Showing papers on "Rise time published in 2023"
TL;DR: In this paper , a linearized version of a system of two coupled differential equations is used to analyze transient photovoltage measurements at different bias light intensities combining rise and decay times.
Abstract: The extraction of photogenerated charge carriers and the generation of a photovoltage belong to the fundamental functionalities of any solar cell. These processes happen not instantaneously but rather come with finite time constants, e.g., a time constant related to the rise of the externally measured open circuit voltage following a short light pulse. The present paper provides a new method to analyze transient photovoltage measurements at different bias light intensities combining rise and decay times of the photovoltage. The approach uses a linearized version of a system of two coupled differential equations that is solved analytically by determining the eigenvalues of a 2 × 2 matrix. By comparison between the eigenvalues and the measured rise and decay times during a transient photovoltage measurement, w e determine the rates of carrier recombination and extraction as a function of bias voltage and establish a simple link between their ratio and the efficiency losses in the perovskite solar cell. This article is protected by copyright. All rights reserved.
5 citations
TL;DR: In this article , a dual stage cascade controller PI-(1+PD) is adopted to maintain and control temperature in greenhouse environment based on a smart and intelligent gorilla troops optimization (GTO) method for evaluating the controller gains to enhance the system response by reducing the error value and minimizing the integral time absolute error (ITAE) fitness functions during simulation.
Abstract: In this paper, a dual stage cascade controller PI-(1+PD) is adopted to maintain and control temperature in greenhouse environment based on a smart and intelligent gorilla troops optimization (GTO) method for evaluating the controller gains to enhance the system response by reducing the error value and minimize the integral time absolute error (ITAE) fitness functions during simulation. The simulation results are obtained by using MATLAB 2019, then compared with two conventional controllers proportional integral derivative (PI and PID) based on evaluation parameters for all controllers in term of peak time, rise time, settling time and overshoot to show its efficient response if compared with other controllers used.
2 citations
TL;DR: In this article , the response time delay of EG-MOAs has been investigated under microsecond-level and nanosecond-level transients, and the dynamic hysteresis loops, the static V-I characteristics, the response-time delay and the full response process of five types of 10-kV MOAs were investigated.
Abstract: Metal-oxide arresters (MOA), including the non-gapped MOAs (NG-MOA) and externally-gapped MOAs (EG-MOA), are the main equipment applied to protect the power system against conducted transient electromagnetic disturbances (TED). However, MOAs exhibit quite different electrical characteristics under microsecond-level and nanosecond-level transients. In order to figure out the response of MOAs under nanosecond-level TED, experimental platforms are built which contain a pulse generator with the amplitude of pulse current adjustable from 0 kA to 5 kA and the rise time of 20 ns. Then the dynamic hysteresis loops, the static V-I characteristics, the response time delay and the full response process of five types of 10-kV MOAs are investigated. From the dynamic hysteresis loops of NG-MOAs, the impedance conversion process can be seen clearly and can be explained by the grain-boundary theory. But EG-MOAs has not this conversion process due to the air-gap. And the experimental results demonstrate that there is no noticeable nanosecond-level conduction delay on NG-MOAs whereas the electric field non-uniformity of the air-gap has a significant influence on the time delay of the EG-MOAs. The response time delay of EG-MOAs changes ranging from tens of nanoseconds to hundreds of nanoseconds. This feature makes EG-MOAs more likely to raise insulation risks under nanosecond-level TED compared with NG-MOAs.
1 citations
TL;DR: In this article , an input-output scaling factor tuning of interval type-2 fuzzy (IT2F) PID controller using a multi-objective optimization technique is proposed, which is applied to an MG frequency regulation problem.
Abstract: The PID controller is a popular controller that is widely used in various industrial applications. On the other hand, the control problems in microgrids (MGs) are so challenging, because of natural disturbances such as wind speed changes, load variation, and changes in other sources. This paper proposes an input-output scaling factor tuning of interval type-2 fuzzy (IT2F) PID controller using a multi-objective optimization technique. The suggested controller is applied to an MG frequency regulation problem. In the introduced controller the effect of variations of renewable energies (REs) and other disturbances are taken into account, and the robustness is investigated. In the multi-objective scheme, some factors such as least overshoot, and minimum settling/rising time are considered. The simulations show that by considering the suitable adjustment the desired regulation accuracy is achieved, such that the frequency trajectory shows the desired overshoot, and settling/rising time.
1 citations
TL;DR: In this paper , a single crystal CVD diamond (3 mm × 3 mm × 200 μm) with (100) orientation is proposed to detect α radiation, which employs gold films on the diamond as an electrical contact, and the origin-symmetric currentvoltage characteristics demonstrated excellent Ohmic contact behavior.
