Passive Snubber Research Articles

Boost DC-DC converter with regenerative snubber

To accommodate the wide range of input voltages supplied by redundant batteries and ensure an adequate hold-up time for communication systems during utility power failures, power supplies used in 5 G base stations typically include a front-end boost converter as the first stage and a second-stage isolated converter. In this paper, a new topology for a regenerative snubber in boost converters is proposed. Compared to traditional active or passive snubber topologies, the proposed snubber offers the advantages of having fewer components and occupying less space. Moreover, it does not require additional active devices and can be driven by widely-used commercial PWM control integrated circuits, achieving a higher level of cost-effectiveness and offering increased industrial applications. The final prototype of a power supply for a networking switch hub (as used in 5 G base stations) is fabricated to demonstrate the feasibility of the proposed method.

Comprehensive Investigation of Promising Techniques to Enhance the Voltage Sharing among SiC MOSFET Strings, Supported by Experimental and Simulation Validations

This paper comprehensively reviews several techniques that address the static and dynamic voltage balancing of series-connected MOSFETs. The effectiveness of these techniques was validated through simulations and experiments. Dynamic voltage-balancing techniques include gate signal delay adjustment methods, passive snubbers, passive clamping circuits, and hybrid solutions. Based on the experimental results, the advantages and disadvantages of each technique are investigated. Combining the gate-balancing core method with an RC snubber, which has proven both technically and commercially attractive, provides a robust solution. If the components are sorted and binned, voltage-balancing techniques may not be necessary, further enhancing the commercial viability of series-connected MOSFETs. An investigation of gate driver topologies yields one crucial conclusion: magnetically isolated gate drivers offer a simple and cost-effective solution for high-frequency (HF) applications (2.5–50 kHz) above 8 kV with an increased number of series devices. Below 8 kV, it is advantageous to move the isolation barrier from the gate drive IC to an optocoupler and isolated supply, allowing for a simple design with commercially available components.

Improved Interleaved Boost Converter with Soft-Switching: Analysis and Experimental Validation

This paper proposes a novel interleaved boost converter for renewable energy applications. The two-phase interleaved boost converter was improved with lossless passive snubber cells to ensure the Zero Voltage Switching (ZVS) condition. The ZVS condition is contributed by a resonant inductor, a resonant capacitor, and two diodes. The proposed converter was operated in continuous current mode on its primary side. The significant merits of this converter are reduced switching losses, better efficiency, and reduced input current ripples without auxiliary switches. The soft-switching ability of this converter is maintained under both light- and heavy-load conditions. This paper also presents the operating principles and design analysis of the proposed converter. Furthermore, a 50-320V prototype was operated at 250 W to validate the soft-switching operation and theoretical analysis, and the experimental results are presented.

A new lossless passive snubber with simple structure for pulse width modulation DC-DC converters

A new lossless passive snubber for pulse width modulation converters is introduced in this paper. This snubber is established zero current switching condition for main switch in the converters for turning on distance. This snubber does not impose any additional current stress on the switch. The snubber can be applied to all single-switch DC-DC converters. A boost converter with the proposed snubber is analyzed and to verify theoretical analysis a 200 W sample is implemented and tested, also the experimental results are presented. In order to investigate the effect of snubber circuit in the converter in terms of efficiency, the boost converter with the proposed snubber has been compared in terms of efficiency with the conventional boost converter and the results show that the efficiency has increased by about 7% despite the snubber.

A Boost Converter with Lossless Passive Snubber for Powering the 5G Small Cell Station

The existing DC-DC quarter-brick or eighth-brick converter with a rated power of 300W is usually designed with a narrow input voltage range from 36 to 72 V DC with limited hold-up time. In this paper, a two-stage power supply unit constructed by a front-end boost converter cascaded with a brick converter is adopted to extend the input voltage range and the hold-up time. A new lossless snubber is proposed and applied to the boost converter to slow the slope of the drain-source voltage rising when the MOSFET is turned off. The experimental results show that the proposed snubber provides a boost converter with a higher conversion efficiency and less electromagnetic interference emissions.

