High Power Density Applications Research Articles

Digital Close-Loop Active Gate Driver for Static and Dynamic Current Sharing of Paralleled SiC MOSFETs

SiC power devices have been extensively for the high-power density application scenarios. To increase the current rating, SiC devices are usually connected in parallel. However, the mismatching current brought by unbalanced electrical parameters can increase the current stress of a device and pose reliability concern of the converter system. Aiming at addressing the current imbalance for paralleled SiC devices, this paper reports the application of an improved active gate driver (AGD) on the paralleled SiC MOSFETs to address the current imbalance problems. The three-level driver voltage can minimize the overshoot voltage and current. The adjustable turn-on voltage and gate signal delay time can realize the current sharing of both static and dynamic process. Current sensors and a digital controller are utilized for close-loop control. The functionality of the proposed AGD is validated in continuous operating experiment.

A Novel Supercapacitor Model Parameters Identification Method Using Metaheuristic Gradient-Based Optimization Algorithms

This paper addresses the critical role of supercapacitors as energy storage systems with a specific focus on their modeling and identification. The lack of a standardized and efficient method for identifying supercapacitor parameters has a definite effect on widespread adoption of supercapacitors, especially in high-power density applications like electric vehicle regenerative braking. The study focuses on parameterizing the Zubieta model for supercapacitors, which involves identifying seven parameters using a hybrid metaheuristic gradient-based optimization (MGBO) approach. The effectiveness of the MGBO method is compared to the existing particle swarm optimization (PSO) and to the following algorithms proposed and developed in this work: ‘modified MGBO’ (M-MGBO) and two PSO variations—one combining PSO and M-MGBO and the other incorporating a local escaping operator (LCEO) with PSO. Metaheuristic- and gradient-based algorithms are both affected by problems associated with locally optimal results and with issues related to enforcing constraints/boundaries on solution values. This work develops the above-mentioned innovations to the MGBO and PSO algorithms for addressing such issues. Rigorous experimentation considering various types of input excitation provides results indicating that hybrid PSO-MGBO and PSO-LCEO outperform traditional PSO, showing improvements of 51% and 94%, respectively, while remaining comparable to M-MGBO. These hybrid approaches effectively estimate Zubieta model parameters. The findings highlight the potential of hybrid optimization strategies in enhancing precision and effectiveness in supercapacitor model parameterization.

Performance Analysis of Positive Output (P/O) Push-Pull Switched Capacitor Converter for High Power Density Applications

The micro-power-consumption technique requires high power density DC/ DC converters and power supply sources. In this research, a PI and Fuzzy Logic Controllers for an elementary circuit of positive output (P/O) push-pull switched capacitor converter has developed for high power density applications with high sustainability under enormous line and load disturbances. The voltage lift technique is a popular application in electronic circuit design. The power converter performs DC-DC step-up voltage conversion with high efficiency, high power density and cheap topology in a simple structure. The proposed converter combines both switched-capacitor and voltage lift techniques. Referable to the time varying and switching nature of the power electronic converter their dynamic behavior becomes highly nonlinear. Conventional controllers are incapable of providing excellent dynamic performance and hence the fuzzy logic controller can be used as a feed forward controller for controlling power electronic converters. The control algorithm is developed to ensure tracking of the reference voltage and rejection of system disturbances by successive measurements of the converter output voltage at certain time instants within a conduction period. The simulation of PI and Fuzzy logic controls have been carried out using MATLAB/Simulink software to evaluate the controller’s performances. Keywords: Luo converter, DCDC converter, PI Controller, Fuzzy Controller.

Characterization, Analysis, and Modeling of Long-Term RF Reliability and Degradation of SiGe HBTs for High Power Density Applications

Characterization, Analysis, and Modeling of Long-Term RF Reliability and Degradation of SiGe HBTs for High Power Density Applications

Overview of piezoelectric energy harvester based on wind-induced vibration effect

In the field of new environmental energy harvesting technology, wind energy and piezoelectric energy harvesting have become research hotspots. By utilizing wind energy into vibration energy, i.e., wind-induced vibration effect is a research hotspot in the field of environmental energy harvesting. This article comprehensively analyzes the research status and development trend of piezoelectric energy harvesters based on wind-induced vibration effects at home and abroad. It was found that the conversion process of wind energy to vibration energy is mainly based on flutter, galloping, and acoustic resonance. The conversion of vibration energy into electrical energy is mainly piezoelectric power generation, supplemented by magnetic induction power generation and friction power generation. For high power density and small volume application scenarios, resonant cavity type wind vibration energy collection is the main development trend.

