Active Snubber Research Articles

Design of a new modular‐isolated‐forward‐based active snubber cell for power switches

AbstractIn this paper, a new modular‐isolated‐forward‐based active snubber cell (SC) for power switches is designed. In the proposed new SC, the zero voltage transition (ZVT) technique is implemented with a forward converter although the current counterparts generally use a flyback converter. In the converter with the new SC, the main switch is turned on with ZVT (full zero voltage switching [ZVS]) and turned off with ZVS, the main diode is turned off with zero current switching (ZCS), the auxiliary switch is turned on with ZCS and turned off with ZVS, and the parasitic capacitor energies are recovered. In addition, thanks to the forward converter, it has been possible to minimize the transformer leakage inductance and greatly reduce the current values of devices in the new SC. The new cell is applied to a single‐phase, grid‐connected, T‐type three‐level inverter (T2‐3LI) as an example. A detailed steady‐state analysis of this inverter was made, and the theoretical analysis was confirmed with measurement results taken from a prototype with 100 kHz and 3.3 kW values. Compared to its hard switching (HS) equivalent, in the converter with soft switching (SS) cell, the total circuit loss was reduced from about 248 W to 86 W, thus achieving an increase in the total efficiency from 92.5% to 97.4%.

Design, analysis, and implementation of DC‐DC boost converter with new active snubber cell

Design, analysis, and implementation of DC‐DC boost converter with new active snubber cell

Proposal of an applicable ZVT Quadratic Boost Converter Topology in Renewable Energies.

In this paper, a new active snubber cell is proposed to contrive a new quadratic Boost pulse width modulated (PWM) converter. This snubber cell provides zero voltage transition (ZVT) for the main switch of a converter. A New ZVT–PWM Quadratic Boost converter equipped with the proposed snubber cell provides most the desirable features of ZVT converters presented previously, and overcomes most the drawbacks of these converters providing a large voltage step-up. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, the main devices do not have any additional voltage and current stresses. In this study, a detailed analysis of the new converter is presented, and this theoretical analysis is verified exactly by simulation and a prototype converter.

An Active Snubber Circuit for High-Capacity DC Chopper to Achieve Soft-Switching Operation for Offshore Wind VSC-HVdc System

An Active Snubber Circuit for High-Capacity DC Chopper to Achieve Soft-Switching Operation for Offshore Wind VSC-HVdc System

Current-Fed Phase-Shifted Full-Bridge Converter With Secondary Harmonic Current Reduction for Two-Stage Inverter in Energy Storage System

For the low voltage, high current, isolated DC-DC converter applications, current-fed type converter has the chance to achieve higher efficiency due to the lower transformer root mean square current compared with other well-known converters such as dual active bridge or LLC. A current-fed phase-shifted full-bridge, CFPSFB converter has the advantages of nearly full range zero-voltage-switching and soft-commutating without large size of passive or active snubber circuit because the phase-shift of secondary full-bridge is controlled to be proportional to the input current. However, as a front-end stage of a single phase inverter, the input secondary harmonic current (SHC) propagating from the output AC load may cause large voltage spike to damage the primary MOSFETs due to losing the soft-commutating property. SHC may also reduce the conversion efficiency and the lifespan of battery intensely. This paper proposes a simple control scheme based on virtual series impedance method with a notch filter in control loop to reduce the SHC and maintain good dynamic performance. A small-signal model of CFPSFB for a reliable controller design is derived and verified by simulation. A 48 V/3 kW maximum output power inverter prototype is built to verify the theoretical analysis. The maximum efficiency of the DC-DC stage is 97.4% and the peak to peak SHC is less than 10% of the average input current.

