High Voltage Stress Research Articles

A valley-sensed emulated peak current controlled buck converter for automotive applications

This paper presents an emulated peak current-mode control topology targeted for a high voltage buck converter for automotive applications, where one of the key challenges is to protect the devices from the high voltage stress. The proposed controller scheme eliminates the issue of the voltage stress and at the same time reduces the design complexity of the current sensing block. In addition to that, the inherent issue of sub-harmonic oscillations in the current-mode controller has been resolved by the proposed adaptive slope compensation. The input operating voltage of the converter ranges from 5 V to 36 V with output of 3.3 V. The proposed controller, designed in TSMC 180-nm Bipolar-CMOS-DMOS (BCD) process achieves a minimum on-time of 28 ns and a minimum off-time of 120 ns. It can drive a maximum load of 3.3 A while operating at a switching frequency of 2.1 MHz. The peak power efficiency, achieved at 2 A load, is 93.63%.

Research on aging state detection of reactor turn‐to‐turn insulation under high‐frequency square wave voltage excitation

In power electronic equipment, magnetic devices are important parts, and their working condition and reliability are closely related to turn-to-turn insulation. With the increasing application of high-frequency square wave voltage in the fields of frequency conversion technology and motor control, the high voltage stress on magnetic devices will accelerate insulation aging, so it is necessary to monitor the aging state of turn-to-turn insulation. At present, researchers mainly detect insulation aging by detecting partial discharge signal. However, this method cannot realize the early monitoring of aging, and the measurement cost is high and the accuracy is low. Therefore, for the dry-type core reactor with epoxy resin as the insulation medium, this paper proposes a turn-to-turn insulation aging state detection method under high-frequency square wave voltage excitation. According to the relationship between the turn-to-turn insulation aging state of the reactor and its parasitic capacitance, the turn-to-turn insulation aging degree of the reactor is predicted by measuring and analyzing the phase information of high-frequency components of the current signal. Finally, the measuring principle and method are introduced and verified by experiments.

Control Optimization of Modular Multilevel Resonant DC Converters for Wide-Input-Range MVdc to LVdc Applications

In this article, the output voltage control strategy of modular multilevel resonant dc converters (MMRDC) for medium-voltage wide-input-range applications is studied. First, the feasibility and influence of the switching frequency regulation and modulation index regulation are investigated in detail. It is found that the switching frequency choice has a significant effect on the voltage stress of arm inductors and the transformer. Then, based on these considerations, the modulation index regulation plus switching frequency regulation based design and control optimization is proposed. With the proposed design and control method, the switching frequency range for adapting to a wide input range is further reduced, especially under light load operating conditions. Besides, the high voltage stress on arm inductors is avoided and the high voltage <i>dv</i>&#x002F;<i>dt</i> on the transformer is also eliminated. Finally, a laboratory prototype with 8&#x2013;16 kV input and 375 V&#x002F;60 kW output has been built and the experimental validation under a wide input range has been done. The efficiency over 96.4&#x0025; under the wide input range proved the effectiveness of the optimized control methods.

A Three-Phase Active-Front-End Converter System Enabled by 10-kV SiC MOSFETs Aimed at a Solid-State Transformer Application

The use of high-voltage silicon carbide (SiC) devices can eliminate multilevel and cascaded converters and their complicated control strategies, making converter systems simple and reliable. A three-phase two-level voltage-source converter system serves as a simple converter system for interfacing any dc source to a three-phase grid. However, when the high-voltage devices are used in two-level converters, they are exposed to a high-voltage peak stress and a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$dv/dt$</tex-math></inline-formula> (up to 100 kV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> s). Operating these semiconductor devices at these stress levels requires careful design not only of the semiconductor die and the module, but also of the gate drivers, busbars, and passive filters. This article demonstrates the operation of 10-kV SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s and discusses the design considerations, advantages, and challenges associated with the operation of the three-phase two-level medium-voltage converter system used as the active-front-end converter system. Reliable operation of the medium-voltage converter system requires the development of reliable high-voltage modules and auxiliary parts, such as gate drivers, busbars, inductors, voltage and current sensors, and proper design of the controller system. Successful tests demonstrating continuous field operation of the medium-voltage active-front-end converter at a nominal rating of 7.2-kV dc-link voltage is demonstrated for the first time in the literature. The results indicate that these devices can accelerate the growth and deployment of medium-voltage SiC devices for field operation, as demonstrated by the operation inside the mobile container.

