Physics-based Compact Model of Integrated Gate-Commutated Thyristor with Multiple Effects for High Power Application

This paper presents a physics-based compact model of integrated gate-commutated thyristor (IGCT) with multiple effects for high power application. The proposed model has both acceptable accuracy and computation time requirement, which is suitable for system level circuit simulation and IGCT’s whole wafer modelling work. First, the development of IGCT model is discussed and the one-dimension phenomenon of IGCT is analyzed in the paper. Second, a physics-based compact model of IGCT is proposed. The proposed model of IGCT includes multiple physical effects that are crucial to IGCTs working in high power applications. These physical effects include the impact ionization effect, moving boundary of depletion region during punch-thourgh (PT) and the local lifetime region. The Fourier series solution is applied for the ambipolar diffusion equation in the base region. Third, the proposed model is implemented in Simulink and compared with the model in Silvaco Atlas, a finite-element (FEM) tool. Finally, the proposed compact model of IGCT is validated by experiments

Environmental Compatible Circuit Breaker Technologies

Recent research and development in the field of high-current circuit breaker technology are devoted to meeting two challenges: the environmental compatibility and new demands on electrical grids caused by the increasing use of renewable energies. Electric arcs in gases or a vacuum are the key component in the technology at present and will play a key role also in future concepts, e.g., for hybrid and fast switching required for high-voltage direct-current (HVDC) transmission systems. In addition, the replacement of the environmentally harmful SF6 in gas breakers and gas-insulated switchgear is an actual issue. This Special Issue comprises eight peer-reviewed papers, which address recent studies of switching arcs and electrical insulation at high and medium voltage. Three papers consider issues of the replacement of the environmentally harmful SF6 by CO2 in high-voltage gas circuit breakers. One paper deals with fast switching in air with relevance for hybrid fault current limiters and hybrid HVDC interrupters. The other four papers illustrate actual research on vacuum current breakers as an additional option for environmentally compatible switchgear; fundamental studies of the vacuum arc ignition, as well as concepts for the use of vacuum arcs for DC interruption

Architecture, Voltage and Components for a Turboelectric Distributed Propulsion Electric Grid

The development of a wholly superconducting turboelectric distributed propulsion system presents hide unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance

Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid

The development of a wholly superconducting turboelectric distributed propulsion system presents unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance

Investigation of FACTS devices to improve power quality in distribution networks

Flexible AC transmission system (FACTS) technologies are power electronic solutions that improve power transmission through enhanced power transfer volume and stability, and resolve quality and reliability issues in distribution networks carrying sensitive equipment and non-linear loads. The use of FACTS in distribution systems is still in its infancy. Voltages and power ratings in distribution networks are at a level where realistic FACTS devices can be deployed. Efficient power converters and therefore loss minimisation are crucial prerequisites for deployment of FACTS devices. This thesis investigates high power semiconductor device losses in detail. Analytical closed form equations are developed for conduction loss in power devices as a function of device ratings and operating conditions. These formulae have been shown to predict losses very accurately, in line with manufacturer data. The developed formulae enable circuit designers to quickly estimate circuit losses and determine the sensitivity of those losses to device voltage and current ratings, and thus select the optimal semiconductor device for a specific application. It is shown that in the case of majority carrier devices (such as power MOSFETs), the conduction power loss (at rated current) increases linearly in relation to the varying rated current (at constant blocking voltage), but is a square root of the variable blocking voltage when rated current is fixed. For minority carrier devices (such as a pin diode or IGBT), a similar relationship is observed for varying current, however where the blocking voltage is altered, power losses are derived as a square root with an offset (from the origin). Finally, this thesis conducts a power loss-oriented evaluation of cascade type multilevel converters suited to reactive power compensation in 11kV and 33kV systems. The cascade cell converter is constructed from a series arrangement of cell modules. Two prospective structures of cascade type converters were compared as a case study: the traditional type which uses equal-sized cells in its chain, and a second with a ternary relationship between its dc-link voltages. Modelling (at 81 and 27 levels) was carried out under steady state conditions, with simplified models based on the switching function and using standard circuit simulators. A detailed survey of non punch through (NPT) and punch through (PT) IGBTs was completed for the purpose of designing the two cascaded converters. Results show that conduction losses are dominant in both types of converters in NPT and PT IGBTs for 11kV and 33kV systems. The equal-sized converter is only likely to be useful in one case (27-levels in the 33kV system). The ternary-sequence converter produces lower losses in all other cases, and this is especially noticeable for the 81-level converter operating in an 11kV network

