency. Switching losses include the current and voltage overlap loss during the switching interval and the capacitance loss during turn-on. Recently, the use of passive soft switching methods has been emphasized as a better alternative to active methods, mainly because they do not require extra switches or additional control circuitry. This paper proposes a passive lossless snubber applied to the interleaved boost converter. The use of a soft commutation cell causes the main switches to be turned on and off under null current and null voltage conditions, respectively, as high efficiency results over the entire load range. The theoretical analysis including the description of the operating stages and the design procedure are included. Experimental results on a 2 kW prototype are presented and discussed to validate the proposal.

家庭用ＩＨ調理器への応用を目的とした簡易型ＰＦＣ機能を持つ２ステージソフトスイッチング高周波インバータ

In recent years, consumer induction-heating (IH) cooking appliances have grown increasingly popular because of their easy cleaning, high efficiency, safety, and controllability. IH food cooking system for consumer home use are indispensable to heat various metallic pans, such as aluminum, copper, stainless steel, and iron cast for further diffusing. Furthermore, these appliances have to satisfy the utility AC grid harmonics regulations of IEC61000-3-2. To meet these requirements, this paper proposes a two-stage soft-switching high-frequency inverter with simple PFC function that is suitable for consumer IH cooking appliances. The proposed system comprises a soft-switching chopper based boost PFC converter with passive snubber and phase-shifted PWM controlled ZVZCS high-frequency inverter. In order to satisfy the utility AC grid current harmonic regulations, a simple PFC control technique with discontinuous current mode is introduced. This technique as well as the fundamental operating performances of the proposed IH system is tested. The effectiveness of proposed IH system is substantially proved from a practical point of view on the basis of the experimental results.

Design and Development of High-Power DC–DC Converter for Metro Vehicle System

This paper presents the design and development of a transformer isolated high-power dc-dc converter. There are several design issues and challenges. In this paper, we focus on three major issues in high-power dc-dc converters. 1) An energy recovery passive snubber circuit and the selection of pulsewidth modulation control methods are first introduced to reduce the voltage spike and power loss across switching devices. 2) Interleaved winding method is then employed to reduce proximity effect in the transformer winding. 3) The voltage oscillation problem in the secondary rectifier diode is addressed, and solutions are provided.

Efficient LED back-light power supply for liquid-crystal-display

A highly efficient light-emitting-diode back-light power supply is proposed for liquid-crystal display. The proposed power supply consists of a bridgeless boost rectifier for power-factor correction and the asymmetrical half-bridge flyback converter with synchronous rectifier (SR) for DC-DC power conversion. In the proposed bridgeless boost rectifier, the diode reverse-recovery losses are reduced by achieving zero-current turn-off of the output diodes, as well as zero-current turn-on of the additional diodes. The reverse-recovery transients of the diodes are improved by a simple passive snubber circuit. For a DC-DC converter, the asymmetrical half-bridge flyback converter operates under zero-voltage switching for the power switches, and the SR switch operates under zero-current switching. The analysis of the proposed converter is presented and its design considerations are discussed in detail. Experimental results based on 28 V, 300 W back-light power are provided to demonstrate the performance of the proposed converter.

Voltage-Clamped Class-E Inverter With Harmonic Tuning Network for Magnetron Drive

A passive lossless snubber utilizing harmonic resonance is proposed for the voltage-driven class-E inverter. This snubber reduces the peak resonant voltage stress across the switch in class-E operation by adding the third-order harmonic current into the fundamental resonant part and can be extended to a higher-order network for further reduction. Though the principle is actually equivalent to the class-F operation in RF power amplifiers, it is first tried for the class-E inverter without a current source inductor. A series of analyses is performed to find component values that provide the optimum harmonic condition, and the experimental results from the inverter power supply for driving a magnetron are presented

A Zero-Voltage and Zero-Current Switching Three-Level DC–DC Converter With Reduced Rectifier Voltage Stress and Soft-Switching-Oriented Optimized Design

A novel zero-voltage zero-current switching (ZVZCS) three-level converter with pulsewidth modulation (PWM) phase-shift control is proposed. The ZCS of the lagging switch is obtained by using a regenerative passive snubber in the secondary. In order to reduce the voltage stress on the rectifier's diodes, a few passive elements are inserted into the primary: a small inductance, two diodes, and a small additional winding of the main transformer. In each half-cycle, one of these diodes will conduct for a short time in order to clamp the voltage of the snubber's capacitor, and thus, the rectifier stress, at (n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sub> /n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> )(V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub> /2), n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , and n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> being the transformer's primary and, respectively, secondary turns number. The three-level configuration allows for the reduction of the voltage stress across the power switches to half of the input voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub> . The conditions for assuring ZVS of the leading switch and ZCS of the lagging switch are found. Design constraints on the parallel capacitances of the switches of the leading switch, on the snubber's holding capacitor, and on the additional inductance and winding are hence established, allowing for an optimized design of the converter parameters. A dc analysis allows for the calculation of the effective duty cycle, which enjoys a boost effect due to the proposed snubber. Thus, a further reduction of the primary current stress and rectifier voltage stress is obtained. All the improvements conclude in a high efficiency. The influence of the choice of the parameters' values on the regulation capability is pointed out. Experiments on a prototype of 4.5kW confirm the results

