Power Semiconductor Technology Research Articles

(Invited) Silicon Carbide Technology Scaling: Challenges and Opportunities across the Value Chain

Silicon Carbide (SiC) technology has emerged as a promising solution to address the growing demand for high-performance power electronics in various applications, ranging from automotive to renewable energy systems. As the industry continues to push the boundaries of SiC technology, scaling opportunities and challenges arise across the entire value chain, from material to device fabrication and new package architectures. In addition, it should be noted that scientific understanding, especially in the areas of defect behaviour in the SiC epitaxy layer, threshold voltage instability, interface trap density, and integrity of the gate insulator, would be increasingly important and necessary for the further development of SiC power devices. To address the economics, and mass produce ultra-high-power electronics devices with improved performance and reliability, we partnered with ecosystem players across the value chain from substrate to power module packaging and set up a 200mm SiC specialty open innovation process line.This talk will provide an overview of the key challenges and opportunities associated with SiC technology. We will discuss the high grow rate (≥50µm/hr) SiC epitaxy process and share methodologies to achieve high-quality epitaxy layer with good doping control (≤10%), tight thickness uniformity (≤3%), low surface roughness (≤3Å) and low crystal defect densities (≤0.4 cm-2) on 200mm 4H-SiC substrate. Moving on to the metal oxide semiconductor (MOS) device interface engineering, we will discuss strategies for achieving low interface trap densities (~1011eV-1 cm-2) and improved threshold voltage instability. Beyond device fabrication, we will highlight the importance of the power module packaging technique in realizing the full potential of SiC technology. This includes the double-side liquid cooling system and the power dissipation capability with different designs and material options for the proposed 6-in-1 power module.Overall, by addressing these challenges collaboratively, we can accelerate the adoption of SiC technology and unlock its full potential to drive power semiconductor technology and beyond. Figure 1

EXPRESS METHOD OF DETERMINING INSTANT CHARACTERISTICS OF ASYNCHRONOUS ELECTRIC MOTORS

A current trend during the last decade is the growing importance of automated electric drives that use asynchronous electric motors. This is due to the development of theoretical methods for modeling their work with high accuracy and a decrease in the cost of power semiconductor technology, which contributed to improving the efficiency and reducing the cost of such systems. This trend has led to the expansion of induction motors not only in traditional electric drive systems with easy starting conditions, but also in traction systems and systems with large starting torques that normally used DC motors. However, this has also led to technical challenges in the design and operation of induction motors due to their particular mechanical characteristics, which have a slightly lower starting torque value. This disadvantage can be eliminated by increasing the motor power in the design, but this can lead to a decrease in efficiency and an increase in the cost of the electric drive. Therefore, it is important to conduct further research to improve the starting characteristics of induction motors. With this in mind, asynchronous motors remain the most common electric machines used in various industries. Their use in industry is growing, and their applications are constantly expanding. The development of express methods for determining torque characteristics, which will allow to reduce the complexity of determining the starting torques of asynchronous motors, is an urgent task that is of great importance in practice. This article offers an express method for determining the torque characteristics of asynchronous electric motors, which helps to significantly reduce the complexity of testing such machines. A general mathematical model for controlling the torque characteristics of electric machines has also been developed, which makes it possible to unambiguously establish the dependence of the starting torque of an asynchronous motor on the angular position of the rotor on the basis of data obtained during experiments.

Novel bidirectional universal 1‐phase/3‐phase‐input unity power factor differential AC/DC converter

AbstractA common 400 V dc bus for industrial motor drives advantageously allows the use of high‐performance 600 V power semiconductor technology in the inverter drive converter stages and to lower the rated power of the supplying rectifier system. Ideally, this supplying rectifier system features unity power factor operation, bidirectional power flow and nominal power operation in the three‐phase and the single‐phase grid. This paper introduces a novel bidirectional universal single‐/three‐phase‐input unity power factor differential ac‐dc converter suitable for the above mentioned requirements. The basic operating principle and conduction states of the proposed topology are derived and discussed in detail. Then, the main power component voltage and current stresses are determined and simulation results in PLECS are provided. The concept is verified by means of experimental measurements conducted in both three‐phase and single‐phase operation with a 6 kW prototype system employing a switching frequency of 100 kHz and 1200 V SiC power semiconductors.

