Carbide Metal Oxide Semiconductor Field Research Articles

Transient turn-on characteristics of Si RBDT and SiC MOSFET under nanosecond current pulse range

With the development of pulse power supplies, solid-state semiconductor switches are required to have fast switching speeds and low losses. Both Reverse blocking diode thyristor (RBDT) and silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET) have fast turn-on speed, making them suitable candidates for short pulse generator. In this paper, the transient turn-on characteristics of Si RBDT and SiC MOSFET are analyzed theoretically and validated experimentally. Si RBDT and commercial 1.2 kV/81A SiC MOSFET are comparatively investigated in switching current pulse with a rise time of several hundreds of nanoseconds. (1) The anode current of RBDT could rise exponentially because of the latch-up effect of Si RBDT, while the drain current of SiC MOSFET tends to be saturated. (2) Utilizing the current rise time (Trise) to represent the switching speed, SiC MOSFET can switch faster when the current is lower than 400A. With the increase of the current, Si RBDT presents faster turn-on speed and lower switching loss due to the regenerative action of the two coupled transistors. (3) The transient characteristics of Si RBDT include a voltage-controlled inductance, while SiC MOSFET contains a current-controlled inductance based on the current rise time, respectively. With the increasing of the main voltage, the equivalent inductance of Si RBDT decreases and tends to be saturated when the main voltage is higher than half of the breakdown voltage of Si RBDT. For SiC MOSFET, the equivalent inductance increases until the drain current remains stable for a given gate voltage. This paper confirms the advantages of Si RBDT and SiC MOSFET in different situations.

Highly Efficient Three-Phase Bi-Directional SiC DC–AC Inverter for Electric Vehicle Flywheel Emulator

Flywheels are nowadays a solution for the dynamic charging of electric vehicles since they act as transient energy storage. The need for a top efficient reversible power converter for the flywheel system is crucial to assure high dynamic performance. The paper presents the design of a 50 kW highly efficient reversible three-phase DC–AC inverter involving the most recent silicon carbide metal oxide semiconductor field effect transistors, and its experimental validation on a home-made emulator. Highest efficiency in reversible mode, compactness, and thermal enhancement are the targeted objectives that have been achieved. The power converter prototype evaluated on an original pulse width modulation testing-bench is able to emulate the working of the flywheel system. High frequency pulse width modulation switching, speed cycle operating, and thermal losses are evaluated. In addition, an efficiency above 99% for the converter has been attained, enabling robust functioning of the flywheel system emulator to perform specific charging profiles for electric vehicles.

Understanding Inherent Implication of Thermal Resistance in Double-Side Cooling Module

The double-side cooling (DSC) packaging becomes more and more popular with the great demands of high power and fast speed, especially for silicon carbide metal oxide semiconductor field effect transistors. Measurements and modeling of thermal resistance are critical for thermal management of DSC module. However, the thermal resistance of DSC module is still unclear due to the asymmetric dual thermal paths. In this article, a clear understanding of thermal resistance of DSC module measured by transient dual-interface method (TDIM) is explained. The thermal impedance of DSC module is analyzed through time- and frequency-domain response of the DSC thermal model. The cooling conditions in TDIM have no influence on the measured thermal resistance of DSC module. The measured thermal resistance from junction to top case (or bottom case) is half of the actual value. The important conclusions are verified by transient simulations and experiments. Based on the results, a new definition of thermal resistance of DSC module is proposed for exact evaluation of thermal resistance and reliability.

