Thyristor Triggering Research Articles

Updates on Impact Ionisation Triggering of Thyristors

High voltage (HV) generators are used in multiple industrial and scientific facilities. Recent publications have demonstrated that triggering industrial thyristors (relatively slow switching devices) in overvoltage mode, also called impact ionization mode, significantly enhances their dU/dt and dI/dt characteristics. This novel triggering methodology necessitates the application of substantial overvoltage between the thyristor’s anode and cathode, delivered with a swift slew rate exceeding 1 kV/ns. The adoption of compact pulse generators constructed from commercially available off-the-shelf components (COTS) opens up avenues for deploying this technology across various domains, including the implementation of high-speed kicker generators in particle accelerators. In our methodology, we employed commercially available high-voltage SiC MOSFETs along with a custom-designed fast gate driver. This driver was conceptualized based on the recent development of gate boosting techniques, featuring a driving voltage exceeding 600 V. The gate driver for these MOSFETs comprises three key components: a level-shifter with NMOS and PMOS transistors, a compact Marx generator with two avalanche transistors, and a GaN HEMT in a high input and low output impedance configuration. The proposed gate-boosting driver achieves a slew rate exceeding 1 kV/ns for the driving pulse. Furthermore, we demonstrate that with this driver, a 1.7 kV rated SiC MOSFET can produce an output pulse of 1.45 kV and a maximum slew rate of ≈2.5 kV/ns. This gate-boosting driver aims to minimize commutation times, achieves a slew rate of over 1 kV/ns, and handle higher loads, making it ideal for impact ionization triggering of industrial thyristors.

Design of High-Precision Thyristor Trigger Unit for CRAFT Magnet Power Converter

Design of High-Precision Thyristor Trigger Unit for CRAFT Magnet Power Converter

Harmonic Modeling of the Series-Connected Multipulse Rectifiers Under Unbalanced Conditions

With the promotion of high voltage direct current (HVDC) system construction around the world, the series-connected multi-pulse rectifiers (SCMPRs) have been widely used in high-power rectifying occasions in the power system. Since the certain order of harmonics cannot be effectively eliminated under the non-ideal conditions, many different phenomena, such as the unbalance of supply voltage and line/transformer parameters, the influence of background harmonics, and the non-equidistance of thyristor triggering pulses, may cause the non-characteristic harmonics (NCHs) of SCMPR. However, the existing frequency-domain harmonic model cannot be used to analyze the harmonic characteristics of the SCMPRs under non-ideal conditions. In this paper, a general frequency-domain harmonic coupling matrix model (HCMM) is proposed. The proposed HCMM can consider most of the above imbalance factors and the model can explicitly illustrate the harmonic coupling relationship between the SCMPRs supplied voltage and the generated harmonic currents. The generality of the SCMPR model under non-ideal conditions is improved accordingly. The HCMM is simplified by comparing and analyzing the effects of the transformer structure and parameters. Moreover, by analyzing the harmonic generation characteristic of the negative-sequence component, the HCMM can be further simplified. Finally, time-domain simulation and lab experimentation are performed to verify the accuracy and efficiency of the frequency-domain HCMM of SCMPRs. The results prove the generality of the proposed model and also illustrate the harmonic generating influence of unbalanced parameters from the transformer and supply voltage.

Improvement of high-power thyristor trigger circuit with switching-mode power supply for differential-mode noise reduction

This paper focuses on the differential-mode (DM) noise of high-power thyristor (HPT) trigger circuit with switching-mode power supply (SMPS) in capacitive pulsed power supply (CPPS). Parasitic parameter models of components are discussed and analyzed. Based on the parasitic parameter models of components, a DM noise prediction model of HPT trigger circuit with SMPS is developed. The generation mechanism and propagation paths of the DM noise in HPT trigger circuit with SMPS are investigated. To reduce the DM noise, a capacitive SMPS technique is adopted in the HPT trigger circuit with SMPS. Simulation results validate the theoretical analysis.

Differential-Mode Noise Prediction and Cancellation for High-Power Thyristor Trigger Circuit

This article is to predict and cancel differential-mode (DM) noise for high-power thyristor (HPT) trigger circuits and improve the reliability of capacitive pulsed power supply (CPPS). A lumped model of HPT trigger circuit is developed for the DM noise prediction within a concerning frequency range. The generation mechanism and propagation path of the DM noise are systematically studied. To attenuate the DM noise, a DM filter is proposed and discussed. The component parameters of the filter are investigated to improve its DM noise suppression effect. The DM spectrum for the HPT trigger circuit and the insertion losses of the DM filter are simulated and analyzed. Ultimately, DM spectrum tests are carried out. Both the simulated and measured results validate the theoretical analysis.

