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This paper will evaluate the surge current robustness of different devices in relation to the active short circuit (ASC). For the purposes of this study, a Si IGBT and its diode, two SiC MOSFETs with different voltage ratings, a SiC JFET, and three GaN HEMTs will be compared. For the GaN devices, a eMode, a dMode, and a cascode device are employed. With the exception of the Si diode, all devices exhibited a current saturation effect. This saturation will result in significant losses and, ultimately, a thermal defect. For all devices, a safe operating area (SOA) criterion is established. For the SiC and GaN devices, the saturation voltage can be employed to define the safe operating area (SOA) criterion. In this context, two on-state resistance models will be defined for these devices. One is solely temperature-dependent, while the other also considers current saturation. Consequently, the saturation voltage and the on-resistance model represent a straightforward methodology for evaluating the ASC robustness of the devices. For all devices, a recommendation for a loss model and SOA criterion will be provided. Finally, the surge current robustness of all devices is compared. The Si, SiC and GaN devices exhibit comparable high surge current robustness in the application, with the exception of the GaN eMode, which is susceptible to strong current saturation. [ABSTRACT FROM AUTHOR]

Efficient management of high-magnitude current spikes during Dynamic Reverse Bias (DRB) reliability testing is critical for early detection of potential issues such as gate oxide degradation in wide bandgap (WBG) devices. This paper addresses the challenges of DRB testing, particularly focusing on current surges caused by rapid dv/dt switching events in WBG devices. Compliance with AQG-324 guidelines, which require a dv/dt of >50 kV/µs, often results in significant current surges due to parasitic capacitance. These surges can reach tens of amperes, leading to excessive self-heating and potentially damaging sensitive measurement circuitry. This study introduces an innovative method to filter out capacitive displacement current spikes without affecting leakage current, reducing surge intensity by over 100 times and enabling efficient DRB testing of up to 1.5 kV WBG devices. The validation process includes simulating a Wolfspeed Power Silicon Carbide (SiC) MOSFET model in LT-Spice and conducting hardware tests on three different 1.2 kV SiC devices from Wolfspeed, Infineon, and Rohm. An optimized PCB design was employed to minimize circuit parasitics, showing good alignment between simulation and hardware testing outcomes.

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper will evaluate the surge current robustness of different devices in relation to the active short circuit (ASC). For the purposes of this study, a Si IGBT and its diode, two SiC MOSFETs with different voltage ratings, a SiC JFET, and three GaN HEMTs will be compared. For the GaN devices, a eMode, a dMode, and a cascode device are employed. With the exception of the Si diode, all devices exhibited a current saturation effect. This saturation will result in significant losses and, ultimately, a thermal defect. For all devices, a safe operating area (SOA) criterion is established. For the SiC and GaN devices, the saturation voltage can be employed to define the safe operating area (SOA) criterion. In this context, two on-state resistance models will be defined for these devices. One is solely temperature-dependent, while the other also considers current saturation. Consequently, the saturation voltage and the on-resistance model represent a straightforward methodology for evaluating the ASC robustness of the devices. For all devices, a recommendation for a loss model and SOA criterion will be provided. Finally, the surge current robustness of all devices is compared. The Si, SiC and GaN devices exhibit comparable high surge current robustness in the application, with the exception of the GaN eMode, which is susceptible to strong current saturation.

The article proposes a new method for the non-destructive measurement of one of the most important maximum permissible parameters of surge current power thyristors. The method is based on continuous control at each moment of time of the dynamic capacitance, the changing in the nature of the time dependence of which predicts the destruction of the semiconductor structure.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The investigation and modelling of the 4H–SiC merged PiN/Schottky (MPS) diode are presented for superior surge current capability design. A bipolar current transmission (BCT) model is proposed for investigating the current transport mechanism of MPS diodes under bipolar operation. The knee voltage (V turn) defining the conversion from unipolar to bipolar operation is precisely modelled for controlling surge current. According to the proposed model, the method of designing a SiC MPS diode with high robustness against surge current is discussed and concluded primarily, which has great significance for improving the reliability of SiC MPS diodes. Meanwhile, we propose a new hybrid stripe cell design according model calculation and simulation for enhancing the surge current capability of the diode while maintaining high forward current capability. The proposed model and design method are verified by experimental results. And the proposed hybrid stripe cell design has superior surge current robustness while it almost avoids the forward current degradation in experiment. [ABSTRACT FROM AUTHOR]