Anomalous PBTI Effects in N-Type Super Junction under High Gate Voltage Stress

In this work, an anomalous thick oxide-degradation phenomenon in n-type 650-V class super-junction VDMOS transistors is investigated. An unexpected threshold voltage (Vt) decrease was observed with high positive bias temperature instability stress, and the saturation current (IDsat) increases with the stress time. Repeatable and reproducible behaviors have been achieved from multiple devices under test. Based on simulation and experimental results, it is found that the high-energy electrons (caused by high positive gate voltage) in the n-type region at the bottom of the gate oxide layer (top of the N-pillar) are injected into the gate oxide. The high-energy electrons generate electron-hole pairs during the transport to the anode, leaving holes in the gate oxide layer, and thus decreased Vt and increased IDsat. Finally, C-V measurement is also carried out which further confirms the above analysis.

Surfactant-assisted fabrication of room-temperature self-healable dielectric elastomer toward actuation application

Dielectric elastomers are widely used for actuation applications in emerging domains such as tunable optics, tactile displays and soft robotics. However, dielectric elastomer actuators (DEAs) are prone to suffering from electrical or mechanical damage under the conditions of high operating voltage and mechanical stress, leading to a short service time and a low reliability. To address these issues, we in this work made an attempt to facilely develop a self-healable dielectric elastomer that combines high stretchability, dielectric properties, large actuation and effective repairing of mechanical and electrical failure by constructing multitype noncovalent interactions under surfactant assistance. It is demonstrated that the as-prepared elastomer possesses good healability at room temperature. After mechanical injury, a gentle pressure can initiate the recovery of damaged region, and the elastomer film could be subjected to a huge strain of 750% after healing for 24 h. In particular, this as-fabricated DEA that suffered from accidental or repetitive breakdown could still be re-actuated stably without significantly decreasing its actuated strain after quick healing (∼5 min). It is also found that embedding a fluoroelastomer with a fluorosurfactant can achieve larger deformation (tan α = 0.57 at 30 MV/m) due to the improved electromechanical properties. Our strategy for achieving self-healing feature and high actuation performance is favorable for extending lifetime, strengthening damage tolerance and lowering excitation voltages required for the DEAs.

Experimental investigation of potential induced degradation of poly-crystalline photovoltaic modules: Influence of superstrate and encapsulant types

Potential induced degradation (PID) is amongst the most critical degradation phenomena affecting reliability of PV modules by causing power losses. In this research, PID was induced on PV modules in an environmental chamber in accelerated temperature and humidity conditions under the application of high voltage stress. The primary focus of this paper was to quantify the degradation extent of PV modules with different encapsulant and superstrate/glass types. The encapsulant types investigated were EVA and newly developed PVB. The superstrate types investigated were Soda-lime and Quartz. The progression and severity of degradation were determined through I-V measurements and EL imaging, revealing losses in Pmax and FF. The leakage current was measured during the PID test and no correlation between leakage current and power was observed. It was demonstrated that the PID loss was strongly dependent on the electrical and physical properties of the superstrate and encapsulant types. The module with quartz/EVA configuration experienced lower (17%) PID losses compared to the soda-lime/EVA module (32%). Similarly, the module with soda-lime/PVB configuration experienced lower (10%) PID losses compared to the soda-lime/EVA module (32%). While the module having both the quartz and PVB, exhibited the lowest PID progression with only 1% degradation in power.

Post‐mortem analysis of a commercial Copper Indium Gallium Diselenide (CIGS) photovoltaic module after potential induced degradation

AbstractAn extensive post‐mortem analysis was conducted on a commercial copper‐(indium‐gallium)‐diselenide (CIGS) photovoltaic module that degraded after exposure to the high voltage stress of a standardized potential induced degradation (PID) test. We employed a custom‐developed coring technique to extract samples from the full‐size field module, which showed degraded and nondegraded areas (regarded as reference) in electroluminescence after the PID test. The resulting solar cell samples were compared based on their electrical properties and sodium profiles using a wide range of laboratory‐based analysis techniques including photoluminescence and lock‐in thermography imaging, current–voltage measurements, and glow discharge optical emission spectroscopy. The samples that were extracted from the degraded areas of the module showed lower photoluminescence intensity and had significantly lower open‐circuit voltage V(oc) and fill factor (FF) values in comparison with reference samples. An increased content of sodium within the absorber layer was also observed for these samples, linking sodium migration to PID. These observations at the module level are consistent with earlier reports on PID‐stressed CIGS cells and mini‐modules. This is to our knowledge the first reported study of a microscopic investigation on a real‐life full‐scale CIGS module after PID.