Soft-Switched Boost–Cuk-Type High Step-Up Converter for Grid-Tied With Half-Bridge Inverter

In this study, a novel two-stage grid-tied high step-up inverter is proposed. The first stage (dc–dc) is a combination of boost and cuk converters as well as a simple dc-link voltage balancing circuit. The balancing circuit is connected in series with the output of the cuk converter to compensate for the output voltage difference between boost and cuk converters. The second stage (dc–ac) comprises a conventional half-bridge inverter. The ground leakage current is eliminated in the proposed topology by the simultaneous grounding of the photovoltaic (PV) module and the grid. A lossless passive snubber with the minimum elements is also proposed and analyzed to provide the soft-switching conditions. In this snubber circuit, the snubber capacitance discharges to the output dc link to decrease the converter circulation losses. The main attributes of the proposed dc–dc converter with lossless passive snubber are the simple structure of the dc–dc converter and snubber circuit, simple control scheme, and high efficiency. Various operation modes of the proposed topology are theoretically analyzed and investigated. The experimental results substantiate the effectiveness and performance of the proposed boost–cuk-based high step-up inverter with the lossless snubber.

A Soft-Switched Single-Stage Single-Phase PFC Converter for Bidirectional Plug-In EV Charger

This paper proposes a novel zero-current assisted soft-switching bidirectional single-stage single-phase isolated power factor correction (PFC) based converter for plug-in EV charger. An isolated topology consists of a current-fed full-bridge converter with bidirectional switches on the ac-side that is connected with a full-bridge converter on the dc-side of a high-frequency transformer (HFT). HFT offers galvanic isolation for safety and high power density, and it is the most desired specification for a battery charger. The converter enables zero current switching (ZCS) of ac-side switches and zero current turn-ON for dc-side switches without any active clamp circuit or passive snubbers, which significantly reduced switching losses, footprints, and cost. The proposed modulation strategy and control technique are presented for promising the soft-switching operation of all semiconductor devices throughout the range for all modes with bidirectional power flow capability. These merits make the converter more feasible, robust, and reliable with high power density for an EV application. A comprehensive study of proposed steady-state operation, design, and simulation results is reported. A proof-of-concept hardware laboratory prototype rated at 1.5 kW is established and tested to validate the claims and proposed converter performance.

Regenerative Passive Snubber Circuit for High-Frequency Link Converters

This letter presents a passive snubber circuit for high-frequency link cycloconverters, which typically suffer from voltage oscillations across matrix-stage semiconductor devices. The proposed passive snubber allows for effective damping of the oscillations and reduction of the peak voltage stress. It is based on an auxiliary transformer and a diode bridge rectifier, which are rated only for a fraction of total converter power regenerated back to the input dc source. The performance of the circuit was verified with 350 Vdc/230 Vac, 1 kW SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MOSFET</small> -based experimental prototype and a reduction of the peak voltage overshoot from 2.24 to 1.55 times the nominal was achieved, without negative impact on the converter overall efficiency. As a result, the blocking voltage rating of the matrix-stage semiconductors can be reduced from 900 to 650 V.

A Flyback Converter With Novel Active Dissipative Snubber

The active clamp flyback converters (ACF) can provide features of high power density and high power efficiency. However, ACF is usually applied to in the applications of medium-to-high power range. For a low power application, the ACF may not be a cost-efficient choice. The flyback converter with a lossless snubber can provide high efficiency for low-power application, but it needs an additional inductor and generates more electromagnetic interference (EMI) emissions. The circuit designers also consider the balance between conversion efficiency, size, and cost. Based on the reasons above, the flyback converter with dissipative RCD snubber is still popular in the applications of low-to-medium power range. When the dissipative snubber is adopted to reduce EMI in the power converters, it increases the loss and hence reduces the efficiency. In this paper, a new concept, called active dissipative snubber, is proposed to suppress the resonance in the discontinuous conduction mode (DCM). In the proposed active dissipative snubber, the digital controller activates the dissipative snubber only when the EMI noise is occurring, then disabled after the noise is decayed or disappears. Digital logic makes the passive snubber smart, which can selectively absorb the EMI noise. Since the proposed snubber is not connected to the main circuit all the time, it can provide lower power loss, but still performs better EMI emissions and maintains conversion efficiency.