In this article, SiC Merged PiN Schottky (MPS) diodes with hexagonal and circular cell designs are investigated and compared in terms of characteristics and ruggedness. It is demonstrated by experimental and simulated methods that the circular cell design brings better performance than the hexagonal one. Owing to the almost simultaneously triggering of the P+ island and the P+ ring of the circular cell under high current stress, the current distribution is more balanced, which significantly reduces forward voltage (${V}_{F}$) and lower energy-dissipated heat, and further enhances the surge current capability. Moreover, the circular shape can relieve the curvature effect and electric field crowding under reverse blocking conditions, thereby improving breakdown voltage (BV) and avalanche capability. These results suggest that circular cell design can be employed to improve the performance and ruggedness of the SiC MPS diodes. [ABSTRACT FROM AUTHOR]

Electronic systems with extensive underground cable installations are endangered by damage or interference during lightning as a result of current and voltage surges induced in the installations. The paper presents the study on the lightning threat to the electronic intrusion detection system based on underground cable sensors during a nearby lightning strike to the pole of the lighting system installed in parallel with the sensory cables. In the extensive intrusion detection system working in a network composed of several controller-sensor-terminator units, a problem arises whether the neighbouring units should or should not be connected galvanically in order the system is less vulnerable to the effects of a lightning electromagnetic pulse. The problem is complex since the threat level may depend on many factors, i.e. the point of the strike, the lightning current, soil parameters, and configurations of the affected systems. The problem has been studied using numerical simulations based on the electromagnetic field theory and method of moments. The results show that the isolated configuration, i.e. without the galvanic continuity between the units, may be better as far as relatively low soil resistivity and low steepness of the lightning current waveform are considered.

The MOS-controlled Thyristor (MCT) has been characterized by MOS-gating, high current rise rate, and high blocking capabilities. The anode short MCT (AS-MCT) is distinguished from the conventional MCT by an anode-short structure, which forms an extracting path for the leakage current at the gate-ground and develops a normally-off characteristic. The AS-MCTs are ideal switches for pulse discharge application. As a composite structure made of metal-oxide-silicon and bipolar junction transistors, AS-MCT is susceptible to ionization damage. This work reports the experimental results for the degradation of zero-load (or short) pulse discharge circuit characteristics induced by the ionization damage of its AS-MCT switch following cobalt- $60~\gamma $ -ray dose up to 9160 Gy(SiO2). The radiation-induced leakage current in AS-MCT accounts for the degradations of charging time and peak surging current of the pulse discharge circuit. These degradations show a “tick”-like dependence on the $\gamma $ -ray dose which are recoverable after high dose exposures, thousands of Gy(SiO2). From device and circuit physics perspectives, the damages on pulse discharge circuit are modelled, and then, this article proposes, the mechanism behind the characteristics degradation of pulse discharge circuit from the total ionization dose damage of AS-MCT switch.

In this work, Sentaurus TCAD was used to study the transient surge current mechanism of the 4H-SiC merged pin and schottky (MPS) diode. For the first time, a structure combining multicells with transition region was used to analyze the transient surge current mechanism of the MPS diode. The electrothermal simulation analysis of the surge characteristics of the MPS diode is carried out. Internal carrier distribution and lattice temperature in the surge current transient process of the device are mainly studied. The simulation results show that the hole current distribution and the electron current distribution in the MPS diode are not uniform. In the transient process of surge current, the transition region first enters the bipolar conduction mode, and then, the cells in the active region enter the bipolar conduction mode in the order from outside (close to transition region) to inside. The voltage–time (${V}$ – ${t}$), maximum temperature–time (${T}_{\text {max}}$ – ${t}$), and ${I}$ – ${V}$ curves of MPS diode in surge current events are obtained by simulation. Combined with the current density distribution diagram, the device behavior of multiple critical time nodes is analyzed in detail, and a reasonable explanation is given. In addition, the influence of different transition region contact types on the internal current distribution of the MPS diode is studied, and the simulation results are reasonably explained. [ABSTRACT FROM AUTHOR]

