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A thermally driven, micrometer-scale switch technology has been created that utilizes the ErH3/Er2O3 materials system. The technology is comprised of novel thin film switches, interconnects, on-board micro-scale heaters for passive thermal environment sensing, and on-board micro-scale heaters for individualized switch actuation. Switches undergo a thermodynamically stable reduction/oxidation reaction leading to a multi-decade (>11 orders) change in resistance. The resistance contrast remains after cooling to room temperature, making them suitable as thermal fuses. An activation energy of 290 kJ/mol was calculated for the switch reaction, and a thermos-kinetic model was employed to determine switch times of 120 ms at 560 °C with the potential to scale to 1 ms at 680 °C.

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Power quality and reliability are of great importance in the modern world, whether it be the power generated by the power utilities or the power consumed by the customer respectively. They need these supplies to be at its optimum value so that the cost is effective, and the safety of devices assured otherwise problems such as overvoltage, under-voltage, and voltage sags caused by disturbances in the power supply could be disastrous. On-load tap changers (OLTC) have therefore been used since the inception of electrical engineering. The main function of the OLTC is to change the turns of the transformer winding so that the voltage variations are limited without interrupting the secondary current.The major idea is that the electronic switches and other smart systems provide more controllability during the tap changing process, unlike mechanical switches.This paper presents an alternative design and implementation of a low-cost solid-state OLTC and employs a control strategy that is microcontroller-based, ensuring the desired flexibility and controllability required in programming the control algorithms.It eliminates the limitations of both mechanical and hybrid OLTCs (arcing, slow response time, losses) and is user-friendly (provides an effective communication medium). Voltage regulation is achieved by varying the turns of the transformer winding whiles it is energized, supplying load current and with the tap selection carried out on the primary side. Therefore, this approach provides a less expensive system but ensures the efficiency and reliability of voltage regulation.

The positron source is one of the most important parts of the circular electron–positron collider (CEPC) linear accelerator. The design goal is to obtain a 3 nC bunch charge positron beam from a 4 GeV primary electron beam with an intensity of 10 nC/bunch. In this study, an all-solid-state, high-current pulse power system was developed to drive a flux concentrator to capture positrons by generating a magnetic field with a peak value of 6 T. Based on the inductive load topology circuit, the optimized parameters were designed to generate a pulse current with a high peak value and a high rise rate pulse current. In addition, a non-reverse voltage was realized to protect the solid-state switch components. For the characteristics of the long-distance transmission between the pulse power supply and the load in the system, the influences of the cable distribution parameters on the pulse were analyzed, and the design of the damping circuit was proposed to suppress the high-frequency ripples of the peak pulse current. An optimized coaxial discharge structure was designed to reduce the stray parameters in the main circuit. The design was verified through simulations and experiments, and the results demonstrated that the developed prototype successfully generated an ideal half-sinusoidal pulse current with a peak value of 15 kA, and a front pulsewidth of $2.5 ~\mu \text{s}$ at a repetition rate of 50 Hz. The pulse repetition stability is better than 0.1%. The final output was consistent with the theoretical analysis. The system can be applied in the CEPC positron source, which also provides a reference for the subsequent development of a positron source system at research facilities. [ABSTRACT FROM AUTHOR]

Hybrid dc circuit breakers (HCBs) usually require a large number of insulated-gate bipolar transistors (IGBTs) with high turn-off capability for series and parallel connections. This requirement entails excessive cost. Compared with IGBTs, integrated gate-commutated thyristors (IGCTs) are another kind of fully controlled power device with high surge current and voltage capability but are low cost. However, the weak turn-off capability of IGCTs hinders their application to high-powered HCBs. On the basis of the complementary advantages of IGBTs and IGCTs, this paper proposes a mixture solid-state switch (MSS) for HCBs that uses the switching action of several IGBTs to create a low-current condition that favors the turning off of large-scale series-connected IGCTs. The MSS topology can significantly reduce cost while maintaining the excellent performance of traditional solid-state switches. This study also introduces two different turn-off modes for MSS, namely, single oscillation and multiple oscillations. Finally, 25 kV/20 kA prototypes in both modes are developed to verify the effectiveness of the MSS topology. [ABSTRACT FROM AUTHOR]