A Review of Power Electronic Devices for Heavy Goods Vehicles Electrification: Performance and Reliability

This review explores the performance and reliability of power semiconductor devices required to enable the electrification of heavy goods vehicles (HGVs). HGV electrification can be implemented using (i) batteries charged with ultra-rapid DC charging (350 kW and above); (ii) road electrification with overhead catenaries supplying power through a pantograph to the HGV powertrain; (iii) hydrogen supplying power to the powertrain through a fuel cell; (iv) any combination of the first three technologies. At the heart of the HGV powertrain is the power converter implemented through power semiconductor devices. Given that the HGV powertrain is rated typically between 500 kW and 1 MW, power devices with voltage ratings between 650 V and 1200 V are required for the off-board/on-board charger’s rectifier and DC-DC converter as well as the powertrain DC-AC traction inverter. The power devices available for HGV electrification at 650 V and 1.2 kV levels are SiC planar MOSFETs, SiC Trench MOSFETs, silicon super-junction MOSFETs, SiC Cascode JFETs, GaN HEMTs, GaN Cascode HEMTs and silicon IGBTs. The MOSFETs can be implemented with anti-parallel SiC Schottky diodes or can rely on their body diodes for third quadrant operation. This review examines the various power semiconductor technologies in terms of losses, electrothermal ruggedness under short circuits, avalanche ruggedness, body diode and conduction performance.

GaN power converter and high-side IC substrate issues on Si, p-n junction, or SOI

The lateral GaN power semiconductor technology enables monolithic integration of complete power converter topologies such as half-bridges, multi-phase and multi-level converters. Fabrication on Si substrates enables low-cost and mass production. However, the operation of monolithic GaN power converters on a common conductive silicon (Si) substrate is limited compared to discrete GaN HEMTs, especially at high-voltage operation, due to substrate-biasing effects such as back-gated or trap-related static and dynamic on-resistance increase, and changed effective device capacitances. To circumvent the Si substrate related effects but still using a low-cost large-diameter Si substrate, this paper reviews isolation approaches for GaN ICs such as Si p-n junction isolation or floating Si substrates (GaN-on-Si) and buried oxide isolation using Silicon-on-Insulator substrates (GaN-on-SOI). Published GaN power converter ICs are reviewed. The effect of the isolation approaches on increased output and input transistor capacitances, influencing the switching behavior and switching loss, is calculated and compared for different voltage classes (below 100 V to 600 V-class). Finally, design guidelines for local substrate termination using the Si-based isolation approaches are discussed exemplary for a monolithic half-bridge with driver circuit. Monolithic GaN power converter integration combined with functional integration will result in a new class of advanced power converter ICs, and enable efficient, compact and low-cost power conversion applications.

MATHEMATICAL MODEL OF THE DEPENDENCE OF THE STARTING TORQUE OF AN ASYNCHRONOUS ELECTRICAL MOTOR ON THE INITIAL ANGULAR POSITION OF THE ROTOR

