Switch Lifetime Research Articles

Cost-effective one-time configuration for bridge-linked thermoelectric generator array using INFO optimizer

One of the key mechanisms of enhancing the power output of Thermoelectric Generators (TEG) under nonuniform temperature distribution (NUTD) is to restructure their arrays to disperse the NUTD profiles. Existing research works in this area primarily propose dynamic reconfiguration techniques of TEG arrays as a potential solution to maximize their output powers while taking no notice of the highly associated costs of their implementation, i.e., sensors, switches, and maintenance, in addition to the complexity of operation and limited service lifetime of switches. To alleviate these drawbacks, this paper introduces an optimization model for a one-time configuration (OTC) of TEG arrays to maximize their output powers while accommodating multiple NUTD profiles simultaneously. Using the INFO optimizer, the introduced optimization model yields the OTC layout for both symmetrical and asymmetrical TEG arrays across various NUTD scenarios. Given its superior performance, the optimization model is applied to the bridge-linked (BL) TEG array and compared to other configurations such as series (S), series-parallel (SP), and standard BL. The results of the proposed OTC model are compared with (1) standard, non-optimized SP and BL configurations and (2) different dynamic-based reconfiguration techniques. Further, the performance of the proposed model is tested and validated experimentally in the laboratory for the available symmetrical hardware setup, 5 × 5, TEG array under varying NUTD profiles. Compared to dynamic reconfigurations, the results show that the proposed OTC technique provides a partially optimal and cost-effective solution to enhance the output power of TEG arrays under different NUTD. Specifically, for 9×9 and 10×15 TEG arrays, the OTC saves approximately 1,498.5 ($) and 2750 ($) compared to dynamic reconfigurations, respectively. Moreover, BL-based OTC enhances the TEG array harvested power by maximum values of 1.7532%, 2.43%, and 3.156% compared with the standard S, SP, and BL configurations, respectively, based on the hardware setup. Throughout the detailed comparison between the proposed OTC and dynamic reconfiguration techniques, this paper contributes to a deeper understanding of the trade-offs between these configuration techniques and addresses a critical gap in the current research landscape of enhancing the output powers of TEG arrays.

Purchase cost based reconfiguration of distribution system under varying loads and renewable generation

Optimal reconfiguration of distribution system is complex process and thus demands high computing power and time. In a competitive market for a distribution system with multiple feeders owned by multiple agencies, the cost of purchasing power for each of those feeds are often different from one another. In such case, reconfiguration of distribution system, exclusively on the basis of loss minimization may not be appropriate. Furthermore, increasing solar PV generation (SPVG) integration is posing new type of operational challenges due to its sudden and high variability. Hence, the conventional approaches of hourly stepwise load curve discretization may not be cost-effective for feeder reconfiguration exercise. In view of these twin objectives, a novel heuristic strategy is proposed for minimizing costs using a two-stage process that takes into account sensitivity. The primary objective of the proposed approach is to reduce the computing load associated with the exercise, while also incorporating the variability of loads and renewable energy sources. This has been achieved without significantly increasing the computational workload, by employing a reconfiguration strategy that best aligns with the specific hour under consideration, which is further divided into four subintervals of fifteen minutes each. Moreover, despite the high variability, the frequency of reconfiguration is not increased in order to extend the lifetime of the gear switches. To show the efficacy of the proposed approach, simulation results for two distinct test systems have been obtained.

Stability, Reliability, and Robustness of GaN Power Devices: A Review

Gallium nitride (GaN) devices are revolutionarily advancing the efficiency, frequency, and form factor of power electronics. However, the material composition, architecture and physics of many GaN devices are significantly different from silicon and silicon carbide devices. These distinctions result in many unique stability, reliability and robustness issues facing GaN power devices. This paper reviews the current understanding of these issues, particularly those related to dynamic switching, and their impacts on system performance. Instead of delving into reliability physics, this paper intends to provide power electronics engineers the necessary information for deploying GaN devices in existing and emerging applications, as well as provide references for the qualification evaluations of GaN power devices. The issues covered in this paper include the dynamic instability of device parameters (e.g., on-resistance, threshold voltage, output capacitance), the device robustness in avalanche, overvoltage and short-circuit conditions, the device's switching reliability and lifetime, as well as the device's ruggedness under radiation and extreme (cryogenic and elevated) temperatures. Knowledge gaps and immediate research opportunities in the relevant fields are also discussed.

