Thyristors

All the thyristor unIts when are in conduction produces power loss that dissipate inside cabinet in term of heating.
Due to this fact the internal temperature of cabinet is higher than ambient temperature.
Here you can find some solution by CD Automation team

It is an important issue to study sea clutter suppression because it could interfere with the detection of targets above the sea surface severely. Spatial spectrum analyses show that the majority of sea clutter has low-frequency characteristics, compared to the high-frequency characteristics of the targets. This paper proposes a frequency-based spatial tracking filter to suppress sea clutter to facilitate targets identification. Experimental results show that the signal-to-clutter ratio can increase by more than 10 dB after filtering and the algorithm is feasible for practical use. In addition, the filtering equation can be optimized to maximize the signal-to-clutter ratio improvement. The equation parameters can also be adjusted to give a proper cut-off frequency for different targets and clutter.

A microcomputer, the Altair 8800, was used to generate the gating signals for a single-phase-to-single-phase cycloconverter, keeping the same firing angle on all thyristors for a particular output voltage and frequency. The power circuit and the required interface circuits were built. Output waveforms for different firing angles and output frequencies were obtained.

This paper proposes a new configuration to help a GTO to achieve unity turn-off gain and snubberless turn-off capability by utilizing a series connected discrete diode. The maximum turn-off gate voltage, which is crucial for realizing a high commutation di/dt in the GTO gate loop, can be increased from about 20 V of a GTO's gate-cathode breakdown to a voltage

Today, the development and integration of train and ship controllers is a more difficult task than ever. Emergence of high-power switching devices has enabled the development of new solutions with improved controllability and efficiency. It has also increased the necessity for more stringent test and integration capabilities since these new topologies come with less design experience on the part of the system designers. To address this issue, a real-time simulator can be a very useful tool to test, validate and integrate the various subsystems of modern rail vehicle devices. This paper presents such a real-time simulator, based on commercial-off-the-shelf PC technology, suitable for the simulation of train and ship propulsion devices.

A three-phase ac power control circuit using power transistors which operate in a high-frequency chopping mode is described. The circuit is capable of handling several kilowatts of power at any lagging load power factor angle and the output voltage can be smoothly controlled from zero to full supply voltage. The circuit has inherently fast response and the high-frequency ripple at the output is easily filtered. The development, study, and experimental evaluation of the circuit with resistive and induction motor loads is described.

Realization of on-chip electrostatic discharge (ESD) protection requires extensive technical experience and know-how. A technology computer-aided design (TCAD) methodology aimed to assist in the design and implementation of robust ESD devices is developed and presented. The methodology provides a systematic and practical means for the evaluation and optimization of ESD devices in a simulation environment. Advanced siliconcontrolled-rectifier devices are considered to illustrate the approach, and experimental data measured from these devices are also included in support of the TCAD development.

Polyimide layers have been applied by a simple blade squeeze technique on double-mesa high voltage thyristor devices for its electrical passivation. Reverse and forward electrical blocking characteristics were measured as a function of polyimide application and curing processing conditions. During high temperature reverse bias reliability test, the thyristors showed appreciable leak-current increment, but after three day thermal process, the devices showed lower leakage currents than that devices fabricated by conventional glassivation technique.

Study about application of thyristors -solid state four layers p-n-p-n semicondutors -in the industry, both in manufacture stage and as part of end product. The thyristors are more commonly represented by Silicon Controlled Rectifiers -the SCRs -but are also represented by many authors by TRIACs, DIACs, MOSFETs and others. In thits study, their represented more accuracy than contactors, relays and other devices, specially on high volgate networks and power conversion.

The 6.5 kV insulated gate bipolar transistor (IGBT) is a new promising power device for high-voltage high-power applications. Due to its increased voltage blocking capability, the new HV IGBT can serve as a good replacement for GTO and IGCT thyristors in medium or medium-to-high power applications. One of its general application fields is railway traction. The paper discusses design and development considerations of the 50-kW auxiliary power supply to be used in 3.0 kV DC commuter trains. Focus is on the implementation of 6.5kV IGBTs in the primary inverter of APS to improve overall power density, system integrity as well as reliability of the whole system. For instance, topology selection, analysis and simulation of functional blocks of a converter for different operation points are described. A prototype of half-bridge isolated DC/DC converter with two 6.5kV 200A IGBT transistors was designed and built. Some design considerations are specified in the paper.