Abstract: Abstract Diamond with extraordinary properties, such as fast response, and extremely high thermal conductivity, is an ideal choice for the next generation radiation detectors. In this paper, a radiation detector based on a single crystal CVD diamond (3 mm × 3 mm × 200 μm) with (100) orientation is proposed to detect α radiation. The detector employs gold films on the diamond as an electrical contact, and the origin-symmetric current-voltage characteristics demonstrated excellent Ohmic contact behavior. At an electric field of 0.4 V/μm, a current dark value of 4 nA was measured. The detector's pulse speed was tested using 5.486 MeV 241 Am sources. The time response of the detector to α particles is fast, with a rise time of 260 ps, a fall time of 650 ps, and a pulse width of 1.6 ns. These findings indicate that the detector can be used as a sensor for α radiation.
TL;DR: In this article , the effect of the rise rate on partial discharge (PD) under nanosecond pulse voltage was evaluated, and the PD amplitude, the number of discharges and the discharge time lag in the falling phase of the pulse were investigated.
Abstract: Film capacitors are used as the key energy storage device for high-power pulse generators, and partial discharge (PD) is an important factor leading to insulation degradation and the failure of film capacitors. To accurately evaluate the effect of the rise rate on PD under nanosecond pulse voltage, experiments on the PD characteristics of biaxially oriented polypropylene (BOPP) films under high rise rate (18.3–140 V/ns) nanosecond pulse voltages were carried out. The PDs were mostly concentrated in the rising and falling phases of the nanosecond pulse. Moreover, the repetitive PD inception voltage (RPDIV) first increased and then remained unchanged as the rise time increased, and the PD amplitude and the number of discharges in the rising phase of the nanosecond pulse increased as the rise rate increased, while the discharge time lag decreased gradually. The PD amplitude, the number of discharges, and the discharge time lag in the falling phase of the nanosecond pulse all increased as the rise rate increased. In addition, when the rise rate was less than 50 V/ns, the PD statistical characteristics changed rapidly as the rise rate increased, and when the rise rate was greater than 50 V/ns, the PD statistical characteristics gradually changed more slowly as the rise rate increased.
TL;DR: In this paper , the authors presented the development and comprehensive tests of a miniaturized sealed-off pseudospark switch, which is adopted to achieve high holdoff voltage and high current capacity.
Abstract: Pulsed power systems can deliver high peak power in a micro/nano-second timescale to various loads in scientific and industrial applications, whose performances are significantly influenced by the pulsed discharge switch. This article presents the development and comprehensive tests of a miniaturized sealed-off pseudospark switch. The structure of double-gap and multi-channel is adopted to achieve the high hold-off voltage and high current capacity. In single pulse tests, the influence of pressure in the switch is analyzed. As the pressure increases, values of multiple parameters decrease, like self-breakdown voltage, trigger delay, and voltage dropping time. In a wide pressure range, trigger jitter is below 3 ns, and the minimum is <1 ns. At low pressure, the transient voltage across two gaps becomes inconsistent, and two types of current quenching are observed, which are related to processes occurring on cathode surface. In repetitive pulse tests, the direct repetitive operation is up to 3.5 kHz while higher repetition rate is limited by the trigger system. In double-pulse tests, the maximum repetition rate can be higher than 8 kHz for 40 kV pulsed voltage. Meanwhile, the insulation recovery speed is higher at lower pressure, and as the time delay between two pulses increases, the second pulse breakdown voltage increases nonlinearly. In high current tests, the switch is also used in metal wire explosion experiments and operates at the condition of 30 kV/40 kA for more than 10 4 shots without performance degradation. Further lifetime tests point out that the switch can work for >10 6 shots stably at moderate current. Experiments prove that the designed switch has superior performances including high hold-off voltage (>50 kV), low jitter (<1 ns), high repetition rate (>3.5 kHz), high peak current (>40 kA), long lifetime (>10 6 shots) and miniaturized size.
TL;DR: In this article , the authors designed a PID control on a DC motor using two tuning methods, namely Trial & Error and Ziegler-Nichols, and the results showed that the system response from the Pittman DC motor was very unstable, in which there were still many oscillations and a high overshoot value.