A Simple and Economical System for Automatic Near-Field Scanning for Power Electronics Converters

Electromagnetic compatibility issues must be considered from the early steps in the design of electronic devices. A specific topic is the near-field emission generated by the device due to the traces on a printed circuit board and the specific routing. The analysis of near-field emission is essential to detect potential electromagnetic interference with nearby devices. This problem is crucial in high power density applications. Therefore, especially in these applications, it is necessary to optimize the circuit and the layout to minimize the generated noise. The design and construction of systems able to scan volumes to determine the spatial distribution of electrical E and/or magnetic B fields in the near-field region of a device under test is a very complex process. The realization of equipment that explores a given surface at a given distance from the device is easier. The main purpose of this paper is to show how it is possible to build a cheap two-dimensional scanner, starting from simple hardware not explicitly designed for near-field scan operations. The presented firmware and software solution can map, with good accuracy, the spatial distribution of fields B and E on a fixed plan close to the board. Finally, the developed system has been used in a GaN-based bi-directional DC/DC Converter.

A deep dive into SiC and GaN power devices: Advances and prospects

The development of GaN and SiC devices has been the subject of intensive research in recent years, and significant progress has been made in terms of device performance, reliability, and cost-effectiveness. However, there are still challenges to be overcome before these materials can become mainstream in power electronics. This review paper compares the properties and performance of SiC and GaN power devices, which are both wide-bandgap semiconductors that offer superior performance compared to traditional silicon-based devices. The paper discusses the material properties of SiC and GaN, including their bandgaps, thermal conductivities, breakdown voltages, and on-state resistances. The paper also compares the switching speeds and costs of SiC and GaN devices, as well as the manufacturing technologies used for these devices. The paper concludes that SiC devices are generally more suitable for high-temperature and high-voltage applications, while GaN devices are more suitable for high-frequency and high-power density applications. The review paper provides insights into the advantages and disadvantages of SiC and GaN power devices and highlights areas for future research.

Fully ceramic versus steel gears: Potential, feasibility and challenges

The most common gear strength calculations performed in accordance with ISO/TC 60/SC 2 include surface durability and root bending strength. Typical geared power transmissions are characterized by high Hertzian contact stresses (surface durability) on the flanks – frequently in the order of 103 MPa – versus almost half an order magnitude lower first principal stresses on the tooth root (tooth bending strength). Therefore, the use of high strength special steel alloys is almost mandatory, especially in high-end applications, mainly to withstand the high contact stress values. Ceramic materials are typically characterized by high compressive strength versus very low flexural strength that at first glance makes them inefficient for gear transmissions since they are unlikely to withstand the tensile root stresses. Nevertheless, ceramic materials possess a number of advantages that makes them potential candidates for geared transmissions, such as their exceptional thermal properties, their low density (weight), their excellent wear characteristics and limited lubrication demands. The present work investigates the main challenges of using high-end ceramic gears and attempts to provide an insight on defining the design envelope of such gears to counter the main disadvantages. The increase of the normal pressure angle beyond the 25° limit set by ISO 6336 is primarily investigated, since in minimizes the tensile tooth root stresses, while also increasing the curvature of the contact surfaces without greatly increasing Hertzian stresses. Comparative assessment of the performance of fully ceramic gear designs versus their conventional steel counterparts is performed through quasi-static FEA simulations to set the basic design requirements for such gears and to promote further investigation of the feasibility of their usage in high power density applications.