The main aim of this work is to damp out power system oscillations, which has been recognized as one of the major concerns in power system operation. In a Static Synchronous Series Co mpensator (SSSC), a controllable A C voltage is generated by a voltage-source converter. There are two control channels for controlling the magnitude and phase of the voltage. This work describes the damping of power oscillations by static synchronous series compensator (SSSC) based damping controllers. The advantage of this approach is that it can handle the nonlinearit ies, at the same time it is faster than other conventional controllers and it improve the reactive power of the system. Simu lation studies will be carried out in Matlab/Simu link environ ment to evaluate the effectiveness of the proposed Static synchronous series compensator (SSSC) of mu lti-area power system. Results will show that the proposed SSSC based damping controllers improve the dampin g performance of the in the event of a major d isturbance.

This paper presents an overview of the state of the art in reactive power compensation technologies. The principles of operation, design characteristics and application examples of Var compensators implemented with thyristors and self-commutated converters are presented. Static Var generators are used to improve voltage regulation, stability, and power factor in ac transmission and distribution systems. Examples obtained from relevant applications describing the use of reactive power compensators implemented with new static Var technologies are also described.

The specifications of a highly flexible controller for a three-phase McMurray inverter are defined and the construction of a suitable controller is described. The controller is capable of operation in either the six step or pulsewidth modulation mode and incorporates safe start-up and shut-down procedures. The operation of the controller is illustrated by a series of inverter and controller oscillograms.

This paper presents a new three-phase pulse width modulated (PWM) half-controlled rectifier using a new PWM control strategy such that the low-order harmonic content in both the input current and the output voltage is reduced. Further, the circuit operates with a unity displacement factor at its input and uses minimum power components. The new PWM strategy developed allows its implementation on a three-phase half-controlled rectifier bridge with only three controlled switches to obtain PWM controlled rectification. Although the circuit operation is explained with force-commutated SCR switches, the basic controlled PWM operation is valid for any alternative controlled switches like GTO or transistors, which do not require the commutating power components. The circuit has wide applications ranging from rectifiers to battery chargers to motor drives. Even if an input current filter is desired, its size will be small due to the PWM pattern used.

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the main objective of this paper is to investigate the enhancement of power system stability via coordinated design of Thyristor Controlled Series Compensation (TCSC) and Power System Stabilizers (PSSs) in multimachine power system. The design problem of the proposed controllers is formulated as an optimization problem. Using the developed linearized power system model, the particle swarm optimization (PSO) algorithm is employed to search for optimal controllers' parameters settings that maximize the minimum damping ratio of all system eigenvalues. The proposed controller is evaluated on a multimachine power system. The nonlinear simulation results and eigenvalue analysis show the effectiveness of the proposed controller in damping power system oscillations.

As power system interconnections become more prevalent, there has been an increase in use of thyristor controlled shunt connected compensation devices for dynamic power compensation and enhancement of real power transmission capacity. In this paper, an enhancement technique of real power transfer capacity of transmission lines is presented. A static var compensator (SVC) is designed and applied to a simple power system for this purpose. Increase in power flow and improvement in bus voltage profile are observed after using the SVC. Stability analysis of the system after experiencing fault as well as consequent fault clearance by time domain analysis has also been performed and satisfactory results are obtained.

Series compensation of transmission lines using fixed series capacitors can cause sub-synchronous resonance (SSR) between electrical and mechanical systems. This phenomenon leads to severe damages to turbine generator shafts. Thyristor controlled series compensator (TCSC) is one of the FACTS devices which can be utilized to damp electromechanical and sub-synchronous oscillations. This device can perform flexible series compensation and SSR damping. The effect of different parameters of the TCSC is studied using complex torque coefficient method. Open loop and closed-loop constant current and constant power control methods are simulated using PSCAD/EMTDC software package. First IEEE benchmark model for sub-synchronous resonance studies and a complete model of TCSC is used to analyze the effect of different parameters and control structure on the SSR damping capability of the TCSC.

A simple model for a thyristor driven dc motor is rigorously established. The derivation is based on the machine equations and on the definition of a pseudoinstantaneous meanvalue function. The influence of the converter on the voltage applied to the dc motor is considered. The final model includes ail significant effects, has the same structure for continuous and discontinuous current conduction modes, and allows simple control synthesis. The model is compared to the classical model of a dc motor and the differences are highlighted. With the proposed model, it is easy to understand the influence of a thyristor converter on the dynamic performance of a dc motor and, therefore, this formulation has a significant educational aspect. A dual-mode adaptive current controller is designed using this model. Experimental and simulation results are compared to validate the work.

