Transient electrothermal simulation of power semiconductor devices

In this paper, a new thermal model based on the Fourier series solution of heat conduction equation has been introduced in detail. 1-D and 2-D Fourier series thermal models have been programmed in MATLAB/Simulink. Compared with the traditional finite-difference thermal model and equivalent RC thermal network, the new thermal model can provide high simulation speed with high accuracy, which has been proved to be more favorable in dynamic thermal characterization on power semiconductor switches. The complete electrothermal simulation models of insulated gate bipolar transistor (IGBT) and power diodes under inductive load switching condition have been successfully implemented in MATLAB/Simulink. The experimental results on IGBT and power diodes with clamped inductive load switching tests have verified the new electrothermal simulation model. The advantage of Fourier series thermal model over widely used equivalent RC thermal network in dynamic thermal characterization has also been validated by the measured junction temperature

Compact Modeling of SiC Insulated Gate Bipolar Transistors

This thesis presents a unified (n-channel and p-channel) silicon/silicon carbide Insulated Gate Bipolar Transistor (IGBT) compact model in both MAST and Verilog-A formats. Initially, the existing MAST model mobility equations were updated using recently referenced silicon carbide (SiC) data. The updated MAST model was then verified for each device tested. Specifically, the updated MAST model was verified for the following IGBT devices and operation temperatures: n-channel silicon at 25 ˚C and at 125 ˚C; n-channel SiC at 25 ˚C and at 175 ˚C; and p-channel SiC at 150 ˚C and at 250 ˚C. Verification was performed through capacitance, DC output characteristics, and turn-off transient simulations. The validated MAST model was then translated into the Verilog-A language, and the Verilog-A model results were validated against the updated MAST model

Modeling of SIC P-Channel Insulated Gate Bipolar Transistors (IGBTS)

A new physics-based IGBT compact model has been developed for circuit simulation of silicon (Si) or silicon carbide (SiC) devices. The model accurately predicts the steady-state output, transfer and switching characteristics of the IGBT under a variety of different conditions. This is the first IGBT model to predict the behavior of p-channel SiC IGBTs. Previous work on IGBT models has focused on Si n-channel IGBTs [1-3]. This unified model is not limited to SiC p-channel IGBTs; the user has the option to select between Si or SiC, and n-channel or p-channel, making it the first IGBT model that captures the physics of all of these device and material types. The model also accounts for temperature effects, often referred to as temperature scaling, that have been experimentally validated up to 300 ºC for SiC. Validation of n-channel and p-channel devices was accomplished by fitting the steady-state characteristics and inductive load switching transient waveforms. 15-kV p-channel IGBTs supplied by Cree were among those used for validation [6]. The fitting was achieved using Certify, a software tool developed at the University of Arkansas. A parameter extraction recipe for the model was developed for simple parameter extraction using data that are readily available from datasheets. That fitting tool is available to the public through the National Center for Reliable Electric Power Transmission website (ncrept.eleg.uark.edu). The model and parameter extraction recipe will also be made available to the public through NCREP

Advanced avionics applications simulation platform (AAASP) for accurate aircraft systems simulation

A persistent problem for Aircraft Manufacturers has been the difficulty in carrying out accurate and robust simulations of the complete aircraft power network, while including numerous models from a variety of individual equipment suppliers. Often the models are of variable or low quality, with ill-defined parameters or behavior, and in many cases of the wrong level of abstraction to be appropriate for large scale network simulations. In addition, individual equipment suppliers often provide poor models for network integration, with a common issue being low robustness of models leading to lack of convergence, excessive simulation times and delays in development due to the need for rework and extensive testing of these models. In order to address this specific issue a complete library of power electronic system models for Aerospace applications has been developed that encompasses the range of functions from elementary components (passives, devices, switches and magnetic components), intermediate building blocks (rectifiers, inverters, motors, protection devices) and finally complete system models (variable frequency starter generators, power converters, battery and storage elements, transformers). These models have been developed in partnership with several key aircraft equipment suppliers and in partnership with Airbus to ensure that the resulting models are complete and robust. Specific equipment models were also developed in this library including permanent magnet generators, synchronous machines, environmental control systems, wing ice protection systems, power electronic modules and advanced power protection systems. The specific models have been validated against reference and measured data to ensure that they are consistent and accurate.This paper will describe the techniques used to achieve more robust models, using model based engineering, the integration of specific equipment models into the complete aircraft network and the validation of the behavior against measured results. The paper will provide the results of a complete aircraft power network highlighting how the individual models are integrated into the overall network model and the inherent robustness ensure effective, accurate and robust simulations.<br/