Abstract: The purpose of this research is to design a PID control on a DC motor using 2 tuning methods, namely Trial & Error and Ziegler-Nichols. The results showed that the Pittman DC Motor system response from the Pittman DC motor was very unstable, in which there were still many oscillations and a very high overshoot value. In the Trial & Error method, the system response value was obtained on the P controller, namely, rise time = 0.000551 s, settling time = 0.00468 s, overshoot = 37.1 %, peak time = 0.972 s, and time delay = 0.00134 s. on the PI controller namely, rise time = 0.000396 s, settling time = 0.00534 s, overshoot = 47.7%, peak time = 1.23 s, and time delay = 0.00102 s. on the PID controller namely, rise time = 0.000223 s, settling time = 0.00502 s, overshoot = 64.6%, peak time = 1.54 s, and time delay = 0.000601 s. In the Ziegler-NIchols method, the response value of the system to the P controller is obtained, namely, rise time = 0.00118 s, settling time = 0.00564 s, overshoot = 15.4%, peak time = 0.178 s, and time delay = 0.00262 s. on the PI controller namely, rise time = 0.000275 s, settling time = 0.00531 s, overshoot = 58.3%, peak time = 1.44 s, and time delay = 0.000767 s. on the PID controller, namely, rise time = 0.00133 s, settling time = 0.00446 s, overshoot = 12.6 %, peak time = 0.0237 s, and time delay = 0.00288 s. The simulation results show that the value for the Ziegler-Nichols tuning method is better than the Trial & Error method, perhaps because the input value for the Trial & Error method is larger.
TL;DR: In this article , a sugeno-PD fuzzy DTC controller was designed to provide a fast and strong response mounted on an AC motor, where the DTC provided a short calculation time and its reasoning includes wide enough data and PD to speed up the response time results.
Abstract: In general, in the industrial world, induction motors are more widely used than direct current motors, due to the characteristics of induction motors that are sturdy, reliable, easy to maintain, and relatively inexpensive. The phenomenon of changing rotational speed when the load changes results in regulation of the speed of the induction motor, which risks slow response time, there is overshoot which should still be minimized, and there are disturbances caused by external environmental factors, so that a controller is needed that is able to work effectively to optimize performance. 3 phase induction motor. The purpose of this study is to design a sugeno-PD fuzzy DTC controller, where the DTC provides a fast and strong response mounted on an AC motor. Fuzzy Sugeno provides a short calculation time and its reasoning includes wide enough data and PD to speed up the response time results. So that the proposed method produces an induction motor rotating speed according to the given setpoint of 100 rad/s with a settling time of 0.45 seconds, a rise time of 0.2 seconds and no steady state error. From the state of the plan output response before being given the controller there is a steady state error of 5 rad/s, a maximum overshoot of 5.4111%, a settling time of 0.1554 seconds and a rise time of 0.1554 seconds
TL;DR: In this paper , a bipolar long-duration pulse generator based on the topology of a linear transformer driver combined with a half-bridge and multi-turn structure is put forward, which can output bipolar waveforms whose amplitudes are 4 kV and the duration can be adjusted from 200 ns to 800 ns.
Abstract: Abstract All-solid linear transformer driver(LTD) generators are widely used to output unipolar high-voltage rectangular pulses in nanoseconds. However in some applications, the bipolar output is necessary and the size of the generator is limited, which is challenging for LTD topology because the size of the magnetic core is related directly to the amplitude and pulse duration of the output waveforms. In this paper, a bipolar long-duration pulse generator based on the topology of a linear transformer driver combined with a half-bridge and multi-turn structure is put forward. The half-bridge topology can output bipolar waveforms easily and can save the number of switches used in the generator. To eliminate the crosstalk voltage that appears during operation, a differential mode inductance is used to protect the circuit. A snubber circuit is applied to suppress the reverse overshoot. The multi-turn design is chosen to make the size more compact. However, the multi-turn usually leads to a lower rise speed. To improve the performance, an optimization method that improves the rising speed by changing the turns of each stage is discussed. The strategy is useful and can be applied on some other occasions. The generator can output bipolar waveforms whose amplitudes are 4 kV and the duration can be adjusted from 200 ns to 800 ns. The rise time can be limited to 70 ns. The size of the generator is 10 cm * 10 cm * 15 cm, which is compact compared to the generators put forward before.
TL;DR: In this article , a proportional integral derivative (PID) based on tuning 1-degree of freedom (1-DOF) and 2-degree-of-freedom (2-DoF) was proposed to stability when the disturbance accours.