The current trend of recent decades is the growing role of the automated electric drive built on the basis of asynchronous electric motors. This is connected both with the development of theoretical approaches that allow to model the behavior of the latter with high accuracy, and with a significant increase in reliability and a decrease in the cost of power semiconductor technology, which in turn made it possible to improve operational characteristics and reduce the cost of such systems as a whole. The consequence of this trend is that asynchronous motors are increasingly used not only in classic electric drive systems with easy starting conditions, but also increasingly used in traction electric drives and electric drives with large starting moments, which were traditionally implemented on the basis of direct current motors. This circumstance leads to the appearance of additional technical difficulties in the design and operation of asynchronous electric motors, which is associated with the peculiarities of their natural mechanical characteristics, which have a slightly underestimated value of the starting torque. And although this shortcoming can be eliminated by increasing the power reserve of the engine when designing the electric drive, such a compromise solution will have significant disadvantages associated with a decrease in efficiency and an increase in the cost of the electric drive as a whole. It is obvious that this circumstance determines the need for further theoretical research aimed at improving the starting characteristics of asynchronous motors. Considering what has been said, today the induction motor remains the most common electric machine used in various fields of activity. Moreover, the share of asynchronous motors used in industry is growing rapidly, and the scope of their use is constantly expanding. A. therefore, the development of a mathematical model of the dependence of the starting torque on the angular position of the rotor, which in the future would allow improving the starting characteristics of asynchronous motors, is an urgent scientific and applied problem that has significant practical value. In the article, the equation of the dependence of the starting torque of an asynchronous motor on the initial position of its rotor is obtained, which makes it possible, taking into account the design features of the AD, to uniquely calculate the value of the mechanical torque that occurs on the motor shaft when it is started with the nominal supply voltage. The mathematical dependence of the deviation of the AD starting moment on the initial rotation angle of the rotor was obtained, which can be used as a corrective mathematical model of the AD control system. The simulation of the dependence of the torque of an asynchronous motor on the initial position of its rotor was carried out, which made it possible to confirm the adequacy of the obtained mathematical dependence. It is shown that the change of the starting torque during rotation of the AD rotor occurs according to the sinusoidal law. It is theoretically proven that deviations of the starting torque at different initial angular positions of the rotor can reach ± 6.5% of the nominal value.

The role of power device technology in the electric vehicle powertrain

In the automotive industry, the design and implementation of power converters and especially inverters, are at a turning point. Silicon (Si) IGBTs are at present the most widely used power semiconductors in most commercial vehicles. However, this trend is beginning to change with the appearance of wide-bandgap (WBG) devices, particularly silicon carbide (SiC) and gallium nitride (GaN). It is therefore advisable to review their main features and advantages, to update the degree of their market penetration, and to identify the most commonly used alternatives in automotive inverters. In this paper, the aim is therefore to summarize the most relevant characteristics of power inverters, reviewing and providing a global overview of the most outstanding aspects (packages, semiconductor internal structure, stack-ups, thermal considerations, etc.) of Si, SiC, and GaN power semiconductor technologies, and the degree of their use in electric vehicle powertrains. In addition, the paper also points out the trends that semiconductor technology and next-generation inverters will be likely to follow, especially when future prospects point to the use of “800 V" battery systems and increased switching frequencies. The internal structure and the characteristics of the power modules are disaggregated, highlighting their thermal and electrical characteristics. In addition, aspects relating to reliability are considered, at both the discrete device and power module level, as well as more general issues that involve the entire propulsion system, such as common-mode voltage.

Modeling vector control of the asynchronous drive of electric rolling stock auxiliary machines

Introduction. The development of power semiconductor devices and technology served the basis for fundamentally new types of frequency-controlled electric drives with traction asynchronous motors on the rolling stock of electrified railways. Therefore, problems of theoretical and experimental study of the operating modes of the mentioned drives become actual. This article is a theme continuation of the asynchronous machines control on the AC locomotive, which was presented in no. 5 of Russian Railway Scientific Journal in 2021.Materials and methods. For analysing the frequency converter operation, the authors used mathematical modeling methods, which allowed evaluating the motor operation in various modes without resorting to time-consuming full-scale tests. Recently, software packages for visual programming have been developed, aimed mainly at domestic users, which are not inferior in their capabilities to leading foreign counterparts. Among such software products is SimInTech software for modeling technical systems, developed by 3V Service. The software focuses on solving various applied problems, particularly, on modeling a vector control system for an asynchronous drive.Results. The authors developed a mathematical model of an asynchronous drive of auxiliary machines of an electric locomotive in a rotating coordinate system d – q by the SimInTech application package and concerning the cross-impact influence of d and q control channels.Discussion and conclusion. The developed complex of an asynchronous motor and a vector control system enable to work out various algorithms for improving the energy efficiency of the operation of asynchronous auxiliary machines of an electric locomotive by applying the proposed algorithm for choosing the optimal value of the rotor flux linkage. The presented vector control structure also enables to implement it on the basis of modern microcontrollers, helping to reduce programming time.