Due to safety and reliability concerns, high-voltage solid-state switch is required for electron cyclotron resonance heating system on J-TEXT Tokamak. It cuts off the power supply within a little time usually in microseconds, when a fault occurs. At present, wide-bandgap semiconductors based on silicon carbide (SiC) show superior material properties enabling potential power device operation at higher voltage, current, and switching speeds than current silicon (Si) semiconductors. SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) are considered to be a better solution for the basic component of the switch than Si insulated gate bipolar transistors (IGBTs). To solve the problem of voltage balancing in series-connected MOSFETs, a submodule with four, 1.7 kV/40 A rated MOSFETs in series has been developed and experimentally tested. A voltage-clamped snubber circuit is designed to control the overvoltage of each MOSFET. The turn-off performance of the proposed circuit and traditional circuit has been compared by simulation, and the submodule has also been evaluated in a dual-pulse test. Finally, the solid-state switch with 16 submodules in series has been tested by a dummy load. The experimental results show that switch can operate successfully, and the switching performance satisfies the anticipated demand. [ABSTRACT FROM AUTHOR]

The eco-mode provides a high-efficiency operation for the double-conversion uninterrupted power supplies (UPSs). Such a mechanism utilizes the solid-state transfer switch (STS) path to power the susceptible loads, and it relies on the converter as an alternate resource when the abnormal grid occurs. The thyristor-based STS system has the advantage of low conduction loss, but the natural commutation often prolongs the overall transfer process. Consequently, the susceptible loads suffer from severe grid faults for a long time. This article investigates the commutation mechanism between the thyristor-based STS system and the double-conversion UPS. A forced commutation control is presented to accelerate the transfer process through the back-to-back neutral-point clamped (BTBNPC) converter. Besides, the waveform qualities and the dynamics of both ac and dc ends are considered for the BTBNPC converter. Finally, the laboratory test results are provided to validate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

At present, it is usually necessary to use fast recovery type diodes to cooperate with the fast switching actions of fully controlled devices such as insulated-gate bipolar transistors (IGBTs). However, the specific nature of the working conditions of the diode-bridge bidirectional solid-state switch (DBSS) provides an opportunity to apply standard recovery diodes for this purpose, which helps to reduce the cost of the bidirectional switch. This letter presents the self-oscillation phenomenon that is caused by the recovery processes of the diodes in a DBSS. Then, the recovery effects of these diodes in different topologies are analyzed from the perspective of the DBSS and optimized designs for both the snubber circuit and the energy-absorbing circuit are proposed. A 500-kV dc breaker is realized based on the proposed DBBS using the standard recovery diodes, which can work reliably with IGBTs, and the cost of the resulting dc circuit breakers is greatly reduced. [ABSTRACT FROM AUTHOR]

A simple and flexible method to realize a discharge-pumped CO2 laser using a fast high-voltage solid-state switch is presented. A longitudinal excitation scheme that implements this simple configuration has been adapted. A fast high-voltage solid-state switch consisting of an avalanche transistor and commercially available series-connected IGBTs is coupled with a compact laser tube filled with CO2 gas to provide the excitation energy. Laser oscillation has been demonstrated successfully and has produced several millijoules of output energy. [ABSTRACT FROM AUTHOR]

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.

A smart Watt-hour meter with load balancing function is designed by taking STC90C51RC single-chip microcomputer as the slaver and using solid state switching technology. It can achieve three-phase equilibrium by changing load access phase when three-phase loads are unbalanced. The slaver realizes the commutation operation in the continuous power supply condition through controlling thyrister and relay; it communicates with electric energy metering chip RN8209 to read the user information including power, voltage, current, frequency and so on in order to record and analyze the loads and power quality. The STC12C5A60S2 is used to transmit control information through MAX485 to control the slaver, and collect the information of all slavers and process the data. The effectiveness of the smart meter load balancing function is verified by experiments. [ABSTRACT FROM AUTHOR]

This paper describes a high-frequency pulsed-power generator for various industrial applications such as water treatment, food and medical apparatus for sterilization, or polluted gas treatment. The system is made of silicon-controlled rectifier as a main trigger switch, capacitors, two-stage magnetic pulse compression stages, and a linear transformer to generate a maximum of 120-kV, 5-kA pulse. The parameters obtained through the development are: output voltage: 120 kV (maximum), pulse repetition ration: 300 pulse per second, pulsewidth: 0.25~\mu \texts , and mean power: 30 kW. The designed pulsed-power generator is confirmed to be used effectively for many high-voltage pulsed-power applications related to environmental industry by simulation and experiments. [ABSTRACT FROM AUTHOR]