Abstract: This paper discusses control mass-spring-dumper (MSD) system used in vehicle suspensions. The vehicle suspension consists of mass, coil (spring), and shock absorber (dumper). MSD provided a shock effect when the vehicle was caused by the frictional force on the load. The dificulty to achive the stability of suspension and the following of set point tracking. Therefore, the proportional-integral-derivative (PID) based on tuning 1-degree of freedom (1-DOF) and 2-degree of freedom (2-DOF) were proposed to stability when the disturbance accours. The MSD equation was obtained by using the laplace transform and validated in Matlab Simulink. The result shows that the proposed PID control reduces disturbance rejection by the smaller set point tracking peak amplitude of 0.01, overshoot of 0.68%, rise time of 0.199 seconds. The 1-DOF tuning achieved set point tracking and disturbance rejection with a peak amplitude of 1.13, overshoot 12.9%, rise time 0.134 seconds, and the 2-DOF tuning achived set point tracking and disturbance rejection with peak amplitude of 1.07, overshoot 6.53%, rise time 1.28 seconds. The proposed PID control has the best performance than 1-DOF and 2-DOF controller.
19 Mar 2023
TL;DR: In this paper , an improved version of the Marx bank circuit with auxiliary triggering topology (ATT) is proposed to improve the reliability of a positive nanosecond pulse generator with high amplitude, fast rise time and narrow pulse width.
Abstract: In plasma-jet-driven magneto-inertial fusion (PJMIF) systems, a high-voltage nanosecond pulsed power supply is required to drive the plasma gun. Marx bank circuit (MBC) is a good candidate to generate nanosecond pulse with high amplitude, fast rise time, narrow pulse width, and low jitter. However, the fundamental topology and operation principle of a positive nanosecond pulse generator are rarely discussed. In this paper, a comprehensive study on the conduction state of fundamental topology and traditional MBC is presented. Furthermore, an improved positive MBC with auxiliary triggering topology (ATT) is proposed. By changing the switching mode from “overvoltage switching-on” to “triggering switching-on”, the system reliability is improved. The output characteristics under different modified stages, triggering capacitors, and main capacitors are investigated. A $4 \times 4$ MBC prototype is implemented with optimized parameters to validate the feasibility of the proposed concept. With spark gap switch load, it can generate a high-voltage pulse with an amplitude of 5.04kV, a rise time of 12.4ns, and an FWHM of 12.6ns.
TL;DR: In this paper , a simple topology is proposed, which is based on the pseudospark switch and the diode opening switch, which can eventually output pulses with an amplitude of 106kV, a rise time of 15.5n, a pulse width of 46n, and a maximum repetition rate of 1 kHz on a 260-Ω resistive load.
Abstract: With the development of technology, low-temperature plasma plays an increasingly important role in industrial applications. The industrial application of low-temperature plasma has the following requirements for plasma, high electron energy, low macroscopic temperature, and uniformity. Low-temperature plasma driven by nanosecond pulses reflects more significant advantages in these aspects compared to direct current plasma and alternating current plasma. In this paper, a simple topology is proposed, which is based on the pseudospark switch and the diode opening switch. A pulse generator is developed, which can eventually output pulses with an amplitude of 106 kV, a rise time of 15.5 ns, a pulse width of 46 ns, and a maximum repetition rate of 1 kHz on a 260 Ω resistive load. The pulse generator can successfully drive needle-plate discharge plasma in ambient air. It has excellent parameters, stability, compactness, and a long lifetime. The proposed topology may be helpful for nanosecond pulse generators with amplitude ranging from tens to hundreds of kilovolts, which could be widely used in industry.
TL;DR: In this article , an intelligent aided PID controller for speed control of induction motor is presented. And the simulation results indicated that the intelligent (FLC) aided classical PID control improved the system performance and achieved the rated speed of the motor.
Abstract: This paper presents design of intelligent based controller for speed control of induction motor. The proposed system integrates a classical proportional-integral-derivative (PID) controller and intelligent algorithm based on fuzzy logic control (FLC). This scheme takes advantages of classical PID and FLC to improve the speed response performance of induction motor analysed in terms of transient and steady state time domain characteristics. The FLC designed was implemented using the fuzzy block of MATLAB/Simulink based on Mamdani model and comprises 9 fuzzy variables and 49 logic (intelligent) rules that define the system behaviour. The FLC takes the loop error and its rate of change to manipulate the input command to the PID control so that the response speed signal matches with the desired speed signal resulting in reduced rise time, peak time, settling time, overshoot, and improved steady state error. The designed intelligent aided PID controller was implemented and the simulation result provided a rise of time of 0.8354 second, peak time of 4.9615 seconds, settling time of 1.2240 seconds, final value (actual speed) of 1724.9 rpm, steady state error 0.1 rpm. Simulation comparison with conventional PID controller showed that the PID yielded a rise time of 1.6723 seconds, peak time of 4.5475 seconds, peak overshoot of 0.6913 %, settling time of 2.9646 seconds, final value (actual speed) 1736.1 rpm, and steady state error of 11.1 rpm. Generally, simulation results indicated that the intelligent (FLC) aided classical PID control improve the system performance and achieved the rated speed of the motor.
