Power Switching Devices Research Articles

Modelling of Power Semiconductor Devices Switching and Conduction Losses in a Power Electronic System

In power converters, power semiconductor devices, mainly Insulated-Gate Bipolar Transistor (IGBT), are generally used as they are less costly and capable of converting electrical energy into high frequency and voltage. It is critical to accurately determine the switching and conduction losses of power devices before they are assembled into an electronic system. The accurate values help to minimize power loss in a power converter system. With the aid of simulation, design problems are identified to help eliminate device destruction, and critical parameters are monitored. In addition, costly equipment for measuring purposes and testing prototypes is not required at the initial design stage. This research uses simulation work in a power converter system to predict IGBT and diode losses with varied frequencies and voltages. The predictive modelling is produced using regression analysis. The models have been validated by R square (R2) and Mean Absolute Percentage Error (MAPE) techniques. This work is aimed at providing a supervised learning technique mainly used in a machine learning environment, in line with the technological development in the semiconductor industry. With the simulation performed in this work, the efficiency of a boost converter system is enhanced as it shows the models have a good fit with an R2 value of almost 1, and MAPE values are noticed to be less than 5%.

Investigation of the Electrical Characteristics of AlGaN/AlN/GaN Heterostructure MOS-HEMTs with TiO2 High-k Gate Insulator

This paper investigates the impact of TiO2 high-k gate insulator on the electrical characteristics of AlGaN/AlN/GaN MOS-HEMT transistors using MATLAB and Atlas-TCAD simulation software. The physical analytical model of the MOS-HEMTs is used for simulation from Al2O3, HfO2, and TiO2 as the gate dielectric materials, which provide higher performance and reliability of the MOS-HEMT devices. The device shows a good improvement in its result of the DC and AC characteristics with different permittivity of insulator materials. Thus, the DC and AC performance of GaN MOS-HEMTs is higher than with other insulators, such as Al2O3 and HfO2 by using TiO2 as the gate dielectric. Moreover, the simulation results proved that TiO2 is the better gate dielectric material to enhance the electrical reliability of the power switching devices for high-temperature applications such as electric automobiles.

ISOS-SAB DC/DC Converter for Large-Capacity Offshore Wind Turbine

This study offers a modular isolated grid-connected DC/DC medium-voltage DC aggregation converter to support offshore full DC wind farms’ need for lightweight and highly efficient power aggregation and transmission. The converter can simultaneously have a smaller transformer size and lower switching frequency during operation through the dual-voltage stabilization three-loop control strategy and phase-shift modulation strategy, which greatly reduces the space occupied by the converter and lowers the switching loss, Additionally, the use of a two-level structure at a lower switching frequency has lower loss, which effectively reduces the cost of the power device compared with the commonly used three-level converter. The input series output series connection between the converter sub-modules effectively lowers the voltage stress on each power switching device and facilitates expansion into a multi-module structure, expanding its application in high-voltage and large-capacity environments. This study analyzes the two working modes of the DC/DC converter and its control approach, in addition to providing a detailed introduction to the application scenarios of this converter. Ultimately, the efficacy and practicability of the suggested topology and control scheme are confirmed by simulations and experiments.

(Electronics and Photonics Division Award) Research Advances Wide- and Ultrawide-Bandgap Power Switching Devices

Wide bandgap semiconductors such as SiC and GaN (WBG) and emerging ultrawide-bandgap materials such as Ga2O3, AlGaN, and Diamond (UWBG) represent the next-generation materials for high performance medium voltage and high voltage power switch technology. Such devices have a wide range of immediate Naval applications, including high-power satellite communications and radar, unmanned underwater and aerial vehicles, ship drive components, and hybrid vehicle inverters. Vertical SiC power device technology has matured rapidly over the past two decades, owing to advances in substrates, a fundamental understanding of epitaxial growth to eliminate performance-limiting defects, as well as device design breakthroughs. This has enabled breakthroughs in highly integrated module design for medium voltage power conversion with switching frequency >100 kHz. In parallel, lateral GaN-based high electron mobility transistor (HEMT) technology has been highly successful for RF power amplifiers and is well positioned to supersede GaAs-based microwave circuits. Recently, GaN-based vertical and lateral power devices have attracted significant interest due to promising device results coupled with progress in native substrate, epitaxial growth, and processing technology developments. This seminar will present an overview of the WBG/UWBG power device efforts at NRL. This research has four primary focus areas – 1) thermal management in III-N power device structures by diamond thin film integration, 2) characterization of substrate materials and homoepitaxial layers used for drift regions of power devices identify appropriate specifications and benchmark performance, 3) process module development, particularly for selective area doping by ion implantation, and 4) pilot production manufacturing of 1.2kV-class PiN diodes including reliability assessments to identify and mitigate performance limiting defects.