A study of the functioning of reed switches under the influence of a magnetic field created by a current in a conductor in a transient mode with the presence of an aperiodic component has been carried out. A well-known method for determining current using reed switches was implemented. At the same time, it was determined that the originally formulated method did not give the required result within the limits of errors. This is most likely due to the peculiarities of the mechanism of movement of the reed switch contacts. Alternatively, the measurements were taken to take the return currents instead of the pick-up currents and the time between the return times. They are more stable. Simulation is performed, experimental determination of the value of surge current by measuring time is carried out. The main element of the created installation was the power transformer coil with low active and high inductive resistance. As part of the study, the reed switches were placed in a magnetic field with an aperiodic component, as in the transient mode. This study will show the applicability of reed switches for the construction of relay protection devices that will not need current transformers to obtain information about the primary current in the conductor. In the course of the research, it was found that the error in determining the magnitude of current was no more than 10 %. Using microprocessors, it is possible to build relay protection devices with a speed of up to 20 ms. This result makes it possible to build new devices. Since in the well-known developments, it was only said about determining the magnitude of current in a steady state. When building relay protection devices on reed switches, without using current transformers, it will be possible to build backup protections that duplicate not only the devices themselves, but also the primary measuring transformers with other sensitive elements. This will improve the reliability of the power supply. [ABSTRACT FROM AUTHOR]

In this letter, we achieved significantly enhanced avalanche ruggedness and surge current capability in GaN junction barrier Schottky (JBS) diode for highly reliable power operation. Based on the selective Mg-ion implantation technology, the GaN JBS diode obtains superior electrostatic performances, including 830-V breakdown voltage, 150-mΩ specific on-state resistance, and 0.5-V turning on voltage. Meanwhile, zero reverse recovery behaviors are observed even under extreme switching conditions of 600 V/10 A. During the reliability evaluation in the inductive load circuits, crucial avalanche capability with avalanche breakdown voltage over 965 V, avalanche energy up to 57.8 mJ, and more than 10 000 repetitive avalanche breakdown events are demonstrated. Together with the surge current tolerance up to 65 A and surge energy of 6.0 J, a large safe-operation-area under both forward and reverse inductive spikes is realized for the GaN-based rectifier. [ABSTRACT FROM AUTHOR]

This letter reports the avalanche and surge current ruggedness of the industry's first 1.2-kV-class vertical GaN p-n diodes fabricated on 100-mm GaN substrates. The 1.2-kV vertical GaN p-n diodes with a 1.39-mm2 device area and an avalanche breakdown voltage of 1589 V show a critical avalanche energy density of 7.6 J/cm2 in unclamped inductive switching tests, as well as a critical surge current of 54 A and a critical surge energy density of 180 J/cm2 in 10-ms surge current tests. All these values are the highest reported in vertical GaN devices and comparable to those of commercial SiC p-n diodes and merged p-n Schottky diodes. These GaN p-n diodes show significantly smaller reverse recovery compared to SiC p-n diodes, revealing less conductivity modulation in n-GaN. The negative temperature coefficient of differential on-resistance and the anticlockwise surge I–V locus are believed to be due to the increased acceptor ionization in p-GaN and the decreased contact resistance at high temperatures. These results suggest a high ruggedness of GaN p-n junctions with small bipolar currents and fast switching capabilities. As the first electrothermal ruggedness data for industry's vertical GaN devices, these results provide key new insights for the development of vertical GaN devices as well as their application spaces. [ABSTRACT FROM AUTHOR]

