Silicon-Carbide (SiC) MOSFETs, due to material properties, are designed with smaller thickness in the gate oxide and a higher electric field compared to Si MOSFETs. Consequently, the SiC MOSFETs have a worse reliability which causes higher leakage currents during instantaneous abnormal operating conditions. This paper investigates the reliability issues of the SiC MOSFET gate oxide under standard short-circuit test conditions. In this paper, 1200-V SiC MOSFETs are newly modeled, and also their short-circuit sustainability (tolerance) have been studied at different drain-source and gate-source voltages. A hardware tester circuit was designed and developed to test the devices under such extreme circuit conditions. Then, the gate reliability of SiC MOSFET devices have been compared to that of Si power devices of similar ratings. The results reveal a higher reduction in the instantaneous gate-source voltage of SiC MOSFETs compared to that of Si devices under the same operating conditions. The gate-voltage reduction phenomenon results from the higher leakage currents through the gate. Furthermore, it was found that the gate-source voltage reduction during the test depends on the gate structures. The gate voltage reduction of SiC MOSFETs with planar gate is higher than that of MOSFETs with shield planar gate. As the pulse duration increases in short-circuit tests, the leakage current in the gate-source of SiC devices increases. The results show that even though the SiC MOSFETs are very capable of processing long pulses and high power in the drain-source, the gate-source side is highly degraded by these pulses in the test. Moreover, whenever a small number of the short-circuit tests are applied, the gate structure of SiC MOSFETs becomes broken while the drain-source is still able to block the dc-link voltage. The paper concludes that the short-circuit reliability of the gate was found to be worse compared with commercial Si devices with similar rating.

Gate Oxide Reliability Issues of SiC MOSFETs Under Short-Circuit Operation

This paper describes a novel power injection model (PIM) of interline power flow controller (IPFC) for power flow analysis. In this model, the impedance of the series coupling transformer and the line charging susceptance are all included. In this situation, it is proved that the original structure and symmetry of the admittance matrix can still be kept, and thus, the Jacobian matrix can keep the block-diagonal properties, and sparsity technique can be applied. The IPFC state variables are adjusted simultaneously with the network state variables in order to achieve the specified control targets. Furthermore, the model can take into account the practical constraints of IPFC in Newton power flow. Numerical results based on the IEEE 57-bus and IEEE 300-bus systems are used to demonstrate the effectiveness and performance of the IPFC model

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A Novel Power Injection Model of IPFC for Power Flow Analysis Inclusive of Practical Constraints

The short-circuit protection of a low-power converter-fed low-voltage dc distribution network is investigated. In a public distribution network, the short-circuit protection is implemented by using fuses and circuit breakers, which may require a current that is over ten times the nominal currents of low-power dc/ac converter units to satisfy the recommendations. In the paper, the operation of the converter in a short circuit is studied, and the control scheme for the short-circuit current control and the fault ride through operation is proposed. The operation of the short-circuit control scheme is verified by measurements. To overcome the problem of high fault current injection, alternative short-circuit protection realizations that are based on a simple low-current compact circuit breaker (but are not approved in standards) are proposed and demonstrated by measurements.

Short-Circuit Protection in a Converter-Fed Low-Voltage Distribution Network

The presence or absence of objects is determined by interrogating or exciting transponders coupled to the objects using pulsed wide band frequency signals. Interrogation is broken down into a number of subsample scan cycles each having interrogation cycles a start time forward in time by a fraction of a period of an expected transponder response signal. Ambient or background noise is evaluated and a threshold adjusted based on the level of noise. Adjustment may be based on multiple noise measurements or samples. Noise detection may be limited, with emphasis placed on interrogation to increase the signal to noise ratio. Matched filtering may be employed. Presence/absence determination may take into account frequency and/or Q value to limit false detections. Appropriate acts may be taken if detected noise is out of defined limits of operation, for example shutting down interrogation and/or providing an appropriate indication.

Method, apparatus and article for detection of transponder tagged objects, for example during surgery

Weak capture in muonic hydrogen (μH) as a probe of the chiral properties and nucleon structure predictions of quantum chromodynamics (QCD) is reviewed. A recent determination of the axial-vector charge radius squared, [Formula: see text], from a model independent z expansion analysis of neutrino-nucleon scattering data is employed in conjunction with the MuCap measurement of the singlet muonic hydrogen capture rate, [Formula: see text], to update the induced pseudoscalar nucleon coupling [Formula: see text] derived from experiment, and [Formula: see text] predicted by chiral perturbation theory. Accounting for correlated errors this implies [Formula: see text], confirming theory at the 8% level. If instead, the predicted expression for [Formula: see text] is employed as input, then the capture rate alone determines [Formula: see text], or together with the independent z expansion neutrino scattering result, a weighted average [Formula: see text]. Sources of theoretical uncertainty are critically examined and potential experimental improvements are described that can reduce the capture rate error by about a factor of 3. Muonic hydrogen can thus provide a precise and independent [Formula: see text] value which may be compared with other determinations, such as ongoing lattice gauge theory calculations. The importance of an improved [Formula: see text] determination for phenomenology is illustrated by considering the impact on critical neutrino-nucleus cross sections at neutrino oscillation experiments.

https://iopscience.iop.org/article/10.1088/1361-6633/aac190/pdf

Nucleon axial radius and muonic hydrogen-a new analysis and review.

