A cancelled conference taps alternate methods to disseminate cutting-edge information
With the growing concerns of the worldwide coronavirus pandemic, the IEEE Power Electronics Society/Industrial Applications Society (PELS/IAS) and Power Supply Manufacturers Association-sponsored 2020 Applied Power Electronics Conference and Exposition (APEC 2020) in New Orleans, Louisiana, was cancelled for the safety of the attendees. While it was a difficult decision, the health, safety, and welfare of the community was paramount for the organizers and sponsors of the 15–19 March 2020 conference. Although this was the first such cancellation in APEC’s 35-year history, the organizers were quick to offer a virtual conference to those registered. In addition, peer-reviewed papers accepted by the conference committee were submitted to IEEE Xplore and are available to all.
Despite the challenges and adversities of COVID-19, the organizers worked diligently to virtually bring the conference and its presentations to the registered community via the APEC 2020 app and the eventScribe web portal. As a result, I was given a password (access key) to access the site and view a variety of the sessions. Before I go through the conference papers and sessions, I would like to take the opportunity to mention the vendors who promptly called IEEE Power Electronics Magazine and presented the latest trends in technologies and products online. The unbelievable situation created by the COVID-19 outbreak did not deter the vendors and emerging companies from taking their latest advances and developments to editors and reporters via phone and virtual meetings and booths. As a result, I was lucky to talk to a variety of power semiconductor companies, passive component suppliers, and power electronics experts, including marketing analysts, and gather the latest advances in power electronics technology.
Starting with market analysis, I first went to the market research firm Yole Développement and obtained the current market situation with projections for the next few years for wide bandgap (WBG) devices. During APEC 2019, after years of development, the focus was on WBG device reliability and the emerging applications getting ready for adoption. The latest WBG study by Yole shows that numerous consumer fast charger applications, such as smartphones, tablets, and notebooks, have adopted gallium nitride (GaN) devices and entered the production phase.
GaN Power ICs and Modules
Early adopters of GaN devices include after-market fast charger companies like Anker, Ravpower, and Hyperjuice. In addition, GaN power devices have also entered Oppo’s inbox high-power fast chargers and Samsung’s accessory mobile fast chargers. “This is only the beginning of the power GaN market’s emergence,” asserts Ezgi Dogmus, a technology and market analyst at Yole. “GaN has taken an important leap in its challenging course and is expected to also enter other major original equipment manufacturers (OEMs), such as Apple and Huawei fast chargers. In this context, 2020 and 2021 are important years to watch for further market acceptance and the speed of GaN-based high power chargers’ proliferation.” As a result, Yole predicts a market worth more than US$350 million in 2024, posting a compound annual growth rate (CAGR) from 2018 to 2024 of 85%.
Driving this growth are vendors like Navitas Semiconductor, Efficient Power Conversion Corporation (EPC), Power Integration, Texas Instruments (TI), Infineon Technologies, GaN Systems, and Transphorm, to name a few. Speaking of production, more than 50 smartphone and laptop chargers have been enabled by Navitas Semiconductor’s GaNFast integrated circuits (ICs). According to Navitas’ Vice President of Sales and Marketing Stephen Oliver, “Customers from NVIDIA to Xiaomi have leveraged the high-speed capabilities of GaNFast power ICs to create the world’s smallest, thinnest and lightest power adapters and fast chargers.” The company’s Chief Technology Officer, Dan Kinzer said, “We are very proud of our excellent quality track record, with zero GaN-related field failures after shipping millions of units in the last two years.”
Likewise, using its eGaN FETs and power ICs, EPC continues to power a variety of applications, ranging from e-bike motors to lidar and wireless power charging. In addition, its eGaN FETs and ICs have also been meeting the stringent requirements of the latest generation of dc–dc converters used in high-density server architectures. Meanwhile, the company also released its phase 11 reliability report. According to Alex Lidow, chief executive officer (CEO) and cofounder of EPC, “eGaN devices have been in volume production for over 10 years and have demonstrated very high reliability in both laboratory testing and high-volume customer applications. The release of EPC’s 11th reliability report represents the cumulative experience of millions of devices over a 10-year period and five generations of technology. These reliability tests have been undertaken to continue our understanding the behavior of GaN devices over a wide range of stress conditions.”