By dramatically decreasing the storage time, the emitter turn-off thyristor (ETO) has a very good match in storage time. Storage time dispersion of less than 100 ns is normal for ETOs and can be further reduced through adjustment of the emitter switch gate resistance. Thus, the capacitance required for dynamic voltage balancing in the ETO series connection is significantly reduced. Uniform current sharing for parallel-connected ETOs is also guaranteed at the device level through the open-base p-n-p turn-off mechanism. The current-balancing inductance can be essentially removed. Theoretical analysis and experimental results of 53-mm ETOs are presented.

Se analiza el proceso de diseño y la simulación de un esquema de filtro activo híbrido aplicable a tensiones medias sin necesitar de transformadores reductores para tal fin. Se muestra el desarrollo del método de compensación usado y los resultados obtenidos cuando se aplica en un sistema de conversión de alterna a continua basado en tiristores. El sistema se simula para diferentes niveles de tensión de alimentación.

A method for determining parameters for a two-transistor SCR model from SCR specification sheet data developed by Hu and Ki (1979) for use with the CAD program SPICE2 was examined. The model was found to need improvement in order to simulate the SCR turn-off transient in an inductive circuit. An improved model was then developed for SPICE2 which was demonstrated to perform satisfactorily through simulation of AC resonant charging circuits having one or two SCR's. The original and the modified Hu-Ki models are presented together with the simulation results.

InGaN-GaN multiple-quantum-well (MQW)-based photodetectors, with a detection edge at 450 nm and a high responsivity, have been fabricated and characterized. We show that the performance of MQW-based photodetectors strongly depends on a proper device design, i.e., number of QWs, and barrier and blocking layer thickness and doping level. Namely, the responsivity can be varied in the 1 to 100 mA/W range in similar structures and with the same number of QWs. These results support a model where the photocurrent increase is due to the improvement of collection efficiency caused by a change in transport mechanism for carriers photogenerated in the QWs. The transport mechanism depends on the location of the QWs in relation to the depletion region.

Silicon-controlled rectifiers (SCRs) are frequently used to build on-chip electrostatic discharge (ESD) protection structures, but SCRs are not sufficiently robust to meet a wide range of ESD requirements in various integrated circuits. In this paper, a novel and robust SCR-based device called the HHLVTSCR is presented. It is demonstrated that HHLVTSCR can exhibit various characteristics useful for ESD solutions. An example is also included to illustrate how HHVLTSCRs can be used to provide ESD protection to a practical application.

Abstruct-A new adaptive control system for dc motor drive with field weakening is proposed. The adaptation mechanism is based on the gain scheduling. A deep knowledge of the phenomena in the drive was necessary to define the scheduled variables that capture the essential nonlinearities of the process considered. However, in practice, to realize the proposed adaptive control system, the only a priori knowledge required is the experimentally determined magnetization curve. Simulation and experimental results indicating high performances of the control system proposed, are presented.

In this paper, a mathematical model is developed for the steady state behavior of thyristor controlled series capacitor (TCSC). The TCSC mathematical model is developed by using firing angles of the thyristors as the modeling input. Based on the model developed and the effective TCSC reactance model presented in the literature, the steady state behavior of TCSC under varying capacitance and inductance values is investigated. The results obtained showed that a multiple-TCSC resonance point occurred when inappropriate values for the TCSC parameters are chosen. As a result, the steady state behavior of TCSC as well as its operating performance is negatively influenced. MATLAB application software is used for this study.

This is DC Motor Controller (any RPM) is widely used application used now a days which is designed using Atmel AT89C51.This Controller is used to increment or decrement. The speed of motor is controlled in 7 steps. That is operated at seven different speeds

This paper describes a feasibility study into the use of a formal requirements modeling method (SCR) to assist with Independent Verification and Validation of change requests for Space Shuttle flight software. The goal of the study was to determine whether a formal modeling technique could automate some of the manual analysis tasks performed on change requests, including consistency checking. To analyze the change request, the key part of the original functionality was modeled in SCR. The model was then updated to reflect the proposed changes. Tool support was used to perform consistency checking and to validate the model against domain properties. The study showed that as an analysis tool, formal modeling offers some advantages over inspectionbased approaches. However, the problem of analyzing change requests is sufficiently different from other requirements modeling tasks that some specialist tools will be needed. The paper ends with a discussion of the demands of these needs.

