Novel Active Snubbers for SSCBs to Improve Switch Voltage Utilization Rate

This paper presents a new ultrafast dc solid-state circuit breaker (SSCB) that uses a silicon carbide cascode as the main switching and limiting semiconductor and an isolated photovoltaic driver to control it. The proposed topology is self-powered and fully implemented with discrete parts. The SSCB's cascode can work in three different states—fully on during nominal operation, linear mode for current limitation, and fully off to disconnect the load. The time the SSCB operates in linear mode and the maximum current limit is easily set by discrete components. Control inputs have also been included to reset the SSCB after a fault has been removed or to remotely switch it on or off . This device can be used in dc distribution avoiding deterioration due to the problems associated with electric arcs and mechanical aging of moving parts, limiting inrush currents and also minimizing conduction losses respect other kind of circuit breakers. Functional, thermal, and efficiency tests have been carried out with three different 380 V prototypes. Experimental results show the excellent behavior of the SSCB, it is able to block a 380 V short circuit failure in 570 ns; the authors have not found any faster results in the literature.

This paper presents a solid state circuit breaker (SSCB) for a low distribution level. When voltage disturbances occurred, the SSCB operates for keeping the system limitations. Power semiconductor devices are compared and selected by using the performances of their devices. SSCB is provided with circuitry for permitting off/on/reset operations actuated by a mechanical toggle control switch for close simulation of magnetic circuit breaker operation. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit, except the static power switch branch, between the source and the load, to provide a high degree of fail-safe protection for the apparatus. The synchronous reference frame is used to detect the current disturbances and control the switches. Simulation results are shown that SSCB offers advantages when compared to present solutions. A switching circuit that is particularly applicable to high voltage 3 phases solid state circuit breakers (SSCB). The circuit comprises a solid state switch; an energy absorbing device connected in parallel with said switch to form a parallel combination; an inductor connected in series with said parallel combination; and a control circuit connected to said solid state switch and adapted to turn off said switch in response to a predetermined voltage/current condition.

Ensuring a protection scheme in a DC distribution system is more difficult to achieve against pole-to-ground faults than in AC distribution system because of the absence of zero crossing points and low line impedance. To complement the major obstacle of limiting the fault current, several compositions have been proposed related to mechanical switching and solid-state switching. Among them, solid-state circuit breakers (SSCBs) are considered to be a possible solution to limit fast fault current. However, they may cause problems in circuit complexity, reliability, and cost-related troubles because of the use of multiple power semiconductor devices and additional circuit configuration to commutate the current. This paper proposes a SSCB with a coupled inductor (SSCB-CI) that has a symmetrical configuration. The circuit is comprised of passive components like commutation capacitors, a CI, and damping resistors. Thus, the proposed SSCB-CI offers the advantages of a simple circuit configuration and fewer utilized power semiconductor devices than the other typical SSCBs in the DC microgrid. For the analysis, six operation states are described for the voltage across the main switches and fault current. The effectiveness of the SSCB-CI against the short-circuit fault is proved via simulation and experimental results in a lab-scale prototype.

Vacuum arc commutation is an important process in natural-commutate hybrid direct current (DC) circuit breaker (NHCB) interruption, as the duration of vacuum arc commutation will directly affect the arcing time and interrupting time of NHCB. In this paper, the vacuum arc commutation model of NHCB was established by simplifying solid-state switch (SS) and vacuum arc voltage. Through theoretical analysis and experiments, the vacuum arc commutation characteristics of NHCB were studied. The mathematical formula of the effect of main parameters on the duration of vacuum arc commutation is obtained, and the changing law of the influence of the main parameters on the duration of the vacuum arc commutation is explored. The concept of vacuum arc commutation coefficient is proposed, and it is a key parameter that influences the vacuum arc commutation characteristics. The research on the characteristics of vacuum arc commutation can provide theoretical foundation for the structure and parameter optimization of NHCB and other equipment that uses vacuum arc commutation.

Increasingly, dc microgrids are attracting attention because of their universality, high efficiency, and potential application market. To enhance the fault protection of dc systems, solid-state circuit breakers (SSCBs) have been developed to perform fast protection. However, there are still challenges including decoupling of the source and load during operation, using the switches of the main path, MOV's reliability, and charged capacitors before reclosing. In this article, three bidirectional dc SSCBs are proposed that address the aforementioned issues using a third switch to bypass the fault current, eliminating the snubber from the power line, not using the main path switches, and placing a snubber that provides a discharged capacitor before reclosing. These also provide the structure extra reliability and increased voltage utilization rate of the switches. These features increase both device and human safety. The working principle and operating modes of these SSCBs along with the equations for calculation of crucial time intervals, voltages, and currents and the design procedure are provided, and the experimental results demonstrate the proper performance of the topology and validate the findings.