Novel Active Snubbers for SSCBs to Improve Switch Voltage Utilization Rate

This paper proposes two novel active snubbers for direct current (dc) solid-state circuit breakers (SSCBs): metal-oxide-varistor with resistor-capacitor-switch (MOV-RCS) and active-MOV with resistor-capacitor-diode (AMOV-RCD). In the snubber branch, either half- or full-controlled switch can be applicable, leading to four novel topologies. There are two main contributions: 1) MOV is disconnected from the power line during SSCB OFF-state, which enhances reliability as neither voltage nor power appears on MOV; 2) voltage utilization rate η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>v</i></sub> of the main switch is remarkably increased, which improves efficiency and power density, and reduces design cost. Experiments of five prototypes are conducted including four proposed snubbers and a comparison with conventional MOV-RCD snubber. Results show that, for 1.2 kV MOSFETs as the main switch, new snubbers can enhance η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>v</i></sub> from 37.5% to 60%, achieving 183 A dc current interruption under 720 V dc bus voltage within 2.4 μs. Meanwhile, the voltage peak is limited to 1.112 kV.

A High-Efficiency QR Flyback DC–DC Converter with Reduced Switch Voltage Stress Realized by Applying a Self-Driven Active Snubber (SDAS)

In this paper, a QR flyback converter using a self-driven active snubber (SDAS) was proposed to solve the problem of voltage surge in the switch of QR flyback converters. In the proposed converter, the SDAS consisting of a clamping capacitor and an active switch can be configured in parallel with the main switch or transformer to reduce the voltage surge in the switch. To confirm the steady-state characteristics of the QR flyback converter to which the proposed SDAS is applied, equivalent circuits for each state were constructed, and the equations and characteristics for each state were determined. A 60 W class small AC–DC adapter was constructed to confirm the effectiveness of the proposed converter and the control circuit method, and the experimental results were analyzed. The size of the experimental AC–DC adapter was 74×29×23 mm, and it had a high power density of 20 W/in3 or more. The experimental circuit was limited to the high power conversion efficiency of up to 91.56%, and the maximum voltage surge in the switch was approximately 450 V. One of the reasons for such high efficiency is the SDAS circuit, which sufficiently reduces the voltage surge of the QR flyback switch, compared with the RCD clamp circuit, and does not consume power in principle.

Nonisolated Boost Converter with New Active Snubber Structure and Energy Recovery Capability

The boost converters have become one of the most important part of renewable energy plants. The two parameters of boost converters, high voltage gain and high efficiency, have received more attention. In this paper, a boost converter with high voltage gain and high efficiency was used. The proposed topology is a boost converter with high transmission power and reduced voltage stress on the converter components, especially voltage stress on the main switch of the converter. This boost converter has a high efficiency using a new loss reduction technique called active snubber circuit with energy recovery. The proposed nonisolated topology converter was designed with a power of about 500[Formula: see text]W, an input voltage of 48[Formula: see text]V and an output voltage of 380[Formula: see text]V and efficiency of more than 97%. The simulation results of the proposed converter showed different modes of the boost converter. A laboratory model was constructed and the claims of the proposed boost converter were proved.

A comprehensive analytical description of the asymmetric active snubber

A comprehensive analytical description of the asymmetric active snubber

Design of a 3.3 kW/100 kHz EV Charger Based on Flyback Converter With Active Snubber

This article presents the feasibility of a flyback charger for electric vehicles (EV) based on silicon-carbide (SiC) devices. The flyback topology is simplest, but its device voltage stresses are strongly affected by the transformer leakage inductance. To reduce the device voltage stresses by recovering the energy stored in the transformer leakage inductance, an active-clamp circuit and active snubber circuit are adopted in both sides of the transformer. Also, the active-clamp circuit helps to reduce the switching losses by making zero-voltage-switching (ZVS) condition. By deriving the loss equations of switching devices and transformer as a function of the switching frequency and magnetic flux swing, design optimization considering loss and volume is attempted. The snubber capacity and diode voltage stress are quantitatively suggested through the analysis of the power absorbed by the active snubber. Based on the analysis, a 3.3 kW/100 kHz prototype is designed and experimented to show the feasibility. Test results demonstrate 96.7% peak efficiency and 96.4% full load efficiency at 330V output voltage.