A family of zero-voltage and zero-current-switching (ZVZCS) three-level DC-DC converters with secondary-assisted regenerative passive snubber

A detailed analysis and optimized-oriented design of a family of three-level soft-switching converters is presented. The zero-voltage-switching (ZVS) of the outer switches and zero-current-switching (ZCS) of the inner switches is realized by employing a pulse-width-modulation (PWM) phase-shift control and a secondary-assisted passive snubber. The switching operation is discussed by comparing the results produced by the use of different passive snubbers (the author's original one and literature-available ones). The voltage on the rectifier diodes is clamped at a reasonable value, specific to each one of the six snubbers taken into consideration. The voltage stress on each transistor is reduced to half of the input voltage. Lower rated transistors and rectifier diodes can be used, thus reducing the conduction losses. Before turning on/off the inner switches, the snubber's capacitor voltage determines the fall of the primary current to zero, thus avoiding wasteful energy circulation and assuring ZCS. The snubber's energy is recuperated to the load. The outcome of these improvements is a high efficiency in energy processing. Soft-switching-oriented constraints on the converter parameters are expressed as implicit equations, whose graphical solution permits the optimized design of the parameters in order to ensure ZVZCS. A comparative analysis of the effective duty cycle and the boost effect of it, due to the use of the secondary snubber, is performed. The influence of the choices of the parameters values on the regulation capability is pointed out. Experimental results prove the expected high performances of the optimized converters.

Pulse current regenerative resonant snubber‐assisted two‐switch flyback‐type ZVS PWM DC‐DC converter

AbstractIn this paper, a two‐switch high‐frequency flyback transformer‐type zero voltage soft‐switching PWM DC‐DC converter using IGBTs is proposed. Effective applications for this power converter can be found in auxiliary power supplies of rolling stock transportation and electric vehicles. This power converter is basically composed of two active power switches and a flyback high‐frequency transformer. In addition to these, two passive lossless snubbers with power regeneration loops for energy recovery, consisting of a three‐winding auxiliary high‐frequency transformer, auxiliary capacitors and diodes are introduced to achieve zero voltage soft switching from light to full load conditions. Furthermore, this power converter has some advantages such as low cost circuit configuration, simple control scheme, and high efficiency.Its operating principle is described and to determine circuit parameters, some practical design considerations are discussed. The effectiveness of the proposed power converter is evaluated and compared with the hard switching PWM DC‐DC converter from an experimental point of view, and the comparative electromagnetic conduction and radiation noise characteristics of both DC‐DC power converter circuits are also depicted. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 74–81, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20081

Study of Passive Snubbers Applied to a Single-phase High Power Factor Rectifier

This paper presents a family of non-dissipative passive snubbers applied to a single-phase rectifier with unity input power factor. This single-phase rectifier presents reduced conduction losses because the current flows through two power semiconductors only, for any stage of operation. The family of lossless passive snubbers presented in this paper guarantees soft-commutation during the turn-on and the turn-off intervals of the switch within a large range of variation of the input current. The snubber circuit not only should slow the di/dt and dv/dt rates of the active switch, but also losslessly recover the energy stored in the zero-current inductor and in the zero-voltage capacitor, leading to reduced voltage stress across the switches and diodes. The association of the family of high performance snubber circuits here presented with the single-phase rectifier with reduced conduction losses results in a high efficiency rectifier, free from overvoltages across the power switches. To access the performance of the proposed family, simulation and experimental results for a single-phase rectifier 3000W laboratory prototype using one snubber of the family are also presented.

Study of Passive Snubbers Applied to a Single-phase High Power Factor Rectifier

Study of Passive Snubbers Applied to a Single-phase High Power Factor Rectifier

A passive soft-switching snubber for PWM inverters

This paper presents a regenerative passive snubber circuit for pulse-width modulation (PWM) inverters to achieve soft-switching purposes without significant cost and reliability penalties. This passive soft-switching snubber (PSSS) employs a diode/capacitor snubber circuit for each switching device in an inverter to provide low dv/dt and low switching losses to the device. The PSSS further uses a transformer-based energy regenerative circuit to recover the energy captured in the snubber capacitors. All components in the PSSS circuit are passive, thus leading to reliable and low-cost advantages over those soft-switching schemes relying on additional active switches. The snubber has been incorporated into a 150 kVA PWM inverter. Simulation and experimental results are given to demonstrate the validity and features of the snubber circuit.