Assessing the effectiveness of different test approaches for power devices in a PCB

Power electronic systems employing Printed Circuit Boards (PCBs) are broadly used in many applications, including some safety-critical ones. Several standards (e.g., ISO26262 for the automotive sector and DO-178 for avionics) mandate the adoption of effective test procedures for all electronic systems. However, the metrics to be used to compute the effectiveness of the adopted test procedures are not so clearly defined for power devices and systems. In the last years, some commercial fault simulation tools (e.g., DefectSim by Mentor Graphics and TestMAX by Synopsys) for analog circuits have been introduced, together with some new fault models. With these new tools, systematic analog fault simulation finally became practically feasible. The aim of this paper is twofold: first, we propose a method to extend the usage of the new analog fault models to power devices, thus allowing to compute a Fault Coverage figure for a given test. Secondly, we adopt the method on a case study, for which we quantitatively evaluate the effectiveness of some test procedures commonly used at the PCB level for the detection of faults inside power devices. A typical Power Supply Unit (PSU) used in industrial products, including power transistors and power diodes, is considered. The analysis of the gathered results shows that using the new method we can identify the main points of strength / weakness of the different test solutions in a quantitative and deterministic manner, and pinpoint the faults escaping to each one

Fault-based Analysis of Industrial Cyber-Physical Systems

The fourth industrial revolution called Industry 4.0 tries to bridge the gap between traditional Electronic Design Automation (EDA) technologies and the necessity of innovating in many indus- trial fields, e.g., automotive, avionic, and manufacturing. This complex digitalization process in- volves every industrial facility and comprises the transformation of methodologies, techniques, and tools to improve the efficiency of every industrial process. The enhancement of functional safety in Industry 4.0 applications needs to exploit the studies related to model-based and data-driven anal- yses of the deployed Industrial Cyber-Physical System (ICPS). Modeling an ICPS is possible at different abstraction levels, relying on the physical details included in the model and necessary to describe specific system behaviors. However, it is extremely complicated because an ICPS is com- posed of heterogeneous components related to different physical domains, e.g., digital, electrical, and mechanical. In addition, it is also necessary to consider not only nominal behaviors but even faulty behaviors to perform more specific analyses, e.g., predictive maintenance of specific assets. Nevertheless, these faulty data are usually not present or not available directly from the industrial machinery. To overcome these limitations, constructing a virtual model of an ICPS extended with different classes of faults enables the characterization of faulty behaviors of the system influenced by different faults. In literature, these topics are addressed with non-uniformly approaches and with the absence of standardized and automatic methodologies for describing and simulating faults in the different domains composing an ICPS. This thesis attempts to overcome these state-of-the-art gaps by proposing novel methodologies, techniques, and tools to: model and simulate analog and multi-domain systems; abstract low-level models to higher-level behavioral models; and monitor industrial systems based on the Industrial Internet of Things (IIOT) paradigm. Specifically, the proposed contributions involve the exten- sion of state-of-the-art fault injection practices to improve the ICPSs safety, the development of frameworks for safety operations automatization, and the definition of a monitoring framework for ICPSs. Overall, fault injection in analog and digital models is the state of the practice to en- sure functional safety, as mentioned in the ISO 26262 standard specific for the automotive field. Starting from state-of-the-art defects defined for analog descriptions, new defects are proposed to enhance the IEEE P2427 draft standard for analog defect modeling and coverage. Moreover, dif- ferent techniques to abstract a transistor-level model to a behavioral model are proposed to speed up the simulation of faulty circuits. Therefore, unlike the electrical domain, there is no extensive use of fault injection techniques in the mechanical one. Thus, extending the fault injection to the mechanical and thermal fields allows for supporting the definition and evaluation of more reliable safety mechanisms. Hence, a taxonomy of mechanical faults is derived from the electrical domain by exploiting the physical analogies. Furthermore, specific tools are built for automatically instru- menting different descriptions with multi-domain faults. The entire work is proposed as a basis for supporting the creation of increasingly resilient and secure ICPS that need to preserve functional safety in any operating context