Impact of nearby lightning on photovoltaic modules converters

PurposeThe lightning phenomenon is one of the main threats in photovoltaic (PV) applications. Suitable protection systems avoid major damages from direct strikes but also nearby strikes may induce overvoltage transients in the module itself and in the power conditioning circuitry, which can permanently damage the system. The effects on the PV system sensibly depend on the converter topology and on the adopted power switch. In the present study, a comparative analysis of the transient response due to a nearby lightning strike (LS) is carried out for three PV systems, each equipped with a different converter, namely, boost, buck and buck–boost, based on either silicon carbide metal oxide semiconductor field effect transistors (SiC MOSFET) or insulated gate bipolar transistors controlled power switch devices, allowing in this way an analysis at different switching frequencies. The purpose of this paper is to present the results of the numerical analysis to help the design of suited protection systems.Design/methodology/approachUsing a recently introduced three-dimensional semi-analytical method to simulate the electromagnetic transients caused in PV modules by nearby LSs, we investigate numerically the effect of a LS on the electronic circuits connecting the module to the alternate current (AC) power systems. This study adopts numerical simulations because experimental analyses are not easy to perform and does not grant a sufficient coverage of all statistically relevant aspects. The approach was validated in a previous paper against available experimental data.FindingsIt is found that the load voltage is not severely interested by the strike effects, thanks to the low pass filters present at the converter output, whereas a relatively high overvoltage develops between the negative pin of the inner circuitry and the “ground” voltage reference. The overcurrent present in the active switches is hardly comparable because of the different topologies and working frequencies; however, the highest overcurrent is observed in the buck converter topology, with SiC MOSFET technology, although it shows the fastest decay.Originality/valueThis research proposes, to the best of the authors’ knowledge, a comprehensive comparison of the indirect lighting strike effects on the converter connected to PV panels. A proper design of the lightning and surge protection system should take into account such aspects to reduce the risk of induced overvoltage and overcurrent transients.

LCL-Filter Design Based on Modulation Index for Grid-Connected Three-Level Hybrid ANPC Inverters

This paper proposes an LCL-filter design based on the modulation index for grid-connected hybrid active neutral point clamped (ANPC) inverters. The three-level hybrid ANPC inverter consists of silicon insulated gate bipolar transistors and silicon carbide metal oxide semiconductor field effect transistors to reduce the switching losses. LCL-filter parameters for the three-level hybrid ANPC inverter are calculated using the current ripple factor. The current ripple factor is affected by phase voltage, which varies according to the modulation index, and therefore the inductance on the inverter side must be considered with the modulation index. To design inductance on the inverter side, the output phase voltage and grid voltage are used to analyze the current ripple factor. The filter capacitor and the inductance on the grid side are designed based on the reactive power absorption and current ripple attenuation. The effectiveness of the proposed LCL-filter design method is validated via simulation and experimental results.

Power Converters in Power Electronics [Book News

This book includes carefully selected papers on power electronic converters and their control, mainly impedance source converters, current-source inverters with ac-side clamping, three-level quasi-switched boost T-type inverters, flying capacitor pulse width modulation and FC multilevel three-level dc-dc converters, all of which are very important in photovoltaic applications. Neutral point clamped multilevel inverters in inductive power transfer to achieve load-independent constant current and load-independent constant voltage outputs, fractional order element-based approaches to wireless power transmission, charge balance and pulse charge for lithium iron phosphate batteries, and command of switching dynamics in silicon carbide metal oxide semiconductor field effect transistors are also considered.

Implementation of 1.7 kV silicon carbide metal oxide semiconductor field effect transistors in auxiliary power supplies for industrial applications

An auxiliary power supply (Aux-PS) has become an essential component of electronic equipment for many industrial applications, such as in motor drives, photovoltaic (PV) inverters, uninterruptible power supply (UPS) systems and modular multilevel converters. The introduction of 1 700 V silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) is useful for such applications, providing benefits with respect to a low on-state resistance, smaller package, low switching loss and single-switching implementation. A single end flyback Aux-PS is designed for industrial applications with a wide input voltage range using 1.7 kV SiC MOSFETs. The special design tradeoffs involved in the usage of SiC MOSFETs are discussed in detail, such as those with regard to gate driving voltage selection, isolation transformer design considerations, and clamping circuit design details. A 60 W demonstration hardware is developed and tested under different working conditions. The results verify the higher efficiency and better thermal performance of the proposed hardware relative to those of traditional Si solutions.