Status and Trends of Power Devices

Advances in power semiconductor technology have improved the efficiency, size, weight, and cost of power electronic systems. Power integrated circuits have been developed for the use of power converters for portable, automotive and aerospace applications. New materials (SiC and GaN) have been introduced for advanced applications. They increase the output power density per area or per volume, reduce the consumption of natural resources, and increase the efficiency of electric systems. Especially the effects of SiC devices are dramatic. The paper reviews the state of these devices in terms of higher voltages, higher power density, and better switching performance.

Lumped Parameter Modeling Based Power Loop Analysis Technique of Power Circuit Board with Wide Conduction Area for WBG Semiconductors

With the development of wide-bandgap (WBG) power semiconductor technology, such as silicon carbide (SiC) and gallium nitride (GaN), the technology of power converters with high efficiency and high-power density is rapidly developing. However, due to the high rate-of-rise of voltage (dv/dt) and of current (di/dt), compared to conventional Si-based power semiconductor devices, the reliability of the device is greatly affected by the parasitic inductance component in the switching loop. In this paper, we propose a power loop analysis method based on lumped parameter modeling of a power circuit board with a wide conduction area for WBG power semiconductors. The proposed analysis technique is modeled based on lumped parameters, so that power loops with various current paths can be analyzed; thus, the analysis is intuitive, easy to apply and realizes dynamic power loop analysis. Through the proposed analysis technique, it is possible to derive the effective parasitic inductance component for the main points in the power circuit board. The effectiveness of the lumped parameter model is verified through PSpice and Ansys Q3D simulation results.

GaN Outperforms Silicon, Enters Mainstream [Expert View

How does one define ‘mainstream’? In the case of gallium nitride (GaN) power semiconductor technology, we believe that since you can now buy a sleek, 65 W mobile charger using GaN for under $25 on Amazon, it is reasonable to assume that it has been fully accepted by the consumer markets, which—almost by definition—makes it a mainstream product. While the benefits of GaN have been discussed regularly at conferences such as IEEE APEC and PCIM for well over a decade, until relatively recently it was positioned as a solution for an exotic corner of the market that leveraged the speed of GaN devices. As size and efficiency demands become mainstream, GaN is now becoming an excellent solution for power applications.

Novel High-Speed Turbo Compressor With Integrated Inverter for Fuel Cell Air Supply

Fuel cell technology is continuously gaining ground in E-mobility applications. Fuel cells require a constant supply of pressurized air, for which high-speed turbo compressors with air bearings are an optimal choice to reduce size, guarantee oil-free operation required for the lifetime of the fuel cell, and increase efficiency. However, the inverter driving the electric motor of the turbo compressor does not scale down with increasing speed; therefore, other technology advances are required to achieve an overall compressor system with low weight. New power electronic topologies (double-bridge voltage sources inverter), cutting edge power semiconductor technology (gallium nitride), and multiobjective optimization techniques allow reducing the inverter size, increasing inverter efficiency, and improving the output current quality and in return lowering the losses in the electric motor. This enables the electrical, mechanical, and thermal integration of the inverter into the compressor housing of very high-speed and compact turbo compressors, thereby reducing the size and weight of the overall compressor system by a factor of two. Furthermore, a turbo compressor with an integrated inverter reduces complexity and cost for operators with savings in casing, cables, coolant piping, and connectors and reduces EMI noise by shielding the high-frequency motor currents with one housing. Beside its main application for fuel cell air supply, the advantages gained by an integrated inverter can also be used in other boosting and air handling applications such as advanced air and exhaust handling in combustion engines. The proposed integration concept is verified with a 280,000 rpm, 1 kW turbo compressor, targeted for the Balance of Plant (BoP) of a 5–15 kW fuel cell. The experimental results show that the temperature limits on the power electronics parts can be kept below the limit of 90 °C up to a coolant temperature of 55 °C, and beside the advantage of lower cabling effort, the efficiency of the compressor system (turbo compressor and integrated inverter) is increased by 5.5% compared to a turbo compressor without an integrated inverter.