Layout Inductance Assisted Novel Turn-on Switching Loss Recovery Technique for SiC MOSFETs

This article proposes a passive snubber circuit for achieving reliable zero voltage turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> transition with the help of layout inductance in a dc–dc converter. A small assist inductance is inserted in the PCB layout for achieving this zero voltage turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> . <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A new regenerative snubber circuit</i> is designed to recover the switching loss corresponding to the voltage overshoots alone. This way energy storage requirement of the snubber circuit is minimized significantly. The proposed snubber circuit is experimentally verified using a 1 kV, 32 A SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> , and 1.2 kV, 30 A Schottky diode in a boost converter setup. For the same voltage overshoot, the proposed snubber circuit has achieved a ten times reduction (89.4%) in switching losses compared to the without snubber case in a boost converter setup at 600 V, 30 A load condition. At 200-kHz switching frequency, the designed boost converter registered a peak efficiency of 98.87% at 5.5 kW load and it achieved 98.45% efficiency at 10 kW load. At 10 kW load, the snubber inductor had an rms current of 0.45 A and a peak current of 4 A flowing through it. The diode and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> snubber capacitors had a peak voltage of 60 V and 190 V, respectively.

Ripple-Free Input Current Flyback Converter Using a Simple Passive Circuit

This article proposes a new ripple canceling circuit (RCC) to eliminate the pulsating input current of the conventional flyback converter (CFC). The ripple canceling procedure occurs by two capacitors, one transformer, and a winding, which is added to the CFC transformer core. Besides, the proposed RCC acts as a passive snubber to reduce voltage spikes on the power switch of the converter. In comparison to the similar existing topologies, the proposed RCC does not employ additional semiconductors, and a lower number of magnetic components are used. The proposed RCC is verified by simulation and experimental results. The results show that using the proposed RCC, the input current ripple is reduced to 6% with the minimum power losses.

High Efficiency DC–DC Boost Converter With Passive Snubber and Reduced Switching Losses

This article presents a novel concept of switch-mode dc–dc boost converters with reduced switching losses. The converters use an auxiliary switching cell to achieve zero voltage switching during the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> of a transistor. The novel concept facilitates an increase in the efficiency or switching frequency of an IGBT-based boost converter. This article discusses the converters topology, the principle of operation, and issues related to the reduction of power losses, the range of optimal operation, and selection of components. The concept of the converter was verified through simulation and a series of experiments that demonstrate the process of zero-voltage turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> and the efficiency of the converter.

Active Voltage Balancing of Series-Connected 1.7 kV/325 A SiC MOSFETs Enabling Continuous Operation at Medium Voltage

This article presents a medium voltage half-bridge circuit where 3.3 kV power switches are built with two 1.7 kV/325 A SiC MOSFETs series-connected inside power modules. Essence of this work is an active balancing method eliminating the voltage imbalances between the devices by means of gate signals modification. The advantage over commonly-used passive snubbers is low cost and limited amount of additional losses. Performance of the half-bridge is illustrated with a model-based Saber simulation at first, then, an experimental full-scale model is designed with on-the-shelf power modules capable operating at power level above 150 kVA. A series of laboratory tests at 1.5 kV DC confirmed reduction of voltage differences across devices in the stack to an acceptable level - the designed system is working correctly despite EMI caused by fast switching transients. Moreover, the observed current and voltage waveforms prove the positive impact of the method as not only voltages but also switching losses are better balanced among the devices. Experimental comparison to a 3.3 kV counterpart shows two times lower turn-off energy, therefore, the presented design with two 1.7 kV SiC MOSFET power modules can beneficently compete not only in terms of lower cost but also switching performance.

