Solid-state Circuit Breaker Research Articles

Application of N parallel-connected SiC MOSFETs to solid-state circuit breakers based on UIS tests

N parallel-connected SiC MOSFETs were investigated to apply to solid-state circuit breakers (SSCB), and it is an extension of a method that was proved valid by experiment of two parallel-connected SiC MOSFETs. The unclamped inductive switching (UIS) test was considered as the emergency interruption of SSCBs in this research. Because of the variations of breakdown voltage among SiC MOSFETs, the current flowing through devices is imbalanced during emergency interruption of SSCBs, which can drive some of the devices into thermal destruction prematurely. There are many compound cases for several SiC MOFETs with a certain maximum breakdown voltage variation. And the worst case, where the breakdown voltage of one device is assumed as the lowest, whereas the other devices have the same breakdown voltage, was extracted from the calculated results of four parallel-connected situation. In the worst case, it was found that the relation of breakdown voltage variations and current capacity is linear. Moreover, the distributions of breakdown voltage were taken as normal distributions. Using the worst case and distributions, a linear relation of breakdown voltage distributions and rated current of an SSCB could be concluded as a function of paralleled-connected numbers (N). Utilizing the function, the necessary breakdown voltage distributions and N of SiC MOSFETs can be evaluated for SSCBs meeting a certain yield ratio and current.

Integration of superconducting fault current limiter with solid-state DC circuit breaker

The onboard direct current (DC) system in electric aircraft could face a severe fault current, which is tens of times the nominal current in a short-circuit fault. It is critical to limit the fault current and clear the fault within a few milliseconds to prevent any damage to the DC system. A protection method using a resistive superconducting fault current limiter (SFCL) with a solid-state DC circuit breaker (SSCB) to manage the DC short-circuit fault is proposed and experimentally verified. A bifilar SFCL coil prototype with two types of connection to achieve low and high inductance is designed and tested, which reduces the fault current considerably from 2000 A to below 1000 A. The performance when integrating the low and high inductance SFCL with a solid-state DC circuit breaker are investigated. It is found that when integrating the SFCL with the SSCB, a high voltage is induced across the high inductance SFCL during current interruption tests. In terms of reliability and durability, the low inductance SFCL is preferred to integrate with the SSCB. The experimental results show that the low inductance SFCL can be an effective solution to protect the DC system from severe fault currents and then SSCB can rapidly and reliably interrupt the fault current at 1000 A.© 2017 Elsevier Inc. All rights reserved.

DC Microgrid Protection System Based on Positive Channel Metal Oxide Semiconductor

DC microgrid has received extensive attention and research because of its natural advantages of improving the consumption efficiency of distributed power sources, and in line with the development trend of clean environment and intelligent operation of power grids in the future. However, short-circuit fault protection of DC microgrid is a major challenge for the development of microgrid. Therefore, the author proposes a DC solid-state circuit breaker with a positive channel metal oxide semiconductor as the main switch, and through simulation, it is verified that this solid-state circuit breaker is feasible. The experimental results show that when the proposed solid-state circuit breaker is normally turned on, the positive channel metal oxide semiconductor is completely turned on, which has no effect on the power flow in the DC microgrid; when a short-circuit fault occurs in the DC microgrid system, the short-circuit current is used to couple the energy, the positive channel metal oxide semiconductor is reliably turned off. The stability and reliability of the system are improved, and it can be applied to the short-circuit protection of the DC microgrid, and has a good application prospect.

Wide Bandgap Devices Continue to Evolve for Aerospace Applications

<fig orientation="portrait" position="float" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <graphic orientation="portrait" position="float" xlink:href="bindr-3196232.tif"/> </fig> From electric aircrafts to satellites and unmanned aerial vehicles (UAVs), the need for fuel saving and greenhouse reduction continues relentlessly. As a result, electrification seems to be catching rapidly in aerospace and aviation applications. This demands new generation of power converters, motor drives, and solid-state circuit breakers with unprecedented power density, efficiency, and reliability. Wide bandgap (WBG) power devices, such as silicon carbide (SiC) MOSFETs and gallium nitride (GaN) high-electron mobility transistors (HEMTs) and gate injection transistors (GITs), are regarded as critical candidates for such applications. While WBG devices have been serving the needs of commercial and industrial systems for more than a decade, there are still many challenges for WBG devices and their circuits for aviation applications, which include radiation hardness, extreme operation temperature, high altitude, high-voltage, high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv/dt</i> , and high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt</i> operation induced issues.