This paper deals with techno-economic analysis (TEA) of a 4 kV/100 A medium-voltage solid-state circuit breaker (SSCB). The aim is to find insights into interactions among design, cost, and performance of the SSCB in practical applications. First, the main design components of the 4 kV/100 A SSCB are realized. Second, the cost distribution among the major components is presented which helps to achieve a cost-effective design. Next, the performance of the SSCB is discussed in terms of efficiency, operating speed, power density, modularity, reliability, and lifetime. The results show that the final cost of SSCB is mostly related to the efficiency of the breaker. Also, a comparison between different solid-state silicon carbide (SiC) MOSFET power modules shows that a trade-off between the breaker cost and efficiency is essential in practice.

This paper presents two-stage high-power mechanical-thyristor switches developed as 40-kA direct current (dc) circuit breakers for the superconducting coil energy dump system of Korea superconducting Tokamak advanced research (KSTAR). An advanced switching system used in the quench protection should allow multishot mode of operation without maintenance and long lifetime with arcless dc current commutation. The system is designed to combine the advantages of the both mechanical and solid-state power switches. The mechanical stage is to conduct dc current for normal superconducting coil operation and the thyristor stage is to provide fast arcless dc current interruption for quench protection (QP). Compared with the all solid-state switches and vacuum interrupters of equal capabilities the proposed switch is much cheaper than the dc breakers and has lower power dissipation in current conducting state "Kuchinski in Proc. Power Ele., 899-903, 1995;" "Benfatto IEEE Power Del., Vol. 3, No. 4, pp. 1372-1376, Oct. 1998." Also, it is much faster than the vacuum interrupters. The system is designed to break 40-kA dc current within 200 ms. Also, KSTAR device, a configuration of the energy dump system and coil power supplies are presented

Fast detection and isolation of direct current (DC) faults are key issues for DC grids. Therefore, it is very necessary to study the fault protection principle for DC grids. This paper firstly presents the main difficulties in DC fault protection. Then, a local protection and local action strategy for isolating the DC faults is proposed. To illustrate the performance of the proposed protection strategy, a four-terminal DC grid with the hybrid high voltage direct current (HVDC) circuit breakers (HVDC CBs) is constructed in the time-domain simulation software PSCAD/EMTDC as the test system. The systematical comparison between the ordinary protection strategy and the proposed strategy is carried out. The protection selectivity of the proposed local detection and local action strategy is thoroughly studied through complete DC line fault scanning of the test system. The simulation results show that the proposed strategy is of high protection selectivity and speed. In addition, the current rating and the voltage of HVDC CB could be greatly reduced with the proposed strategy, which proves the economic benefits of the proposed strategy.

For high voltage multi-terminal direct current (MTDC) system using overhead lines for power transmission, such as Zhangbei demonstration project, mechanical direct current circuit breakers (DCCB) with current commutation drive circuit (CCDC) are used to deal with short-circuit DC faults. Considering most of the short-circuit faults occurring to overhead lines are temporary, mechanical DCCB should be capable of auto-reclosing, and this paper is aimed to realize its auto-reclosing function without overcurrent and overvoltage. In this paper, the topology and working principle of mechanical DCCB with CCDC is presented first. Then, the auto-reclosing strategy for mechanical DCCB with CCDC is proposed. By using this auto-reclosing strategy, the permanent fault and the temporary fault could be easily distinguished, and no overcurrent and overvoltage, which might cause damage to vulnerable devices in converters, are produced. In the end, simulation model in PSCAD is established to verify this auto-reclosing strategy.

<title>ABSTRACT</title> <p>Electrical power system upgrades needed to fulfill mission objectives for next generation vehicles will require technology advances such as greater power density, increased functionality, and higher operating temperature. To meet these requirements, electrical power demands will exceed the capabilities of currently available low voltage power systems. High Voltage DC (HVDC) systems, e.g., 270 – 800 VDC, are being considered to meet next generation vehicle requirements, but these electrical power systems have the potential for extremely large fault currents in case of electrical equipment failure. Improved battery safety and intelligent Solid State Circuit Breakers (SSCB) and Solid State Power Controllers (SSPC) are needed to improve mission effectiveness, reliability, and personnel safety of next generation military and commercial ground, air, and sea vehicle electrical power systems. In this paper we present three enabling technologies developed by Creare: (1) an intelligent Battery Management System (BMS); (2) a fast-acting Silicon Carbide (SiC) SSCB; and (3) an intelligent SiC SSPC. All three technologies integrate into existing vehicle communications systems via CAN bus to support emerging system level management tools and power system architectures. Modularity and integration with existing and evolving system architectures is achievable through firmware upgrades, e.g., to support Stryker modernization, VICTORY, JLTV, and GCV architectures. The flexibility of these three key technologies provides advanced capabilities for a variety of applications including military and commercial ground, air, and sea vehicles.</p>