Ultrawide-bandgap gallium oxide (Ga2O3) devices have recently emerged as promising candidates for power electronics; however, the low thermal conductivity (kT) of Ga2O3 causes serious concerns about their electrothermal ruggedness. This letter presents the first experimental demonstrations of large-area Ga2O3 Schottky barrier diodes (SBDs) packaged in the bottom-side-cooling and double-side-cooling configurations, and for the first time, characterizes the surge current capabilities of these packaged Ga2O3 SBDs. Contrary to popular belief, Ga2O3 SBDs with proper packaging show high surge current capabilities. The double-side-cooled Ga2O3 SBDs with a 3 × 3-mm2 Schottky contact area can sustain a peak surge current over 60 A, with a ratio between the peak surge current and the rated current superior to that of similarly-rated commercial SiC SBDs. The key enabling mechanisms for this high surge current are the small temperature dependence of on-resistance, which strongly reduces the thermal runaway, and the double-side-cooled packaging, in which the heat is extracted directly from the Schottky junction and does not need to go through the low-kT bulk Ga2O3 chip. These results remove some crucial concerns regarding the electrothermal ruggedness of Ga2O3 power devices and manifest the significance of their die-level thermal management. [ABSTRACT FROM AUTHOR]

Both forgetting to unplug mobile phone chargers after using and generating large surge current when the charger is plugged into power, will accelerate the aging of high-voltage electronic components. It is also prone to failure and fire. In addition, the charger consumes 100~800 mW power when it is in standby mode for a long time. Therefore, a fireproof and energy saving mobile phone charger is proposed. This kind of charger can reduce the standby power consumption to 13 mW, so it is unnecessary to pull out the charger to meet the habit of the users. It can absorb the surge current, meanwhile, it also has the functions of timing charging, overcurrent and short circuit protection, so as to prevent the occurrence of fire.

This work has aimed to design a system that can eliminate the surge current. Surge current occurs in circuits where very high capacitances are charged. The proposed system solves this problem in a new way. Using a Mosfet transistor, it limits the amount of current that flows into the circuit. This solution has many advantages over conventional methods of limiting surge current during capacitor charging. The exact amount of charging current in the system can be set. Furthermore, there is no surge current. According to the conditions of the application, the parameters can be changed, and effectively adapted to the application. For this reason, it is possible to use the system for various applications where it is necessary to limit the surge current, which has adverse effects on the device. The advantage of this is also the reduction of power loss. The proposed system has been validated with a simulation. The system has worked properly by simulation. While charging high capacities and high input DC voltage, surge currents have been reduced. [ABSTRACT FROM AUTHOR]

In this article, a novel structure design concept [plasma spreading layer (PSL)] is introduced into silicon carbide (SiC) merged PiN Schottky (MPS) diode to improve the surge current capability. Compared to the isolated P+ island design in traditional MPS diode, the P+ islands in the proposed new structure are connected by the P+ plasma spreading layers which can spread bipolar current from P+ islands to the other parts of the device during the surge pulse. Therefore, the effective conducting area of the device is increased and the energy dissipation capability can be improved. In this article, 1.2-kV SiC MPS diodes with two types of plasma spreading layers are designed and fabricated. Their forward characteristics and surge current capability are compared to traditional stripe cell and hexagonal cell designed MPS diodes. The experimental results show that, with the help of the plasma spreading layers, a 20% increase of energy dissipation capability is achieved by the new structure design, which results in a 10% improvement of the surge current capability. [ABSTRACT FROM AUTHOR]

Contact bounce is a common phenomenon in the closing process of the electromagnetic relay under capacitive loads. The investigations on the contact characteristics are mainly conducted by experimental methods. However, the experimental method is extremely complicated and time-consuming in structural design, and it cannot clearly reveal the mechanism of contact bounce. Therefore, a new theoretical model is proposed to investigate the dynamic characteristics of the electromagnetic relay under capacitive loads. The model allows for simulating dynamic process and collecting bounce parameters in a simple and effective way compared with conventional simulation and experimental methods. The physical mechanism of contact bounce for the electromagnetic relay is presented. The nonlinear contact force between the fixed and moving contacts is evaluated according to the Kelvin–Voigt viscoelastic contact model. The equations of motion considering the coupling of electromagnetic and mechanical fields are established. The theoretical results obtained in this study are validated by comparison with experimental data. The influences of the structural parameters, coil current, surge current, and contact resistance on the contact bounce are analyzed. The numerical results well demonstrate that the contact bounce can be effectively weakened by adjusting the parameters of contact spring and the mass of the moving contact. [ABSTRACT FROM AUTHOR]