Weighted Sum Metrics – Based Load Balancing RPL Objective Function for IoT

The technological development of Internet of Things (IoT) applications is emerging and attracting the attention of the real world in the automated industry, agriculture, environment, and scientific community. In most scenarios, extending the network lifetime of an IoT network is highly challenging because of constrained nodes. The wireless sensor network (WSN) is the core component of IoT applications. In addition, the WSN nodes are required for the network processes, particularly routing, energy maintenance, load balance, congestion control, packet delivery, quick response, and more. The failure of any of the above network processes will affect the entire network operation. IPv6 Routing Protocol for Low-power and Lossy network (RPL) provides high routing solutions to IoT applications requirements. The load balance, congestion control, traffic load, and bottleneck problems are still open issues in the RPL. To resolve the load balance issue, we propose a weighted sum method objective function (WSM-OF), which provides the ability to select the alternative parent in routing by RPL metrics. WSM-OF adopts congestion control and load balancing to avoid heavy traffic and extend the network's node lifetime. The network parameters of control overhead, jitter, packet delivery ratio, parent switching, energy consumption, latency, and network lifetime are implemented and analyzed through the COOJA simulator. The result shows that the WSM-OF improves the network performance and significantly enhances the network lifetime by up to 7.8%.

An improved intermittent power supply technique for electrostatic precipitators

Abstract A cost-effective power supply design proposed for electrostatic precipitators (ESP) is presented in this work. The cost minimization is done in terms of eliminating the power transformer and reducing power consumed by the ESP unit. Usually, transformers are used to boost the voltage level in conventional systems on its input side, which is replaced by a combination of a high-frequency converter along with a voltage multiplier in a modular arrangement. By interconnecting these modules, the suitable voltage is built-up easily. An intermittent pulse energized supply is developed by the proposed system to reduce back corona and to save energy consumption. The modular arrangement also increases the lifetime of converter switches, by reducing the switching stresses developed across them during its high-frequency operation and by reducing the Total Harmonic Distortion (THD). The complete system is designed and analyzed using MATLAB SIMULINK. The obtained results are better than the existing methods used for generating intermittent energization, the THD is reduced to 35.78% and the voltage stresses also reduced to 1800 V. And a module is experimented and found that it is capable of producing 3 kV.

A battery-powered over-voltage triggering method for two-electrode spark gaps in Marx generator.

Triggered gas switches with trigger electrodes, such as three-electrode spark switches and trigatron type spark switches, have been widely used in repetitive operating Marx generators due to their large current flowing capability. However, the ablation of trigger electrodes during repetitive operation is inevitable, which reduces the working life of triggered gas switches. In this paper, we introduced an over-voltage triggering method for two-electrode spark switches by replacing one of the charging inductors of the Marx generator with a pulse generator. The experimental results showed that a high-voltage trigger pulse with an amplitude of 60 kV and a rising speed of 7.65 kV/100 ns was obtained from a single stackable module with a 12 V lithium battery pack as the energy source. Due to the absence of trigger electrodes, the triggering method is beneficial to extend the lifetime of switches and realize a maintenance-free repetitive operating Marx generator.

A Python Toolbox for Unbiased Statistical Analysis of Fluorescence Intermittency of Multilevel Emitters.

We report on a Python toolbox for unbiased statistical analysis of fluorescence intermittency properties of single emitters. Intermittency, that is, step-wise temporal variations in the instantaneous emission intensity and fluorescence decay rate properties, is common to organic fluorophores, II–VI quantum dots, and perovskite quantum dots alike. Unbiased statistical analysis of intermittency switching time distributions, involved levels, and lifetimes are important to avoid interpretation artifacts. This work provides an implementation of Bayesian changepoint analysis and level clustering applicable to time-tagged single-photon detection data of single emitters that can be applied to real experimental data and as a tool to verify the ramifications of hypothesized mechanistic intermittency models. We provide a detailed Monte Carlo analysis to illustrate these statistics tools and to benchmark the extent to which conclusions can be drawn on the photophysics of highly complex systems, such as perovskite quantum dots that switch between a plethora of states instead of just two.

