Solid-state Circuit Breaker Research Articles

Cascaded SiC JFET Topology for High-Voltage Solid-State Circuit Breaker Applications

With evolving landscape of direct current (DC) power transmission and distribution, a reliable and fast protection against faults is critical. High performance DC solid-state circuit breakers (SSCBs) can be designed using silicon carbide (SiC) junction field-effect transistors (JFETs), which utilize the device's intrinsic normally-ON characteristic and low ON-resistance. However, for SSCB that require high-voltage (HV) blocking capability, a proper number of JFETs need to be connected in series to achieve the desired voltage blocking rating. It has been conventional to add a controlling normally-OFF transistor, such a metal-oxide-semiconductor field-effect transistor (MOSFET), resulting in a circuit with normally-OFF behavior. However, disparities both in the voltage rating and in the ON-resistance between MOSFETs and JFETs tend to complicate the circuit design, and physically, they may lead to serious localized thermal stresses. A significant challenge remains with ensuring equal voltage balancing across the JFETs during the switching transitions as well as the blocking stage as it is crucial to prevent permanent damages from over-voltage stresses. Therefore, this article presents a new switch topology, in which a cascaded JFET configuration is operated without using a control MOSFET or other added control device. The dynamic voltage balancing network to synchronize both the JFETs' turn ON and OFF intervals is described analytically. Moreover, a novel static voltage balancing network is proposed to establish equal sharing of the total blocking voltage across the series connection of JFETs while maintaining low power loss.

Low-Voltage dc System Building Blocks: Integrated Power Flow Control and Short Circuit Protection

Low-voltage direct current (LVdc) systems are a promising technology for systems with a high penetration of renewable sources and storage that operate with bidirectional power flow. In this article, a fundamental building block for LVdc is presented for different applications, such as charge controllers, voltage regulation in street-lighting systems, and current limiters in meshed dc grids. The developed building block integrates a solid-state circuit breaker (SSCB) and partially rated power flow control converter (PFCC) capable of achieving the given control objectives with extremely high system efficiency and full short circuit protection.

Smart Plug 2.0: A Solid-State Smart Plug Device Preventing Fire and Shock Hazards

Electrical faults cause fire or shock hazards in homes and offices. Flexible power cords are particularly susceptible to metal or insulation degradation that may lead to a variety of electrical faults. This article introduces a new Smart Plug 2.0 device which offers all-in-one protection against short-circuit, overload, arc, and ground faults in addition to the wireless power control and monitor function of conventional smart plug devices. It offers microsecond-scale time resolution to detect and respond to a fault condition, and significantly reduces the electrothermal stress on household electrical wires and loads. A new arc fault detection method is developed using machine learning models based on load current <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">di/dt</i> events. Comparing to other solid-state circuit breaker designs which typically respond to overcurrent conditions only, Smart Plug 2.0 integrates additional protective functions into the same hardware structure with minimal cost penalty. A 120 V/10 A solid-state Smart Plug 2.0 prototype using power <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">moseft</small> s is designed and tested. It has experimentally demonstrated the comprehensive protection features against all types of electrical faults.

Monolithic Bidirectional WBG Switches Rekindle Power Electronics Technology [Expert View

There are numerous mass volume power applications where it is necessary to control the flow of bidirectional power, including electric vehicles (vehicle to grid, vehicle to home, and vehicle to vehicle), distributed and grid-tie power systems using regenerated energy and/or energy storage components, and solid-state circuit breaker protection. Silicon carbide (SiC) and gallium nitride (GaN) based bidirectional power switches can enable these applications with their compelling advantages of high efficiency, high blocking voltage capability, and low system weight and volume. In particular, monolithic switches that allow for bidirectional symmetric conduction and voltage blocking with a chip area close to that of a similarly rated unidirectional switch are ideally suited to fuel a revolution in power electronics technology.

A Novel Oscillating-Commutation Solid-State DC Breaker Based on Compound IGCTs

Medium voltage dc system has fast rise rate in the event of a short-circuit fault. To avoid high-peak fault current, it is necessary to configure dc circuit breaker with fast operation. Solid-state dc circuit breaker has short breaking time and high reliability, which is suitable for Dc system. In this letter, a novel oscillating-commutation solid-state dc circuit breaker based on compound integrated gate-commutated thyristors (IGCTs) is proposed. By combining IGCTs with different advantages, such as high current breaking and high withstand-voltage capability, the proposed dc breaker has the advantages at less breaking time, high performance, low cost, and small volume. The working principle of the proposed scheme is described in detail, and an 8 kV prototype with 7 kA current breaking ability is built to verify its feasibility.