The trend to move toward the solid-state and repetitive pulsed power supply requires the high-voltage, high-current, and high-speed semiconductor devices, which makes an insulated gate bipolar transistor (IGBT) preferred for this application. However, as a bipolar device, the IGBT is limited by the switching speed and switching loss. In this paper, the potential of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) for the pulsed power application is investigated. The surge current capabilities of 1.2-kV, 30-A commercial Si IGBT and SiC MOSFET are characterized and compared by the capacitor discharge experiment. In addition, the effects of various circuit parameters, including gate resistance, dc-link voltage, and dc-link capacitance, on the capacitor discharge process are investigated. It is found that the pulse current of SiC MOSFET is around two times of Si IGBT, which achieves good agreement with the datasheet. Using $di/dt$ to represent the discharging speed, the SiC MOSFET is 10 times faster than the Si IGBT. It is because the SiC MOSFET shows a lower ON-resistance in the saturation region resulted from the short-channel effect. This paper confirms the high-speed and high-current advantages of SiC MOSFET in the pulsed power application. [ABSTRACT FROM AUTHOR]

The behavior of switching arcs is well known for time periods of several milliseconds. In other devices such as surge protective devices, where the operation is based on spark gap technology, the time periods are within microseconds. These devices are tested with 8-/20- $\mu \text{s}$ surge currents. The behavior of the arc during this time period is rather unknown. In the event of overvoltages, the basic requirement is to establish an arc with a high conductivity between the main electrodes to conduct the surge current to the equipotential bonding. Due to the high conductivity, an additional current from the distribution grid ensues. This follow current needs to be switched OFF using the current-limiting breaking principle. In order to analyze the arc behavior, when changing from a surge current conduction to a follow current, a basic experimental setup is established. Due to the grid’s alternating voltage, the influence of the synchronization angle is regarded for the two worst-case angles of 90° and 270°. The setup consists of a surge current generator for 8-/20- $\mu \text{s}$ currents up to 25 kA, a distribution transformer with 130 kVA, and a modular spark gap that contains two parallel electrodes in a narrow gap. In this setup, the surge current, follow current, arc voltage, and transformer voltage are measured and discussed. In addition, a high-speed camera is used to visualize the plasma between the electrodes. The data are discussed in order to propose a simplification for the occurring arc. [ABSTRACT FROM AUTHOR]

We demonstrate the presence of dual simultaneous nonlinear mechanisms: field-induced optical rectification (FIOR) and field-induced surge current (FISC) for the generation of terahertz (THz) pulses from p-type and n-type Fe:In0.53Ga0.47As surfaces upon excitation with femtosecond laser pulses centered at 800 nm wavelength. Experimental investigations of the dependence of the generated THz waves on the incident angular optical polarization, optical irradiance, and the direction and magnitude of applied electric DC fields give confirming results to the proposed THz generation mechanisms. Applying external DC electric fields in the plane of the incident optical field shows efficient capability in manipulating the direction and phase of the generated THz waves, and controlling the refractive index of Fe:In0.53Ga0.47As material in the THz range, in addition to enhancing the emitted THz power up to two orders of magnitude. The fast and reliable response of Fe:In0.53Ga0.47As to the changes in the direction and magnitude of the optical and electrical fields suggests its use in amplitude and phase modulators, and ultrafast optoelectronic systems. [ABSTRACT FROM AUTHOR]