Integration of Gold Nanoparticle-Carbon Nanotube Composite for Enhanced Contact Lifetime of Microelectromechanical Switches with Very Low Contact Resistance.

Electrical circuits require ideal switches with low power consumption for future electronic applications. However, transistors, the most developed electrical switches available currently, have certain fundamental limitations such as increased leakage current and limited subthreshold swing. To overcome these limitations, micromechanical switches have been extensively studied; however, it is challenging to develop micromechanical switches with high endurance and low contact resistance. This study demonstrates highly reliable microelectromechanical switches using nanocomposites. Nanocomposites consisting of gold nanoparticles (Au NPs) and carbon nanotubes (CNTs) are coated on contact electrodes as contact surfaces through a scalable and solution-based fabrication process. While deformable CNTs in the nanocomposite increase the effective contact area under mechanical loads, highly conductive Au NPs provide current paths with low contact resistance between CNTs. Given these advantages, the switches exhibit robust switching operations over 5 × 106 cycles under hot-switching conditions in air. The switches also show low contact resistance without subthreshold region, an extremely small leakage current, and a high on/off ratio.

Enhancement Mode GaN-FETs in Extreme Temperature Conditions, Part II: Dynamic Parasitic Parameters

Abstract Parasitic components in eGaN-FETs impact the dynamic performance of switching stages. The capacitances seen, primarily on the output characteristics, of these devices are a main contributor towards switching losses and therefor converter efficiency. Additionally, the threshold voltage of the device has an impact towards the switching speed and therefore the efficiency of a power stage. This study shows the impact of extreme temperatures towards the parasitics that impact the switching behaviour of a power stage. A literature research is conducted exploring the various mechanisms and temperature dependancies, which are then related towards transient operations of eGaN-FETs. A device was chosen to perform measurements on output-, reverse transfer capacitance and threshold voltage while increasing temperature from 100°C op to 225°C. The presented results show a large impact of temperature in these parasisic elements that show that high temperature switch-mode power converters need additional design work to ensure switching performance and lifetime.

Very Low Sampling Frequency Model Predictive Control for Power Converters in the Medium and High-Power Range Applications

Several control strategies have been proposed with the aim to get a desired behavior in the power converter variables. The most employed control techniques are linear control, nonlinear control based on linear and nonlinear feedback, and predictive control. The controllers associated with linear and nonlinear algorithms usually have a fixed switching frequency, featuring a defined spectrum given by the pulse width modulation (PWM) or space vector modulation (SVM) time period. On the other hand, finite set model predictive control (FS-MPC) is known to present a variable switching frequency that results too high for high power applications, increasing losses, reducing the switches lifetime and, therefore, limiting its application. This paper proposes a predictive control approach using a very low sampling frequency, allowing the use of predictive control in high power applications. The proposed method is straightforward to understand, is simple to implement, and can be computed with off-the-shelf digital systems. The main advantage of the proposed control algorithm comes from the combination of the model predictive control and the SVM technique, drawing the principal benefits of both methods. The provided experimental results are satisfactory, displaying the nature of space vector-based schemes but at the same time the fast response as expected in predictive control.

MKRVM Prediction of Capacitive RF-MEMS Switching Life

The elastic coefficient K, a factor affecting the life of capacitive RF-MEMS switch, is selected as the research object. First, we use differential evolution based quantum particle swarm optimization (DE-QPSO) to obtain sparse functions of multiple kernel relevance vector machine (MKRVM), and use the MKRVM algorithm to predict the lifetime of such switches. Then the experimental results show that the method can obtain the health index HI of 3.1043e+06 s, the 3.0657e+06 s. closest to the original data in 0.21 s. At the same time, the conclusion of the longest switching life is obtained when the elastic coefficient is in the range of 4-16 N/m.