Wide Facets ZnCo2O4 Nanosheets for High Electrochemical Supercapacitor Performances

ZnCo2O4 nanosheets show excellent supercapacitive performance due to their well-developed and uniform architecture. The unique nanosheets with wide facets deliver outstanding electrochemical supercapacitor performance. As a result, the catalyst exhibits a specific capacitance of 700 F/g at a current density of 1 A/g. Interestingly, the material also shows outstanding cycling stability and loses only 2.75% even after 5000 cycles. The study confirms that ZnCo2O4 based materials can be applied in high-energy as well as high-power density applications (energy storage, electric vehicles, and flexible electronic devices) due to their excellent morphology, wide facets, outstanding stability, and capacitance.

Model Based Comparative Analysis of GDC and YSZ Based Solid Oxide Fuel Cells

Designing solid oxide fuel cell (SOFCs) stacks for transportation applications places new challenges on SOFC architecture and operation with respect to power density, dynamic response, and thermal management. Recent developments in SOFCs with either thin-film yttria stabilized zirconia (YSZ) electrolytes (thickness ≤ 5 μm) or highly conductive, gadolinia-doped ceria (GDC) electrolytes (thicknesses ≥10 μm) enable thigh-power-density stack operation at inlet temperatures well below 700ºC with the potential for using compliant seals and lower cost ferrous interconnect materials. Applications, such as hybridized aircraft engines, can use such SOFC stacks if they meet strict requirements with respect to specific power and thermal management. Highly conductive GDC-based electrolytes offer pathways to high power-density SOFCs at operating temperatures below 650ºC, but the rise in mixed ionic electronic conductivity (MIEC) above 650ºC reduces open circuit voltages and thus fuel cell efficiency [1,2]. This necessitates thermal management to maintain operating temperatures and mitigate thermo-mechanical stresses within an SOFC. Thin-film YSZ electrolytes offer lower power densities below 650ºC, but avoid the penalties associated with MIEC behavior at higher temperatures and therefore reduce the challenges associated with thermal management at high power densities. In this work, a model-based approach is used to compare SOFC stack operation with thin-film YSZ electrolytes and with GDC-based electrolytes for operation on hydrogen and reformate fuels at high-power densities relevant for transportation applications.To calibrate models to experimental cell performance, polarization curves of a commercially available YSZ-based cell operating between 600-750ºC and of a high-power-density GDC cell operating between 500-650ºC are used to fit electrochemical model parameters for both electrolytes. Modeling of the YSZ based cell can neglect electronic charge transfer through the membrane electrolyte, but GDC-cell modeling must account for the multiple charge carriers (ceria polarons and oxygen vacancies) in the electrolyte [3]. Electrochemical parameters for ionic conductivities and electrochemical reaction rate parameters for oxide cathodes and nickel-electrolyte-composite anodes are fit to the experimental polarization data over the broad range of operating temperatures. Global rate expressions to account for internal reforming on the active nickel surfaces of anode are adopted from literature [4,5]. The calibrated cell model for each cell type is adopted to a down-the-channel discretized cell simulation to predict heat loss and temperature gradients at high current densities.This presentation compares GDC- and YSZ-based SOFCs in high power-density applications from fundamental and practical perspectives. The open-circuit voltages for GDC-based cells drops with increasing temperature to about 0.85 V/cell at 650°C which is lower than the Nernst open-circuit voltage of YSZ-based cells (≥ 1.05 V/cell) at similar conditions. Both types of cells can sustain power densities around 1.0 W/cm2 with high excess cathode air ratios ≥ 5 to keep temperature gradients near 10°C/cm. These results show that GDC-based cells support higher power densities at lower cell flow inlet temperatures < 600°C, whereas thin-film YSZ cells provide superior performance at flow inlets that drive cell temperatures > 600°C. Higher stack power densities > 1.0 W/cm2 must be supported by stack designs that alleviate high thermal stresses and allow steeper gradients of temperature. A summary of stack design and operational strategies that meet the stringent requirements of high power-density operation will be presented in the light of the modeling resuls..