Concurrently, EPC introduced an 80-V, 12.5-A power stage IC for 48-V dc–dc conversion used in high-density computing and motor drives. The first member in the ePower stage IC family is EPC2152, a monolithic GaN power IC that integrates on-chip input logic interface, level shifting, bootstrap charging, and gate drive buffer circuits along with eGaN output FETs configured as a half-bridge (Figure 1). Housed in a chip-scale land grid array form factor, it measures only 3.9 × 2.6 × 0.63 mm. According to EPC, when used in a 48-V to 12-V buck converter at 1-MHz design, it can achieve more than 96% efficiency and 33% smaller size on the printed circuit board as compared to an equivalent multichip discrete implementation.
EPC plans to expand its GaN-based ePower stage IC family with members operating at higher frequencies up to 5 MHz and current ratings going from 15 A to 30 A. For evaluation, the company has readied a development board EPC90120 featuring EPC2152 and all other critical components, including magnetics.
Last year, Power Integrations (PI) President and CEO Balu Balakrishnan announced in-house development of GaN technology called PowiGaN for rapid conversion from silicon transistors to GaN in many ac–dc power conversion applications. At the virtual APEC this March, PI demonstrated a fully integrated GaN solution for system-level power supplies used in chargers, adapters, and open frame supplies. New members of PI’s highly integrated, offline flyback switcher IC family—InnoSwitch3—were the first beneficiaries of PowiGaN switches (Figure 2). The new INN3x78C devices incorporate a smaller 750-V PowiGaN transistor, enabling compact, efficient power supplies delivering 27–55 W without heatsinks. The ICs are housed in the same high-creepage, safety-compliant InSOP-24D package as larger members of the GaN-based InnoSwitch3 families, which target up to 120 W. According to Balakrishnan, the innovative PowiGaN technology can satisfy market demand for more efficient, more robust, and more compact power supplies while effectively managing costs.
To enable the selection of the best components and generate the full schematic, magnetics, and bill of materials from basic parametric inputs, the PowiGaN-based devices are supported by the PI Expert automated power supply design software suite, which also supports silicon MOSFET-based devices. “We will be using GaN extensively going forward in all our products,” stated Balakrishnan. “The future of GaN is very bright and we are certainly part of it.”
Similarly, expanding its GaN product line, TI touted a broad portfolio of 150-mΩ, 70-mΩ, and 50-mΩ 600-V GaN FETs in mass production enabling high-density designs in industrial, telecom, server, and consumer applications. As part of this announcement, TI unveiled a natural convection-cooled 900-V, 5-kW bidirectional ac–dc inverter platform for applications such as automotive, grid-tied storage, and solar energy. It uses four-level flying capacitor topology to feature a 600-V, 50-mΩ GaN FET with integrated driver and overcurrent protection in a compact quad flat no-lead (QFN) package along with the C2000 digital controller to enable 99% efficiency and three times higher power density than silicon while supporting bus voltages up to 1,400 V. In summary, the ac–dc inverter was optimized to deliver 5 kW from 400-V three-phase ac to 800-V dc with only natural convection for cooling. This ac–dc inverter design uses 18 600-V GaN FETs switching at 140 kHz.
“Shrinking form factors, increasing performance, and extending robustness are key market trends driving the next-generations systems,” asserted Steve Tom, TI’s GaN product line manager. Speaking of robustness, he added, “GaN devices have been tested for >30 million device reliability hours and >3 GWh of power conversion to-date.”