Application of Modular Multilevel Converter technology to HV power supplies of Neutral Beam injector

Evaluation of the possible application of Modular Multilevel Converter at the AGPS of NBI

Aspects and directions of internal arc protectio

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ADVANCED TERMINATION STRUCTURES FOR HV POWER SEMICONDUCTOR DEVICES

Thesis is in the field of power electronic devices. They operate in power conversion system as power switches able to impose the ON/OFF condition. A power device present two macroscopic areas: 1) active area; 2) termination area. The first one is responsible of conduction during the On-state of the device; while the second one mainly contributes to withstand the voltage rate during the Off-state condition. The actual trend of power devices tends to a technological scaling to increase the switching frequency and reduce the costs. As consequence, the percentage of the die area occupied by the termination is even more growing since its dimension is related to the voltage rate. This introduce the necessity to develop new termination design able to sustain the same voltage rate with a reduced consumption of area. At the same time, the new designs must also guarantee the required standard in term of reliability and ruggedness consolidated in classical designs. The scaling has also effects on the active area, where current density is even more growing leading to reliability problem from the thermal point of view. The design of new termination structure, as well as, reliability analysis of the active area have been the main focus of my third year research activities. Two new termination structure have been designed by means of 2D TCAD simulations. The new design realize an improvement of the classical Junction Termination Extension (JTE) technique to sustain a voltage rate of 1.2 kV. JTE design offers the possibility to considerably reduce the occupation of area but present great limitations in term of reliability. JTE needs of optimizing a low-doped P-region to maximize the breakdown voltage of the device. The critical point is that the breakdown voltage is strongly affected by the doping profile of the low-doped region. The breakdown stability is guaranteed only around the optimal value of the doping concentration. A deviation from the optimal value of about 7-8% already produces an inacceptable degradation of the breakdown capability. Since technological process can be subjected to fluctuation or/and contamination of external impurity able to modify the doping profile have led the JTE design to be less attractive for industry. In my activity two innovative two innovative JTE-based terminations have been presented providing a well precise optimization methodology to maximize the breakdown voltage. Both designs have been developed in order to increase the reliability of the device guaranteeing the breakdown stability in a wide range of doping concentration of the low-doped P-region. The first one design exploits the action of a special passivation layer named SIPOS; while the second one is made combining both JTE and a classical Floating Filed Ring technique. The performances of both terminations are than compared with that an advanced Floating Field Ring structure appropriately optimized. Termination ruggedness has been evaluated by means of Unclamped Inductive Switching simulations as the capacitance of power absorption until the failure event. Therefore, current crowding phenomena occurring in avalanche condition are deeply analyzed together with its relation with the Negative Differential Resistance branch on the I-V avalanche curve. During the third year I spent three months period to the Franhoufer Institute (ISIT). My research was focused on aspects regarding technological process of power devices. During this period I realized an emulation process flow of a Floating Field Ring termination for a 600V Punch-Through IGBT. The reliability of the active area was analyzed by means of Short-Circuit test. It is an industrial test able to evaluate the capacitance of power absorption during the Short-Circuit condition of a device. During the Short-Circuit, the device is driven in conduction at high voltage and the current is limited only by the internal resistance. The influence of design parameters on the Short-Circuit capability of a FS-IGBT device has been analyzed. A commercial device has been experimentally characterized by means of static curves tracker, Inductive Load Switching test and Short-Circuit test. The Short-Circuit capability analysis was led with a simulation approach by means of 3D TCAD electro-thermal simulations. The physical models of the elementary cell of the IGBT device have been calibrated to fit the characteristics of the commercial device at different temperatures. An innovative design has been proposed to increase the Short-Circuit capabilit