Parameter Calculation and Working Characteristic Analysis of a New Type of Magnetic Integrated CRT

The working characteristic of an electromagnetic equipment is an important reference standard for measuring its working performance. In this paper, we take a new type of magnetic integrated controllable reactor of transformer type (CRT) as the research object, establish its equivalent mathematical model and deduce its calculation short-circuit impedance and winding current formulas. On this basis, the relationship between the working winding instantaneous current, harmonic current coefficient and equivalent impedance of the new magnetic integrated CRT and the thyristor trigger angle is quantitatively analysed, and the working characteristic curves, such as the instantaneous current waveform, harmonic characteristic curve, control characteristic curve and volt-ampere characteristic curve of the working winding, are obtained. On the basis of the MATLAB/Simulink simulation platform, a new magnetic integrated CRT simulation model is established to simulate the working winding current under different trigger angles to verify the established formulas. Mean-while, the response speed of the CRT is simulated and analysed. Results show that the analytical calculation results of the winding cur-rent of the magnetic integrated CRT are consistent with the simulation results. The new type of magnetic integrated CRT has the characteristics of hierarchical smooth regulation and low harmonic current and the ad-vantages of fast response speed and high sensitivity. Furthermore, the CRT’s volt-ampere characteristic is approximately linear. This study is expected to provide some theoretical guidance for the in-depth understanding of the working characteristics of the magnetic integrated CRT and the structural design and optimisation of the CRT.

THE ROLE OF STATIC VAR COMPENSATOR AT REACTIVE POWER COMPENSATION

The need for electricity is increasing and the cost of energy generation is arising. For this reason, it is important to use the generated energy in good quality, safely and efficiently. Reactive power compensation is one of the most effective application to reduce transmission losses, prevent voltage drops, prevent consumers from paying for reactive energy, facilitate operating, increase efficiency and save energy in energy systems. However, due to improvements in semiconductor technology, reactive power compensation systems have gained a new dimension. The power compensation made by the use of semiconductor power elements is called Static VAr Compensation. This compensation is used for the compensation of loads such as arc furnaces, elevators, automotive; paper packaging, food and textile, point welding machines, port cranes, flat welds. Transient events are minimized, losses are reduced, back up possibility, control flexibility and reliability are ensured by using Static VAr Compensation systems in power network. In this study, thyristor triggering angles and power factor values of a system, that contains reactive loads and controlled by Static VAr Compensation, were obtained by using the computer software developed by Microsoft C Sharp (C#) programming language. The results were discussed in terms of importance of using such controlling structures in power networks.

An analysis of generator trip caused by mistransmitting high temperature signal from excitation transformer

The excitation transformer is a device that specifically provides three-phase AC excitation power for the generator excitation system. The excitation system converts the three-phase power to the generator rotor DC power through the thyristor to form the generator excitation magnetic field, which is adjusted by the excitation system thyristor trigger angle, to achieve the purpose of adjusting the motor terminal voltage and reactive power. This article analyzes an accident in which the excitation transformer high temperature signal is erroneously caused to cause the unit to trip. The unplanned shutdown accident is specifically analyzed from the aspects of on-site situation investigation, cause analysis, main problems exposed, treatment and preventive measures.

Researches on the trigger pulse width’s compression of high power thyristor

The width compression phenomenon of the trigger signal in triggering high power thyristor was first observed in the experiments. The trigger pulse was measured by the oscilloscope in the experiments. The experiments showed that with the increase of the voltage supplied to the thyristor from 1kV to 7kV, the width of the trigger pulse was compressed gradually from 70us(the width with no compression) to 45us. Then with the increase of work voltage from 7kV to 10kV the width of the trigger pulse was not compressed further. This research is very valuable for the design of the thyristor trigger signals.

Hole-transmission enhancement in 4H-silicon carbide light triggered thyristor for low loss *

In this paper, a 20 kV silicon carbide (SiC) light triggered thyristor (LTT) with n-type blocking base is simulated using Synopsys Sentaurus TCAD. In order to reduce the power dissipation, a method that enhances the hole-transmission through electric field induced by gradual doping profile in the n-buffer layer is proposed. The results indicate that the method enhancing the hole-transmission is effective in reducing the power loss of SiC LTT with n-type blocking base. By changing the doping profile of n-buffer layer from uniform to gradual, both on-state loss and switching loss are efficiently reduced. Compared to the conventional SiC LTT with 2.5 μm thick n-buffer layer, when the doping gradient is 1.0 × 1021 cm−4, the on-state and the switching losses of the hole-transmission enhanced SiC LTT are reduced by 34.7% and 17.9%, respectively.