A design for switched capacitor and single‐switch DC–DC boost converter by a small signal‐based PI controller

AbstractIn this study, a switched capacitor (SC)‐based single‐switch DC–DC boost converter structure operating under the high voltage gain and the low duty ratio is proposed using the PI control technique. High current and voltage stresses across the power switches and power diodes can be reduced by using the projected SC block. In addition, the proposed converter can achieve high voltage gain through shorter duty cycles, which directly reduces the voltage stress and dynamic losses in the power semiconductors. On the other hand, because the proposed converter includes a single power switch under different output powers and different loads, the control process is simpler than multiswitch structures. With the proposed converter, an output voltage of 10 times greater rather than the input voltage is obtained at 0.57 of the duty cycle. In this study, the fundamental functions of the proposed converter and the controller design steps are analyzed mathematically and tested in MATLAB/SIMULINK environment. As a result of the analysis, it was determined that the proposed topology works with a high performance at high frequency and variable load ranges. To validate the proposed converter and theoretical calculations, a 200‐W prototype was established under a continuous conduction mode (CCM) working state, with 48‐VDC input voltage and 400‐VDC output voltage. Finally, the simulation results were tested and verified through the experimental results.

A Comprehensive Review on Wireless Capacitive Power Transfer Technology: Fundamentals and Applications

Capacitive power transfer (CPT) technology is becoming increasingly popular in various application areas. Due to its limitations, such as low frequency, low coupling capacitance, and the high voltage stress on metal plates, the studies on high power CPT applications fell behind previously. Therefore, the wideband gap (WBG) semiconductor devices and the compensation topologies are further adopted to tackle these limitations. The main purpose of the paper is to review CPT applications in terms of performance parameters, advantages, disadvantages, and also challenges. Initially, the basic principles of CPT technology are examined, which cover compensation topologies, coupler structures, transfer distance, power electronic components, and system control methods. Then, CPT applications are evaluated for performance parameters (i.e., power level, operation frequency, system efficiency, transfer distance) along with compensation types, inverter types, and coupler types. The applications are categorized into six main groups according to industrial topics as safety, consumer electronics, transport, electric machines, biomedical, and miscellaneous. Herein, power level changes from <inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> to kW ranges, the operation frequency varies from 100s of kHz to 10s of MHz ranges as well. The maximum system efficiency is recorded as 97.1 &#x0025;. The transfer distance varies from <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> range to 100s of mm ranges. The full-bridge inverter topology and four-plate coupler structure are noticeable in CPT applications. Finally, advantages, disadvantages, and challenges of CPT applications are evaluated in detail. This review is expected to serve as a reference for researchers who study on CPT systems and their applications.

Solar PV Fed DC Microgrid: Applications, Converter Selection, Design and Testing

In this research article, major applications which use solar PV fed DC microgrid for either their routine operation or gain additional advantages over existing electrical power architecture are elaborated. The role of power converters in interfacing the input with the required output is highlighted. The advantages of solar PV fed DC microgrid are demonstrated by designing and testing a non-isolated high gain high power (HGHP) DC-DC converter to meet the DC distribution voltage level. The proposed converter is synthesized by using hybrid combination of three-phase interleaved boost converter (IBC) with voltage lift technique along with coupled inductors (CIs) and voltage multiplier cell (VMC). The proposed concept is practically demonstrated and the adopted design techniques are validated using simulation and experimentation. The proposed converter with 60V/1.1kV, 100kHz and 3kW rating operates at 92.3% full-load efficiency under practical conditions. Due to the gain extension techniques adopted, the switches used in the proposed converter are subjected to a voltage stress which is only 36% of the output voltage. Due to interleaving technique, the input current ripple and the current stress on the switches are only 15% and 33% of the input current respectively. Key performance parameters of this converter are thoroughly investigated and benchmarked with some state-of-the art converters to appreciate the salient features of the presented converter. The ability to yield higher voltage gain at safe duty ratio, high power handling capacity, low voltage and current stresses on the power switches are the main advantages of the proposed converter.