Fast Y-Type Thyristor-Based DC SSCB Using Complementary Commutation in a Capacitor–Capacitor Pair Structure

This article proposes a new thyristor-based dc solid-state circuit breaker (SSCB) named Y-type. Main contributions focus on a new complementary commutation circuit including a capacitor–capacitor pair, which features three remarkable advantages. First, a fast commutation is achieved using a countercurrent pulse injection by the capacitor–capacitor pair structure. Second, metal-oxide varistors (MOVs) are disconnected from the power line when SSCB is <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> , which solves the reliability issue due to the MOV degradation and enhances the voltage utilization rate of the main switch. Third, benefiting from the capacitor–capacitor pair structure, reliable reclosing and rebreaking are obtained for practical applications. Experiments are conducted on a 400 V/120 A prototype to validate the proposed Y-SSCB. The peak voltage on the main and auxiliary thyristors reaches 773 and 400 V, respectively. Also, the peak voltage on the auxiliary capacitors pair reaches 740 and 400 V. The Y-SSCB achieves a fast reaction time of 80 μs in interrupting 120 A short-circuit fault current.

Fast protection strategy for monopole grounding fault of low-voltage DC microgrid

• This paper presents a low-voltage DC microgrid ground short-circuit fault protection system based on positive channel metal oxide semiconductor (PMOS). • In case of ground short-circuit fault in DC microgrid, the coupling energy of the short-circuit current makes the PMOS to be turned off reliably. • In addition, because the primary inductance of the transformer plays a certain current limiting role, the turn-off current of PMOS will not increase sharply. Low voltage DC microgrid has attracted more and more attention in smart grid with its advantages such as low network loss, large transmission capacity and easy direct access to distributed power supply. However, compared with the traditional AC microgrid, the DC microgrid lacks inertia support and the fault develops rapidly, which makes the existing short-circuit current protection technology difficult to meet the requirements of accurate and efficient troubleshooting. Therefore, this paper presents a low-voltage DC microgrid ground short-circuit fault protection system based on positive channel metal oxide semiconductor (PMOS) self-powering DC solid-state circuit breaker protection elements, and verifies the feasibility and effectiveness of the protection system through simulation experiments. The experimental results show that the proposed protection system based on solid state circuit breaker will not affect the voltage of DC microgrid when it is normally on; In case of ground short-circuit fault in DC microgrid, the coupling energy of the short-circuit current makes the PMOS to be turned off reliably. In addition, because the primary inductance of the transformer plays a certain current limiting role, the turn-off current of PMOS will not increase sharply. The solid-state circuit breaker can effectively block the fault without a buffer circuit, which has a good application prospect.

Resonant Network-Based MVDC Circuit Breaker Topologies With Fast Current Breaking Capability

This paper presents two improved circuit breaker (CB) topologies based on resonant networks for medium voltage DC (MVDC) applications, such as shipboard power distribution and subsea oil and gas production. The topologies feature simple LC resonant networks that efficiently suppress fault current in just a few tens of microseconds, making them suitable for integration with existing solid-state or hybrid DC CB. Moreover, they also help to minimize the CB energy and reduce (if not eliminate) the requirement for protection devices like surge arresters during fault events. The proposed topologies are first tested using Typhoon Hardware-in-the-Loop (HiL) simulations at 1.2 MW (6 kV, 200 A) power levels and thyristor-based solid-state circuit breakers (SSCB). Then, scaled-down laboratory prototypes, also based on thyristor-based SSCB, are experimentally validated. The results show that both topologies quickly bring the current of the CB’s main switch to 0 A. The main circuit pathway requires only a small inductor and switch, resulting in a steady-state efficiency of >99.9%. The resonant network-based design allows for a fast response time of less than 50 μs using a simple and low-cost auxiliary circuit, eliminating the need for complex charging circuitry and protection devices typically used to suppress voltage surges during faults.

Protection of DC Microgrids Based on Complex Power During Faults in On/Off-Grid Scenarios

The DC microgrid is an effective platform for integration of renewable energy sources, energy storage systems, and smart electronic loads. However, the integration of distributed generators can result weak fault currents with change in its direction during fault conditions, which lead to failure of conventional over-current relays with poor coordination. The above scenario may exhibits relay mal-operation and force the DC microgrid into blackout mode which is extremely undesirable. Thus, this paper proposes an complex power concept (real and imaginary), which can be extracted using Fast Fourier Transform (FFT) to construct the effective protection schemes for rapid short-circuit fault detection and fault isolation in a DC microgrid. To achieve fault isolation, solid-state DC circuit breakers are used in conjunction with proposed real and imaginary power, which is extracted from the total FFT power signal (i.e. by using bus voltage and line current). Further, the relay trip threshold value for real and imaginary power is also determined under various pole-pole (P-P) and pole-ground (P-G) fault scenarios in the DC microgrid. The proposed protection scheme is validated on simple and modified IEEE 9-bus DC microgrids under various P-P and P-G fault scenarios during On/Off-Grid modes through MATLAB/Simulink software. The simulation results reveal that the proposed protection scheme based on real and imaginary power has accurately identified the fault in the simulated DC microgrids. Thus, the proposed complex power based fault identification approach can be quite effective for protection of DC microgrids during On/Off-Grid scenarios.