Hybrid data-driven modelling methodology for fast and accurate transient simulation of SiC MOSFETs

To enable fast and accurate models of SiC MOSFETs for transient simulation, a hybrid data-driven modeling methodology of SiC MOSFETs is proposed. Unlike conventional modeling methods that are based on complex nonlinear equations, data-driven Artificial Neural Networks (ANNs) are used in this paper. For model accuracy, the I-V characteristics are measured in the whole operation region to train the ANN. The ANN model is then combined with behavior-based equations to model the cutoff region and to avoid overfitting the ANN. In addition, the C-V characteristics are modeled by ANNs with a logarithmic scale for accuracy. The proposed model is implemented and simulated in SPICE simulator SIMetrix. The simulation results are compared with experimental results from a double-pulse tester to validate the proposed modeling methodology. The model is also compared with the Angelov model created by the Keysight MOSFET modeling software. The comparison results show that the proposed model is more accurate than the Angelov model. Besides, when compared to the Angelov model, the proposed model requires 30% less computation time when simulating a double pulse tester. In addition, the proposed modeling method also has better adaptability to model different types of SiC MOSFETs

Advanced avionics applications simulation platform (AAASP) for accurate aircraft systems simulation

A persistent problem for Aircraft Manufacturers has been the difficulty in carrying out accurate and robust simulations of the complete aircraft power network, while including numerous models from a variety of individual equipment suppliers. Often the models are of variable or low quality, with ill-defined parameters or behavior, and in many cases of the wrong level of abstraction to be appropriate for large scale network simulations. In addition, individual equipment suppliers often provide poor models for network integration, with a common issue being low robustness of models leading to lack of convergence, excessive simulation times and delays in development due to the need for rework and extensive testing of these models. In order to address this specific issue a complete library of power electronic system models for Aerospace applications has been developed that encompasses the range of functions from elementary components (passives, devices, switches and magnetic components), intermediate building blocks (rectifiers, inverters, motors, protection devices) and finally complete system models (variable frequency starter generators, power converters, battery and storage elements, transformers). These models have been developed in partnership with several key aircraft equipment suppliers and in partnership with Airbus to ensure that the resulting models are complete and robust. Specific equipment models were also developed in this library including permanent magnet generators, synchronous machines, environmental control systems, wing ice protection systems, power electronic modules and advanced power protection systems. The specific models have been validated against reference and measured data to ensure that they are consistent and accurate.This paper will describe the techniques used to achieve more robust models, using model based engineering, the integration of specific equipment models into the complete aircraft network and the validation of the behavior against measured results. The paper will provide the results of a complete aircraft power network highlighting how the individual models are integrated into the overall network model and the inherent robustness ensure effective, accurate and robust simulations.<br/

Experiments with Ultracold Strontium in Compact Grating Magneto-Optical Trap Geometries

In this thesis, we present the construction of a new apparatus for conducting experiments withultracold strontium. The new apparatus is designed with a high-flux atomic source, a custom science chamber optimized for optical access, high-current Bitter electromagnets, and an updated computer control system. We discuss in-depth the implementation of an insulated-gate bipolar transistor (IGBT) for fast current control of the magnetic field coils. We also present the design of JQI AutomatioN for Experiments (JANE): a programmable system on chip (PSoC)-based pseudoclock device that we use as the main clocking device for our experiments. Next, we report the realization of the first magneto-optical trap (MOT) of an alkaline-earth atom with a tetrahedral trap geometry produced by a nanofabricated diffraction grating. We have demonstrated a broad-line MOT in bosonic 88Sr and fermionic 87Sr. We trap approximately 4x10^7 atoms of 88Sr and achieve temperatures of around 6 mK, with a trap lifetime of around 1 s. Finally, we demonstrate sawtooth wave adiabatic passage (SWAP) in a narrow-line MOT of 88Sr atoms. In the narrow-line MOT, we trap approximately 3x10^6 atoms, with an average temperature of 3.4 µK and a trap lifetime of 0.77 s. We also discuss the possibility for a narrow- line grating MOT of the fermionic isotope. Our work with strontium grating MOTs is a step in the direction of compact quantum devices with alkaline-earth atoms