09 Mar 2023
TL;DR: In this paper , a DC motor speed control test using the Proportional Integral Derivative (PID) method was carried out by trial and error testing of the four DC motors, the best PID value was obtained with ; ; ; and with the Rise Time system message: 14.7452; Overshoots: 0.6667; Settling Time: 52.0100; Undershot: 0, Settling Min: 136; Peaks: 151; Setting Max : 151; and Peak Time: 65.
Abstract: Robot or Artificial Intelligence (AI) can be interpreted as a machine with some computer intelligence and controlled by a computer, and has physical abilities like humans. One of the drives of robots that is often used is a DC motor, a DC motor is a motor with an electronic device that converts electrical energy into kinetic energy or motion. However, DC motors often experience a decrease due to the existing load, so that the speed becomes not constant, so it is necessary to design a controller. The controller used is Proportional Integral Derivative (PID). In the PID there are several parameters such as , , and which are selected or determined so that the plant characteristics match the desired criteria. The general parameters are rise-time, settling-time, maximum, overshoot, and steady-state error for a given input. From the results of the DC motor speed control test using the PID method which was carried out by trial and error testing of the four DC motors, the best PID value was obtained with ; ; ; and with the Rise Time system message: 14.7452; Overshoots: 0.6667; Settling Time: 52.0100; Undershot: 0; Settling Min: 136; Peaks: 151; Settling Max : 151; and Peak Time: 65.
07 May 2023
TL;DR: In this paper , the effect of square rise time and pulse width on PD behaviors was investigated under different pulse widths and rise times, and a specially designed down-mixing PD detection method was applied.
Abstract: As high-voltage power modules are applied widely, the partial discharge (PD) occurring in the packaging insulation under high-voltage square pulse becomes the main issue resulting in power module failure. Varying pulse widths and rise times are prominent characteristics of the square pulse, which are also factors affecting PD behaviors. Focusing on the effect of square rise time and pulse width on PD behaviors, a specially designed down-mixing PD detection method is applied. The PD experiments under the square pulse of different pulse widths and rise times are carried out. The statistics of PD magnitudes indicate that a longer rise time leads to a declining trend of PD magnitude and a lag tendency of the occurrence phase, which can be explained based on the initial electron appearance delay and the PD occurrence process. During the rising edge, pulse width affects little on the PD behaviors while at the falling edge, the PD magnitude shows an increasing trend and the occurrence phase shows a shifted tendency as the pulse width becomes longer.
TL;DR: In this paper , a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test by establishing the equivalent circuit model of the Nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated.
Abstract: Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated. The influence of the action performance of the steepening gap on the characteristics of output nanosecond pulse was analyzed. The nanosecond pulse test system was established through the structural design of the nanosecond pulse-generating circuit, the development of a high-performance corona-stabilized switch, and the measurement of a fast-response resistance divider made of metal oxide thin-film resistors. The nanosecond pulse test system has the capability to output a double exponential nanosecond pulse voltages in the amplitude range of 10–60 kV with a rise time of 2.3 ± 0.5 ns and a half-peak time of 23 ± 5 ns. In addition, the output pulse voltage has a high consistency and stability in the full amplitude range. The maximum relative standard deviation of the peak value is 1.517%, and the relative standard uncertainty is less than 5‰.
TL;DR: In this paper , the rise time of the exciting voltage on the DC corona discharge characteristics in a coaxial electrode system is presented, and the simulation results reveal that the corona inception which occurs at a fast rise time produces more dense plasma charged species, while the density of the excited atoms is not much affected by the applied voltage climb time.
Abstract: In this paper, the rise time of the exciting voltage on the DC corona discharge characteristics in a coaxial electrode system is presented. The current one-dimensional simulation study focused on the distribution of the plasma species (ions and electrons as well as the excited atoms) during two different times of the applied voltage climb was classified as a fast rise time (615 ns) and a slow rise time (2710 ns). The growth time of the corona excited voltage was controlled by the external feed RC circuit that connected with the central electrode. The simulation results reveal that the corona inception which occurs at a fast rise time produces more dense plasma charged species, while the density of the excited atoms is not much affected by the applied voltage climb time. The density of excited atoms tends to depend on the rise time of the exciting voltage at the steady state.
TL;DR: In this paper , a solid-state inductive adder-based quasi-rectangular pulser featuring a low characteristic impedance has been developed in the laboratory to demonstrate the technical viability of using such a pulser for the HEMS muon source.