With the ever increasing power demand for next generation aircraft, hybrid propulsion and more electrical systems, fault detection and protection are crucial to flight safety and reliable operations, especially for DC distribution network. Solid State Circuit Breakers (SSCB) using state of the art (SOA) wide bandgap (WBG) semiconductor devices are potential candidates to meet the fast action, high power density and high efficiency requirements for aerospace electrical systems. The objective of this paper is to introduce test methods to evaluate the operation and performance of these fast-acting protection devices. A literature review of the current SSCB technology is included in the introduction, followed by the design phase test criteria. Test circuits and experimental setup for both the dynamic breaking and steady state efficiency evaluations are described in detailed. Fault current interruption capability and to verify efficiency at nominal operating conditions of a medium voltage DC (MVDC) SSCB were demonstrated and verified through the test results.

A Direct Current (DC) circuit breaker (CB) needs to interrupt fault current very quickly to avoid catastrophic system damage. A significant barrier of DC power transmission and distribution is the lack of adequate breakers for fault protection. In this paper, a Gallium Nitride (GaN) switch based Resonance Current Source (RCS) is modeled, designed and tested. The RCS is used for creating an artificial zero current crossing in an vacuum interrupter of a medium voltage Ultra-fast Resonance Direct Current Breaker (UFRDCB). The performance of the RCS has been tested separately and in a hybrid dc breaker system. The high speed operation of the GaN significantly reduced the size and cost of the inductor and capacitor of the RCS circuit. In this application, the voltage rating of the GaN switches required are a fraction of the line voltage and cooling is not necessary for the semiconductors resulting in significantly reduced volume and cost of the breaker. Finally, the performance of the RCS is verified by experiment and test results are presented.

Solid-state circuit breakers (SSCBs) are increasingly employed for overcurrent protection in the emerging DC power distribution systems due to their rapid response time and arc-free interruption capabilities. This research identifies the previously unreported phenomenon of the SSCB's false triggering in voltage source inverters equipped with DC-link decoupling capacitors. These converters demonstrate significant overshoot current and low-frequency oscillations in the DC bus, caused by the discontinuous input current and the RLC responses of the resonant tank formed by the DC-link decoupling capacitance and the SSCB's stray inductance, leading to an unexpected triggering event. A mitigation strategy utilizing an RC bypass circuit is proposed to address this issue. The effectiveness of this method is validated through a double pulse test, demonstrating a 70 % reduction in the DC bus current overshoot, enhancing the operational reliability of SSCBs in particular applications.

With the development of a distributed generation, direct current (DC) load and energy‐storage equipment, voltage‐source‐converter‐based medium‐voltage DC systems (VSC‐MVDC) have attracted more attention due to its low power consumption, high reliability, independent power control and so on. However, VSC‐MVDC has the problem of DC fault isolation, which requires the fast‐acting DC circuit‐breakers to isolate faulty lines and ensure low cost. This problem can be solved by coordinating resistive type superconducting‐fault‐current‐limiter (R‐SFCL) and integrated‐gate‐commutated‐thyristor (IGCT) based hybrid circuit breaker. Based on this, IGCT based superconducting DC circuit breaker (SDCCB) is proposed and analysed. Combining R‐SFCL with IGCT could realise large current limiting and interruption and ensure low cost. In addition, the IGCT based hybrid DC circuit breaker (IGCT‐HDCCB) is compared with the traditional insulated gate bipolar transistor (IGBT) based hybrid DC circuit breaker (IGBT‐HDCCB) to evaluate which circuit breaker is more suitable for VSC‐MVDC. The results show that, coordination based on R‐SFCL and SDCCB, the fault current is successfully limited from 17.6 to 2.1 kA, and then interrupted within 3.8 ms. In addition, IGCT‐HDCCB overcomes the disadvantage that IGCT has less interrupting capacity than IGBT, retains the advantage of low cost of IGCT and is more suitable for MVDC system.

Solid-state high-voltage direct current (HVDC) circuit breaker safeguards the power system of more-electric aircraft against fault transients, within which power components are soldered in print circuit boards (PCB) for operation at low air pressure and limited space. The electric field near the components can be influenced by the insulation polarization, and flashover could be induced at ramp voltage. It is of great significance to study the flashover characteristics of PCBs at ramp and DC voltage. In this paper, PCB layouts with different polygon shapes and insulation distances were prepared and their flashover voltage subjected to different ramping rates were measured at different pressures. The relation between the flashover voltage, gas pressure, surface insulation distance, and ploygon shape was studied. The content of this paper is of great significance for the development of PCB layouts and busbars for use in future aerospace hybrid propulsions.