Other suppliers driving the market include Infineon Technologies, GaN Systems, and Transphorm, among others. For applications that demand high power with higher efficiency (>93%) and power density, Infineon has added 600-V e-mode high-electron mobility transistors (HEMTs) with a dedicated GaN EiceDriver to its CoolGaN family. Taking to the virtual route, GaN Systems’ CEO Jim Witham discussed the use of its GaN devices, and high power modules, in a wide range of applications including electric vehicle (EV) on-board chargers, traction inverters, motor drives, and consumer applications. Besides disclosing its new Gen2 650-V, 60-A automotive GaN power transistor with AEC-Q101 performance, Witham also bragged about the company’s high power GaN modules, which include a 650-V/150-A full-bridge module with integrated driver, a 650-V/150-A half-bridge IPM, and a 650-V/300-A three-phase module and driver.
Speaking of GaN modules, Transphorm indicated that China’s Hangzhou Zhongheng Electric Co., Ltd. (HZZH) has developed an ultra-efficient, GaN-based power module, the 3-kW ZHR483KS, using the manufacturer’s 650-V GaN devices. Offering 98% efficiency, the 3-kW interleaved bridgeless totem-pole power factor correction (PFC) module ZHR483KS offers standardized output connector configurations with existing same-wattage power modules to achieve a high-reliability, higher-performing solution at a lower overall system cost, said Transphorm. HZZH said that the power module is in production and outperforms previous similar modules that employed superjunction silicon MOSFETs.
Another entrant into this market is start-up NexGen Power Systems, Inc., who has readied a vertical GaN transistor for commercial use (Figure 3). Unlike others who employ lateral structure, NexGen is the first GaN supplier to take vertical GaN transistors to production using its fabrication plant in Syracuse, New York. “We make these vertical GaN transistors at costs that are competitive to silicon MOSFETs and IGBTs,” claimed Dinesh Ramanathan, CEO and cofounder of NexGen. Using GaN-on-GaN technology, NexGen has built 1,200-V and 700-V GaN power devices with on-resistance of 85 mΩ that can switch at higher frequencies (>1 MHz). According to Ramanathan, “The small device area of NexGen’s 1,200-V vertical GaN technology leads to much smaller device capacitances compared to 1,200-V silicon carbide (SiC) devices at similar RDS(on) and drain currents. Vertical GaN-based devices are also smaller than comparable lateral GaN devices which also have a much lower breakdown voltage specification of 600 V.” He added, “In particular, Coss (and consequently Qoss and Eoss) is very small, greatly reducing turn-on losses, which is key to the high efficiency and high switching frequency operation of applications enabled by vertical GaN junction FETs.” NexGen will provide early samples in T0-247-4 and
8 × 8 dual-flat no-leads (DFN) packages to customers participating in its Quick Start Program in the second quarter.
Concurrently, global semiconductor company STMicroelectronics also announced its entry into the GaN arena. The company announced a majority stake in French GaN startup Exagan based in Grenoble, France. Its GaN power switches are designed for manufacturing in standard 200-mm (8-in) wafer fabrications. In a statement, STMicroelectronics’ President and CEO Jean-Marc Chery said, “The acquisition of a majority stake in Exagan is another step forward in strengthening our global technology leadership in power semiconductors and our long-term GaN roadmap, ecosystem and business. It comes in addition to ongoing developments with CEA-Leti in Tours, France, and the recently-announced collaboration with Taiwan Semiconductor Manufacturing Company.”
SiC Devices and Modules
Similarly, in the SiC arena, the devices are mainly adopted by EV/hybrid EV (EV/HEV) applications, EV charging infrastructure, and industrial power supplies. Continuing to proliferate, the Yole report expects the SiC market to reach beyond US$3 billion by 2025 at a CAGR of 28.5% (Figure 4). As a result, suppliers like Wolfspeed, Infineon Technologies, ROHM, ON Semiconductor, Microchip, and UnitedSiC have been expanding both capacity and product portfolio to meet the market demands.