Discrete model and non‐linear characteristics analysis of magnetic coupled resonant wireless power transfer system with constant power load

AbstractMagnetically coupled resonant wireless power transfer (MCR‐WPT) system with constant power load (CPL), finds extensive applications in military, industrial, and medical treatment. However, this system can easily exhibit complex non‐linear behaviors under certain parameter conditions due to the influences of constant power loads, switching devices, and feedback controllers. These behaviors limit the effectiveness of controllers and reduce the efficiency and stability of the system. It is necessary to study the non‐linear characteristics of the MCR‐WPT system with CPL. The stroboscopic discrete mapping of the MCR‐WPT system with CPL is established. Then the system's non‐linear dynamics are analyzed theoretically using a bifurcation diagram, the maximal Floquet multipliers, and the maximal Lyapunov exponent spectrum obtained from the proposed discrete mapping. The results show that the MCR‐WPT system with CPL will exhibit rich non‐linear dynamics with the variation of the power of CPL, such as cyclic fold bifurcation, Neimark–Scaker bifurcation, border collision bifurcations, chaos, etc. The excellent alignment of experimental and theoretical outcomes in corresponding states confirms the accuracy of the proposed discrete mapping and the nonlinear analysis of the system. The results of this study can provide a reference for selecting parameters for an actual MCR‐WPT system with CPL.

A Junction Temperature Smoothing Control Method for SiC MOSFETs Based on the Gate Driving Signal Delay

Low frequency junction temperature fluctuation caused by changes in load current or ambient temperature can severely accelerate the aging development and reduce the operational lifetime of power switching devices. Therefore, junction temperature smoothing control (JTSC) is important for high reliability operation. Conventional JTSC methods require complex additional hardware. Moreover, they are invasive with compromising on the output power quality of the converter. To solve these problems, a novel JTSC method is proposed based on the adjustment of the gate driving signal delay ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ). <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">First</i> , the relationship between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> and the power loss is analyzed. It is discovered that the power loss is positively linear to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> , which is the basis for JTSC. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Second</i> , a JTSC strategy is proposed based on the proportional-integral control. The gate driving signal delay can be adjusted adaptively according to the proposed control algorithm. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Third</i> , the effectiveness of the proposed JTSC method is verified by experiments. The junction temperature fluctuation can be eliminated by 50 % in various load conditions. Compared with conventional JTSC methods, the proposed method has almost no compromising on the output power quality of the converter, and it requires no additional hardware with low cost.

Optimal siting and sizing of custom power system and smart parking lot in the active distribution network

AbstractNon‐linear loads, electrical vehicles (EVs) and power electronics are the sources of harmonic generation in the power system. Harmonics are the reason for the disturbance in the technical constraints and quality of the power system. These disadvantages are formed in the current and the voltage of the system branches and buses. To reduce these harmonics, active and passive power filters are used. Since active power filters (APFs) include electronic power switching devices, they are used to eliminate or reduce current or voltage harmonics. To properly reduce these harmonics and supply consumer demand, private investors (PIs) are considered to enhance the power quality, by investing in the APF units and the distribution network operator (DNO) coordinating and feeding the EVs, by equipping the network with smart parking lots. Total harmonic distortion, bus voltage profile, active power loss and energy not supplied (ENS) are considered problem attributes. Using techniques for order of preference by similarity to the ideal solution (TOPSIS), it is determined how the addition of photovoltaic (PV), energy storage system, and batteries affects the ranking of attributes from the perspectives of both DNO and PI. The best solutions are obtained in the first stage using a genetic algorithm (GA), and the attributes have been prioritized from a utility perspective in the second stage by TOPSIS. To verify the performance of GA and TOPSIS, all of the obtained results are compared with the other algorithms. As seen clearly, active, reactive power loss and ENS in scenarios with the participation PV are reduced. Furthermore, comparing the results of different algorithms confirms the efficiency of GA and TOPSIS.