This paper presents the design and implementation of the 60-Hz ferroresonant transformer (FRT) for the light emitting diode (LED) street lamp to achieve high-frequency (HF) noise attenuation and ac-line voltage clamping. The HF transformer (HFT) used in the LED driver system for the outdoor LED street lamps cannot effectively suppress the surge current to avoid damage to the LED street lamp. However, instead of the HFT, the low-frequency transformer (LFT) can be applied to protect the LED street lamps from the surge current. The LFT has a higher turns number, which provides larger leakage inductances and parasitic capacitances that effectively suppress and shunt the surge current. With the magnetic shunt, a 60-Hz FRT is proposed to effectively regulate the ac-line voltage to not overstress the LED street lamp systems as compared with the conventional LFT. When the ac-line voltage is higher than the rated voltage, the additional magnetic flux generated from the primary-side winding flows through the magnetic shunt but not the secondary-side winding. The rated output voltage of the secondary side can be sustained to achieve ac-line voltage clamping. A prototype of the LED street lamp with a 60-Hz FRT has been designed and implemented to verify the feasibility of the HF noise attenuation and ac-line voltage clamping. [ABSTRACT FROM PUBLISHER]

Serious damage in telecommunication facilities can occur due to lightning surges. Cable surge protectors are effective in reducing the damage to telecommunication facilities caused by penetration of lightning surges to metallic cables. This article introduces the improvements that have been made to new cable surge protectors developed by NTT EAST. This is the thirty-fifth article in a series on telecommunication technologies. This month's contribution is from the EMC Engineering Group, Technical Assistance and Support Center, Maintenance and Service Operations Department, Network Business Headquarters, NTT EAST. [ABSTRACT FROM AUTHOR]

SiC merged-pin-Schottky (MPS) diodes possess fast switching ability combined with low losses. Compared to conventional Schottky diodes they also provide a high surge current capability making them rugged against surge current pulses of more than seventeen times the rated current for a 10 ms half-sine pulse. In this paper further aspects of device ruggedness are presented such as the surge current capability of two diodes in parallel and the turn-off behavior at application condition and at overcurrent. It was found that the turn-off characteristics are almost independent from the applied voltage. Further, the diode could withstand turn-off from fifteen times the rated current. [ABSTRACT FROM AUTHOR]

Due to the continually expansion in size of electricity distribution networks, the demand for the reliability of power supply is on the increase, and in the case of transferring load, a closed-loop operation is usually needed. However, in the course of the closed-loop operation, a larger surge current may be induced, and this current can cause the equipped over-current protection take action incorrectly. In this paper, a flux-coupling type superconducting fault current limiter (SFCL) is suggested to suppress the surge current caused by the closed-loop operation. The structure and principle of the suggested SFCL are introduced, and considering the SFCL′s current-limiting impedance, the mathematical process for calculation of the surge current is presented. Furthermore, according to the simulation analysis of a practical 10 kV power distribution network integrated with the SFCL, the surge current′s dynamic characteristics and the SFCL′s performance behaviors are both assessed. From the demonstrated results, the SFCL′s positive effects on reducing the surge current and improving the system′s robustness against the closed-loop operation can be verified. At the last of the paper, a few technical discussions regarding the SFCL′s engineering application are conducted, and some useful conclusions related to the practicability of experimentally building the SFCL are obtained. PACS codes: 85.25.Am; 84.30.Jc. [ABSTRACT FROM AUTHOR]

Describes how energy efficient power supply management system cleaning electrolysis of aqueous solutions, taking into account the concentration of substances in the working solution in terms of the pH. Established major shortcomings of modern control systems electrolysis power supplies for water treatment systems. The proposed energy-efficient way to manage the electrolytic power supply based on adaptive selection of the optimal form of impulse load current with regard to disturbances pH working solution. [ABSTRACT FROM AUTHOR]

The paper presents the investigations of causes of failure of the crystals of semiconductor power diodes while surge current pulses pass through them. It is shown that when currents values are lower than the surge current, the impact resistance and reliability of the diode do not change. At surge current, the resistance of the diode increases with each repeated pulse. After several pulses have passed, the diode fails, because its forward resistance increases 3 times, and the temperature greatly exceeds the acceptable level. The authors explain the observed effects.