Wolfspeed, a Cree company, for example, continues to expand its product portfolio with new releases. Lately, the company added new 650-V SiC MOSFETs to enable next generation EV onboard chargers, data center power supplies, and other renewable power systems with leading power efficiency. According to Wolfspeed, the new 15-mΩ and 60-mΩ 650-V devices, which use Cree’s industry-leading, third-generation C3M MOSFET technology, deliver up to 20% lower switching losses than competing SiC MOSFETs, and provide the lowest on-state resistances for higher efficiency and power dense solutions.
Recently, Cree implemented its 650-V, 60-mΩ (C3M) SiC MOSFETs in a 6.6-kW bidirectional converter targeting high-efficiency and high-power-density on-board charging (OBC) applications. This demo board consists of a bidirectional totem-pole PFC ac–dc stage and an isolated bidirectional dc–dc stage based on a CLLC topology with quasi-constant dc link voltage. It utilizes high switching frequency to enable a smaller, lighter, and overall more cost-effective solution. The 6.6-kW OBC demo board can accept 90–265 VAC input and provide 250–450 VDC at the output with >96.5% efficiency in both charging and inversion modes.
Employing a state-of-the-art trench semiconductor process, Infineon Technologies added a 650-V SiC MOSFET to its CoolSiC MOSFET family. The 650-V CoolSiC MOSFETs are rated from 27 mΩ to 107 mΩ and are available in classic TO-247 3-pin as well as TO-247 4-pin packages, which allows for even lower switching losses. To ensure high-performance operation of these devices, the supplier offers dedicated one-channel and two-channel galvanically isolated EiceDRIVER gate-driver ICs.
To tap the growing market for SiC power devices, Microchip Technology also unveiled an expanded family of Schottky barrier diode (SBD)-based power modules with 700, 1,200, and 1700-V breakdown capability. Available in a variety of forms, they come in dual diode, full-bridge, phase leg, dual common cathode, and three-phase bridge configurations, in addition to different current and package options. It complements its discrete MOSFET portfolio. Because optimal gate drivers are critical for efficiently driving SiC MOSFETs, the company acquired gate driver specialist AgileSwitch late last year. Combining AgileSwitch’s digital programmable gate drivers with its discrete SiC MOSFETs and SBDs, including microcontrollers, Microchip is now building system-level solutions for a variety of EV, industrial, and military applications. One such design kit is a reference design for a 150-kVA three-phase SiC power stack developed in conjunction with Mersen (Figure 5). A 30-kW three-phase Vienna PFC reference design for EV/HEV charger and high-power switched-mode power supply applications was also developed prior to AgileSwitch becoming a part of Microchip.
Likewise, ON Semiconductor expanded its WBG portfolio with the introduction of new 900-V and 1,200-V n-channel SiC MOSFETs for high-growth applications like solar power inverters, EV OBCs and charging stations, uninterruptible power supplies, and server power supplies. While the 1,200-V devices are rated at up to 103 A (ID Max.), the 900-V parts offer as high as 118 A. For applications requiring higher currents, the ON Semiconductor MOSFETs can be easily operated in parallel due to their positive temperature coefficient/temperature independence, according to Ali Husain, product manager at ON Semiconductor. He further indicated that automotive qualified versions are AEC-Q100 qualified and Production Part Approval Process capable. All of the new SiC MOSFETs are housed in industry standard TO-247 or D2PAK packages with on-resistance ranging from 20 to 80 mΩ.
Also, leading the SiC march to mainstream is UnitedSiC, based in Monmouth Junction, New Jersey. The latest addition to its SiC FET series is the 750-V cascode transistor with RDS(on) of 6 mΩ, the lowest figure for 750-V SiC devices in a DFN 8 × 8 package. It offers a current rating of 18 A (limited by wire count in the package), and a maximum operating temperature of
150 °C. Additionally, the parts also feature a Kelvin gate return to enable cleaner drive characteristics. The company uses its fourth generation SiC process to reduce on-resistance per unit area while improving Qrr and Eon/Eoff losses at a given Rds(on). Meanwhile, AC Propulsion has readied power modules using UnitedSiC’s 4-lead 1,200-V SiC FETs for a 200-kW drive unit inverter. It delivers >99% efficiency. According to Vice President of Engineering Anup Bhalla, UnitedSiC will also employ its bare die FETs to produce SiC power modules as standard products. The company plans to release them to production in the second half of this year.
