Snubber Circuit Research Articles

Design and Analysis of a DC Solid-State Circuit Breaker for Residential Energy Router Application

Energy routers act as an interface between the distribution network and electrical facilities, which meet the requirements of clean energy substitution and achieve the energy sharing and information transmission in the energy network. However, the protection of the dc load side of residential energy routers including interruption and isolation of short-circuit fault currents is vital for discussion. Since the traditional mechanical and hybrid circuit breakers for dc fault protection have the drawback of slow operation, a solid-state circuit breaker (SSCB) is an optimal solution for fast dc fault interruption. In this paper, a dc SSCB is proposed that uses an RCD + MOV snubber circuit, which is considered the best and most complete circuit used in common SSCBs. There are two main contributions in this paper: First, a dc SSCB is designed, which isolates both positive and negative terminals of a circuit and its working principle and operating modes along with the formulas for calculation of crucial time intervals, voltages, and currents along with the design procedure are provided. Second, a soft turn-on auxiliary is designed to prevent a high current surge caused by the capacitance difference between the source and the load. The experimental results demonstrate the proper performance of the topology and the validity of the findings.

A Dual-Current-Fed Dual-Active-Bridge DC/DC Converter With High-Frequency Current-Ripple-Friendly Ports

The current-fed isolated dc/dc converters are suitable solutions for applications requiring low high-frequency current ripple and convenient current control, such as fuel cells and Li-ion batteries. The existing current-fed isolated dc/dc converters are combined with a current-fed bridge-type terminal and a voltage-fed bridge-type terminal, which can only partially obtain the merits of the current-fed terminals. In this article, a dual-current-fed dual-active-bridge dc/dc converter is proposed with the inductor connection on both terminals. Hence, low high-frequency current ripple and convenient current control can be realized on both sides. Besides, it can also realize the voltage spike suppression without snubber circuits and has the inherent soft-switching operation and voltage boost function. Then, the operation principle, design process, and loss analysis of the proposed converter are presented in detail. The experimental results based on a proof-of-concept laboratory prototype are given to verify the steady-state and dynamic performance of the proposed converter.

A Hybrid Dynamic Voltage Sharing Scheme for Series-connected SiC MOSFETs with Single Gate Drive

At present, the voltage level of a commercial SiC MOSFET can hardly meet the requirements of high-voltage field. For the sake of achieving the application of MOSFETs in high-voltage fields, the method of series-connected MOSFETs has become a practical and effective solution. However, multiple series-connected SiC MOSFETs face the problem of voltage unbalance, especially dynamic voltage unbalance. Generally, the problem of dynamic unbalance could be solved using load side voltage sharing schemes or the methods of gate side. This paper uses a hybrid dynamic voltage sharing scheme for the single-driven series-connected SiC MOSFETs. That is to say, based on a sequential lagging single gate drive topology, combining active clamping circuits with RCD snubber circuits are introduced to solve the problem of dynamic voltage unbalancing of the whole module in this paper. Compared to the circuit without any dynamic voltage sharing scheme, the dynamic voltage imbalance degree of the circuit with a hybrid dynamic voltage sharing scheme is decreased to 3.75% during the switching-on and switching-off periods. The equalization effect would be verified through the simulation under clamped inductive load in LTspice.

Voltage-Fed Isolated Matrix-Type AC/DC Converter for Wind Energy Conversion System

In this article, a voltage-fed isolated matrix-type ac/dc converter (VF-MC) is proposed for wind energy conversion system (WECS). Instead of the line-frequency transformer, the high-frequency transformer (HFT) is used for isolation between the generator and the grid. The direct matrix converter (MC) is employed to connect the wind power generator and the HFT, and the intermediate dc capacitors are saved in the ac/ac conversion. Moreover, the proposed VF-MC can work without use of filter capacitors on generator side, and enable more compact size. The dedicated space-vector-modulation scheme and commutation method are proposed for safe operation of the MC. The voltage spikes due to the leakage inductance of HFT are thus reduced and the additional snubber circuit is avoided in the proposed system. A 1-kW laboratory prototype of the proposed VF-MC-based WECS is built to verify the effectiveness of the system experimentally.