The critical charge density which determines the maximum voltage ramp (dV =dt) of a thyristor, the minimum value of the gate control current, and the parameters of current filamentation has been determined in SiC thyristors both theoretically and experimentally. For 4H-SiC thyristors blocking 300 to 400 V, the critical charge density has been found to be 2210 15 cm 03 and 10 14 cm 03 at a forward voltage of 5 and 100 V,

Various trends in power systems increase the need for network investments on the transmission level. In this paper we compare different investment criteria and transmission technologies to determine where and how the network should be reinforced. We deploy an agent-based model taking explicitly into account that generation companies might behave strategically by submitting bids to the marketplace deviating from their true marginal cost. In a subsequent step we formulate the optimization problem of the Independent System Operator relying on the wellknown Locational Marginal Pricing market design. In a last step the ISO can decide for transmission investments, by reinforcing existing lines or installing Flexible AC Transmission Systems. We show that the decisions regarding which technologies should be used and what locations are to be chosen are not influenced by the strategic behavior of market participants. Additionally, we demonstrate -both analytically and through simulationsthat maximizing social welfare as investment criterion complements the objective of mitigating strategic behavior of individual players.

Differences between the tap-changing process in conventional mechanical and electronic tap-changers are briefly reviewed. A model of the controller of a mechanical tap-changer system is then presented. Modifications to this controller are then proposed for adaptation to an electronic tap-changer. A general structure of an electronic tap-changer and the simulation of the modified controller are then presented. A number of experimental results shows the performance of the modified controller.

The model of interconnected numerical device segments can give a prediction on the dynamic performance of large area full wafer devices such as the GCTs and can be used as an optimization tool for designing GCTs. In this paper we evaluate the relative importance of the shallow p-base thickness, its peak concentration, the depth of the p-base and the buffer peak concentration.

The turn-on mechanism of a silicon-controlled rectifier (SCR) device is essentially a current triggering event. While a current is applied to the base or substrate of the SCR device, it can be quickly triggered into its latching state. In this paper, a novel design concept to turn on the SCR device by applying the substrate-triggered technique is first proposed for effective on-chip electrostatic discharge (ESD) protection. This novel substrate-triggered SCR device has the advantages of controllable switching voltage and adjustable holding voltage and is compatible with general CMOS processes without extra process modification such as the silicide-blocking mask and ESD implantation. Moreover, the substrate-triggered SCR devices can be stacked in ESD protection circuits to avoid the transient-induced latch-up issue. The turn-on time of the proposed substrate-triggered SCR devices can be reduced from 27.4 to 7.8 ns by the substrate-triggering technique. The substrate-triggered SCR device with a small active area of only 20 m 20 m can sustain the HBM ESD stress of 6.5 kV in a fully silicided 0.25-m CMOS process.

InGaN-GaN multiple-quantum-well (MQW)-based photodetectors, with a detection edge at 450 nm and a high responsivity, have been fabricated and characterized. We show that the performance of MQW-based photodetectors strongly depends on a proper device design, i.e., number of QWs, and barrier and blocking layer thickness and doping level. Namely, the responsivity can be varied in the 1 to 100 mA/W range in similar structures and with the same number of QWs. These results support a model where the photocurrent increase is due to the improvement of collection efficiency caused by a change in transport mechanism for carriers photogenerated in the QWs. The transport mechanism depends on the location of the QWs in relation to the depletion region.

New insights regarding the interpretation of the VFTLP IV-curve and the fast transient current and voltage waveform data are presented. These insights are used to determine the design factors affecting the turn-on time and triggering behavior of SCRs in a 90 nm bulk CMOS technology.

A compact algorithm based on power analysis for reactive power compensation as well as load balancing through the static var compensator (SVC) in three-phase three-wire system is developed in this paper. The structure of the SVC is thyristor controlled reactors with fixed capacitors (TCR-FC). By the proposed algorithm the required compensation susceptances for each phase of the SVC is obtained from a very simple function of voltage and reactive power signals which are measured from the network. The salient feature associated with the proposed method is that the circuit representation of system load is not required and the load is recognized just by its active and reactive consumptions. The load's type and connection, hence, do not matter and this method is valid for the case of active loads too. The validity and performance of the new approach are analyzed via a numerical example and the obtained simulation results are thoroughly discussed.