Flaunting its fourth generation trench process, ROHM Semiconductor introduced its low on-resistance 650- and 1,200-V SiC MOSFETs with gate voltage of 15 V. ROHM’s previous generation SiC MOSFETs were rated for 18-V VGS. To keep them cost competitive, the manufacturer will produce these parts on a 6-in substrate.
Additionally, PI unveiled an AEC-Q100 certified gate driver IC for SiC MOSFETs used in automotive applications. Labeled SIC118xKQ SCALE-iDriver, this high-efficiency, single-channel device incorporates sophisticated safety and protection features to support the gate-drive voltage requirements of commonly used SiC MOSFETs. The SIC1182KQ (1200-V) and SIC1181KQ (750-V) gate driver ICs incorporate PI’s revolutionary FluxLink communication technology, providing unparalleled isolation capability and enabling safe, cost-effective designs for inverters up to 300 kW. Key features include optimized advanced active clamping, undervoltage lock-out for primary and secondary side, ultrafast short-circuit detection, rail-to-rail stabilized output voltage, and unipolar supply voltage for secondary side.
Silicon Products and Assembly Material
Concurrently, silicon vendors are also displaying their capabilities and advances made to stay competitive with emerging technologies. Silanna Semiconductor, for instance, launched a higher-power and smaller form factor active-clamp flyback controller IC using 0.35 μm CMOS process. Employing the company’s OptiMode digital control architecture, the new controller (SZ1110 and SZ1130) adjusts the device’s mode of operation on a cycle-by-cycle basis to maintain high efficiency, low electromagnetic interference (EMI), fast dynamic load regulation and other key power supply parameters in response to varying line voltage and load. “Unlike conventional active clamp flyback (ACF) designs, tight tolerances of the clamp capacitor and leakage inductance values are not required for proper operation of the circuit in high-volume production,” asserted Ahsan Zaman, director of marketing at Silanna. According to the manufacturer, the ACF ICs are well-suited for high-efficiency and high-power-density ac–dc power adapters used in laptops and notebooks. They are designed for up to 33-W (SZ1110) and 65-W (SZ1130) output power, including USB-PD and quick charge applications. The silicon-based ACF ICs will be qualified in June 2020 with volume production in the third quarter.
According to Silanna’s CEO, Mark Drucker, the ACF controller is technology agnostic, so it is feasible to work with alternative switching technologies in the future. Currently, the company is using 700-V LDMOS MOSFETs in the ac–dc power supply package. In addition, the company is also developing dc–dc converters using its new controller, targeted to be released shortly.
Combining its expertise in passives and 3D packaging with unique two-stage architecture, Murata has developed a whole new generation of power management ICs and modules for notebooks and other similar applications. “This unique architecture halves the losses and shrinks the size of inductor required,” stated Stephen J. Allen, pSemi’s senior director of strategic marketing. pSemi is a Murata company focused on semiconductor integration. Consequently, the maker has released two new series of dc–dc converters. The MYW series from the MonoBK dc–dc converter family offers a 50% smaller footprint as compared to competing solutions and high efficiency, while the 6-A buck regulator delivers high efficiency from a low-profile, compact package. The MonoBK MYW series are four-channel dc–dc converters that integrate all passive components, including inductors, into a tiny form factor of 9.3 mm × 9 mm ×
2.9 mm (Figure 6). The products feature an input voltage range of 2.8–5.5 V and programmable outputs of 0.4–3.58 V up to 3 A. Most applications will require few external components, said the supplier.