A H-Bridge-Multiplexing-Based Novel Power Electronic Transformer

Cascaded H-bridge power electronic transformers (CHB-PET) play a pivotal role in distribution grids and their efficient operation. The input series and output parallel (ISOP) configurations result in a huge number of power switching devices, high-frequency transformers (HFT), and capacitors in high-voltage, high-capacity CHB-PET, leading to the need for high hardware costs and huge-sized CHB-PET, which further poses a significant challenge to the engineering feasibility and marketability of the CHB-PET. To address these issues, a CHB-PET topology is proposed in this paper. The novel topology exploits the concept of multi-frequency modulation to achieve power decoupling and power unit multiplexing through reasonable LC resonant frequency selection, which optimizes the ISOP structure and ultimately reduces the hardware cost and size of the CHB-PET. In this study, the effectiveness of reducing the number of power switching devices and HFT is firstly analyzed, and after describing its working principle, the control strategy of each power conversion link of PET is discussed before the correctness and effectiveness of the CHB-PET topology and control strategy proposed in this paper are verified via simulation.

Distribution and transport of holes in the p-GaN/AlGaN/GaN heterostructure

The p-GaN/AlGaN/GaN heterostructure, predominantly epitaxially grown on large-scale silicon wafers, has been widely used for producing consumer power switching devices and recently manifested favorable for developing GaN-based complementary devices and circuits. This work investigates the hole distribution and transport in this structure based on wide-temperature-range (20–600 K) Hall measurements and TCAD simulations. It is revealed that the p-channel thereof is composed of the bulk holes in the p-GaN and the two-dimensional hole gas (2DHG) at the p-GaN/AlGaN interface, and both substantially contribute to the lateral p-type conduction at room temperature. Their complementary temperature responses lead to conductivity enhancement at both high- and low-temperature regimes. The high-density (1.2 × 1013 cm−2) 2DHG is formed owing to the polarization-induced potential well and the ionization of the Mg acceptors that thermally diffused into the barrier during the epi-growth. Such ionized Mg acceptors would partially deplete the two-dimensional electron gas (2DEG) at the access region in the n-channel side where the p-GaN is removed and result in a trade-off between the carrier density of 2DHG and 2DEG.

Junction Temperature Optical Sensing Techniques for Power Switching Semiconductors: A Review.

Recent advancements in power electronic switches provide effective control and operational stability of power grid systems. Junction temperature is a crucial parameter of power-switching semiconductor devices, which needs monitoring to facilitate reliable operation and thermal control of power electronics circuits and ensure reliable performance. Over the years, various junction temperature measurement techniques have been developed, engaging both non-optical and optical-based methods, highlighting their advancements and challenges. This review focuses on several optical sensing-based junction temperature measuring techniques used for power-switching devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs). A comprehensive summary of recent developments in infrared camera (IRC), thermal sensitive optical parameter (TSOP), and fiber Bragg grating (FBG) temperature sensing techniques is provided, shedding light on their merits and challenges while providing a few possible future solutions. In addition, calibration methods and remedies for obtaining accurate measurements are discussed, thus providing better insight and directions for future research.

An experimental study on switching waveform design with gate charge control for power MOSFETs

Designing switching waveforms is a technique for mitigating a trade-off between loss and noise in switching power devices. A novel and simple method has been proposed to compute the gate waveform to realize a designed switching waveform. The gate current pulse is calculated to eliminate the deviation between the designed target waveform and the observed waveform at the moment using a linear combination of drain-source voltage or drain current responses to a small gate charge pulse train. In this paper, a verification system including a simple gate current pulse generator consisting of operational amplifiers and transistors was built together with a conventional voltage source gate driver, and validation of the proposed method was experimentally performed using the drain-source voltage waveform of a Si MOSFET during the turn-off phase. Applying the obtained drain-source voltage responses to the proposed method, the gate current pulse to be added to realize a given target waveform was calculated and superimposed on the output of the gate driver. The measured drain-source voltage waveform was well-matched to the target. In addition, the impact of the drain current values on the design of the drain-source waveform was verified.