SiC JFETs Modular Cascaded Method with Active Clamp Control Strategy for DC Solid-State Circuit Breaker

SiC JFETs Modular Cascaded Method with Active Clamp Control Strategy for DC Solid-State Circuit Breaker

Oscillation Issue and Solution for Solid-state Circuit Breaker Using High Power IGBT Module

Oscillation Issue and Solution for Solid-state Circuit Breaker Using High Power IGBT Module

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 Current Limiting Strategy for WBG-Based Solid-State Circuit Breakers With Series-Connected Switching Cells

The current limiting function enables the solid-state circuit breaker (SSCB) to have proper protection coordination. It allows sustained overcurrent for a certain period while preventing the fast fault current increase in dc systems. For the conventional method of using switches alone to limit the current, the high loss results in a short withstand time and low current limiting capability of the SSCBs. In this letter, a control strategy is proposed to utilize the energy absorption component to handle the major part of the energy during the current limiting stage to increase the current limiting capability for series-connected SSCB switching cells. The proposed method is experimentally verified to have more than 3X current limiting withstand time compared to the conventional control strategy in a case study.

A Modular Bidirectional Solid-State DC Circuit Breaker for LV and MVDC Grid Applications

Direct current (dc) microgrids are increasingly gaining attention in industrial applications due to their simpler and more efficient integration with renewable energy resources and energy storage elements. The dc grid demands a faster, compact, cost-effective, and fault-tolerant protective system for reliable operation. To address the above challenges, this article proposes a bidirectional solid-state dc circuit breaker topology that guarantees reliable operation of dc grids [low voltage dc (LVDC) and medium voltage dc (MVDC)]. A modular extension of the proposed circuit breaker is also presented, resulting in better reliability, scalability, and fault-tolerant operation. The circuit breaker is derived using power semiconductor devices [silicon-controlled rectifiers (SCRs) and insulated-gate bipolar transistors (IGBTs)], with SCR acting as a main power interruption device. Salient features of the proposed topology include modularity, use of low-power rated devices, low-current rated sensors, and pre-fault interruption. A detailed mathematical analysis validating the design and operation of the proposed modular circuit breaker is presented. Moreover, the article also highlights the merits and limitations of the proposed concept. Finally, a laboratory prototype is developed with a system specification of 400 VDC/14 A to validate the performance of the proposed circuit breaker with single and modular operations, which is in line with the obtained simulation results. To verify current sharing between the modules, a few non-ideal conditions such as the use of non-identical main SCRs and turn-on delay are considered and tested on the developed prototype.

A Power-Electronics Free Protection Device for Superconducting Electrical Propulsion Aircraft

Research into developing cryogenic protection devices for superconducting electrical systems is lacking. One of the few investigations was of cryogenic switches in the form of a solid-state circuit breaker (CB). It was reported that these breakers would take up nearly 40% of the superconducting electrical system mass and losses. This article designs a cryogenic switch, free of power electronics, whose conduction loss is only 4.1% of a comparable solid-state CB’s total loss. Protection considerations of a 1-kV/40-MW cryogenic system are referred to validate its application in a superconducting electrical powertrain. The designed cryogenic switch’s dc and ac interrupting ability were verified by experiments to interrupt 750-V/1500-A dc and 1-kV/6.3-kA ac, very close to the dc and ac limits of the proposed 40-MW Center for High Efficiency Electric Aircraft (CHEETA) system. For fault conditions, a noninductive pancake resistive superconducting fault current limiter unit was designed to help with the unacceptable fault current. The 750-V/10-kA prospective current was suppressed to 1.4 kA in 588 <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> and interrupted by the switch in 12 ms. Cooperation of the cryogenic switch and superconducting fault current limiter shows potential in dealing with fault currents in future electric aircraft.

Controlled Bidirectional DC Circuit Breaker With Zero Negative Current for High Load Shift Applications

Global electricity generation by renewable energy sources and the electrification of the transportation system are gaining more importance to mitigate climate change. The dc system plays a significant role in these developments. To protect dc systems, dc circuit breakers with advanced technology are required that are fast and reliable. Various solid-state dc circuit breakers, such as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Z$</tex-math></inline-formula> -source and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$T$</tex-math></inline-formula> -source circuit breakers, have been presented in the literature to meet the dc system demand; however, these topologies suffer from limitations such as high conduction loss, complexity in design, no physical isolation, and presence of negative current flow in load during reclosing. To overcome the aforementioned limitations, a bidirectional solid-state dc circuit breaker (BD-SSCB) that detects the overload or short-circuit faults and responds instantaneously to mitigate the fault current has been proposed in this article. The controllable shutoff function is much needed in applications where sudden load change occurs continuously during the normal operation, such as varying acceleration of an electric vehicle. The proposed BD-SSCB is validated using spice simulations and hardware experiments with varying system parameters for a system rating of 400 V/10 A.