Research on the Transient Interrupting Voltage of Mechanical HVDC Circuit Breaker and Its Influences on the Postarc Dielectric Recovery Process

The flexible high-voltage direct current (HVDC) power system develops quickly with the large-scale utilization of new energy and the increase of direct current (dc) loads in recent years. HVDC circuit breakers are very important components in the flexible HVDC power system. The mechanical HVDC circuit breaker including vacuum interrupters is a potential solution for HVDC interruption. After the current interruption, a transient interrupting voltage (TIV) generated from the interaction with the external circuit will be applied to the mechanical HVDC circuit breakers and might cause a failure interruption. However, there are still few studies about the influences of TIV on the postarc dielectric recovery process of mechanical HVDC circuit breakers. In this article, a circuit model based on the simplification of a 10-kV mechanical HVDC circuit breaker is developed for the purpose of studying the characteristics of TIV. Then the effects of the parallel snubber circuit on the TIV are discussed. Moreover, the influence of TIV on the postarc residual plasma dissipation process is simulated by a particle-in-cell (PIC) model. The results show that the TIV with a parallel snubber circuit has little effect on the whole dissipation time compared with that without a parallel snubber circuit. It should be noted that the microdissipation processes of the above two situations are different.

The Optimization Design for Suppression of CRAFT TF Magnet Power Converter Switching Overvoltage

The switching overvoltage due to the operation of the switching device is considered to be one of the important research contents during the design phase of a high-power supply system based on thyristor rectifier topology in the comprehensive research facility for fusion technology (CRAFT). Switching peak overvoltage is suppressed by resistors–capacitors (RC) snubber circuit generally; however, the traditional RC design often relies on some simple empirical formulas and blind amplification margins, which is unable to meet the precision requirements of engineering design. All the work that has been done is based on the cophase counter parallel connection structure of the converter module, and a new strategy is proposed to optimize the RC snubber circuit in order to suppress the operating peak overvoltage better. First, the no-load transformer breaking overvoltage is analyzed, then RC parameters are designed based on a new strategy. Compared with traditional methods, the RC parameters selected by this strategy are more accurate, which meets the accuracy requirements of engineering design and suppresses switching better than before.

A Small and High Efficiency Circuit Topology with Significantly Improved Trade-off Between Switching Losses and dv/dt for Series Connected Devices with Regenerative Snubber Circuits

A Small and High Efficiency Circuit Topology with Significantly Improved Trade-off Between Switching Losses and dv/dt for Series Connected Devices with Regenerative Snubber Circuits

A Unified Modeling Approach to Tapped Inductor Converters Accounting for the Leakage Inductance Effects

This article suggests a unified modeling approach to the analysis of tapped-inductor converters. The leakage inductance, inherent to coupled magnetic structures, and the associated snubber circuit effects were considered and incorporated into the suggested model. The proposed nonideal tapped inductor switcher model is formulated as an equivalent subgraph that can help to model most, if not all, converter topologies that comprise a two-winding tapped inductor. Both the continuous current mode and the discontinuous current mode were modeled. To validate the proposed approach, analysis of a Flyback converter with an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> snubber is presented. Theoretical prediction of the steady-state and small-signal behavior of the converters were confirmed by simulation and experimental results.

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.

Dynamic Modeling Framework for Evaluating Electromagnetic-Electro-Thermal Behavior of Power Conversion System During Load Operation

Abstract This study introduces a modified dynamic multiphysics modeling framework to characterize the electromagnetic-electrothermal (EET) coupled behavior of a power conversion system during a long load operation. The modeling framework extends the prior model with more comprehensive analysis and enhanced computational efficiency and modeling simplicity. This framework incorporates a fully integrated electromagnetic circuit (FIEC) model for extracting parasitics, including self and mutual inductances and also exploring their effect on the switching characteristics and power losses, and a dynamic power loss-temperature thermal (PTT) model for describing the temperature-dependent instantaneous electrical behavior and power loss. Moreover, a simple resistance-capacitance (RC) snubber circuit design is applied to prevent overvoltage and diminish voltage oscillations and spike value during the operation, and their power losses are also assessed and considered in the dynamic EET coupled modeling. Furthermore, the proposed PTT model employs an equivalent thermal RC network to calculate the chip junction temperature with a given power. Additionally, a simple power-temperature relationship derived from the FIEC cosimulation is applied for modeling simplicity and computational efficiency. This framework is tested on a three-phase inverter operating with a 180-deg conduction mode. The proposed FIEC cosimulation and computational fluid dynamics thermal models are validated by double pulse (DPT) and infrared thermography experiments, respectively. Moreover, the PTT model is validated compared with the conventional dynamic coupled electrothermal model. Finally, a design guideline for enhanced thermal performance of the tested power conversion system is sought through parametric analysis.