Structure and the Thermal Management of a 3-D Silicon Carbide MOSFET Module

Silicon carbide (SiC) device has higher switching frequency, higher breakdown voltage, and lower on-state voltage drop, which makes it subversive potential in the high power density applications. However, the traditional packaging structure cannot cope with the high power density of SiC devices, so the existing commercial SiC power module can only be used in derating applications. This paper proposed a 3-D packaging design method for high power density MOSFET power module, in which the cooling system is integrated inside the module to reduce the thermal resistance and the temperature difference of the SiC MOSFET chips. At the same time, the heat dissipation process of the new structure is modeled and analyzed, and the accuracy of the model is proved by experiment and simulation.

An Overview of Active Electrode Materials for the Efficient High-Performance Supercapacitor Application

Recent energy research focuses on the efficiency enhancement of supercapacitor devices for multipurpose applications. Several materials have been used as electrode materials to achieve the maximum specific capacitance. The present review article concludes with three different types of materials recently used to enhance the efficiency of supercapacitors. The first type involves carbon-based materials for storage and supercapacitor applications. The carbon materials could be obtained naturally and synthesized manually based on need. The additional advantage of carbon material is these materials can be obtained from natural sources. The second type discusses the recent advances in metal oxide materials for high-performance supercapacitors. The metal oxide materials are involved in different types of attachment through the bi-tri metallic bonding, which enhances the specific capacitance. The third type involves recently advanced materials for high energy and power density application. The power and energy density of the materials is enhanced by the surface modification of the materials. In recent days, the MXene and nanocomposite materials seem to be an appropriate material to increase the power and energy density of the device. The modification and surface treatment of respective materials could enhance the specific capacitance of the material.

Tailoring the discharge performance of extruded Mg-Sm-Al anode for Mg-air battery applications via control of Al content

We investigated the discharge performance and electrochemical properties of an as-extruded Mg-5Sm-xAl (x = 0,1,3) anode for Mg-air batteries. Adding Al modified the phase composition and grain size of the anode. The addition of 1 wt% Al (Mg-5Sm-1Al) induced a high discharge voltage and power density due to the stimulation of the evenly distributed, fine Al11Sm3 particles. However, these particles increased the parasitical anodic hydrogen reaction rate, resulting in a decrease in anodic efficiency. These properties make the anode suitable for high-power density applications. The addition of 3 wt % Al (Mg-5Sm-3Al) promoted the formation of an aluminium oxide film on the anode surface, which suppressed the anodic hydrogen reaction to improve the anodic efficiency. This film increased the battery's internal resistance resulting in low voltage. This anode is a good candidate for heavy-duty battery applications, where a steady voltage output and long service life are desired. By controlling the Al content, the tailoring of discharge performance of the Mg-Sm-Al anode is feasible to satisfy different battery load requirements.

Enhanced Lithium Storage Performance in Si/MXene Porous Composites

As a potential negative electrode material for lithium-ion batteries (LIBs), silicon has a relatively high specific lithium storage capacity. However, the large volume change during the cycle may result in the isolation with the current collector and therefore the rapid capacity decay during cycling. The poor electric conductivity of the silicon limits the high-power density application in LIBs. To meet the above challenges, a stable Si/Ti3C2Tx composite material was designed. Si nanoparticles are bonded with -NH2 group so that the silicon surface has a positive charge, which can then be electrostatic self-assembly with negatively charged MXene nanosheets in a facile freeze-drying method. Silicon nanoparticles were anchored on the surface or inside the interspace of the MXene nanosheets, which could improve the conductivity of the composites. The composite material (NH2-Si/MXene) presented a stable and porous structure with extra room for silicon expansion and plentiful channels for carrier transportation. Benefiting from the improved structural stability and enhanced charge storage dynamics, the discharge capacity of NH2-Si/MXene is 1203.3 mAh g−1 after 100 cycles at 200 mA g−1. These results provide new insights for the application of silicon-based negative electrode materials in high-energy-density LIBs.

Correction: Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications

Correction for ‘Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications’ by Daniel Avram et al., J. Mater. Chem. C, 2023, https://doi.org/10.1039/d3tc01391j.

Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications

Efficient Gd–Er bidirectional energy transfer in NaGdF4:Yb, Er nanoparticles makes this upconversion system relevant for high-power density applications.