An Interleaved Zero-Voltage Zero-Current Switching High Step-Up DC-DC Converter

An interleaved zero-voltage zero-current switching (ZVZCS) high step-up DC-DC converter is proposed for modern photovoltaic power generation systems. The proposed converter can achieve high voltage conversion gain without operating under extreme duty cycles. The voltage conversion gain can be readily adjusted by selecting different numbers of the diode-capacitor multiplier (DCM) cells in the circuit at the design stage. Moreover, with the passive snubber circuit in the proposed converter, all power switches and diodes in the DCMs can achieve zero-voltage turn-off and zero-current turn-on, which effectively reduces switching losses and increases the overall converter efficiency. The operational principles and analysis of the performance analysis with two DCMs are presented for demonstrative purpose. The effectiveness of the proposed ZVZCS DC-DC converter is validated using an 800W experimental prototype.

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.

A Lossless Passive Snubber Circuit for Three-Port DC–DC Converter

In this article, a soft-switched nonisolated high step-up three-port dc-dc converter is presented for hybrid energy system applications. In the proposed converter, the soft-switching condition is provided for semiconductor elements by a passive lossless snubber without adding any extra active switch or adding any additional semiconductor element in the main power path. The proposed converter is a high integration of single-stage power conversion with multiple input sources and battery port, while the voltage stress of the main switch is kept low. All these benefits have led to high efficiency in comparison to other converter counterparts. Operating principles of the proposed converter are discussed in detail, and design considerations are presented. Finally, experimental verifications are provided to illustrate the feasibility and effectiveness of the proposed converter.

A new lossless snubber for DC-DC converters with energy transfer capability

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.

A New Simple-Structure Passive Lossless Snubber for DC–DC Boost Converters

A new soft-switching boost converter with simple-structure passive lossless snubber is proposed in this article. It shows various advantages as low cost, few auxiliary elements, and low-voltage stress on the switch. The passive snubber circuit consists of an inductor, two capacitors, and two diodes. It provides zero current switching (ZCS) turn-on and zero voltage switching (ZVS) turn-off for the switch. The main diode turns on under ZVS and turns off under zero-voltage ZCS, therefore, reverse recovery problem is solved. Also, total efficiency and conducted electromagnetic interference of the proposed converter compared to the conventional boost converters are improved. To prove it, 220 W prototypes are implemented. The experimental results along with the theoretical analysis confirm an increase of 3% in efficiency of the proposed converter.

Passive Lossless Snubber for PFC AC–DC Converters

Passive Lossless Snubber for PFC AC–DC Converters

High voltage gain soft switching full bridge interleaved Flyback DC-DC converter for PV applications

This paper introduces a soft switching full bridge interleaved Flyback DC-DC converter with high gain. Half bridge Flyback converter will cause many problems in comparison with full bridge structure such as high-volume split capacitors and complex control for charging and discharging them for proper operation. By applying full bridge interleaved structure, the output current ripple can be reduced, and more power can be supplied to the load. Besides, the greatest way for reducing the weight, size and volume of the converter is applying soft switching methods. As well, the switching frequency is increased to boost the power density. To reduce switching losses, clamp circuit with a passive lossless snubber is applied in the suggested full bridge interleaved Flyback converter. In the proposed topology, soft switching conditions for all semiconductor elements are achieved by the passive snubber. It absorbs the stored energy in parasitic elements at the turn-off instant. The main superiority of the proposed topology in comparison with many other similar converters is that its passive snubber is load independent. A 110 W prototype of the topology is implemented. The experimental results confirm the aforementioned advantages of the converter such as high efficiency (92% at full load) and high gain (23.2).