Abstract: Abstract A solid-state inductive adder-based quasi-rectangular pulser featuring a low characteristic impedance has been developed in the laboratory to demonstrate the technical viability of using such a pulser for the HEMS muon source. The pulser consists of five layers connected in series, with each layer comprising 24 parallel branches. The paper mainly presents the design of the low characteristic impedance quasi-rectangular pulser from three aspects: primary driver circuit, coaxial central structure and transformer magnetic core. The experimental results show that through the careful design of the above three items, a quasi-rectangular pulse with fast rise and fall time can be achieved. The typical parameters of pulse voltage, pulse current, pulse flattop, repetitive rate, rise time and fall time at a charging voltage of 700 V are 3.5 kV, 560 A, 315 ns, 1 kHz, 47 ns, and 66 ns, respectively, on a 6.25 Ω matching resistor. In addition, the output characteristics of the pulser are investigated by varying critical parameters such as the charging voltages, the load resistances, and the number of parallel branches. The findings and results outlined in this paper offer valuable insights for the initial phase of developing an inductive adder pulser. They can aid in assessing the feasibility of the project, selecting critical parameters for essential components, and enhancing the output pulse's performance. A full-scale pulser with a peak pulse current of 3 kA and rise and fall time of ≤ 75 ns for HEMS muon source will be developed in the near future.
TL;DR: In this paper , the effects of pulse voltage rise time on the nanosecond pulsed breakdown of the nitrogen spark switch at atmospheric pressure are analyzed based on the assumption of initial electrons generation due to the field emission.
Abstract: In this paper, the effects of pulse voltage rise time on the nanosecond pulsed breakdown of the nitrogen spark switch at atmospheric pressure are analyzed. Based on the assumption of initial electrons generation due to the field emission, the simulations are performed using a three-dimensional particle-in-cell, Monte Carlo-collision model for the pulse voltage with a rise time of 40, 60, and 100 ns, respectively. The breakdown experiments of the nitrogen spark switch are carried out for three different rise times. The results obtained are as follows. First, the nanosecond pulsed breakdown of the switch includes the formation and fast propagation of the streamer, which depend on the multiplication of the electron avalanche, and the intense ionization due to photoelectrons and energetic electrons, respectively. Second, with the rise time of pulse voltage increasing, the generation of runaway electrons becomes more difficult and the streamer branches, which are mainly caused by photoionization and captured energetic electrons, become more obvious. Finally, the breakdown time delay of the switch becomes shorter and the breakdown voltage becomes higher at the same pressure for the decreasing rise time of pulse voltage, which is consistent with the measurement results.
TL;DR: In this paper , a comparative analysis among the two design variants of PSS (Lead Lag and PID) is performed by comparing the overshoot and settling time of generator active power after disturbance.
Abstract: : Rising load demand and possibilities of short interruptions either due to temporary faults or equipment switching may lead to transient instability in terms of growing oscillations and eventually result in cascaded outages if not being damped properly and timely. To dampen such oscillations, the power system stabilizers (PSS) are invariably installed to regulate the excitation of synchronous generators. In this research, a comparative analysis among the two design variants of PSS i.e., Lead Lag and PID, is performed by comparing the overshoot and settling time of generator active power after disturbance, to observe the effect of each on the system characteristics and nominal conditions. The settling time with PID based PSS is reduced by 46% in case of three phase short circuit fault and 80% in case of the single line to ground fault as compared to Lead Lag PSS. Thus, the results obtained show a better performance of PID based PSS having better overshoot response and reduced settling time for symmetrical and unsymmetrical faults.
TL;DR: In this paper , a test system that can conduct partial discharge (PD) and endurance lifetime tests under repetitive pulse voltage and controlled pressure was introduced. But, the results showed that PD inception voltage decreases with decreasing pressure, while the changing of PD magnitude, time lag and its induced insulation lifetime do not change monotonously.
Abstract: Reduction of air pressure can influence insulation material’s behavior with respect to resisting partial discharge (PD) generation and its induced aging process. This may bring threat to the insulation reliability of medium frequency transformers working under low pressure condition, considering they are exposed to high probability of PD inception caused by pulse width modulation (PWM) voltage. Aiming at investigating the performance of insulation of medium frequency transformer being operated in an environment with a decreasing pressure, this article introduces a test system that can conduct PD and endurance lifetime tests under repetitive pulse voltage and controlled pressure. Using this test system and focusing on polyimide film, which is one of the main insulation materials used by medium frequency transformers, PD and endurance lifetime tests are conducted under different pressures. The results show that PD inception voltage decreases with decreasing pressure. However, the changing of PD magnitude, time lag and its induced insulation lifetime do not change monotonously. Surface of the failed insulation samples show that the erosion area caused by PD is larger under lower pressure. The mechanisms behind the changing of PD time lag, discharge magnitude, endurance lifetime, along with the discharge eroded area with pressure are discussed in detail.
