Passive Lossless Snubber Research Articles

Research on High Power Density Flyback Converter With a New Passive Lossless Snubber

ABSTRACTThis paper proposes a flyback converter with a new passive lossless snubber. It eliminates the power dissipation of the traditional RCD snubber, while providing protection against MOS breakdown from energy stored in the power‐transformer leakage. This energy is used to power the power chip, which simplifies the design of the transformer. Meanwhile, an optimal design method for high power density planar transformers is presented. Applying the principle of flux cancellation, a matrix transformer that originally needed an independent magnetic core was integrated into a single magnetic core to reduce the volume of the core. This method effectively reduces the printed circuit board (PCB) layer number of the planar transformer and increases the possibility of the application of the planar transformer in the flyback converter. The detailed operation principle and design considerations are presented. Finally, a multi‐output flyback converter with a frequency of 100 kHz is designed to verify the practical performance of the structure.

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 non‐isolated step‐up common‐ground cost‐effective microinverter for AC‐module application

AbstractThis research proposes a cost‐efficient microinverter. The proposed microinverter can eliminate the leakage current using common‐ground configuration. It uses three switches and only one of them operates at high frequency. In addition, a passive lossless snubber is applied to limit voltage stress and provide soft‐switching performance for the high‐frequency switch. A pair of coupled inductors is used to provide higher voltage gain which makes it possible to keep the operating duty cycle in the normal range and makes the proposed inverter suitable for AC module application. The input current of the proposed microinverter is continuous which reduces the loss of the input capacitor by high‐frequency current component reduction. The operating principle of the proposed inverter is described in both positive and negative current modes. In positive current mode, the proposed microinverter works similar to SEPIC converter and in negative current mode its performance is similar to CUK converter. The dynamic behavior of the proposed microinverter is analyzed through simulation and a simple PI controller is designed to accommodate the worst case. Theoretical loss analysis is applied and finally the results of this research are compared with other researches. The performance of the proposed inverter is justified by simulation and practical results of a 300‐watts prototype.

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 New Passive Lossless Snubber

Galvanically isolated photovoltaic (PV) microinverters based on single-stage flyback topology have advantages: simplicity, better reliability, and low cost. But isolated flyback topology comes with voltage stresses on semiconductor switches caused by transformer leakage inductance. An improved regenerative snubber has been proposed to meet the ever-growing demand for higher efficiency of PV microinverters. The proposed topology is the inductor-capacitor-diode (LCD) snubber with flying capacitor modified to reduce circulating currents. Theoretical analysis reveals a number of advantages. Experimental results are presented to verify the performance.

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 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

Evaluation of high power density achievement of optimum 4‐level capacitor‐clamped DC–DC boost converter with passive lossless snubber circuit by using Pareto‐Front method

This study presents the evaluation of the proposed optimum 4-level capacitor-clamped DC-DC boost converter (CCBC) for high power density achievement by using Pareto-Front method. The 4-level CCBC with considering high switching frequency can greatly reduce the inductor size and volume. High switching frequency caused the switching devices to suffer high semiconductor losses. Consequently, the cooling device volume is increased as well. Thus, this study presents soft-switching technique in the 4-level CCBC for semiconductor losses reduction. The combination of optimum design of inductor, improvement of circuit structure and soft-switching technique may lead to the highest power density of the converter. A 400 W of the 4-level CCBC converter is designed and experimentally verified. The results show that the inductance and inductor volume required in the 4-level CCBC is reduced by 88.89 and 80.75%, respectively. Besides, Pareto-Front curve shows the highest power density of soft-switching technique with the proposed 4-level CCBC is 6.51 kW/dm 3 at 800 kHz of switching frequency with efficiency of 97.20%.

A Single-Switch Single-Magnetic Core High Conversion Ratio Converter With Low Input Current Ripple and Wide Soft-Switching Range for Photovoltaic Applications

In this article, a novel high conversion ratio dc-dc converter suitable for photovoltaic applications is presented. Utilizing single-switch and single-magnetic core, low ripple input current and low voltage stress across the semiconductors are the major advantages of the proposed converter. In order to provide a soft-switching condition for the converter switch at a wide range of output power, a passive lossless snubber is employed. The presented converter is adequate for photovoltaic applications due to the mentioned properties. Operating principles are analyzed and design considerations are provided. In order to validate the theoretical analysis, a prototype of the proposed converter is implemented and the experimental results are exhibited.

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).

Soft-Switching Bidirectional Buck/Boost Converter With a Lossless Passive Snubber

This article introduces a new lossless passive snubber for the bidirectional buck/boost converter. The proposed snubber comprises a low number of passive components which jointly contribute to achieve soft switching condition at both the buck and boost operations of the converter. Without using the auxiliary switch, soft switching condition is ensured over a wide load range with a relatively low circulating current. Also, there is no need for any complex control method to diminish circulating current at light loads. Consequently, by using a simple auxiliary circuit and the conventional control methods, excellent efficiency is acquired over a wide load range. The proposed topology is analyzed in detail and to confirm the theoretical analysis, the experimental results of a 500 W-100 kHz prototype for both the boost and buck modes in full-load and 20% of full-load are presented.