A Novel GaN-Based Solid-State Circuit Breaker With Voltage Overshoot Suppression

This article proposes a novel ultra-fast self-powered bidirectional solid-state circuit breaker (SSCB) with voltage overshoot suppression that uses gallium nitride switches with very low conduction losses. This SSCB can be used in low and medium ac/dc networks for both short-circuit protection and overcurrent protection. An exhaustive methodology for RCD snubber design applied to SSCBs is provided. A comprehensive review of the technical literature is presented exhibiting that the proposed SSCB reduces conduction losses and detection time in comparison with other similar SSCBs. The performance features of the proposed SSCB are verified through the functional tests that are carried out employing a hardware-implemented prototype. Experimental results confirm that our proposal is able to detect and process the short-circuit failure in 282 ns; the authors have not found any faster results in the literature.

Coordination of Ultrafast Solid-State Circuit Breakers in Radial DC Microgrids

This article proposes a comprehensive method for optimal coordination of ultrafast solid-state circuit breakers (SSCBs) in radial dc microgrids. The proposed method consists of two consecutive steps. In the first step, SSCBs are optimally coordinated for overload, short circuit, and instantaneous protections. Inverse time-current characteristics (ITCC) curves are formulated to systematically coordinate SSCBs. The trip curve of each SSCB includes overload, short-circuit, and instantaneous profiles. In determining overload protection, the thermal capability of SSCBs is considered; while the short-circuit and instantaneous tripping profiles are realized based on short circuit thermal capability and ultrafast response time of SSCBs. Coordination time interval (CTI) is included between upstream and downstream SSCBs to achieve selectivity. To avoid miscoordination in practice, CTI is chosen by incorporating the SSCBs’ metal-oxide varistor (MOV) conduction time interval during turn-off process and dc current measurement error. In the second step, the operating speed of the protective scheme is optimized by applying distance-based secondary protection (DBSP). The DBSP is used to minimize the tripping time when short circuit faults occur close to upstream SSCBs. This significantly reduces the consumed energy by faults, prevents damage, reduces absorbed energy by SSCBs, and enhances the safety of operators. The proposed coordination removes the need for communication links between SSCBs and presents high reliability. A 400-V dc microgrid benchmark with photovoltaic (PV) and energy storage systems (ESSs) is examined as a case study in simulation. Besides, experiments are conducted in a 400-V dc system to evaluate the effectiveness and accuracy of the DBSP.

A DC Solid-State Circuit Breaker Based on Transient Current Commutation

This article proposes a new dc solid-state circuit breaker (SSCB) based on silicon carbide (SiC) MOSFETs. There are two main contributions. First, a transient current commutation (TCC) is obtained in the main switch during current interruption. To achieve this, a compact and fast active injection circuit (AIC) is employed. TCC brings two main benefits: 1) it eliminates the effects of parasitic inductances in circuit connections and removes voltage oscillations on the gate of the main switch, which prevents spurious turn-on and 2) it eliminates the transient power shock on the switch during turn-off, which extends the lifetime of SSCB and increases its reliability. Second, the voltage on the employed metal oxide varistor (MOV) is reduced to zero during the OFF-state. This extends the maximum allowable dc bus voltage on the SSCB and solves the MOV reliability issue in the SSCBs. The presented SSCB employs a time-sequence control and needs no real-time detections of the dc current, which simplify the design. LTspice simulations of 380 V/80 A and 600 V/80 A are presented, and the results are compared with MOV- and MOV resistor–capacitor–diode (MOV-RCD)-based SSCBs. Also, experiments of a 380 V/80 A prototype validate the effectiveness of the proposed SSCB in practice where the voltage on the SSCB is clamped to 721 V with a fixed response time of 9.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> .

A Surgeless Diode-Clamped Multilevel Solid-State Circuit Breaker for Medium-Voltage DC Distribution Systems

In conventional medium-voltage solid-state circuit breakers (SSCBs), series-connected semiconductor switches are used with metal oxide varistors (MOVs) in parallel with each of them to extend the voltage ratings of the breakers without incurring the dynamic voltage unbalance. Besides, for isolating the faults at faster speeds, the clamped surge voltages of the MOVs are always much higher than the system voltages. For those reasons, the voltage ratings of all the switches in the SSCBs have to be overdesigned according to the surge voltage values, which causes high material costs along with nonideal conduction losses in the SSCBs employed for medium-voltage dc distribution systems. To solve this dilemma, a surgeless diode-clamped multilevel SSCB is proposed in this article. It offers an ultrafast isolation speed with no significant surge voltages or dynamic unbalanced voltage across the semiconductor switches. With these attributes, the proposed SSCB can potentially use the semiconductor switches rated at lower voltages compared to conventional SSCBs and have higher efficiency along with faster isolation speed. The simulation and experimental results are presented to validate the technical feasibility and practical values of the proposed SSCB.