The maker claims that its unique packaging process allows the module to offer high thermal performance that can support a wide temperature range of –40 to +105 °C. Based on a fixed-frequency synchronous buck converter switching topology, this high-efficiency point-of-load module features on/off control and power-good signal out as well as protections for overcurrent, overvoltage, undervoltage, and overtemperature. Target power applications include field-programmable gate arrays, CPUs, and datacom/telecom systems. The buck regulator features an input voltage range of 6–14.4 V and a programmable output of
0.7–1.8 V at up to 6 A. Housed in a package measuring
9 × 10.5 × 2.1 mm, the module offers a 25% lower profile than competing products. Other improvements include
5× reduction in input ripple, lower EMI, and a wide temperature range of –40 to +105 °C.
Traditional silicon giants Infineon and TI were also demonstrating their respective silicon-based power devices for myriad applications. Infineon, for instance, disclosed a family of integrated point-of-load (POL) regulator modules, the OptiMOS IPOL, with a fast constant-on time engine for improved output regulation and higher switching frequency (up to 2 MHz). This multichip all-ceramic capacitor design offers best-in-class steady-state regulation without external compensation while providing for a wide-input voltage range of 2.0–17 V and 0.8-V precision output voltage. Consisting of three members, the 25-A IR3888M, 30-A IR3887M, and 30-A IR3889M, this family is housed in compact power QFN packages, targeting server, storage, and data communications/telecommunications applications. Likewise, TI introduced a stackable 40-A dc-dc buck converter in a 5-mm × 7-mm QFN package. This is a highly integrated, non-isolated buck converter, and up to four such devices can be interconnected to provide up to 160 A on a single output. Labeled TPS546D24A, it features selectable high switching frequency (up to 1.5 MHz) and PMBus interface and uses an integrated 0.9-mΩ low-side MOSFET for higher efficiency and wide input and output voltage range. A two-phase evaluation module is also available.
Newer semiconductor devices and power electronics components are presenting unusual challenges for assembly on boards and substrates. Toward that goal, materials supplier Indium Corporation continues to innovate and advance assembly materials technology. In March, Indium’s senior product manager for solder preform and thermal technology, Tim Jensen, introduced new products for die attach applications in power semiconductor assembly and thermal interface materials (TIMs) for better thermal conductivity in these applications. The first new metallurgical advancement was QuickSinter, a new pressureless silver sintering dispense paste that can also be used in pressured processes. By comparison to other sintering products that require silver metallization to create a reliable bond, QuickSinter bonds directly and fast to copper surfaces and can be sintered using conventional reflow equipment. Plus, according to the company’s product development road map, future innovations will lead to copper sintering materials. The second assembly material was InFORMS, a reinforced matrixed solder composite for die attach applications (Figure 7). Per Jensen’s explanation, InFORMS are solder preforms with embedded metal matrix for bondline control and improved reliability. “Future innovations include additional options for fixed bondlines and innovative matrix technologies to further decrease voiding,” stated Jensen. Lastly, the product manager unveiled TIMs, which include solid metal Heat-Spring, solid/liquid hybrid, and amalgams. The company’s patented Heat-Spring is a soft metal with a unique pattern to improve compressibility. The solid/liquid hybrids are novel materials that combine metals that are liquid at room temperature with solid metals to provide a product that is applied like a thermal grease but performs 5–20 × better. And the amalgam offering is a product that is applied as a liquid but converts to a solid material by reacting with itself at or near room temperature.
Virtual Plenary and Industry Sessions
As in the past, there were six virtual plenary session talks this year. Prof. John Kassakian of the Massachusetts Institute of Technology, and founding president of PELS, kicked off the session with his talk “Power Electronics: Where Have We Been? Where Are We Going?” He suggested that, with the invention of the silicon-controlled rectifier at GE, followed by the development of the first silicon power transistors, power electronics became an explicit focus of the IEEE in 1983 with the formation of the Power Electronics Council. The launching of IEEE APEC in 1986 and the creation of PELS in 1988 solidified its role in the IEEE. Applications have grown rapidly, as have component and manufacturing technologies. Today, “we are challenged to meet requirements of evolving applications that demand multidisciplinary thinking, high levels of integration, very high efficiencies, high gravimetric and volumetric specific power, and significant cross-field collaboration,” stated Prof. Kassakian. “Industrial processes, EVs, robotics, decreasing logic voltages, electric aircraft, attention to energy conservation and global warming, and even 5G are providing power electronics with a fertile and exciting future,” he added.