Spectroscopic Investigation of Metal Content in Prestrike Arc During Making Operation in a Low-Current Model Switch

Energy dissipation during prestrike arc is the critical factor for electrical contacts erosion and welding in medium voltage load break switches. Using air-filled devices as an alternative to SF6 makes the switch environmentally friendly, but leads to a more challenging process due to a higher prestrike arcing time between contacts. Therefore, understanding the erosion process of electrical contacts is crucial to improve the switch lifetime. Determination of contacts surface evaporation by optical emission spectroscopy is one of the most precise methods to investigate the prestrike arc interface with the contacts. In this article, the temporal and spatial profiles of copper and tungsten emitted species during prestrike arc are presented. For this purpose, a circuit consisting of a synthetic dc high voltage part is used to initiate the arc. The temporal evolution of CuI, CuII, and WI shows evaporation of the cathode and the anode surfaces during the prestrike arc, and the spatial profiles show an inhomogeneous distribution of the vapors alongside the arc root.

Solar Energy based low cost Converter for Rural Houses Electrification

A Rectified Sinusoidal based Pulse generation method for a DC – DC converter is proposed in this discussion. To exhibit this, the methodology is applied to a Self-Lift topology based SEPIC converter. In this paper a two stage grid connected system is used. In stage I the said converter is used for boosting and DC rectification. This converter is considered, can provide the required voltage from a renewable source. The DC rectification is done by using the RSPWM technique. Stage II uses an inverter which inverts the DC rectified signal to produce AC signal. The usage of the bulky transformers are avoided by using the proposed modulation technique. The notable advantages of the RSPWM technique are : (i) the switches of the inverter are functioned at low frequency (50Hz), (ii) harmonic content of the output waveform is reduced because of RSPWM, (iii) decrease of the filter size and (iv) inverter switches life time are increased as complicated control techniques are avoided. These features are validated through simulations.

A study of material stoichiometry on charging properties of SiNx films for potential application in RF MEMS capacitive switches

This work presents an in depth investigation regarding the effect of PECVD silicon nitride (SiNx) stoichiometry on its charging mechanisms. The investigation took place in SiNx dielectric films with different Si-content (x = 0.47–1.04) with the aid of Metal-Insulator-Metal capacitors. The experimental assessment involved a single-point Kelvin probe System, the monitoring of Current – Voltage characteristics and the employment of Thermally Stimulated Depolarization Currents technique. The results indicate that when Si-content increases the injected charge distribution is expected to extend deeper in the dielectric films and charges are displaced faster through the bulk material and towards the bottom electrode. The effective temperature is used in order to investigate hopping conduction that dominates charge transport in the bulk material and thus a more realistic approach of the discharging process is presented. Finally, the increase of Si-content seems to introduce defect states in SiNx, which are probably associated to Si-dangling bonds, and the presence of discrete depolarization mechanisms are investigated, the characteristics of which are analytically described taking into consideration the effect of stoichiometry. These results that can be useful in material engineering in order to improve the lifetime of RF MEMS capacitive switches.

Sparse Kernel Ridge Regression Assisted Particle Filter Based Remaining Useful Life Estimation of Cascode GaN FET

This article proposes a novel sparse kernel ridge regression assisted particle filter (SKRR-PF) based remaining useful life (RUL) estimation method to address the reliability of the cascode gallium nitride field-effect transistors in emerging power electronics systems. The proposed method will overcome three main challenges in this area: first, a large variation in the RUL estimation under the severe noise uncertainty; second, sample degeneracy and sample impoverishment; and third, the low capability of tracing the dynamic and abrupt change in the fault precursor trajectory. The state-of-the-art RUL estimation methods require a significant number of samples to address such issues, including particle degeneracy and sample impoverishment. Also, the state-of-the-art methods mostly fail to apply under a system's dynamic condition changes over a switch's lifetime. The proposed method will significantly enhance the estimation accuracy by introducing SKRR in resampling the posterior probability density function estimation, especially under the dynamically varying system's health condition due to the harsh industrial operation. Thus, the proposed method will offer fast tracing the sudden change in the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> trajectory, leading to a significant accurate RUL estimation. The performance of the proposed method has been rigorously validated through the purposely designed power cycling testbed.