Thyristor-based “phase hopping” frequency conversion technique

This study proposes a new AC/AC phase hopping frequency conversion method based on the analyses of the disadvantages of the conventional cosine wave-crossing method. The advantages of this new method include no circulating current, no dead time, and an output frequency close to the power frequency. This study also introduces the basic principles of the phase hopping method and analyzes these principles combined with the voltage phase-changing comparison to that of the cosine wave-crossing method. The phase hopping principles are used to analyze the generation of thyristor trigger pulses, including the generation time and duration. A simulation is conducted in MATLAB, and the simulation output waveform and harmonic analysis results are then obtained. The proposed approach is verified on an experimental platform. Consequently, the results are in good agreement with those of the theoretical and simulation analyses.

The Design on Pulse Distributor and its Online Status Diagnosis for ITER PF ac/dc Converter

The International Thermonuclear Experimental Reactor (ITER) poloidal field (PF) ac/dc converter operates in four quadrants to provide the control of current necessary to PF coils for plasma initialization and the plasma shape control. The technical details for thyristor triggering of high-power ac/dc converter lay the foundation for the regular operation of ITER PF ac/dc converter. With the characteristics such as high power, complex operating modes of ac/dc converter, the synchronization, reliability, and high security have to be critically concerned in the pulse distributor design. In this paper, a pulse distributor is designed to convert the optical signal to high current electrical trigger pulse with less than 1- $\mu \text{s}$ rising time, thereby triggering the paralleled thyristors reliably and isolating 20-kV voltage from the converter unit to controller. Furthermore, the signals of crucial status are online acquired and encoded, then transmitted to controller by optical fiber, thus implementing the online status diagnosis to guarantee the safety operation of ITER PF ac/dc converter. The pulse distributor has been experimented in ITER PF ac/dc converter and all functions have been effectively verified.

Performance Comparison of ETT- and LTT-Based Pulse Power Crowbar Switch

High-voltage high-power pulse switches are built with semiconductor devices, preferably thyristor, due to the superior performance that they offer. Triggering methods classify the thyristor as electrically triggered thyristor (ETT) and light triggered thyristor (LTT). Due to the specialized gate constructions and many build-in protections, the cost of LTT is much higher than ETT. The operating modes in applications, such as crowbar, do not require all these build-in protections. In this paper, the operation of a crowbar is analyzed, and the build-in protections of LTT are reviewed. This paper proposes three experiments for the design selection of thyristor, between ETT and LTT, for crowbar applications. The experiments cover the electrical performance as well as electromagnetic emissions in a 10-kV, 1-kA crowbar built with both ETT as well as LTT, which can be used to benchmark the performance of the crowbar circuit. From the three experiments, the performance of ETT-based crowbar is found to be comparable with LTT-based crowbar. Based on the experiments carried out with the proposed benchmarking approaches, this paper shows that ETT-based crowbar is a cost-effective solution for crowbar applications.

Performance Analysis of an All Solid-State Linear Transformer Driver

The performance of an all solid-state linear transformer driver (LTD) is evaluated based on experimentally verified behavior of a single stage. The single-stage LTD utilizes a low-profile design with robust thyristor switches and high-energy-density mica capacitors to minimize overall system inductance. Subnanosecond jitter is achieved with simultaneous thyristor triggering. The stage is magnetically coupled to a secondary winding through a central nanocrystalline core. A dc current source, decoupled with a large inductance, actively resets the core between pulses. The overall result is a low-impedance ( $ per stage) pulse generator that rivals the performance of traditional Marx systems with the improved reliability, increased lifetime, and fast rep-rate capabilities of solid-state switches. The stage is tested with charging voltages up to 8 kV into various loads and compared with simulations based on an analog behavioral thyristor switch model previously developed at Texas Tech University. The simulation is expanded into a full-scale, multistage LTD simulation and compared with a previously constructed Marx generator.