An Interleaved Two Switch Soft-Switching Forward PWM Power Converter with Current Doubler Rectifier

Forward converters have been broadly used in the power supply industry due to their simplicity, worthy efficiency, and low cost. A novel prototype soft-switched zero-voltage and zero-current ZVZC PWM DC-DC power converter with low voltage/current stresses is introduced for telecommunication power feeding in this paper. A new two-switch interleaved forward converter circuit is introduced to minimalize current circulation with no supplementary auxiliary snubber circuits. This converter circuit includes some outstanding benefits such as reduced components, improved efficiency, high power density and economic circuit configurations for high power conditioning applications. The simple operation principle is demonstrated on the basis of steady-state analysis. Furthermore, the effective feasibility of the proposed circuit topology is evaluated and verified practically for a 500 W–100 kHz prototype breadboard. The operation principle and steady-state characteristics are demonstrated from a theoretical point of view. To verify the practical effectiveness of the proposed power converter, a 500 W–100 kHz prototype converter using ultrafast IGBTs is implemented for a distributed telecommunication energy plant. The studied soft-switching converter is evaluated in comparison with the previously-proposed PWM converters in terms of voltage, current stresses, and operating efficiency.

Overvoltage Suppression Scheme for Minimized Snubber Requirements in MVDC Solid-State Breakers With Series-Connected IGBTs

Solid-state dc breakers are the ultimate technology for protecting medium-voltage dc grids having equipment vulnerable to excessive fault-current stress, due to the very short fault-clearing times. A typical implementation of such breakers is based on insulated gate bipolar transistors (IGBTs). However, as the rated voltage of the grid increases, series connection of IGBTs is inevitable and impose challenges on transient and steady-state blocking voltage distribution. This article presents a novel voltage-balancing scheme that combines passive resistive-capacitive-diode (RCD) snubber circuits and a gate driver containing a gate-current balancing magnetic-core. The proposed concept aims at minimizing the required snubber capacitances, which may be high. The impact of the proposed configuration on the breaker design and its performance are studied under different fault scenarios. Using the proposed breaker configuration, the snubber capacitance has been reduced by up to 60%. Besides, both simulations and experimental results reveal the mitigation of high peak voltage stress across the early turned-off IGBTs under gate signal propagation delays.

Bidirectional Q-Z-Source DC Circuit Breaker

In this article, a novel Z-source dc circuit breaker topology with a Q-shaped impedance network (Q-Z-source circuit breaker) is presented. The new topology has a better performance and is more resilient properties than those of the recently published O-Z-source circuit breaker. The new Q-Z topology provides bidirectional protection but only requires one semiconductor switch in its current path during normal operation, leading to a simpler and smaller physical structure and a lower conduction penalty. It also drastically improves the sensitivity issue on the magnetic coupling coefficient that manifests in the existing O-Z-source circuit breaker. In a realistic, practical application with a nonideal magnetic coupling coefficient, the new topology requires a smaller capacitance that can be translated into lower weight and/or lower cost. Detailed mathematical models are built to analyze and compare the short-circuit fault responses of a variable coupling coefficient. The bidirectional snubber circuit and its connection to the Q-Z topology are discussed for achieving faster fault clearing. Finally, a prototype is built in the laboratory to verify the theoretical analysis and improved performance of the proposed bidirectional Q-Z-source dc circuit breaker.

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.

1㎸, 1㎄, 12㎾ 펄스 출력을 위한 Discharge Closing Switch의 스너버 회로 설계

This paper deals with the overall structure of 1㎸, 1㎄, and 12㎾ pulse modulator and the snubber circuit design of the discharge closing switch for pulse. This high-voltage, high-current pulse modulator is used in various fields such as the field of printed electronics. However, overshoot and noise are unavoidable considerations due to the features of pulse power that instantaneously outputs high voltage and current. To reduce such overshoot and noise, a snubber circuit has been proposed. The snubber circuit consists of a resistance, capacitor, diode(RCD) and is additionally equipped with one more capacitor. Therefore, in this paper, we analyze the operational principles of the proposed snubber circuit. Finally, a waveform without overshoot and malfunction was confirmed through a pulse output experiment.