07 May 2023
TL;DR: In this paper , the authors adopted the silicon photomultiplier (SiPM) optical partial discharge detection method to explore the lifetime mechanism of polyimide (PI) in inverter-fed motor.
Abstract: As the insulation of inverter-fed motor, polyimide (PI) works under square wave voltage, with high frequency and steep rising/falling edge. Partial discharge (PD) is a major cause of insulation degradation. Meanwhile, PDs tend to occur at the rising/falling edges. Therefore, it is of great significance to study the PD characteristics of PI at steep rising/falling edges to explore the lifetime mechanism. In order to avoid electromagnetic interference (EMI), this paper adopts the silicon photomultiplier (SiPM) optical PD detection method. PD and insulation lifetime experiments of PI were carried out under bipolar square wave voltage with the rise time from 50 to 500 ns. The result shows that the magnitude of PD increases with the shortening of the rise time. The discharge delay time exhibits the opposite trend. When the rise time increases to a certain extent, multiple discharges occur within half a period, which is similar to the PD mechanism under the sinusoidal voltage. As for the insulation lifetime, the steeper the rising edge, the shorter the lifetime. The severe PD under short rise time accelerates the damage of insulation. Based on discharge energy, a new insulation lifetime evaluation method is proposed and preliminarily verified. Subsequent experiments and studies are necessary to further verify and improve it.
TL;DR: In this article , a double-pulse transformer isolates the circuit's high and low-voltage sides and synchronously drives series-connected cascode SiC FETs to form its push-pull topology.
Abstract: Ultra-fast high-voltage switches (UFHVSs) are a core component of time-of-flight mass spectrometers for realizing high accuracy ion acceleration, deceleration, and temporal focusing. The desirable features of high performance UFHVSs include a large range of adjustability of pulse width, a high maximum output amplitude, and minute rising and falling times. Besides the simplicity of the driver circuit, the total cost of the whole device is also critical to its practical applications. In this work, we present a low-cost and easy-fabrication 5000 V bipolar solid-state UFHVS for a high-resolution mass spectrometer. A double-pulse transformer isolates the circuit’s high- and low-voltage sides and synchronously drives series-connected cascode SiC FETs to form its push–pull topology. This scheme allows transmitting drive signals with long widths but without the magnetic saturation of the transformer. Testing results show that output pulses reach a maximum voltage of 5000 V and a width of 150 µs, with rising and falling times of 8.5 and 18.3 ns, respectively. More importantly, they have nearly no voltage decay.
TL;DR: In this article , a branch module for an inductive voltage adder has been designed and assembled for a maximum charging voltage of 1.2 kV and an output current of 200 A considering the current doubling due to the short circuit termination.
Abstract: For driving kicker magnets terminated in a short circuit, a branch module for an inductive voltage adder has been designed and assembled. The module has been designed for a maximum charging voltage of 1.2 kV and an output current of 200 A considering the current doubling due to the short circuit termination. It features three consecutive modes of operation: energy injection, freewheeling, and energy extraction. Therefore, the topology of the branch module consists of two independently controlled SiC MOSFET switches and one diode switch. In order not to extend the field rise time of the kicker magnet significantly beyond the magnet fill time, the pulse must have a fast rise time. Hence, the switch for energy injection is driven by a gate boosting driver featuring a half bridge of GaN HEMTs and a driving voltage of 80 V. Measurements of the drain source voltage of this switch showed a fall time of 2.7 ns at a voltage of 600 V resulting in a voltage rise time of 5.4 ns at the output terminated with a resistive load. To meet both the rise time and current requirements, a parallel configuration of four SiC MOSFETs was implemented.
01 Jan 2023
TL;DR: In this paper , the formation principle of square wave of two coaxial Blumlein transmission line is analyzed through the wave propagation process, and the synchronous control of solid-state switch is introduced.
Abstract: High voltage nanosecond pulse generator is needed to study pulsed discharge plasma. Based on the two-stage coaxial Blumlein transmission line and the series connection technology of solid-state switch, the formation principle of square wave of two coaxial Blumlein transmission line is analyzed through the wave propagation process, and the synchronous control of solid-state switch is introduced. The high-level suspension drive of solid-state switch is realized through self-powered drive, so as to generate 3 kV negative high-voltage nanosecond pulse. A prototype of high-voltage nanosecond pulse generator based on two-stage coaxial Blumlein transmission line was built and the related performance tests were carried out. The parameters of the pulse generator under 200 Ω matching load are: amplitude is adjustable within 0~−3 kV, pulse width is adjustable within 100 ns–300 ns, repetition rate is adjustable within 0–50 kHz, falling edge time of negative pulse is 13 ns.