A Bidirectional MVDC Solid-State Circuit Breaker Based on Mixture Device

The mixture unidirectional solid-state circuit breaker (SSCB) based on transistor-based devices [i.e., IGBT-based line commutation switch (LCS)] and the thyristor-based devices can combine their respective advantages, however, the conduction loss and cost may increase significantly when expanding to a bidirectional topology because the number of IGBTs had to be doubled with the expansion of unidirectional LCS structure to bidirectional LCS structure composed of two groups of IGBTs in reverse series. In this letter, a full-bridge mixture bidirectional SSCB (FB-MSSCB) requiring only one unidirectional LCS is proposed, the required number of IGBTs can be reduced by at least half compared with other mixture bidirectional SSCB topologies in the same voltage and current level applications. As a result, the FB-MSSCB has advantages of more economic design and higher efficiency, the conduction loss can be reduced by at least 23.3% in 10 kV MVdc system, while retaining other advantages of mixture bidirectional SSCB, such as the ability to actively interrupt bidirectional fault currents, without introducing additional thyristors, charging power supply, and charging strategy. The working principles and designing guidelines is presented in detail. The feasibility and effectiveness are verified by experiment results and comparative analysis.

Unclamped Inductive Switching Robustness of SiC Devices With Parallel-Connected Varistor

Unclamped inductive switching (UIS) robustness of SiC devices with parallel-connected varistor was evaluated to design the cutoff current capability of solid-state circuit breakers (SSCBs). Because the operation of UIS tests is similar to that in the interruption of SSCBs, UIS tests of SiC devices without varistor and with a parallel-connected varistor were implemented. It was found that the cutoff current of SiC devices with the varistor was much larger than that without varistor. The effect of varistor on the increase of cutoff current depended on the device type and rating current. The cutoff current was 3–6 times higher for planar MOSFETs and 5–10 times higher for trench MOSFETs compared with no varistor condition. In contrast, the effect of varistor for JFET was small because the gate drive condition strongly affected the current switching time from SiC-JFET to varistor. The index of rating current for cutoff current capability was changed by parallel varistor connection because the destruction mechanism of SiC devices was changed because of the change in self-heating timing during the UIS.

Modular Bidirectional Solid-State DC Circuit Breaker for Next-Generation Electric Aircrafts

The design of electric power systems (EPSs) for the aviation industry has become a major research area to reduce the global annual CO2 emission caused by the transportation sector. DC power distribution is envisaged to meet the high load demand of more-electric and all-electric aircraft power architectures. Nonetheless, the development of dc distribution is significantly impeded by the challenges associated with dc system protection. Aircraft EPS demands high speed and high current protection. Among various dc circuit breaker (DCCB) technologies, solid-state dc circuit breakers (SSCBs) operate at higher speeds. To make them withstand high current ratings, modular structured DCCBs with the highest power density, reliability, and bidirectional fault interruption capability are presented in this article. The existing DCCBs fail to comply with the design constraints such as faster response, high current breaking, and compact design. This article proposes a coupled inductor-based modular bidirectional SSCB that employs the magnetic coupling principle for counter-current commutation of thyristors. The proposed modular SSCB exhibits a fast fault interruption time of approximately 200 <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> . The analysis, design, and experimental validation of the proposed SSCB are presented in detail. Each module in the prototype is designed for a system rating of 270 V/15 A. The performance of this SSCB for single- and two-module operations is experimentally verified for a 270-V/20-A dc system.

Smart Grid Performance Improvement with AC Solid-State Circuit Breaker having Charging and Rebreaking Capabilities

Although traditional electromechanical circuit breakers have a proven track record as efficient and reliable circuit safety devices. Emerging power distribution technologies and architectures such as DC microgrids require advanced breaking performance characteristics (e.g., higher switching speed). The need for faster switching coupled with modern developments in advanced power semiconductor technologies has fueled the growth of semiconductor circuit breaker research and development. The current AC SSCB is a rectifier of silicon which needs auxiliary mechanical devices to accomplish their closure before blame recuperation. Moreover, the new AC SSCB can achieve quick turnoff, after which it can be turned back on without an alternate mechanical device or complicated control, even in a permanent short circuit. In this case, the commutation capacitors are fully charged without auxiliary or main thyristor control. The design and simulated results of a single-phase SSCB are used in this study first to illustrate the execution features of the AC SSCB, followed by the use of three-phase models and results. A flowchart for circuit design is also provided for your convenience.