The series configuration of fast semiconductor switches seems to be the key component in the high-voltage and fast rising time pulse generation. In this approach, two important issues must be considered. The first is to provide a safe operating condition for the switches in transient intervals. The second is to design a gate drive system with the capability of driving a large number of discrete devices simultaneously. The aim of this paper is to obviate these two requirements. First, different factors affecting the unbalanced voltage sharing between the series switches are discussed. In this investigation, the switch-to-ground parasitic capacitance effect has been recognized as the major effect on the unbalanced voltage sharing in the transient interval. Two schemes for abating this effect are proposed. To solve the unbalanced voltage distribution, the structure with a snubber circuit in the clamp mode operation is suggested. This scheme can be used for any number of switches without destructively affecting their behavior. In addition, the output pulse with a fast rising time could be obtained by the proposed gate drive system. In order to evaluate the operation of the proposed structure, a stacked switch with the voltage capability of 36 kV is tested experimentally. The characteristics of the obtained pulse are the fast rising time (69.5 ns) with the dV/dt of 460 kv/ \mu \texts and the wide range of the pulsewidth adjusting to 0.5–15 \mu \texts . In addition, the voltage variance of the switches level in the series structure is about 10%. [ABSTRACT FROM AUTHOR]

This paper describes a multiterminal DC compact node consisting of voltage-source converters and DC-DC converters as a promising arrangement to feed electric vehicle (EV) charging stations with renewable power sources. This research analyzed the behavior of the node currents under DC faults, and more specifically their natural response, which can produce challenging electrical protection requirements. An electrical protection system was thus designed based on the use of protective devices that included protective relays, solid state circuit breakers and hybrid circuit breakers. These protective devices monitor local readings to detect and isolate DC faults as quickly as possible. This highlighted the fact that there are devices, available on the market, that comply with the fast response requirement to prevent damage or destruction of the converters and filter capacitors of the node. [ABSTRACT FROM AUTHOR]

This paper combines an unbalanced Blumlein-type multilayered microstrip transmission line with solid-state switches to develop a high-voltage nanosecond pulse generator. This study was performed to emphasize the importance of a compact nanosecond pulse generator for biomedical applications. The unbalanced Blumlein-type transmission line reduces current flow through the solid-state switches. A multilayered microstrip transmission line is stacked onto the four-layered printed circuit board to minimize the system volume. Voltage wave propagation analysis is used to explain the principle of the system, which produced a rectangular pulse. The strategy to produce different pulse widths and the controlled timing of the related solid-state switches is interpreted according to this analysis, highlighting the approach needed to achieve a 50–100 ns pulsewidth. Also, the relevant principle of the variable load impedance of the unbalanced Blumlein-type multilayered microstrip transmission line system is also analyzed. To demonstrate the performance of the generator, a miniaturized system is established. Eventually, the nanosecond pulse generator produces a rectangular pulse on a resistor load of 50 $\Omega $ , with amplitude of 0–2 kV, pulsewidth of 50–100 ns, rise time of approximately 20 ns, and repetition frequency of 0 to several kilohertz. Also, when a 500 $\Omega $ resistor is used instead of a 50 $\Omega $ resistor, the output of the nanosecond pulse voltage is approximately two times that of the applied charging voltage. [ABSTRACT FROM PUBLISHER]

We developed a solid-state switch with static induction thyristors for the klystron modulator of the L-band electron linear accelerator (linac) at the Institute of Scientific and Industrial Research, Osaka University. This switch is designed to have maximum specifications of a holding voltage of 25 kV and a current of 6 kA at the repetition frequency of 10 Hz for forced air cooling. The turn-on time of the switch was measured with a matched resistor to be 270 ns, which is sufficiently fast for the klystron modulator. The switch is retrofitted in the modulator to generate 1.3 GHz RF pulses with durations of either 4 or 8 μs using a 30 MW klystron, and the linac is successfully operated under maximum conditions. This finding demonstrates that the switch can be used as a high-power switch for the modulator. Pulse-to-pulse variations of the klystron voltage are measured to be less than 0.015%, and those of RF power and phase are lower than 0.15% and 0.1°, respectively. These values are significantly smaller than those obtained with a thyratron; hence, the stability of the main RF system is improved. The solid-state switch has been used in normal operation of the linac for more than a year without any serious trouble. Thus, we confirmed the switch’s robustness and long-term reliability. [ABSTRACT FROM AUTHOR]