Comparative Evaluation of Voltage Source Converters With Silicon Carbide Semiconductor Devices for High-Voltage Direct Current Transmission

Recent advancements in silicon carbide (SiC) power semiconductor technology enable developments in the high-power sector, e.g., high-voltage-direct-current (HVdc) converters for transmission, where today silicon (Si) devices are state-of-the-art. New submodule (SM) topologies for modular multilevel converters offer benefits in combination with these new SiC semiconductors. This article reviews developments in both fields, SiC power semiconductor devices and SM topologies, and evaluates their combined performance in relation to core requirements for HVdc converters: grid code compliance, reliability, and cost. A detailed comparison of SM topologies regarding their structural properties, design and control complexity, voltage capability, losses, and fault handling is given. Alternatives to state-of-the-art SMs with Si insulated-gate bipolar transistors (IGBTs) are proposed, and several promising design approaches are discussed. Most advantages can be gained from three technology features. First, SM bipolar capability enables dc fault handling and reduced the energy storage requirements. Second, SM topologies with parallel conduction paths in combination with SiC metal-oxide-semiconductor field-effect transistors offer reduced losses. Third, a higher SM voltage enabled by a higher blocking voltage of SiC devices results in a reduced converter complexity. For the latter, ultrahigh-voltage bipolar devices, such as SiC IGBTs and SiC gate turn-off thyristors, are envisioned.

Latest Trends of Next Generation Power Semiconductor Technologies

Latest Trends of Next Generation Power Semiconductor Technologies

The Essence of the Little Box Challenge-Part B: Hardware Demonstrators & Comparative Evaluations

In order to expedite the development of power electronic systems towards higher power density and efficiency at a lower cost of implementation, Google and IEEE initiated the Google Little Box Challenge (GLBC) aiming for the worldwide smallest 2 kVA/450 VDC/230 VAC single-phase PV inverter with η > 95% CEC weighted efficiency and an air-cooled case temperature of less than 60 °C by using latest power semiconductor technology and innovative topological concepts. This paper, i.e. Part B of a discussion of The Essence of the Little Box Challenge, presents the hardware implementations and novel control concepts of two GaN-based inverter systems selected by the authors to counter the challenge: (i) Little Box 1.0 (LB 1.0), a H-bridge inverter with two interleaved bridge-legs both operated with Triangular Current Mode (TCM) modulation which features a power density of 8.18 kW/dm 3 (134 W/in 3 ) and a nominal efficiency of 96.4% and (ii) Little Box 2.0 (LB 2.0), an inverter topology with single bridgeleg DC/|AC| buck-stage operated with constant frequency PWM and a subsequent |AC|/AC H-bridge unfolder, which features a remarkable power density of 14.8 kW/dm 3 (243 W/in 3 ) and a nominal efficiency of 97.4% Implemented using latest GaN power semiconductor technology, Zero Voltage Switching (ZVS) throughout the AC period and a variable switching frequency in the range of 200 kHz-1 MHz in order to shrink the size of filter passives, the LB 1.0 was ranked among the top 10 out of 100+ teams actively participating in the GLBC. The LB 2.0 is the result of further research and considers lessons learned from the GLBC and achieves despite moderate 140 kHz constant frequency PWM and hard-switching around the peak of the AC output current a higher power density ρ and a higher efficiency η. For both implemented prototypes experimental results are provided to confirm that all GLBC technical requirements are met. The experimental results include steady-state and step-response waveforms, EMI and ground current measurements, as well as efficiency and operating temperature measurements. The reason for the ηρ-performance improvement of LB 2.0 over LB 1.0 are then discussed in detail. Furthermore, the solutions of other GLBC finalists are described and then compared to the performance achieved with the hardware prototypes presented in this paper. This leads to findings of general importance and provides key guideline for the future development of ultracompact power electronic converters.

A Review of Solid-State Circuit Breakers

Although conventional electromechanical circuit breakers have a proven record as effective and reliable devices for circuit protection, emerging power distribution technologies and architectures, such as dc microgrids, require improved interruption performance characteristics (e.g., faster switching speed). The need for faster switching operation, in combination with the latest developments of advanced power semiconductor technologies, has spurred an increase in the research and development in the area of solid-state circuit breakers. This article provides a comprehensive review of various solid-state circuit breaker technologies that have been reported in the literature during recent years. First, we categorize solid-state circuit breakers based on key features and subsystems, including power semiconductor devices, main circuit topologies, voltage clamping methods, gate drivers, fault detection methods, and commutation methods for power semiconductor devices. Second, we discuss the various challenges associated with the design of solid-state circuit breakers from the perspective of generic applications and provide a comparison of several solid-state breaker technologies based on key metrics. Finally, we provide a useful framework and point of reference for future development of solid-state circuit breakers for many emerging power distribution applications.