A SiC-Based Liquid-Cooled Electric Vehicle Traction Inverter Operating at High Ambient Temperature

This paper describes the design process of a high-power-density 100 kW (34 kW/L) traction inverter for electric vehicles, operating at an ambient temperature of 105 °C. A detailed thermal analysis is performed based on the thermal behavior of the switching devices, and the results are used to estimate the semiconductor device junction temperature and to determine the requirements of the cooling system to achieve the target power level. A high-temperature gate drive board aiming for reliable system operation in electric vehicles is developed. An overcurrent protection scheme based on parasitic inductance between the power source and the Kelvin source of the power module has been implemented. A dc-link decoupling snubber circuit is designed numerically based on a detailed forth-order high-frequency equivalent circuit of a double pulse test circuit. The approach to optimize the snubber circuit, not only for the voltage spike suppression but also for good thermal performance, is proposed. Finally, a hardware prototype with SiC power modules has been built and tested at 60 kW continuous power and 100 kW for 20 seconds at 105 °C ambient temperature and 65 °C inlet coolant temperature.

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.

A Trans-Inverse Magnetic Coupling Single-Phase AC-AC Converter

This paper introduces a new single-phase AC-AC converter based on an impedance source circuit. Like the existing single-phase impedance source AC-AC converters, it has the buck-boost ability and direct ac conversion. The input and output voltage possesses the same ground, and the phase angle is maintained and reversed smoothly. The presented converter utilizes a coupled transformer which allows the designer to exploit the transformer’s turns ratio as a variable to attain the desired output voltage. Additionally, the used transformer provides an option to obtain higher voltage gain by decreasing the turns ratio. Hence, smaller size of the coupled inductors is required for the higher voltage cases. To eliminate the switching voltage and current spikes on the power switches, a safe commutation strategy is used instead of utilizing snubber circuits. Furthermore, the input current is continuous and sinusoidal with low harmonics thanks to embedding the input inductor in series with the input source. Additionally, a dynamic voltage restorer is presented based on the proposed converter to compensate the voltage sag and swell faults. Simulation results are provided to evaluate the theoretical analysis. Finally, a laboratory prototype has been fabricated to demonstrate the validation of the presented converter.

Avalanche and Short Circuit Robustness of Vertical GaN FET [Expert View

GaN power semiconductor devices have been the recent focus of intense development efforts due to the promising material properties of GaN for next-generation power electronics applications. For power switching and rectifying applications, the ruggedness in breakdown is a critical requirement as addition of snubber circuits reduce the performance and efficiency of the system. Lateral GaN high-electron mobility transistors (HEMTs) have been commercialized up to 900 V class recently, but they lack avalanche capabilities. Vertical GaN transistors demonstrate several advantages over lateral GaN HEMT: 1) higher breakdown voltage (BV) and current for a given chip area, 2) higher reliability, 3) easier thermal management, 4) avalanche capabilities, and 5) short-circuit robustness.

Modeling of High-Voltage Nonpunch-Through PIN Diode Snappy Reverse Recovery and Its Optimal Suppression Method Based on RC Snubber Circuit

The snappy reverse recovery (SRR) and failure of high-voltage nonpunch-through (NPT) PIN diodes under extreme working conditions are of great significance to the reliability evaluation of operating diodes in actual power electronic devices. In this article, the analysis of the physical mechanism of the diode SRR and the restrictions of the traditional PT-PIN diode model are made. Then, the traditional model for soft recovery is improved in order to accurately describe the diode SRR characteristics. Simulations of key dynamic performances of the established model agree well with the experimental results. Furthermore, a suppression method for diode SRR based on the optimal RC snubber circuit is proposed. A high-voltage NPT-PIN diode used in the dc−dc converter with different RC snubber circuits is simulated using the proposed diode snappy model and tested. The comparison results show good consistency between the simulated and measured voltage and current peaks and the diode SRR are suppressed effectively. The developed model and results are of much importance to the prediction of the safe operation area of the diode and to the reliability improvement of power electronic device.