In‐depth analysis of the static behaviour of a SiC MOSFET and of its associated parameters using both compact modelling and physical simulation

In this study, the authors aim at investigating the static electro-thermal behaviour of two new generations of power silicon carbide metal oxide semiconductor field effect transistors (SiC MOSFETs). The studied devices are commercialised and have a vertical structure. Two approaches are followed: device modelling and physical simulation. An improved compact model based on an accurate method of parameters extraction is introduced. The simulation results obtained with this method perfectly fit the measurements. The parameters extracted precisely from the model (threshold voltage, saturation region transconductance and transverse electric field parameter) are used to accurately analyse the static behaviour of 1200 V Gen 2 and 900 V Gen 3 SiC MOSFETs. Physical simulation is conducted to understand the impact of the temperature and the physical parameters on the threshold voltage and the on-state resistance.

A Non-Segmented PSpice Model of SiC mosfet With Temperature-Dependent Parameters

A non-segmented PSpice model of silicon carbide metal-oxide semiconductor field effect transistor (SiC mosfet ) with temperature-dependent parameters is proposed in this paper, which can improve the model's convergence and temperature characteristics. The non-segmented equations and the parameter-extraction method for the proposed SiC mosfet PSpice model are introduced first. Simulation and experiment results are given to verify the correctness of the model while considering the temperature-dependent parameters. The static characteristics of the model are verified by comparing the simulation curves with the static characteristic curves in the SiC mosfet 's datasheet, and its dynamic characteristics are verified by comparing the simulation results with experimental results under different ambient temperatures (25, 75, and 125 °C) based on a double-pulse test platform. Moreover, the proposed non-segmented model, the conventional segmented model, and the model from the manufacturer are adopted and simulated in a full-bridge inverter. The simulation results show better convergence of the proposed non-segmented model. Therefore, an accurate and practical simulation model of SiC mosfet is provided for circuit design in this paper.

An Improved SPICE Model for the Study of Electro-thermal Static Behavior for two New Generations of SiC MOSFET

This paper aims to model the static behavior of two generations of Silicon carbide Metal Oxide Semiconductor Field Effect Transistors (SiC-MOSFETs) subjected to temperature and input voltage variations. The description of the studied device, its electro-thermal characterizations and the comparison of two generations of SiC-MOSFETs are presented. The SPICE model provided by the constructor is studied. The comparison between the simulation results of the SPICE model and measurements reveals limitations in terms of temperature behavior and electrical effects. In order to overcome these limitations, a compact model is used. This model accurately describes the static behavior of two generations of SiC-MOSFETs. The threshold voltage extracted from the compact model is exploited to analyze the physical behavior and to compare the performance of two generations of SiC-MOSFETs.

Design of an Highly Efficient AC-DC-AC Three-Phase Converter Using SiC for UPS Applications

With the constant increase of energy consumption in the world, the efficiency of systems and equipment is becoming more important. Uninterruptible Power Supply (UPS) is an equipment that provides safe and reliable supply for critical load systems, that is, systems where a supply interruption can lead to economical or even human losses. The Double Conversion UPS is the most complete UPS class in terms of load protection, regulation, performance, and reliability, however, it has lower efficiency and higher cost because of its high number of power converters. Silicon Carbide devices are emerging as an opportunity to construct power converters with higher efficiency and higher power density. The main purpose of this work is to design a three-phase AC-DC-AC converter using Silicon Carbide for Double Conversion UPS applications. The aim is to maximize efficiency and minimize volume and mass. The methodologies to size and choose the main hardware components are described in detail. Experimental results obtained with the prototype prove the high efficiency and high power density achievable with Silicon Carbide Metal Oxide Semiconductor Field Effect Transistor (MOSFETs).

Reliability study on positive bias temperature instability in SiC MOSFETs by fast drain current measurement

The gate threshold voltage (Vth) shift under positive gate bias stress is one of the most important reliability concerns in silicon carbide metal–oxide–semiconductor field effect transistors (SiC MOSFETs). Because dynamic recovery is observed as soon as the gate bias stress is removed, it is remarkably difficult to accurately evaluate Vth shifts. Many studies have focused on how to evaluate Vth shifts of SiC MOSFETs under positive gate bias stress. In this study, this issue is investigated by introducing a fast measurement technique. We show that the measured Vth shift is modified to take the Vth recovery term into consideration. Furthermore, we show that the Vth shift is a saturation phenomenon and that the maximum Vth shift can be predicted using an electron capture and emission model.