High boost‐ratio bidirectional converter for interfacing low‐voltage battery energy storage system to a DC bus

Supply and demand mismatches in renewable energy systems are addressed by integrating battery banks. Selecting battery bank terminal voltage to match DC-bus voltage (350–450 V for single-phase AC loads), necessitates employing battery banks with long-string connections along with their attendant shortcomings. To employ short-string battery banks, high-boost-ratio bidirectional interfaces are required between the DC-bus and battery bank. Current literature lacks a single source where high-boost-ratio converters’ are categorised and their strengths and weaknesses identified. Comprehensive literature review is hence carried out to determine attributes of various high-boost-ratio DC–DC converters and also categorise them. The key attributes of a topology to interface battery storage to a DC-bus are determined. Based on these a bidirectional tapped-inductor boost converter emerges as the best candidate. Moreover, in order to regulate output voltage, voltage-gain versus duty-ratio characteristics should not be very steep. Since battery terminal voltage varies with state-of-charge, closed-loop control is necessary. Converter's small-signal transfer-functions are derived and a two-loop controller to regulate output voltage and inductor current while allowing bidirectional power flow designed. A novel bidirectional passive lossless snubber circuit is employed to clamp the voltage spikes across the active switches, without altering the normal operation of the converter.

4-level capacitor-clamped boost converter with hard-switching and soft-switching implementations

This paper presents parameters analysis of 4-level capacitor-clamped boost converter with hard-switching and soft-switching implementation. Principally, by considering the selected circuit structure of the 4-level capacitor-clamped boost converter and appropriate pulse width modulation (PWM) switching strategy, the overall converter volume able to be reduced. Specifically, phase-shifted of 120° of each switching signal is applied in the 4-level capacitor-clamped boost converter in order to increase the inductor current ripple frequency, thus the charging and discharging times of the inductor is reduced. Besides, volume of converters is greatly reduced if very high switching frequency is considered. However, it causes increasing of semiconductor losses and consequently the converter efficiency is affected. The results show that the efficiency of 2-level conventional boost converter and 4-level capacitor-clamped boost converter are 98.59% and 97.67%, respectively in hard-switching technique, and 99.31% and 98.15%, respectively in soft-switching technique. Therefore, by applying soft-switching technique, switching loss of the semiconductor devices is greatly minimized although high switching frequency is applied. In this study, passive lossless snubber circuit is selected for the soft-switching implementation in the 4-level capacitor-clamped boost converter. Based on the simulation results, the switching loss is approximately eliminated by applying soft-switching technique compared to the hard-switching technique implementation.

A new family of non‐isolated PWM DC–DC converter with soft switching

In this study, a new family of soft-switching pulse-width-modulated (PWM) converters with a lossless passive snubber is introduced. The switch is turned on under zero-current switching and turned off under zero-voltage switching and all diodes turn on and off under soft switching conditions. The proposed snubber consists of two resonant inductors a resonant capacitor and three diodes which can be applied to all non-isolated DC–DC converters. A buck converter with the proposed snubber is analysed and to verify theoretical analysis, a 100 W prototype is implemented and efficiency of converter compared with hard switching counterpart. Also to confirm the effectiveness of the proposed snubber to reduce conducted electromagnetic interference (EMI), the conducted EMI of a buck converter with proposed snubber cell is compared with conventional buck converter.

Interleaved PFC balance charger with passive lossless snubber for series-connected batteries

Interleaved PFC balance charger with passive lossless snubber for series-connected batteries

Implementation of Resonant and Passive Lossless Snubber Circuits for DC-DC Boost Converter

This paper presents the comparison of resonant and passive lossless snubber circuits implementation for DC-DC boost converter to achieve soft-switching condition. By applying high switching frequency, the volume reduction of passive component can be achieved. However, the required of high switching frequency cause the switching loss during turn-ON and turn-OFF condition. In order to reduce the switching loss, soft-switching technique is required in order to reduce or eliminate the losses at switching devices. There are various of soft-switching techniques can be considered, either to reduce the switching loss during turn-ON only, or turn-OFF only, or both. This paper discusses comparative analyses of resonant and passive lossless snubber circuits which applied in the DC-DC boost converter structure. Based on the simulation results, the switching loss is approximately eliminated by applying soft-switching technique compared to the hard-switching technique implementation. The results show that the efficiency of resonant circuit and passive lossless snubber circuit are 82.99% and 99.24%, respectively. Therefore, by applying passive lossless snubber circuit in the DC-DC boost converter, the efficiency of the converter is greatly increased. Due to the existing of an additional capacitor in soft-switching circuit, it realizes lossless operation of DC-DC boost converter.

High Step-Up Coupled-Inductor Cascade Boost DC–DC Converter With Lossless Passive Snubber

In this paper, a high step-up coupled-inductor cascade boost dc–dc converter with lossless passive snubber is proposed. Although a conventional cascade boost converter has larger voltage gain compared to a boost converter, it is still not suitable for high step-up voltage conversion. In the proposed converter, a coupled inductor is adopted for the cascaded boost converter to further increase the voltage gain. However, a leakage inductance of the coupled inductor causes a high voltage spike at a main switch. A resistor–capacitor–diode snubber is commonly used to simply solve this problem, but it is also the cause of additional power loss. Therefore, the lossless passive snubber is suggested in this paper in order to prevent efficiency drop by a snubber circuit. In conclusion, the proposed converter has high voltage gain and improved power efficiency. Experimental results from an output 400-V 200-W prototype at a constant switching frequency of 50 kHz are presented to verify the performance of the proposed converter.