An international collaboration plans to measure the lifetime of the muon to a precision of 1 part per million . The "MuLan" experiment will take place at the Paul Scherrer Institut (PSI) in Northern Switzerland. The MuLan experiment requires a fast beam line kicker, which can turn the beam on and off, to invoke an artificial time structure on the continuous beam which has a 50.6-MHz time microstructure. The kicker needs to run with a standard "on-off time cycle" or in a "Muon on Request" mode. The MuLan kicker consists of two pairs of deflector plates mechanically in series, driven by four modulators. Each modulator consists of two stacks of MOSFETs operating in push-pull mode. The specifications for the kicker demand that the rise and fall times of the deflector plate voltage do not exceed 45 ns. There is a requirement for an adjustable output voltage from 0 V to /spl plusmn/12.5 kV per deflector plate, a minimum pulse duration of 200 ns, and adjustable repetition rate up to a maximum of 50 kHz, continuous. Short turn-on and turn-off delays are required for the "Muon on Request" mode; the measured propagation delay is 200 ns. The specifications also require that the polarity of the pulses on the plates be selectable, although not on a pulse-by-pulse basis. This paper describes the novel design of the kicker and presents both predictions and measurements.

A 25 kV, 75 kHz, kicker for measurement of muon lifetime

The next linear collider (NLC) accelerator proposal at Stanford Linear Accelerator Center (SLAC, Menlo Park, CA), requires a highly efficient and reliable, low cost, pulsed-power modulator to drive the klystrons. A solid-state induction modulator has been developed at SLAC to power the klystrons; this modulator uses commercial high voltage and high current insulated gate bipolar transistor (IGBT) modules. Testing of these IGBT modules under pulsed conditions was very successful; however, the IGBTs failed when tests were performed into a low inductance short circuit. The internal electrical connections of a commercial IGBT module have been analyzed to extract self- and mutual partial inductances for the main current paths as well as for the gate structure. The IGBT module, together with the partial inductances, has been modeled using PSpice. Predictions for electrical paths that carry the highest current correlate with the sites of failed die under short circuit tests. A similar analysis has been carried out for a SLAC proposal for an IGBT module layout. This paper discusses the mathematical model of the IGBT module geometry and presents simulation results.

/pdf/analysis-of-high-power-igbt-short-circuit-failures-4sidqzidb5.pdf

Analysis of high power IGBT short circuit failures

Proton beams will be injected into LHC at 450 GeV by two kicker magnet systems, producing magnetic field pulses of approximately 900 ns rise time and up to 7.86 /spl mu/s flat top duration. One of the stringent design requirements of these systems is a flat top ripple of less than /spl plusmn/0.5%. Both injection systems are composed of 4 traveling wave kicker magnets of 2.7 m length each, powered by pulse forming networks (PFN's). To achieve the required kick strength of 1.2 Tm, a low characteristic impedance has been chosen and ceramic plate capacitors are used to obtain 5 /spl Omega/. Conductive stripes in the aperture of the magnets limit the beam impedance and screen the ferrite. The electrical circuit has been designed with the help of PSpice computer modeling. A full size magnet prototype has been built and tested up to 60 kV with the magnet under ultra high vacuum (UHV). The pulse shape has been precision measured at a voltage of 15 kV. After reviewing the performance requirements the paper presents the magnet design, emphasizing several novel design features, and discusses the test results.

/pdf/the-lhc-injection-kicker-magnet-31vqwvuht3.pdf

The LHC injection kicker magnet

Two counter-rotating proton beams will be injected into the LHC at an energy of 450 GeV by two kicker magnet systems, producing magnetic field pulses of approximately 750 ns rise time and 6.6 /spl mu/s flat top duration. To avoid dilution of the beam emittance during injection, a stringent design requirement of the system is a flat top ripple of the magnetic field of less than /spl plusmn/0.5%. Both injection systems are composed of 4 travelling wave kicker magnets of 2.17 m length each, powered by pulse forming networks (PFNs) and matched to their characteristic impedance. To achieve the high required kick strength of 1.2 Tm, for a compact and cost efficient design, a comparably low characteristic impedance of 5 /spl Omega/ has been chosen. The electrical circuit of the system is being designed with the help of PSpice computer modelling. Most known parasitic elements are included in the model to obtain a realistic pulse response prediction. The present paper reports on design and modeling results of the LHC injection kicker magnet system that has several novel and demanding design requirements.

/pdf/design-of-the-injection-kicker-magnet-system-for-cern-s-14-2it5ts9lzk.pdf

Design of the injection kicker magnet system for CERN's 14 TeV proton collider LHC

A pulse generator has been developed which has many potential applications. The pulse generator consists of a high-voltage modulator incorporating two stacked Field-Effect Transistor switches operating in a “push-pull” mode. A continuous 1 kV to 6 kV pulse train has been obtained with a prototype pulse generator over a frequency range from 1 Hz to 20 kHz. Pulse widths in the range from 250 ns to 1 s have been achieved with rise and fall times of 30 ns into a capacitive load of 26 pF. A 3 kHz, 5 kV version of this pulse generat,or has been installed and t,ested in the 300 keV injection line for t,he 500 MeV TRIUMF cyclotron. The circuit performance was evaluated with the aid of PSpice in t,he design stage and confirmed by measurement,s in the prototype. Results of measurements and simulations are presented.

G.D. Wait

Papers

A 25 kV, 75 kHz, kicker for measurement of muon lifetime

Analysis of high power IGBT short circuit failures

The LHC injection kicker magnet

Design of the injection kicker magnet system for CERN's 14 TeV proton collider LHC

A FET based frequency and duty factor agile 6-kV pulse generator