Ultrafast Solid-State Circuit Breaker With a Modular Active Injection Circuit

This article proposes a new modular active injection circuit (AIC) for solid-state circuit breakers (SSCB). The modular AIC is used to achieve soft switching turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> during dc current interruption to mitigate the effects of the parasitic components in the main branch. The proposed AIC presents the following contributions: selectable resonant currents are achieved to obtain a reliable artificial zero-crossing point in dc currents; current rating scalability is provided; passive components of the AIC are optimized using particle swarm optimization (PSO) algorithm and new proposed objective functions; an external wireless charger is developed to charge the injection capacitor of the AIC to provide voltage isolation, compactness, and flexibility in choosing the precharge voltage value on the injection capacitor; the proposed AIC needs no discharge circuits, which simplifies the control and accelerates reclosing process. The proposed SSCB is simulated in a 6-kV system in power systems computer aided design/electromagnetic transients for dc (PSCAD/EMTDC) in interrupting currents of normal and different scenarios. The designed SSCB can interrupt the dc currents up to 200 A with the adaptive response time from 3.74 to 6.71 μs, faster response time in interrupting higher values of dc currents. The effectiveness of the proposed SSCB in practice is validated by experiments of a downsize 380 V/20 A prototype with only 2.8 μs response time and 99.91% efficiency.

Multiphase Interleaved IPT Based Current-Source Converter for High-Current Application

This article proposes a multiphase interleaved inductive power transfer (IPT) based dc–dc converter for high-current applications. There are three main contributions. First, the proposed converter is designed based on a loosely coupled IPT system with series compensation capacitors, which permits large leakage inductance and avoids magnetic saturation. Second, series capacitors are used to compensate the magnetic coupler, which achieves load-independent output current, namely a current-source converter. Third, a scalable multiphase converter is achieved with an input-parallel output-parallel structure for high current. Meantime, an interleaved control strategy is implemented to an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -phase system with an angle shift of 360°/(2× <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> ), reducing output current ripples. A 2-kW/100-A three-phase converter prototype is implemented with zero-voltage switching and harmonic loss suppression. Experimental results show a load-independent output current, which is linearly regulated by input dc voltage. With an input voltage of 480 V, the output current reaches 101.5 A with a small peak-peak ripple of 2.4 A. Output power reaches 2.07 kW with a 91.39% dc–dc efficiency. A steady-state test for a solid-state circuit breaker (SSCB) is conducted using the proposed high-current converter, showing its application in evaluating the steady-state efficiency and thermal performance of SSCB.

Electronic MOV-Based Voltage Clamping Circuit for DC Solid-State Circuit Breaker Applications

Traditional metal oxide varistor (MOV) based voltage clamping circuits (VCC) used in solid-state circuit breakers reduce the efficiency of the system due to the high voltage requirement imposed on the main solid-state device. The voltage burden arises from the material properties of the MOV which fixes its clamping voltage at a value more than twice its maximum continuous dc voltage rating. This letter proposes a novel and reliable VCC termed as the electronic MOV (eMOV) to altogether decouple the peak clamping voltage of the MOV from the nominal dc voltage of the system aiming to improve the voltage suppression index (VSI = <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_pk</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> ) of the VCC, thereby reducing the system conduction losses. The eMOV introduces a breakover diode to share the system dc voltage during the standby state and a Silicon controlled rectifier to provide the bypass path for the fault current for quick MOV insertion. Comprehensive design criteria are developed to guide the component selection and overall design. Experimental results at 2 kV dc and 1.1 kA peak current are presented to validate the operation of the proposed eMOV based VCC.

An integrated multi-port hybrid DC circuit breaker for VSC-based DC grids

DC circuit breakers are of great significance for the reliable and flexible operation of VSC-based DC grids. The hybrid DC circuit breaker (HDCB) combines the advantages of low on-state loss of the mechanical DC circuit breaker and fast breaking speed of the solid-state DC circuit breaker, showing excellent application prospects. However, the cluster of two or more HDCBs connected to the same DC bus could significantly increase the total project investment. At present, the solution based on multiport HDCB (M-HDCB) has been proposed to practically reduce the construction cost, but the power transmission among adjacent healthy DC lines will also be interrupted after the isolation of DC bus fault, which is still a challenging problem. Therefore, in order to solve this problem, a novel integrated multiport HDCB (IM-HDCB) is proposed in this paper. In addition to the shared transfer and energy dissipation branches, the key auxiliary units composed of diode-stacks and thyristor-stacks are also integrated into the IM-HDCB to enhance the overall performance. Compared with existing solutions, it is shown that the proposed IM-HDCB has more excellent performance. Finally, the capabilities of the proposed novel IM-HDCB are validated by simulations in PSCAD/EMTDC.