The second presentation was by David Dwelley, vice president and chief technology officer, Maxim Integrated. His talk, “Power in Automotive: Performance in Several Dimensions,” looks beyond power and shows that there are several other important areas to consider when designing power supplies. They are quality and diagnostics, safety, functionality, qualification, and documentation. These important items, as well as traditional power performance, need to be designed in at the start of the product development project. In this presentation, Dwelley discusses strategies to create power devices that meet the wide variety of automotive performance requirements.
In the third talk, “Emerging Technologies in Power Electronics,” Burak Ozpineci of Oak Ridge National Laboratory focused on EV drive charging challenges and approaches to achieve high power densities and fast charging. In addition, Ozpineci also covered other emerging technologies such as additive manufacturing, artificial intelligence/machine learning, cybersecurity issues, and high-performance computing and their use in power electronics. The abstract for the fourth talk, “Switched Capacitor Power Electronic Converters” by Prof. Robert Pilawa-Podgurski of the University of California, Berkeley, proposes novel circuit topologies and control techniques to meet the future power density and efficiency demands. It reveals key areas of research for further improvements in power density and efficiency, along with considerations of reliability and cost.
The next presentation was “Power Electronics for Consumer Applications” by Power Integrations CEO Balu Balakrishnan. It details the market forces driving product developments and the response to those demands by semiconductor manufacturers. His talk discusses how the combined requirements of efficiency, robustness, and compactness have driven the first high-volume use of high-voltage GaN transistors, as well as the implementation of thermal foldback, and load-driven real-time voltage and current adjustments with tens of millivolt and milliampere accuracy—achieving all of this performance while maintaining affordability. The abstract for the final presentation, “SiC Power Technology: Answering Automotive Readiness,” by John Palmour of Wolfspeed, shows that a significant number of automotive OEMs are now targeting SiC MOSFETs to power drive trains. As this market grows, the push to 200-mm substrates is inevitable, and these have been demonstrated in R&D activities, says Palmour.
The APEC technical program offered many industry sessions spread over three days that reveal emerging technology trends in the field. While it is not possible to look into all of the sessions, I will explore a few. One such session (#IS02), “Data Center Power Solution Ecosystem,” is chaired by Shuai Jiang and Mobashar Yazdani of Google LLC. There are seven papers in this session with a focus on 48-V technology, server architecture, and digital power. The first paper, “Driving 48-V Technology Innovations Forward—Hybrid Converters and Trans-Inductor Voltage Regulator (TLVR)” is written by Google engineers. They are Shuai Jung, Xin Li, Mobashar Yazdani, and Chee Chung. It begins by providing an overview of a 48-V dc–dc power architecture and hybrid converter basics, including the evolution of hybrid converters in data centers. This is followed by a discussion on TLVR operating principles and transient response, and physical implementation. In summary, this paper shows that a two-stage 48-V dc–dc power solution ecosystem is being established and hybrid converters are emerging as attractive solutions for the 48-V one-stage fixed-ratio or regulated intermediate bus conversion. An advantage of TLVR technology is that it clears the long-standing theoretical bandwidth barrier. More innovation is needed for this application, as noted by the Google engineers.
Another paper on 48-V server platform architecture is written by engineers from Intel Corp. In this paper, “48-V Server Platform Architecture and Design Challenges,” Intel designers Horthense Tamdem, Meng Wang, Behzad Vafakhah, Yinghua Ye, and Fan Zhengguo show that it requires multiple sources for a cost-efficient ecosystem and an industry standard for 48-V layout guidelines, as well as efficiency above 98% for regulated 48-V to 12-V converter solutions. Another paper of interest is on digital power in the data center by Renesas. It emphasizes the fact that digital VR technology is playing a key role in the move to 48-V data centers.