Development and Research of Heavy Pulse Current LTT Switches

The results of research of 100 kA pulse current switches built on light triggered thyristors (LTTs) are presented. Transients in a semiconductor switch are analyzed at a capacitor discharge on an inductor and in a pulse forming network (PFN), which incorporates an inductor and crowbar diodes. Maximal currents for a semiconductor structure, at which thermo-generation peaks appear on oscillograms of forward voltage drop, have been determined. The LTT switch-ON process has been investigated and the need for application of speedup $R$ – $C$ circuits for a fast and stable transition of the LTT semiconductor structure to the conducting state has been shown. Transients at reverse recovery of LTTs in a discharge circuit with an inductor have been analyzed, and the snubbers providing suppression of pulse overvoltages and survivability of semiconductors have been chosen. For PFN, the current switching into the crowbar diodes and pulse overvoltage generation at a reverse recovery of LTTs has been analyzed, and the snubbers for suppression of these overvoltages have been chosen. The results of testing performed at a pulse current up to 100 kA confirm the validity of the accepted technical solutions.

Design of series-connected thyristor switch and synchronous triggering circuit

In order to meet the requirement of pulsed power source on high voltage and large current switches，a series-connected thyristor switch with a rated voltage of 10 kV and a rated current of 500 A was developed the traditional voltage sharing method. According to the principle of thyristor trigger, a trigger system was developed for synchronous triggering multiple thyristors. As to generate low-voltage pulse with variable pulse widths, the trigger system used an IGBT switch to cut the DC voltage. In the trigger system, the voltage amplitude of the pulse was increased and the synchronous trigger signals were generated through some isolated pulse transformers. Finally, the thyristor trigger system and the series-connected thyristor switch were tested, Showing that the trigger system could produce multi-channel synchronous trigger signals with a voltage of 20 V, a current of 1 A, a pulse repetition rate of 100 Hz and pulse durations from 30 s to 60 s. Static voltage fluctuation and active voltage fluctuation of the series-connected thyristor switch were small, indicating it could reliably work under the condition of high voltage and large current.

Optical triggering of 4H-SiC thyristors (18 kV class) to high currents in purely inductive load circuit

Optical switch-on of a very high voltage (18 kV class) 4H-SiC thyristor with an amplification step (pilot thyristor) to the current Imax = 1225 A is demonstrated using a purely inductive load and a calibrated air transformer. Increasing the inductance of the transformer primary winding slows down the turn on process. However, the inductance has little effect during the initial stage of the switch-on process when the voltage drop on the thyristor and its internal resistance is high. The results show that a further switch-on current increase can be only achieved by introducing additional amplification steps in the pilot thyristor.

Temperature and Humidity Controller Based on P89LPC920FDH

This paper describes the design of a temperature and humidity controller, the controller takes P89LPC920FDH SCM as the core. P89LPC920FDH micro-controller integrated with internal comparator, watchdog timer, and reset circuit modules. The main control circuit board uses comparator to detect alternating current zero crossing point, uses the timer after a time delay to thyristor trigger pulse to control the hair AC conduction angle, thereby heating power control circuit to control the temperature and humidity of the environment, the purpose of.

66 kV SVC Light Control Water-Cooled Valve Protection and Application

Improve power quality problems, the company introduced the "tag through 66kV Static dynamic reactive power compensation device (SVC)", which means water cooling valve parts, using the international advanced technology and light control thyristor, the real control cabinet and valve all-fiber connections between groups, no valve trigger circuit boards, etc., to ensure safe and reliable high-pressure environment. Light control while protecting 66kV more stable water-cooled manifold, also designed the various protection functions. Reactive power compensation device based on electrical design principle, the protection of the valve design principles, summarized the valve characteristic is a light-controlled thyristor trigger and pulse trigger laser fiber distribution device as one of the valve, the valve overcurrent analysis protection, undervoltage protection, return status display, RC protection, BOD protection, protection and cooling system valve structural protection, light control demonstrates the necessity of 66kV water cooling valve protection; through the reactive power compensation and benefits case situation the comparative analysis to verify the correctness of the application of SVC devices.

The Design of Trigger Circuit for Power Thyristor

In this paper, for the strong electromagnetic interference environment, a kind of 6500V/1000A thyristor controller is designed. The controller includes a main trigger state detection module, an optical fiber communication module, a temperature detection module, a main controller module, and a trigger module. It highlights the thyristor trigger circuit and its corresponding detection circuit, this trigger circuit can provide a strong trigger pulse to ensure a reliable triggering of thyristors at any moment, the detection circuit can improve the reliability of the system.