A Series-Type Hybrid Circuit Breaker Concept for Ultrafast DC Fault Protection

A new series-type hybrid circuit breaker (S-HCB) concept for dc fault protection is reported that is fundamentally different from other prior-art hybrid circuit breakers (HCB) or solid-state circuit breakers (SSCB) in the literature. The S-HCB conducts its load current through metal wires instead of power semiconductor switches and curtails its fault current to near zero throughout the entire opening process of a series mechanical switch. It offers the low <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -resistance of the conventional mechanical contacts for normal operation and µs-scale fault response even faster than the fast-acting SSCBs. A proof-of-concept S-HCB prototype experimentally demonstrates the interruption of a fault current of 30 A within 10 μs at a dc voltage of 600 V. The operating principle, simulation, and experimental results are discussed in this letter.

Design of a Reliable Bidirectional Solid-State Circuit Breaker for DC Microgrids

DC microgrids have drawn more and more attention in industrial applications. However, achieving efficient and reliable interruption of faults is still a challenging task in dc microgrids. In this article, a reliable bidirectional solid-state circuit breaker (RB-SSCB) is proposed for dc microgrid protection. The proposed RB-SSCB can break and rebreak bidirectional faults with no fault current surges to the source and load, and its breaking capability is stable and controllable. Consequently, when compared with the existing SSCBs, the RB-SSCB can provide more reliable protection for dc microgrids. Increased power efficiency, reduced costs, and simplified structure can also be obtained in the proposed topology. Based on circuit analysis and modeling, design guidelines for selecting the components in the RB-SSCB are given. Finally, a laboratory prototype has been built to verify the practical value and the feasibility of the proposed solution.

Capacitive Couple-Based Transient Current Commutation in Solid-State Circuit Breakers

This letter presents a new auxiliary circuit to achieve transient current commutation (TCC) in dc solid-state circuit breakers (SSCBs). The auxiliary circuit consists of two parts: active injection circuits (AIC) and capacitive couplers. There are two contributions. First, coupling capacitors between AIC and the main branch are introduced to prevent short circuit failures in the auxiliary branch. Second, a boost converter-based resonant circuit is presented for AIC to achieve TCC in the main branch through couplers. The presented AIC tunes the duration time and amplitude of injected countercurrent pulses during dc current interruption. The working principle and design procedure of the auxiliary circuit are presented. The proposed topology is verified by experiments of a 2&#x00A0;kV&#x002F;100 A dc SSCB prototype under load current interruption. The experimental results show that the injected pulse current through couplers reaches 110 A, and it decays to zero within 12.5&#x00A0;&#x03BC;s. The total reaction time interval including the communication delay and the AIC current rising delay is 108&#x00A0;&#x03BC;s. Meanwhile, the peak voltages across the main branch and the coupler reach 2099 V and 2193&#x00A0;V, respectively.

Implementing Symmetrical Structure in MOV-RCD Snubber-Based DC Solid-State Circuit Breakers

This article deals with metal-oxide varistor (MOV) and resistor&#x2013;capacitor&#x2013;diode (RCD) snubber-based solid-state circuit breakers (SSCBs). There are two main contributions. First, a design methodology of MOV-RCD snubber parameters is proposed by considering thermal dissipation and snubber charging time for the first time. The thermal profile of the main conduction switches determines nominal current under passive cooling. Based on the nominal current, the fault current magnitude is derived, and a design method of key parameters of an MOV-RCD snubber is proposed. Four snubbers are designed with different fault currents and dc voltages. Second, symmetrical layouts with distributed parallel cells are proposed for high current capability, which enables scalability. Q3D simulations facilitate the evenly distributed stray inductances among paralleled branches. Both low- and medium-voltage SSCBs are implemented, ranging from 500&#x00A0;V&#x002F;300&#x00A0;A to 2&#x00A0;kV&#x002F;1&#x00A0;kA. The power density achieves 37.8&#x00A0;kW&#x002F;L at 500&#x00A0;V&#x002F;1&#x00A0;kA. Experiments demonstrate that the reverse voltage reaches 4.88&#x00A0;kV with an ultrafast interruption speed of 24&#x00A0;&#x03BC;s for 2&#x00A0;kV&#x002F;1.144&#x00A0;kA fault current including the MOV conduction time interval.