Other industry sessions of interest are on vehicle electrification (IS16), silicon and WBG switch performance (IS04), energy harvesting enabling the IoT and 5G (IS11), GaN applications and integration (IS19), and addressing EMI challenges with WBG devices (IS24). In the session on production use cases of WBG semiconductors (IS08), there are three papers.
“Cost Effective ToF Lidar Using GaN Devices,” by John Glaser and Alex Lidow of EPC, indicates that time of flight (ToF) lidar are finding use in autonomous vehicles because of their precise measurement capabilities and that GaN can deliver performance to meet the requirements for this ToF lidar application. Citing examples of Waymo’s self-driving cars and Audi’s Advanced Driver Assistance Systems, the EPC authors suggest that lidar is the best choice for all autonomous vehicles.
“High-Density 65 W USB-PD GaN Chargers: Market Demand, Technical Solutions and Pricing,” by Steve Oliver of Navitas Semiconductor identifies numerous 65-W and above ac–dc adapters and chargers in the smartphones and laptops that are powered by its GaN power ICs. This presentation highlights the progress GaN technology has made in the consumer power supply market.
“Leading the GaN Revolution,” by Philip Zuk of Transphorm and Sean Luangrath of Inergy demonstrates portable power using examples of a 3-kW electric generator and a 6-kW residential solar system, both based on GaN devices. Inergy is calling its off-grid whole-home solar system-in-a-box Home Base.
Overall, the program offered four workshops on topics ranging from magnetics to transportation electrification, 12 professional education seminars, six plenary talks, 30 industry sessions, 19 technical dialog sessions, and 40 technical sessions.
In the technical sessions program, there were many sessions devoted to renewable energy, WBG devices, components and magnetics, and cutting-edge power converters. The growing popularity of EVs has stimulated many sessions addressing the challenges of building power trains, driving motors, and fast charging batteries.
In the renewable arena, session T03 offered several papers on renewable energy applications and highlighted the move to 200-mm wafers for GaN-on-silicon HEMTs, and papers T12.4 and session T08 addressed the challenges of building PV inverters and microinverters. Advances in battery integration, management, and protection were presented in session T27 with a focus on energy storage systems. Revealing a number of trends, the WBG space was covered in numerous sessions: T12 on “GaN/Si Devices and Components,” T20 on “SiC Devices and Components,” and T40 on “Wide Bandgap DC-DC Converter and Circuit Modeling.” For instance, paper T12.1 highlighted the move to 200-mm wafers for the manufacturing of GaN-on-silicon HEMTs. Papers T12.4 and T12.5 identified emerging applications benefiting from GaN devices.
Furthermore, the design, modeling, and applications of wireless power transfer were the focus of session T15, and sessions T16 and T32 divulged advances in transportation power electronics. Other technical sessions of interest included sessions on novel ac-dc and dc-dc conversion architectures, covered in T23, T24, and T33.
Despite the current adversities, APEC organizers and vendors did a great job in bringing a virtual version of APEC 2020 to its power electronics audience. Alas, nothing can replace in-person meetings. We hope that coronavirus will be defeated and that a live in-person APEC 2021 will happen next March in Phoenix, Arizona. See you, and stay safe and well.
About the Author
Ashok Bindra (bindra1@verizon.net) received his M.S. degree from the Department of Electrical and Computer Engineering, Clarkson College of Technology (now Clarkson University), Potsdam, New York, and his M.Sc. degree in physics from the University of Bombay, India. He is the editor-in-chief of IEEE Power Electronics Magazine and a Member of the IEEE. He is a veteran freelance writer and editor with more than 35 years of editorial experience covering power electronics, analog/radio-frequency technologies, and semiconductors. He has worked for leading electronics trade publications in the United States, including Electronics, EE Times, Electronic Design, Power Electronics Technology, and RF Design.