Predictive Algorithm for Control of Common Mode Voltage and Switching Frequency in Direct Matrix Converter Fed System

Multiobjective model predictive control (Mo-MPC), owing to its simplicity and adaptability to comply with diverse constraints, has gained popularity in the control of direct matrix converters (DMCs). However, the MPC strategy makes the converter operate at an uncontrolled and variable switching frequency, which may inhibit high power density applications due to increased power losses. This article proposes a method for controlling the switching frequency of the converter and simultaneously regulating the common mode voltage in the DMC fed system while maintaining sinusoidal load and source currents at near unity input power factor. Furthermore, in order to streamline the control while simultaneously dealing with these objectives, a suitable normalization technique is implemented for scaling the errors in each objective. This method is validated through simulation and experimental results.

Performance Comparison of Superconducting Machines With Induction Motors

The demand for high power density electrical machines grows in aircraft and ships for their propulsion systems. Superconducting machines can be an attractive alternative for these applications. In this context, the present work presents a study comparing a superconducting motor with a squirrel-cage induction motor operating at room and cryogenic temperatures. The superconducting electric machine uses 2G tapes stacked on the rotor. The study is based on experiments with bench prototypes of conventional induction motors and superconducting motors having equal dimensions. The rotor is composed of three superconducting tape rows, which are stacked in a spiral shape around a soft ferromagnetic core. The operating principle of this machine considers the interaction of the rotating field produced by the stator with the magnetic field trapped in the superconducting tapes stacked in the rotor. A commercial 0.5-hp squirrel-cage induction motor was adapted for the tests in different circumstances for operation in an extensive temperature range. The induction machine was tested at liquid nitrogen temperature and room temperature. The results of all prototypes were compared. The authors observed that, up to 80% of the rated load, the superconducting machine works in a synchronous regime, and for higher torque’s levels, it is asynchronous. Besides, it increased the torque 1.24 times and 2.43 times for the induction motor operating at room temperature and 77 K, respectively. The results showed that this superconducting machine has the potential for high power density applications.

A 98.4% Efficiency 380V-12V DCX With 1.3kW/in3 Power Density Using Low NFoM Devices and Resonant Drive Transformer

The MHz series resonant converter (SRC) dc transformer (dcX) is attractive for its good soft-switching characteristics, which is suitable for high efficiency high power density applications. For a 380–12 V dcX, it has been proved that using series-connected low voltage devices with low NFoM can reduce the conduction loss of the switches [Wu and Shi (2020)]. However, its large driving loss at megahertz frequency becomes a concern, which restricts the further improvement of the efficiency. Furthermore, numerous drivers are required for the series-connected devices and the power density is deteriorated. To reduce the driving loss and improve the power density, a low-profile multioutput resonant drive transformer is applied to the SRC dcX in this article. However, without a well-designed drive speed, the dead time provided will be inappropriate, leading to increased losses or even loss of ZVS in SRC. By properly designing the parameters of the drive circuit, ZVS can be both achieved for the SRC and the drive circuit, diving loss and footprint are reduced significantly and symmetry drive voltages can be achieved. A 380–12V/170A 1 MHz dcX prototype with the reduced power magnetics and the proposed resonant drive transformer is built up, which achieves 98.4% peak efficiency and 1.3 kW/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density.

Fringing Field Analytical Calculation of High Frequency Planar Magnetic Components

When the switching frequency is above 100 kHz, the winding loss of the round wire magnetic component will increase sharply due to skin effect and proximity effect, which greatly limits its wide application. On the contrary, the planar magnetic component can not only work at such high frequency, but also suitable for high power density applications for its low profile. However, in order to avoid core saturation and change the inductance, the air gap is usually required in the design of the planar magnetic component, which will produce fringing effect and further increase the winding loss. Based on Roshen’s assumptions, this paper analyzes the planar magnetic component with center air gap. Firstly, the Schwartz-Christoffel mapping is used to establish the mapping relationship between the air gap fringing region and the strip region. Then the magnetic field intensity in complex form is obtained by the complex potential function and the one in vector form is given, which is represented by the strip region coordinate. Finally, the magnetic field intensity verification and the thermal verification are carried out. The method proposed in this paper provides effective guidance for the design of planar magnetic components operating at high frequency.