Contemporary materials for semiconductor switches in an isolated bidirectional DC-DC converter using a closed loop system with linear quadratic regulator control

This research seeks to create a novel bidirectional DC-DC converter capable of high step-up/down power transfer for diverse applications, such as grid systems, energy backup systems, fuel cell vehicles and hybrid electric vehicles. The converter features an inductor linked to an electric power grid to facilitate multi-layer energy conversion with galvanic isolation for improved voltage ratio and galvanic isolation. Notable among its features is this converter's capacity to recycle energy from a leaky inductor without needing additional snubber mechanisms or clamped circuits. To facilitate efficient operation, the converter employs power switches capable of soft switching both step-up and step-down modes. This option permits using MOSFETs with low on-state resistance, which is advantageous due to reduced voltage endurance at the primary side. This research explores the application of a linear quadratic regulator (LQR) for use with a constant frequency bidirectional DC-DC converter. Leveraging the high-order nature of converters, LQR controllers make full use of their potential by offering rapid dynamic response time, reliability and minimal changes in settling time for an array of operating conditions. Thorough analyses were carried out into the availability and stability conditions of an LQR controller in step-up mode using MATLAB/Simulink simulation results as evidence. This study also emphasizes the significance of performance and effectiveness in electronic power-switching devices, which rely heavily on material properties for operation. While silicon has traditionally been employed for these switches, advances in material science have seen wider band-gap semiconductors adopted to improve switching device performance. Therefore, this research encompasses selecting and implementing appropriate semiconductor materials into power electronic switches used by DC-DC converters.

An Asymmetrical Dual Quasi-Z-Source Based 7-Level Inverter for PV Applications

This paper presents a new single-stage quasi-z-source (qZS) based power converter for Photovoltaic (PV) applications. This seamless topology is obtained by the fusion of two quasi-z-source networks with a 7-level cascaded multilevel inverter (MLI). The proposed converter requires fewer passive components and power switching devices compared to the seven-level topologies with impedance and quasi-impedance sources, reported in the literature. The proposed modulation technique achieves the required level of voltage boosting using the qZS networks while synthesizing seven levels in the output voltage waveform. While the proposed power converter can regulate the output voltage in the standalone mode, it can inject active power into the grid at Unity power factor (UPF) in the grid-connected mode of operation. This paper also aims to mitigate the leakage current, which is one of the major issues in transformerless PV inverters, by reducing the magnitude of voltage transitions in the parasitic capacitor and the suppression of higher-order harmonics in the ground leakage current. The steady-state and the dynamic performances of the proposed power converter during grid-connected mode of operation is assessed with simulation studies and are validated with experimental results.

A Simple Switching-Event Dependent High-Frequency Sampling Method for Power Conversion System

Precise current and voltage sensing are challenging for digital control in high-frequency power conversion systems. Given that the power electronics circuitry is triggered repetitively by power device switching events, a switching-time dependent sampling method is proposed to realize an equivalent high-frequency signal sampling with a low-speed Analog Digital Converter (ADC) and digital controller. Two sampling modes are developed in the proposed methods in terms of sampling rates lower and higher than the digital controller clock frequency, respectively. A fast and simple signal reconstruction method is designed to ensure the feasibility in a low-cost processor. A series-resonant dual-active-bridge (SR-DAB) is taken as an example for the theoretical analysis and experimental verification. The resonant current and Miller plateau voltage in the topology are sampled to verify the potential of the proposed method for online parameter recognition of DC-DC converters and device behavior monitoring of power devices.

Squeeze-Printing Ultrathin 2D Gallium Oxide out of Liquid Metal for Forming-Free Neuromorphic Memristors.

Two-dimensional (2D) metal oxides exhibit extraordinary mechanical and electronic properties, leading to new paradigms in the design of electronic and optical systems. However, as a representative, a 2D Ga2O3-based memristor has rarely been touched, which is hindered by challenges associated with large-scale material synthesis. In this work, the ultrathin 2D Ga2O3 layer (∼3 nm thick) formation on the liquid gallium (Ga) surface is transferred with lateral dimensions over several centimeters on a substrate via the squeeze-printing strategy. 2D Ga2O3-based memristors exhibit forming-free and bipolar switching behaviors, which also reveal essential functions of biological synapse, including paired-pulse facilitation, spiking timing-dependent plasticity, and long-term depression and potentiation. These results demonstrate the potential of 2D Ga2O3 material for neuromorphic computing and open up an avenue for future electronics application, such as deep UV photodetectors, multimode nanoresonators, and power switching devices.