Calculation of a short circuit current of a symmetrical fault in a high-power synchronous machine in accordance with national standards is time-consuming and imprecise. The process involves multiple graphic operations and a triple transition from an analog transient process to its discrete form and back. As a result, optimizing procedures cannot be applied to transient identification techniques that meet national standards and it is impossible to compensate for random factors in the identification process. Therefore, a surge current derived from experimental data is not adequate for transients in high-power synchronous machines. Modern equipment for recording of short-term transients solves many processing problems. Express determination of a surge current is obtained using a digital waveform recorder, which allows precise calculation of 50-Hz peaks and discrete representation of the 100-Hz component of the transients. This method of information extraction and processing replaces all the time-consuming graphic operations of the national standards. Results of a study of a 110-MW synchronous machine based on laboratory tests for various stator voltages are presented. The study has confirmed the viability of the proposed approach for express determination of a surge current without the need to determine the parameters of transients. [ABSTRACT FROM AUTHOR]

This paper gives an overview about different failure mechanisms which limit the safe operating area of power devices. It is demonstrated how the device internal processes can be investigated by means of device simulation. For instance, the electrothermal simulation of high-voltage diode turn-off reveals how a backside filament transforms into a continuous filament connecting the anode and cathode and how this can be accompanied with a transition from avalanche-induced into thermally driven carrier generation. A similar current destabilization may occur during insulated-gate bipolar transistor turn-off with a high turn-off rate, when the channel is closed quickly leading to strong dynamic avalanche. It is explained how the current filamentation depends on substrate resistivity, device thickness, channel width, and switching conditions (gate resistor and overcurrent). Filamentation processes during short-circuit events are discussed, and possible countermeasures are suggested. A mechanism of a periodically emerging and vanishing filament near the edge of the chip is presented. Examples on current destabilizing effects in gate turn-off thyristors, integrated gate-commutated thyristors, and metal–oxide–semiconductor field-effect transistors are given, and limitations of current device simulation are discussed. [ABSTRACT FROM PUBLISHER]

This paper presents a power gating design that considers process variation for proper wakeup control. First, the surge current constraint is examined and refined for a simpler and more realistic view of inter-module reliability. Following that, several circuits are proposed on top of a delay chain to adapt the timing control of power switches to process variations. Experimental results show that the proposed design is able to track process variation such that the surge current and the wakeup time are both kept to expectation in all process corners. [ABSTRACT FROM AUTHOR]

The radiated electromagnetic fields from the cable excited by surge current in mine environment were studied. The mathematical models for the radiated electromagnetic fields in time domain were deduced by using the theories of retarded vector potential and traveling wave antenna. The analytical expressions and simulation results of the radiated electromagnetic fields were given. The results show that surge current can cause high transient radiated electromagnetic fields nearby a cable, but the strength of radiated field attenuates quickly with increasing radial distance from a cable; the radiated field strength is proportional to the peak value of surge current and, within the radial distance of the same transverse section in a tunnel, the radiated field strength is inversely proportional to the distance from a cable. It has been obtained from simulation that, when the surge peak current reaches 1 kA, the transient peak radiated electric field strength is about 15 kV/m and the peak magnetic field strength is about 40 A/m at the field point 4 m away from the cable. That indicates, if there is no shielding measures to be taken, the radiated electromagnetic fields of surge current could cause malfunction of monitoring system and communication system in tunnels. [ABSTRACT FROM AUTHOR]