Research on current limiting solid state circuit breaker for DC microgrid

In order to reduce the breaking pressure of solid-state circuit breaker when removing DC fault and improve the ability of restraining fault current, a current limiting solid-state circuit breaker topology is proposed. Compared with the traditional current limiting solid-state circuit breaker, this structure has certain advantages in cutting off the fault line speed and restraining the fault current. It is suitable for DC microgrid with fast development speed and high amplitude of fault current. In this paper, the blocking process of the topology is analyzed theoretically, and the design method of relevant parameters and energy consumption calculation are given. In order to verify the feasibility of the scheme, a simulation model is built in saber software. The simulation results show that the proposed structure can suppress the rise rate of fault current by 53.9%, and shows excellent performance in fault isolation speed.

Study and Analysis of Different Types of Circuit Breaker

Circuit breakers play an important role in an electrical system performance in terms of system safety, control, maintenance and cost. In some cases, the conventional mechanical circuit breakers (MCB) may be too slow for the electrical network to operate within the desired safety limits. Besides their other limitations, the MCB also forces the network elements to be rated much higher. The uses of power semiconductor devices to overcome some of their limitations are discussed in this paper. These usages are in terms of solid state circuit breaker (SCB) and hybrid circuit breaker (HCB) concepts. This paper summarizes and reviews the various circuits of SCB and HCB available in the literature. The relevant simulation results for some example circuits have also been presented in this paper. This study will provide a useful framework and point of reference for the future development of HCB and SCB technologies. The breaker can not only open a circuit in response to a current spike, but can also react to a sustained moderate current draw, just above its rated current. Operation of the circuit breaker is simple, but utilizes complex mechanisms. Essentially there are to main internal mechanisms; the trigger and the switch. The trigger is the device that senses the abnormal current load. A sharp spike in current will cause a magnetic field to form in the trigger, releasing the switch. A slightly elevated, but more constant current draw through the breaker will cause the bi-metal composition of the trigger mechanism to deflect in an arc like manner, which is also capable of releasing the switch. The circuit breaker's best point is that the device is effective and compact. The switch can be set to open or closed from the outside of the breaker's case, but can only be set to the tripped position internally, as a results of the trigger mechanism. Once the breaker has been tripped internally, it must be reset externally by switching it off, and then back on. The features enable the breaker to do several jobs at once, eliminating the need for multiple elements in the circuit. For example, it provides the user with an easily assessable on/off switch, fault protection against current spike, and fault protection against heavy current draw. On the other hand it is not 100% effective and must also be manually reset which can be problematic if it is dark and no lights are available with which to see the fuse box. Another bad point is that the circuit breaker has many moving parts, which complicates construction. Simpler or fewer parts might drive cost down and make manufacturing more efficient.

A Novel Thyristor-Based Bidirectional SSCB With Controllable Current Breaking Capability

In view of low conduction loss and low cost, thyristors are good candidates for configuring solid-state circuit breakers (SSCBs). However, due to the half-controlled characteristic of thyristors, it is difficult for the thyristor-based SSCBs (TCBs) to achieve a fully controllable current breaking capability. In this article, a novel bidirectional TCB is proposed, which can fully control the current breaking process with simple structure and control strategy. Besides, the proposed TCB can break current without creating current surges to the source and load, thereby enhancing the reliability of direct current systems. Typical advantages of high power efficiency and low cost can also be obtained from the novel topology. Operation process and circuit design of the proposed TCB are presented. The effectiveness of the proposed solution is verified by the experimental results.

Fault control and line protection strategy for LVDC microgrids based on modified high-frequency-link DC solid state transformer

Fault current with high amplitude and rate of change, together with the vulnerability of electronic devices, poses a great challenge to the line protection in low voltage DC (LVDC) microgrids. A fast fault control and protection method are proposed for LVDC microgrids, based on the modified topology of the high-frequency-link DC solid state transformer (DCSST). By installing two bidirectional antiparallel thyristors in the DCSST and isolation devices at the interface converter side, the freewheeling diodes are protected and current zero-crossings occur due to the submodule capacitor discharge during the fault. Then the line protection could be realized by improved current differential protection, and the mechanical circuit breaker can be tripped around current zero-crossings. It alleviates the high requirement for fast tripping devices (such as solid-state circuit breakers) and fault identification within several milliseconds. The scheme combines the converter fault control with line protection to ensure slow but more economic and reliable fault identification for LVDC grid protection. The proposed strategy is verified by PSCAD/EMTDC simulations and the results show that the fault-tripping-recovery process only takes few tens of milliseconds.