Evaluation of Start-Up Performance of Induction Motor Speed Sensorless Vector Control Using Adaptive Flux Observer Considering Inverter Voltage Error

Speed sensorless vector control for induction motors using an adaptive flux observer makes it difficult to output high and stable torque at a standstill condition when the output voltage error mainly due to dead-time of the inverter. This voltage error leads to a speed estimation error. Consequently, axis misalignment occurs, and a torque value that tracks the reference command value cannot be output. A method has been proposed to compensate for this voltage error by using a current command value; however, the compensation accuracy is limited because of the forward voltage drop and nonlinear characteristics of power switching devices. This study applies the conventional dead-time compensation to the model reference adaptive system, and the effect of varying the amount of compensation, instead of investigating the true dead-time length, on the start-up is evaluated using a 2.2 kW experimental system and through dynamic analysis.

Simulation of Pulse Sharpening Mechanism of Vertical Diamond Avalanche Diode

The extremely low leakage, fast response, and excellent thermal conductivity of diamond facilitate its potential application in pulse power switching devices. In this study, we investigated the static and transient characteristics of diamond avalanche diodes (DADs) via 2-D device simulation. DAD is based on a Schottky barrier diode (SBD) structure. The static breakdown voltage is 590 V. Under an input pulse voltage with a peak voltage of 2400 V and a rise time of 2 ns, the output voltage on a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> load driven by the device has a peak value of 1.83 kV and a rise time of 1.282 ns. The behavior and mechanism of the sharpened rising pulse response waveform are analyzed phase by phase. The generation and dynamic changes in carrier plasma inside the device and their effect on the altered electric field, impact generation, and carrier density, as well as the transient output of the device are investigated.

Research on Low Switching Loss Control Strategy of High-Speed FESS Based on NPC Three-Level Converter

The high-speed flywheel energy storage system (FESS) has been used in urban rail transit system to provide network stability and regenerative braking energy recovery due to its merits of high-power density, almost infinite charging–discharging cycles, nonexistent capacity deterioration, and environmental friendliness. The electrical fundamental frequency of the FESS motor/generator will be significantly increased when the rotor is mainly composed of carbon fiber composites to achieve higher speed. In addition, in view of the 1500-VDC power supply of the urban rail transit system, the switching loss of the power switching devices will be significantly increased or the system failure may be occurred when the high switching-to-fundamental frequency ratio (SFFR) control strategy is applied. Therefore, a low SFFR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$=$ </tex-math></inline-formula> 1 control strategy of the I-type neutral point clamped (NPC) three-level converter for the high-speed FESS with brushless direct current (BLDC) motor in two-phase conduction mode is designed, and the matching midpoint voltage balance strategy is proposed. The effectiveness of the proposed control strategy is verified by simulation and experiments. The stable and low switching loss operation of the high-speed FESS rated at 1500 VDC, 330 kW, and 36 000 r/min is realized, and the midpoint voltage balance is strongly controlled.

Design and simulation of an asymmetrical 23-level inverter with modulation Techniques

For medium voltage, high power regulation the Multilevel Inverters (MLI) are attracting industry and academic researchers. MLI generates the desired output in the form of stepped waveforms with reduced harmonics. The MLI is expected to be realised using a variety of traditional topologies. Traditional MLIs have the disadvantage of requiring additional components, which increases the complexity of gate pulse production. As a result, MLI's overall costs will rise. This research proposes a hybrid topology to alleviate these drawbacks. With the increase in the number of steps in output voltage, the number of dc sources, power switching devices, converter cost, and space required is significantly reduced compared to typical MLIs. The design and simulation of a hybrid converter using several types of PWM approaches are covered in this work. This hybrid converter combines a T-Type structure and a half bridge inverter that is back-to-back connected. The proposed construction is designed and simulated by MATLAB Simulink software. The proposed 23 level inverter circuit is designed and simulated by Equal phase angle modulation technique and half height modulation technique, THD is compared.

High Al-content AlGaN channel high electron mobility transistors on silicon substrate

The rapidly increasing power demand, downsizing of power electronics and material specific limitation of silicon has led to development of AlGaN/GaN heterostructures. Commercial GaN power devices are best available for radio frequency (RF) and high voltage switching applications. Emerging AlxGa1-xN channel based heterostructures are promising to enhance the limits of next generation high voltage GaN power switching devices. In this work, we report on the study of electrical performance of AlGaN channel HEMTs-on-Silicon using various Al content. The fabricated devices exhibited outstanding buffer breakdown electric field above 2.5 MV/cm considering the submicron thin heterostructures grown on silicon substrate. Furthermore, we also experimentally demonstrate high temperature operation of fabricated AlGaN channel HEMTs.