Study of a novel soft‐switched Vienna rectifier using simple active technique

SummaryIn recent years, efficient power transfer is getting increasing attention in high‐power conversion systems such as fast battery charger systems primarily necessitate an energy efficient, compact, and reliable power electronic converter scheme. This has stirred vigorous research in high‐power converter‐based power electronic systems which are feasible in actual practice and perform efficiently. In view of this fact, a novel soft‐switched T‐type boost rectifier Vienna topology is proposed, which can be considered as a potential candidate in high‐power conversion systems. The proposed converter scheme operates at high‐switching frequency with soft‐switching conditions by employing a simple active snubber circuit, which results in high‐efficiency and high‐power density with low cost. The low components count, simple power and control circuitry, comparable stresses, and performance are the distinctive features of the proposed converter scheme. Furthermore, the proposed topology achieves high‐switching operation while reducing reverse recovery rectifier diode losses and semiconductor losses. The proposed converter scheme's construction, operating principle, and practical implementation are carried out using a low‐scale laboratory prototype. In order to evaluate, a comparison with existing soft‐switched rectifier topologies is performed in terms of components count. In addition, a MATLAB/Simulink designed subsystem is used to assess the semiconductor devices switching power losses in comparison to its hard‐switched counterpart.

Design and Simulation of an Inverter Drive System with a Display for a Renewable Energy System in the Rural Isolated Communities of Uganda

In medical diagnostics, therapeutic, laboratory, intensive care unit devices, and machines application, two form of Electrical Energy is utilized. Alternatives current (AC) and Direct current (DC) form. In this paper an inverter driver system with a display model is made using MATLAB and its specific tool box of Simulink, the process will involve converting single phase alternating current power to direct current using rectifier made from ordinary normal diodes then converted to three phase using three-arm insulated gate bipolar transistors this is commonly known as inverter bridge which is sufficient enough to run three phase loads depending on the application requirement. The system uses a five-level inverter with low levels of distortions and ripples in the equipment output, this increase and improves the performance of the system. Using carefully selected passive and active elements such as capacitor resistors, inductors, diodes, and transistor system in inverter, decreases the number of switches and boosts the efficiency of the system. This inverter drive system helps us to run three phase machines in the health facility at the same frequency of single phase. The inverter system allows a smaller smoothing capacitor in the DC-AC link as proposed. Large smoothing capacitors are conventionally essential in such converters to absorb power ripple at twice the frequency of the power supply. The proposed network topology consists of an indirect matrix converter and an active snubber to absorb the power ripple, and does not necessitate a reactor or large smoothing capacitor. Simulation result is shown using MATLAB software and used to verify system operation principle as well as circuit development and their control mechanism for a single-to-three-phase power inverter system. The results from experiment show that for a 1 kW-class prototype circuit system, the power ripple at twice the frequency of the power supply can be adequately suppressed using a buffer capacitor of low values.

A Modified Multi-Winding DC–DC Flyback Converter for Photovoltaic Applications

DC–DC power converters have generated much interest, as they can be used in a wide range of applications. In micro-inverter applications, flyback topologies are a relevant research topic due to their efficiency and simplicity. On the other hand, solar photovoltaic (PV) systems are one of the fastest growing and most promising renewable energy sources in the world. A power electronic converter (either DC/DC or DC/AC) is needed to interface the PV array with the load/grid. In this paper, a modified interleaved-type step-up DC–DC flyback converter is presented for a PV application. The topology is based on a multi-winding flyback converter with N parallel connected inputs and a single output. Each input is supplied by an independent PV module, and a maximum power point tracking algorithm is implemented in each module to maximize solar energy harvesting. A single flyback transformer is used, and it manages only 1/N of the converter rated power, reducing the size of the magnetic core compared to other similar topologies. The design of the magnetic core is also presented in this work. Moreover, the proposed converter includes active snubber networks to increase the efficiency, consisting of a capacitor connected in series with a power switch, to protect the main switches from damaging dv/dt when returning part of the commutation energy back to the source. In this work, the operating principle of the topology is fully described on a mathematical basis, and an efficiency analysis is also included. The converter is simulated and experimentally validated with a 1 kW prototype considering three PV panels. The experimental results are in agreement with the simulations, verifying the feasibility of the proposal.