High, Low, and Zero Field Spin Dependent Recombination in 4H SiC Mosfets

Silicon carbide metal oxide semiconductor field effect transistors (MOSFETs) have great promise in high power and high temperature applications. Among the many polytypes, 4H is the most promising for MOSFET applications. Unfortunately, the effective channel mobility in these devices remains disappointingly low and the devices frequently exhibit as yet poorly understood bias temperature instabilities. The underlying causes of the low effective channel mobility and the bias temperature instabilities are as yet not fully understood but clearly involve the presence of electrically active point defects very close to the silicon carbide-silicon dioxide interface. Electron paramagnetic resonance (EPR) has unrivaled sensitivity and analytical power in the identification of point defects in semiconductors and insulators. However, the detection limit of conventional EPR in solids is about ten billion defects under near ideal circumstances. Thus, conventional EPR lacks the sensitivity to detect these defects in a transistor even remotely approaching technological relevance. The electrically detected magnetic resonance (EDMR) technique called spin dependent recombination (SDR) provides a sensitivity at least ten million times higher than that of conventional EPR. SDR/EDMR can also provide information about the physical location and energy levels of defects, with the additional advantage that it is readily made sensitive to only those defects which actually affect the performance of the device under observation. In this study, we utilize SDR/EDMR measurements carried out over a wide range of magnetic fields, frequencies, and temperatures utilizing multiple electronic measurement platforms (spin dependent charge pumping, spin dependent gated diode recombination current measurements, and bipolar amplification effect spin dependent recombination measurements) to identify defects on both sides of the silicon carbide-silicon dioxide interface. Our measurements identify multiple defect centers, some in the silicon dioxide near the interface, others in the silicon carbide near the interface. The silicon dioxide centers include simple oxygen vacancy centers and hydrogen complexed oxygen vacancy centers. The silicon carbide centers include silicon vacancies and, as yet only partially identified hydrogen complexed defects. Of particular interest are defect centers which are either created or activated by bias temperature stressing.We show that the presence of one near interface silicon carbide defect is strongly correlated with the interface trap density in as processed devices, the silicon vacancy. We also show that the amlitudes of several SDR/EDMR spectra, those associated with oxygen vacancy centers in the oxide and at least one hydrogen complexed center are correlated with bias temperature instability response.We believe our work will be useful to SiC device process designers in particular. We also believe that the work will be of interest to a broader audience, including those involved in research dealing with other wide band gap semiconductors because the novel low to near zero field SDR measurements we utilize can likely be readily adapted to devices based upon virtually any wide band gap material.

Performance evaluation of high-voltage 1.2 kV silicon carbide metal oxide semi-conductor field effect transistors for three-phase buck-type PWM rectifiers in aircraft applications

This study investigates the use of 1.2 kV silicon carbide (SIC) metal oxide semi-conductor field effect transistors (MOSFETs) against standard insulated gate bipolar transistors (IGBTs) for the practical implementation of a three-phase buck-type pulse width modulation (PWM) rectifier for aircraft power networks, showing the design details and the benefits attained. The two main performance targets when designing and building power converters for aircraft applications are high reliability followed by reduced weight. The low switching losses of the 1.2 kV SiC MOSFET allow the converter to switch at higher frequency, allowing lighter passive filters with reduced size, which significantly reduces the weight of the complete converter system. The three-phase buck-rectifier can be used in an aircraft power system as a pre-stage converter for two main different applications: either to generate the main dc network (+270 V) by adding a simple boost converter or to generate the isolated 28 V dc network by adding a dc/dc converter in conjunction with a high-frequency transformer. A 4.5 kW prototype has been specifically designed and built to demonstrate the performance and advantages of the SiC MOSFET implementation.

Observation of Deep Level Centers in 4H and 6H Silicon Carbide Metal Oxide Semiconductor Field Effect Transistors

Utilizing an very sensitive electron spin resonance (ESR) technique, spin dependent recombination (SDR) we have identified interface and near interface trapping centers in 4H and 6H SiC/SiO2 metal oxide semiconductor field effect transistors (MOSFETs). We extend our group’s earlier observations on 6H devices to the more technologically important 4H system and find that several centers can play important roles in limiting the performance of SiC based MOSFETs.