A fault detection and isolation scheme for low-voltage dc-bus microgrid systems is presented in this paper. Unlike traditional ac distribution systems, protection has been challenging for dc systems. The goals of the proposed scheme are to detect the fault in the bus between devices and to isolate the faulted section so that the system keeps operating without disabling the entire system. To achieve these goals, a loop-type dc-bus-based microgrid system, which has a segment controller between connected components, is proposed. The segment controller consists of master and slave controllers that monitor currents and control the segment separation, which include solid-state bidirectional switches and snubber circuits. The proposed system can detect faults on the bus regardless of fault current amplitude or the power supply's feeding capacity. The proposed concepts have been verified by OrCAD/PSpice simulations and experiments on hardware test bed. [ABSTRACT FROM PUBLISHER]

This paper proposes a simple enough yet challenging lab setup illustrating the application of power electronics to power system devices through a thyristor-assisted under-load tap changer. After a preliminary analysis of the special switching concepts involved in this application, a thorough description of the main steps comprising the proposed experiment is carried out. This lab setup has been included in the electrical engineering curriculum (major in power engineering) of most senior undergraduate students (fifth year in several European countries). [ABSTRACT FROM AUTHOR]

A thermoresponsive crown ether/amine-type rotaxane switch worked under solvent-free condition was developed. The wheel component moved to switch the local position on the axle by the solid-state acidbase reaction between tert-amine moiety of the rotaxane and trichloroacetic acid. The wheel shuttling on the axle proceeded via neutralization by heating and protonation with trichloroacetic acid, being confirmed by ¹NMR and TGA. [ABSTRACT FROM AUTHOR]

A kind of architecture of optical steering of a phased-array antenna (PAA) based on a fast optical delay-line switch is proposed and experimentally studied. A 4-bit fast optical delay-line switch with switching speed of less than 30 μs is constructed using cascaded solid-state optical switches. A distributed feedback laser integrated with electro-absorption modulator is employed for radio-frequency feeding and delivery. Our experimental system of transporting X-band microwave signals over one antenna element shows a signal-to-noise ratio better than 55 dB and low crosstalk of less than -50 dB. The structure features a compact design, a low-cost solution, a fast tilting speed, and true-time-delay beam steering. The proposed scheme of optical steering is very promising for wideband X-band PAA applications. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1449–1452, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21631 [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• The switching-off features between SiC MOSFETs and Si IGBTs are compared. • A 40 kV/20A solid-state switch based on SiC MOSFETs with voltage-clamped snubber circuits are designed and tested. • The verification of the switch in ECRH operational conditions is reported and discussed. Cathode power supply provides high voltage and large energy for electron gyrotron on J-TEXT tokamak. When faults (e.g. internal arc fault) happen on electron gyrotron, the power supply should interrupt within few tens of microseconds. Although the cathode power supply could switch off quickly by itself, frequent failures could decrease the reliability of the power supply without additional protection measures. For the safety of electron cyclotron resonance heating (ECRH) system, solid-state switch is necessary in ECRH protection. A design of a 40 kV/20A solid-state switch was proposed in this paper. To improve the switching performance of the switch, the power devices connecting in series was silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET), which replaced traditional solution such as silicon (Si) insulated gate bipolar transistor (IGBT). For the purpose of evaluating and comparing the characteristic of SiC MOSFET and Si IGBT, a dual-pulse test was completed and SiC MOSFET showed the significant advantages. Furthermore, a voltage-clamped snubber circuit was adopted to ensure the voltage balance for each SiC MOSFETs during static and dynamic process. Then, the analysis and validation of the circuit was provided. Finally, the solid-state switch was built and tested by experiment. The results show that the switch works adequately, the switching-off time is 4.7us with 38 kV voltage and 20A current capacity. [ABSTRACT FROM AUTHOR]