4H-SiC Junction Barrier Schottky (JBS) diodes (1.2 and 3.5 kV) have been processed using the same technology with two different layouts. From 4 A and for the whole temperature range, the 3.5-kV diodes exhibit a bipolar conduction independent of the layout. However, the behavior of the 1.2-kV diodes depends on the design. At 500 V-300 °C, the leakage current is only 100 nA and 10 μA for the 3.5- and 1.2-kV diodes, respectively. The switch-off performances show a reverse peak current of only 50% of the nominal current at 300°C for all JBS diodes. The JBS diodes have a surge current capability of around 80 A, two times higher than the Schottky diodes. DC electrical stresses are performed during 50 h, and all the 1.2-kV diodes exhibit no bipolar degradation. Nevertheless, some slight bipolar degradation is observed in 3.5-ky JBS diodes. Electroluminescence measurements exhibit the expansion of stacking faults in 3.5-kV diodes unlike in 1.2-kV diodes. [ABSTRACT FROM AUTHOR]

• A semi-controlled charging method is presented for firing IGBTs. • A group modulation method for HMMC with unbalanced voltages is proposed. • An improved AC-side startup method is proposed to suppress the inrush current. Hybrid modular multilevel converter (HMMC) topology consisting of full-bridge submodules (FBSMs) and half-bridge submodules (HBSMs) is one of the promising technical solutions for long-distance high voltage direct current (HVDC) power transmission systems. However, the HMMC has very different charging circuit characteristics from the conventional half-bridge MMC (HB-MMC) topology and suffers from low and unbalanced precharge capacitor voltages and surge current when starting from the AC-side, due to its hybrid submodule configuration. In this paper, an AC-side startup scheme for the HMMC is proposed, including an additional semi-controlled charging process and an improved controlled charging method, which allows the HMMC to smoothly charge its submodule capacitors and establish the DC-link voltage without requirements of auxiliary sources. The improved controlled charging method is composed of a group modulation and a group voltage balancing control strategies, which enables the HMMC to operate stably with enhanced AC voltage output capability under the condition of low and unbalanced capacitor voltage in the HBSM group and FBSM group, thereby eliminating converter overmodulation and surge current during the startup procedures. In addition, DC-side startup strategy is also discussed in this paper. PSCAD/EMTDC simulation results based on a practical ±200 kV/750 MW HMMC-HVDC system demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: The electrical performance of 3.3kV SiC Schottky, JBS and PiN diodes are compared. In forward mode, the 25mm2 Schottky exhibits better performances than the 2.6mm2 JBS and PiN diodes. On the other hand, due its very large active area, the Schottky diode show a leakage current of 1mA, which is 100× and 1000× higher than that of the JBS and PiN diodes, respectively. In switching mode, the Schottky and JBS diodes show similar reverse current peaks (2A at 300°C), whereas it is 5× higher for the PiN diode. Concerning the surge current capability, the three diodes present similar surge current capability (around 55A) at 25°C. At 225°C, we have observed a 50% decrease in the surge current of the Schottky diode whereas it is almost the same for the PiN and JBS diodes. [Copyright &y& Elsevier]

A comparative study of surge current reliability of 1200 V/5 A 4H-SiC (silicon carbide) MPS (Merged PiN Schottky) diodes with different technologies is presented. The influences of device designs in terms of electrical and thermal aspects on the forward conduction performance and surge current capability were studied. Device forward characteristics were simulated and measured. Standard single-pulse surge current tests and thermal impedance measurements were carried to show their surge capability and thermal design differences. An advanced thermal RC (thermal resistance-capacitance) model, with the consideration of current distribution non-uniformity effects, is proposed to accurately calculate the device junction temperature during surge events. It was found that a thinner substrate and a hexagonal layout design are beneficial to the improvement of the bipolar conduction performance in high current mode, as well as the surge current capability. The thinner substrate design also has advantages on thermal aspects, as it presents the lowest thermal resistance. The calculated failure temperature during the surge tests is consistent with the aluminum melting phenomenon, which is regarded as the failure mechanism. It was demonstrated that, for a SiC MPS diode, higher bipolar conduction performance is conducive to restraining the joule heat, and a lower thermal resistance design is able to accelerate the heat dissipation and limit the junction temperature during surge events. In this way, the MPS diode using a thinner substrate and advanced layout design technology is able to achieve 60% higher surge current density capability compared to the other technologies. [ABSTRACT FROM AUTHOR]