Standalone electric vehicle charging station using an isolated bidirectional converter with snubber

AbstractThe rise of green technologies in transportation requires electric vehicles (EV) as a prominent solution for reducing greenhouse gas emissions. An off‐grid EV charging station plays a significant role in remote regions leading to increased use of EVs. Solar energy promises to be the best solution due to its abundance and simple installation. As solar energy is not constant over a 24‐hour period, there is a need for an energy storage unit (ESU) along with a photovoltaic array. In this paper, we present an efficient design approach that uses a fast‐charging station with a maximum power point tracking boost converter, a bidirectional DC‐DC converter with a snubber circuit, and ESU. The power electronic converters with an active snubber and two capacitive‐diode snubbers act as the energy sources that interface with the ESU. The snubber circuits achieve near zero voltage switching and zero current switching for the converter, thus improving overall efficiency. ESU meets the energy demand for EVs when there is insufficient generated solar energy. On the other hand, during the excess generation of solar energy, ESU utilizes this energy to develop an optimal power management system. This results in a green, reliable, and efficient off‐grid EV charging station. The proposed method is validated using the MATLAB/Simulink environment to verify system performance.

Zero‐voltage switching half‐bridge pulse width modulation DC–DC converter with switched capacitor active snubber cell for renewable energy applications

SummaryIn this paper, soft switching isolated half‐bridge converter with a new active snubber cell that uses switched capacitor for renewable energy applications is proposed. The proposed snubber cell does not consist any magnetic element so that its structure is quite simple. Furthermore, the auxiliary switches in the proposed active snubber cell are exposed to only half of the input voltage. There is no additional voltage and current stress on any semiconductor devices. All semiconductor power devices in the proposed converter are operated by soft switching. The proposed converter is analyzed thoroughly, and the theoretical analyzes are affirmed by an implementation having 300‐VDC input, 20‐VDC output, 75‐W output power, and 150‐kHz switching frequency. The overall hard switching efficiency of the converter is increased from 86.4% to 92.9% by aid of the proposed soft switching snubber cell.

WITHDRAWN: Design and simulation of a soft switched converter for renewable energy systems

Abstract This paper proposes an alternate soft switching scheme for a dc-dc boost converter applicable to renewable energy systems. An auxillary circuit is value added along with the boost circuit to provide soft switching features like zero voltage switching (ZVS) for main switch turn ON and zero current switching (ZCS) for main switch turn OFF. Active snubber circuit uses a single switch and some passive components. The converter circuit as a whole uses fewer components with smaller size and simple controls. The proposed converter is analyzed mode wise and therefore the simulations are meted out in PSIM beneath big selection of loading conditions. The circuit attains sensible potency and low element stresses.

Efficient AC-DC power factor corrected boost converter design for battery charger in electric vehicles

With the widespread use of electric vehicles (EVs), the design of a highly quality and efficient battery charger has become an important research topic. In this study, an efficient AC-DC power factor corrected (PFC) boost converter with active snubber cell (ASC) is proposed for the battery charger. ASC integrated into the AC-DC PFC boost converter turns on the main switch with zero voltage transition (ZVT) and turns off with zero current transition (ZCT), which among soft switching techniques for eliminating the switching losses. In addition, it has been provided that other switching elements are operated with soft switching. Soft switching conditions and unity power factor (PF) are achieved from light load to full load conditions. Unlike the soft-switched PFC converter circuits in the current literature, no current and voltage stresses have been observed on any component in the main converter and ASC circuits. The paper also presents the steady-state operating principles and design guidelines of the proposed converter in detail. The efficiency improvement between the hard switched counterpart has been verified by making detailed loss analysis. The proposed converter has been constructed as 3.3 kW and tested according to European efficiency standards with various case studies. The total harmonic distortion (THD) of input current has been measured as less than 5% in compliance with EN 6100-3-2 Class D Limits (A) standards.