An Improved Phase-Shifted DPWM Method for Reducing Switching Loss and Thermal Balancing in Cascaded H-Bridge Multilevel Inverter

This paper proposes an improved discontinuous pulse-width modulation (DPWM) method based on phase-shifted PWM (PS-PWM) for three-phase cascaded H-bridge (CHB) multilevel inverters. Due to the CHB multilevel inverters employ a large number of power semiconductor switches, they suffer from device failures because the switches are one of the major failure factors in a power electronic system. Therefore, the reliability and life-time of CHB multilevel inverters are mainly determined by the reliability of switches. The most failure of switches is occurred by its accumulated thermal stress which is generated by power losses including the conduction and switching loss. By applying the conventional DPWM, the life-time of switches can be extended because it reduces the switching loss. The conventional DPWM, however, still operates with high speed carrier frequency and it is not enough to reduce the switching loss of the CHB multilevel inverter with a large number of inverter cells. The proposed novel DPWM method provides the improved switching loss reduction through the different switching behaviors for each leg. Additionally, the rotation scheme promises even power distribution and life-time management among inverter cells in a CHB multilevel inverter. The simulation results and experimental results confirm the switching loss reduction and even power distribution abilities of the proposed modulation method.

Transient Contact Opening Forces in a MEMS Switch Using Au/MWCNT Composite

Most failures in micro electromechanical system (MEMS) switches can be attributed to the degradation of contact surfaces and sticking contacts. A wear-tolerant composite contact material, composed of a Au film supported by multi walled carbon nanotubes (Au/MWCNT), has been engineered to provide wear resistance and enhanced switching lifetime with conductive properties close to pure Au. Switching lifetimes of billions of cycles have been demonstrated, representing greatly increased performance over thin film Au. Below the arcing threshold (~12 V) the wear mechanism has been shown to be a combination of the fine transfer of contact material by the molten metal bridge (MMB) phenomenon and a delamination of the Au. In this study, the composite contact is hot switched at low current DC conditions (4 V DC and 20 mA) while the contact force is measured at the micro Newton scale in nanosecond resolution. The characteristic voltage waveform associated with the MMB is observed with forces detected as the contact softens, melts, and separates. The presence of a delamination event (DE) is also observed, where the contact opens abruptly with no MMB phenomenon apparent. The DE contact openings are associated with a transient peak force of 21.6 ± 2.3 µN while the MMBs are linked to a lower peak force of 18.1 ± 2.5 µN.

A Compact and Repetitively Triggered, Field-Distortion Low-Jitter Spark-Gap Switch

This paper describes the development of a small field-distortion spark gap switch. Comprehensive experimental studies made with the switch revealed its self-breakdown characteristics, voltage operating range, time delay and jitter, repetition frequency, and finally the electrode erosion processes and duration of its service lifetime. A series of design improvements were required to be implemented in the switch design. For example, to reduce the structural inductance of the switch and to improve its working characteristics, the main electrode was designed as a circular track structure. Similarly, to increase the operation stability and reduce the self-breakdown probability, the trigger electrode was designed as a disk-like structure. Moreover, to balance the gas pressure in the discharge region and increase the stability during closure, a circular hole was added at the center of the trigger electrode. The compact switch has a small size of only 150 mm $\times42$ mm, a weight of 1.5 kg, and can be successfully operated at a voltage over 110 kV, at a repetition rate between 1 and 50 Hz and having a jitter of less than 4 ns. It was experimentally demonstrated that during normal operation conditions, the switch lifetime exceeds 100 000 shots.

Reliability analysis of discrete time redundant system with imperfect switch and random uncertain lifetime

Reliability analysis of discrete time redundant system with imperfect switch and random uncertain lifetime

A novel drive circuit with overcurrent protection for solid state pulse generators

In recent years, semiconductor switches have been widely used in pulse generators. In order to generate bipolar or rectangular pulses, switches in these generators operate in different time sequences. However, the dv/dt induces false triggering of the semiconductor switches that leads to local short circuits. Breakdown of the load will also produce a high short-circuit current which will affect the switches' reliability and lifetime. In this paper, a new gate drive circuit is proposed to protect switches from short-circuit currents. A 52-stage solid state Marx generator using the proposed drive circuit was tested to verify the overcurrent protection. The experimental results show that the short-circuit current is limited within a safe range and the output voltage increased significantly.