The Essence of the Little Box Challenge-Part A: Key Design Challenges & Solutions

In order to expedite the development of power electronic systems towards higher power density and efficiency at a lower cost of implementation, Google and IEEE initiated the Google Little Box Challenge (GLBC) aiming for the worldwide smallest 2 kVA / 450 V DC / 230 V AC single-phase PV inverter with η > 95 % CEC weighted efficiency and an air-cooled case temperature of less than 60 °C by using latest power semiconductor technology and innovative topological concepts. This paper, i.e., Part A of a discussion of The Essence of the Little Box Challenge, documents all important RD Part B is intended to convey the main findings and lessons learned from the participation in the GLBC. First, the key technical challenges of the GLBC are discussed and the technologies and concepts selected by the authors among different options are described in detail. Relevant design considerations, such as constant frequency pulse width modulation (PWM) or triangular current mode (TCM) operation of the bridge-legs, selection of power semiconductor technology, interleaving of bridge-legs, sizing of the power buffer capacitor, limitation of ground/leakage currents, etc., to achieve an ultra-compact implementation are discussed. Based on this overview, two promising inverter concepts to tackle the GLBC, (i) an H-bridge based inverter with DC-link referenced output filter and (ii) a DC/|AC| buck-stage with series-connected low-frequency (LF) |AC|/AC unfolder inverter, are then analyzed in detail. Based on the results of a multi-objective ηρ-Pareto optimization, a comparative evaluation of the performance in terms of efficiency (η) and power density (ρ) of the two considered inverter concepts is provided. It is shown that with the DC/|AC| buck-stage and |AC|/AC H-bridge unfolder inverter operated with 140 kHz PWM a power density of 14.7 kW/dm 3 (240 W/in 3 ) with a maximum efficiency of 98.1% at 2 kW output power can be achieved. These claims are then verified in Part B by means of experimental results obtained from prototype realizations and compared to the achievements of other GLBC finalists. The conclusions are of general importance and are providing key guidelines for the future development of ultra-compact power electronic converters.

High-Density Power Conversion and Wide-Bandgap Semiconductor Power Electronics Switching Devices

Power electronics switching devices made on wide-bandgap (WBG) semiconductors are known to have the potential to make a transformative impact on 21st century energy economy. However, their market penetration has been slow primarily due to high cost and unknown application-level reliability. This article presents a comprehensive report on the history, current state of the art, and impending challenges in WBG power semiconductor technologies in order to break open this gridlock.

Automation of the design and development stages of semiconductor devices

The scientific article analyzes the thermal conditions of heat transfer in semiconductor devices, developed a calculation algorithm; a computational methodology for printed circuit boards was chosen, and the proposed methods were implemented by the example of printed circuit boards for calculating the thermal conditions of printed circuit boards that are used to implement power semiconductor technology of oil and gas facilities. It has been established that the automation of design of semiconductor elements and devices involves the initial stages of the thermal calculation in order to optimize the placement of elements and devices to improve the weight and size. It is shown that the analytical approach to the selection of elements and devices allows to reduce the preliminary labor costs for layout, as well as to optimize the placement of elements and devices according to the criterion of minimizing the weight and size indicators. Analysis of transient thermal processes on the printed circuit board can significantly improve the quality of the calculation and obtain more reliable results, bringing them closer to the most reliable.

Solid-State Relay Solutions for Induction Cooking Applications Based on Advanced Power Semiconductor Devices

This paper focuses on providing an improved and efficient alternative to electromechanical relays (EMRs) in view of the growing demand characteristics for an effective power multiplexing in induction heating applications. A major analytical approach to the design and implementation of bidirectional switches (BDSs) based on different power semiconductor technologies is presented, including thorough static and dynamic characterizations. Emerging gallium nitride high-electron-mobility transistors (GaN HEMTs) and silicon carbide (SiC)-based devices are identified as potential candidates for the mentioned applications.