An Asymmetric Switched-Capacitor Multicell Inverter With Low Number of DC Source and Voltage Stress for Renewable Energy Sources

Asymmetric multilevel inverters generate high-quality output voltage using the same number of components as symmetric multilevel inverters. The main drawback of these topologies is that they require many DC voltage sources, and the power switches must endure high voltage stress. In this paper, a switched-capacitor sub-module inverter topology is proposed to reduce the number of DC voltage sources and the voltage stress on the switches of asymmetric multilevel inverters. The proposed sub-module inverter can generate 15 voltage levels by using two DC power supplies and a capacitor. The voltage of the capacitor can be automatically charged at half of the input DC power supply without the need for any sensors. In addition, the capacitor charging operation does not produce an inrush current because it is charged by the direction of the output current; this is an advantage over switched capacitor multilevel inverters. A modular topology is also presented based on the proposed sub-module inverter to achieve high voltage levels while reducing the number of elements. A comprehensive comparison between the proposal and other multilevel inverter topologies is performed to validate the design of the proposed inverter. In addition, thermal and loss distribution simulations of the proposed sub-module inverter are performed. Finally, the performance, efficiency, and accuracy of the proposed inverter are confirmed through laboratory prototyping.

High gain multiphase boost converter based-on capacitor clamping structure

&lt;p&gt;In the last few years, the non-isolated dc converters involving high voltage gain with adequate performance are becoming quite popular in industrial applications. This is resulting in high voltage and current stress on the power device (switches and diodes), as well as a limited output voltage with a high duty cycle. This paper proposes a multi-phase non-isolated boost converter that uses capacitor clamping to increase output voltage while reducing stress across the power device. There are two stages in the proposed converter (first stage is three inductors and three switches and the second stage is clamper circuit of three capacitors and three diodes). The proposed converter is high voltage gain, with low voltage stress through switches transistors. To justify the theoretical analysis, the concept was validated through mathematical analysis and by simulation using MATLAB/SIMULINK. The results carried out the results permit the converter behavior and performance to be accurately.&lt;/p&gt;

Local capacitance-voltage profiling and high voltage stress effect study of SiO2/SiC structures by time-resolved scanning nonlinear dielectric microscopy

We investigate SiO2/SiC structures by a nanoscale capacitance-voltage (CV) profiling method based on time-resolved scanning nonlinear dielectric microscopy (tr-SNDM). Owing to the high sensitivity to the variation in the tip-sample capacitance, wide bandwidth of the measurement, and high flexibility of offline processing, tr-SNDM permits the more accurate acquisition of the microscopic CV characteristics localized below the scanning tip. We demonstrate that tr-SNDM based local CV profiling is able to distinguish the different features of untreated and nitrided SiO2/SiC structures and image intrinsic spatial non-uniformity of the interfaces. We also investigate the nanoscale impacts of high voltage stress on the SiO2/SiC structures. By inspecting the local CV characteristics under high voltage stress, we suggest that the interface defect density locally increases during the stress application.

An Embedded Half-Bridge Γ-Z-Source Inverter with Reduced Voltage Stress on Capacitors

In this paper, an embedded half-bridge Z-source inverter based on gamma structure is proposed. In contrast with the classical half-bridge inverter, the proposed inverter can generate zero voltage levels in output. High voltage gain and low voltage stress on capacitors are the main advantages of the proposed converter. The value of the boost factor in the proposed structure is increased by changing both the shoot-through (ST) duty cycle and turns ratio of the transformer. The operating principle of the proposed converter in four operating modes is presented. We also calculate the critical inductance and compare the proposed converter with conventional topologies. In addition, power loss and THD analysis are presented. Finally, PSCAD/EMTDC software is used to verify the correct operation of the proposed inverter and the experimental results.

High Frequency Multipurpose SiC MOSFET Driver

This article describes a new multipurpose Silicone-Carbide (SiC) Metal Oxide Semiconductor Field Effect Transistor (MOSFET) driver, which was designed and manufactured for a high frequency operating SiC transistor as a semiconductor switching device of power converters. The design of the introduced driver enables to adjust the output voltage levels easily by choosing the integrated linear voltage stabilizers with suitable output parameters used for Printed Circuit Board (PCB) mounting. The voltage insulation of the proposed driver between the primary control side and the secondary output side is performed by MGJ6D12H24MC muRata Ps DC-DC converter with a declared dv/dt immunity 80 kV/1000 ms at 1.6 kV and by IX3180 IXYS High Speed gate driver optocouplers with a declared 10 kV/1000 ms minimum common mode rejection at 1.5 kV. The voltage insulation of these coupling elements is accompanied by safety gaps on the PCB. These insulation features enable the proposed driver to work on high frequencies as a high-side transistor of H-bridges as same as in other power converter topologies with a high frequency and high voltage stress of the insulation border. The proposed driver also provides the possibility of tripping the signal, when the short circuit of the controlled power transistor occurs.