Switching Losses Analysis of a Constructed Solar DC-DC Static Boost Converter

The DC-DC converter is majorly used in several renewable energy applications. It is usually relevant in a hard-switching operating mode at the cost of increasing power losses and declining efficiency. Power losses are comprised of switching losses and conduction losses, which affect the reliability and speed up the aging of the switch. Therefore, soft-switching techniques are inescapable to reduce electromagnetic interference EMI, minimize losses, and enhance power conversion efficiency. Among the sundry techniques of soft-switching, passive snubbers are uncomplicated and vigorous, besides it has been spotlighted as a finer alternative compared to the active snubbers that involve extra switches and an additional control circuit. This paper investigates the power loss of a conventional solar DC-DC static converter designed and controlled through Maximum Power Point Tracking (MPPT). It evaluates the switch's temperature in the hard-switching operating mode. Besides, this paper presents a new research initiative that aims to allow a zero switching and stabilizing the temperature of the switch through a novel approach of design for RLD and RCD snubber cells. This new design allows the switch to achieve soft-switching, by abolishing the voltage stress, minimizing the power losses, and stabilizing the junction temperature. This snubber has a simple structure with a few components and ease of control, which helps to upgrade the power conversion efficiency through controlling the high voltage and current stress in the switch. In this treatise, elements of the snubber are designed and adjusted for maximum reliability through the simulation in OrCAD environment. Furthermore, the effectiveness of the model is approved through experimental results on a 1600 W conventional boost to validate the proposal.

Trends and Challenges in Grid-Tied Inverters for Photovoltaic Applications

Grid-Tied inverter has gained the attention of many researchers and power generation industry due to its capability of integrating distributed power generation systems using renewable energy resources with the existing centralized power generation system. Yet the inclusion of a transformer in the Photovoltaic (PV) inverter makes it bulkier, heavier and more expensive. A primary solution to the aforementioned problems is the transformerless PV Grid-Tied inverter. This paper presents a review of different transformerless, single-phase Grid-Tied inverter topologies. The objective of this paper is to study parameters such as leakage current, common-mode voltage, total harmonic distortion, and the efficiency of transformerless Grid-Tied inverters. The paper also provides a discussion on existing Grid-Tied inverter topologies, such as H5, oH5, Novel H5, H5-D, FBDC, H6D2, Hybrid H6, High-efficiency MOSFET H6, Improved H6, 3L H6, H6-A, B, High-Efficiency H6, H6-N, Improved H6, H6-active clamping, Active clamped snubber based H6, Heric, oHeric, Enhanced Heric, Heric-with mid-DC-link, Active clamping, PN-NPC, Improved FBNPC, T-Type 3L, ANPC, HBNPC, NIFB-NPCI, VNIIFBC, M-NPC, Virtual DC bus based inverter, Active Virtual Ground, Type I, Type II, Type III Common Ground, Flying Capacitor and Multilevel Common Ground. Though it is found that many topologies available in the literature, other new topologies can be proposed to improve the performance of the inverter. Furthermore, it is also noted that the performance analysis of the inverter must be carried out in the presence of junction capacitance and shoot-through problem so that new strategies can be introduced in the existing typologies to address these issues.

A novel active snubber cell for soft-switched isolated PWM half-bridge converter

A novel active snubber cell for soft-switched isolated PWM half-bridge converter