24 May 2023
TL;DR: In this paper , the authors investigated the lifetime characteristics for insulation of type II rotating machines performed by breakdown measurement of pulse voltage at different waveforms and rise time, and found that the rise time of the pulse voltage is considered the main influence on the life of insulations, it leads to insulation failure in a lower time.
Abstract: with the increasing application of power electronic components in driving rotating machines, the electrical stress factors were significantly changed. This paper deals with the investigation of lifetime characteristics for insulation of type II rotating machines performed by breakdown measurement of pulse voltage at the different waveforms and rise time. The results were compared with those gathered at power frequency, using different time scaling parameters (number of pulses, effective time). It is found that the effective time of stress voltage provides a clearer perception to study the lifetime behaviour than the number of pulses, especially for comparing the effect of the different applied voltage waveforms on acceleration aging. The results indicate that the rise time of the pulse voltage is considered the main influence on the life of insulations, it leads to insulation failure in a lower time. Additionally, the effect of combined stress (electrical, thermal, mechanical) was studied by using a specially developed sample, which included the curved parts of windings. It was found that the most critical part of such "coil-windings" are those curved parts because they are stressed not only by higher mechanical but also by larger electrical field strength.
01 Jan 2023
TL;DR: In this article , tuning rules for PID control of time-delay plants such as pure TD, FOPTD, SOPTD and IPTD are developed inspired by IMC approach.
Abstract: Inspired by IMC approach, tuning rules for PID control of time-delay plants such as pure TD, FOPTD, SOPTD and IPTD are developed. Control systems for the first three plants can be designed in a consistent way, since they are described by the same transfer function for commonly used controllers. Analytic rules are given for critical damping. Nomograms characterize overdamping for settling time specification and underdamping for overshoot. Practical experiment confirms fairly good correspondence of closed-loop responses to specifications.
07 Feb 2023
TL;DR: In this article , a linearized version of a system of two coupled differential equations is used to analyze transient photovoltage measurements at different bias light intensities combining rise and decay times.
Abstract: The extraction of photogenerated charge carriers and the generation of a photovoltage belong to the fundamental functionalities of any solar cell. These processes happen not instantaneously but rather come with finite time constants, e.g., a time constant related to the rise of the externally measured open circuit voltage following a short light pulse. The present paper provides a new method to analyze transient photovoltage measurements at different bias light intensities combining rise and decay times of the photovoltage. The approach uses a linearized version of a system of two coupled differential equations that is solved analytically be determining the eigenvalues of a 2 x 2 matrix. By comparison between the eigenvalues and the measured rise and decay times during a transient photovoltage measurement, we determine the rates of carrier recombination and extraction as a function of bias voltage and establish a simple link between their ratio and the efficiency losses in the perovskite solar cell.
TL;DR: In this paper , the authors design PID control on BLDC motors using two tuning methods, namely Cohen-Coon and Trial & Error, and compare the performance of the two methods.
Abstract: The purpose of this research is to design PID control on BLDC motors using 2 tuning methods, namely Cohen-Coon and Trial & Error. PID control of formula calculations with calculations in Simulink Matlab. From the simulation results shown in graphical form, the use of the PID control gives a better effect than the use of the P and PI controls. This can be seen in the comparison curve which shows the speed of the initial start process when using the PID control. In the Trial & Error method, the response value of the system to controller P is obtained, namely, rise time = 0.0151 s, settling time = 0.6 s, overshoot = 75.9%, peak time = 1.74 s, and time delay = 0.424 s. on the PI controller namely, rise time = 0.0148 s, settling time = 0.591 s, overshoot = 76.3%, peak time = 1.74 s, and time delay = 0.0416 s. on the PID controller namely, rise time = 0.0496 s, settling time = 0.55 s, overshoot = 44 %, peak time = 1.31 s, and time delay = 0.128 s. In the Cohen-Coon method, the response value of the system to controller P is obtained, namely, rise time = 0.0168 s, settling time = 0.575 s, overshoot = 73.3%, peak time = 1.71 s, and time delay = 0.0469 s. on the PI controller namely, rise time = 0.0573 s, settling time = 0.603 s, overshoot = 39.3%, peak time = 1.23 s, and time delay = 0.142 s. on the PID controller namely, rise time = 0.276 s, settling time = 0.658 s, overshoot = 2.42 %, peak time = 0.159 s, and time delay = 0.576 s. From the simulation results it is shown that the value for the Cohen-Coon tuning method is better than the Trial & Error method, perhaps because the input value for the Trial & Error method is larger.