A New Three-Winding Coupled Inductor Nonisolated Quasi-Z-Source High Step-Up DC–DC Converter

This article presents a new three-winding coupled inductor high step-up quasi-Z-source dc–dc converter with single magnetic core and voltage multiplier techniques. Conventional quasi-Z-source-based dc–dc converters not only suffer limited voltage gain and high voltage stresses on semiconductors but also have utilized two or more magnetic cores in their structures. However, the suggested converter shares high voltage gain with continuous input current, low normalized voltage stresses on switch and diodes, low total voltage stresses on semiconductors, and common ground between input energy source and load. Also, this converter with single power switch and magnetic core has not limited the duty cycle. Furthermore, the proposed converter has good efficiency at high output voltage, and hence it is suitable for high voltage dc bus of three-phase inverters in renewable energy applications. The mathematical analysis, operating principle for the proposed converter, and comparison with other Z-source-based converters are provided. At last, a 400-W prototype is built in the laboratory, which has validated the accuracy of the proposed converter.

A high gain noninverting DC–DC converter with low voltage stress for industrial applications

AbstractA noninverting DC–DC converter with high voltage gain and low voltage stress on the switches for industrial applications is proposed in this research article. The proposed converter has used a voltage multiplier cell twice in the circuit that gives the proposed converter a symmetrical configuration and provides low voltage stress across both the switches. The symmetrical configuration of the proposed converter makes it easier to select the components. The proposed converter provides a voltage gain that is more than three times of the conventional boost converter. A 200‐W hardware prototype of the proposed converter has been developed and tested under continuous conduction for static and dynamic conditions. The power loss analysis is done using PLECS software by incorporating the real parameters of switches and diodes from the datasheet. The converter performance is found to be good in open‐loop conditions and is in agreement with the theoretical analysis.

A High Voltage Multiplier Using Stacked Hybrid Cockcroft– Walton/Dickson Multipliers

A high voltage multiplier is one of the most important components for shockwave non-thermal food processing systems. In the design of the high voltage multiplier for shockwave non-thermal food processing systems, not only high voltage gain but also high speed operation and low voltage stress of circuit components are required. In this paper, a novel high voltage multiplier with stacked topology is proposed for shockwave non-thermal food processing systems. Unlike conventional high voltage multipliers, the proposed multiplier is designed by stacking hybrid Cockcroft-Walton/Dickson multipliers (HCWDMs). In the proposed multiplier, high speed operation is achieved, because the stacked topology can reduce the number of multiplier stages. Furthermore, voltage drop of higher multiplier stages and voltage stress are mitigated by the stacked topology using HCWDMs. The validity of the circuit design is confirmed by the laboratory experiments regarding the prototype of the shockwave non-thermal food processing system. The experimental results demonstrate that the proposed multiplier can generate about 3.9 kV within 113 s by converting the ac input 100 V at 60 Hz.

Cu-Doped TiNxOy Thin Film Resistors DC/RF Performance and Reliability

We fabricated Cu-doped TiNxOy thin film resistors by using atomic layer deposition, optical lithography, dry etching, Ti/Cu/Ti/Au e-beam evaporation and lift-off processes. The results of the measurements of the resistance temperature dependence, non-linearity, S-parameters at 0.01–26 GHz and details of the breakdown mechanism under high-voltage stress are reported. The devices’ sheet resistance is 220 ± 8 Ω/□ (480 ± 20 µΩ*cm); intrinsic resistance temperature coefficient (TCR) is ~400 ppm/°C in the T-range of 10–300 K; and S-parameters versus frequency are flat up to 2 GHz with maximum variation of 10% at 26 GHz. The resistors can sustain power and current densities up to ~5 kW*cm−2 and ~2 MA*cm−2, above which they switch to high-resistance state with the sheet resistance equal to ~200 kΩ/□ (~0.4 Ω*cm) caused by nitrogen and copper desorption from TiNxOy film. The Cu/Ti/TiNxOy contact is prone to ageing due to gradual titanium oxidation while the TiNxOy resistor body is stable. The resistors have strong potential for applications in high-frequency integrated and hybrid circuits that require small-footprint, medium-range resistors of 0.05–10 kΩ, with small TCR and high-power handling capability.