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In power-conversion systems, which are needed to provide the correct power supply to multiple electronic devices, it is essential to obtain the highest possible efficiency. On one hand, the most recent regulations introduced globally require the construction of power-conversion stages with minimal losses. On the other hand, the environmental issue and the need to reduce CO2 emissions are increasingly orienting manufacturers and consumers toward “green” solutions.
At electronica 2022, held in Munich last month, panelists gathered by Maurizio Di Paolo Emilio, editor-in-chief of Power Electronics News, spoke about the technical trends and innovative technologies related to power-conversion applications.
In this panel, the speakers shared new technical solutions, such as silicon carbide (SiC) and gallium nitride (GaN) semiconductors, to support power conversion in different applications and markets.
Trends in power conversion
Improvement in power-factor correction (PFC) and reduction in standby power consumption can be achieved thanks to cutting-edge power-management devices that provide energy-efficient solutions for all industrial, consumer and automotive applications. To fulfill the rising performance and efficiency criteria, power-conversion topologies must be innovative and viable.
How can challenging requirements like efficiency, high power density, small-form factor and excellent thermal management be satisfied?
“The best way to achieve high efficiency is to eliminate losses, and in doing so, you have to take a holistic system approach,” said Silanna Semiconductor North America CEO Mark Drucker. “We’re heading to improve efficiency by reducing losses.”
Eggtronic, in Modena, Italy, has developed proprietary power-conversion technologies specifically designed to deliver smaller and higher-efficiency power converters, power adapters and power chargers.
“Our target at Eggtronic is mainly to provide to the end user more efficient power devices and architectures,” said Matteo Ovi, head of B2B sales and business development at Eggtronic. “For low-power devices, we provide ZVS [zero-voltage–switching] solutions, whereas for higher power, up to and above 500 W, we have developed new architectures with single-stage PFC and isolated resonant regulator.
“The main advantage of our solution is clearly the efficiency because we are cutting the losses,” he added. “And the second one is a reduction in the number of active components. At the end, that allowed us to achieve an efficiency level higher than 85% at 240 W and be compliant with USB PD 3.1 for 48 V.”
The proliferation of connected devices and the ever-expanding use of the cloud require huge amounts of data to be stored and made accessible over the network. All of this has a significant impact on power draws, considering that data centers consume several terawatts of power each year. What solutions are available today to make data centers more efficient?
“I don’t think we can stop data centers from gobbling up electricity if we all want access to entertainment, connectivity and things like that,” said Steve Shultis, senior vice president of sales & marketing at Empower Semiconductor. “At Empower Semiconductor, we follow a different approach. Our technology is specific to point-of-load power-delivery regulation and our objective regarding data center environments is more about flattening the curve.
“We believe that through high-performance and high-bandwidth voltage regulation, we can unleash more performance out of core silicon GPUs and processors,” he added. “By enabling that, then you can scale meeting both the power needs of data centers and the system-efficiency targets.”
The recent global chip shortage has affected the power industry as well. To fight this issue, manufacturers are expanding their capacity both building with new facilities and adopting larger wafers that provide higher yield and reduce costs.
“It’s very important to control the entire supply chain,” said Pietro Scalia, director of automotive traction solutions at onsemi. “We need to eliminate the defectivity of semiconductors, as it makes the solution expensive. I would say that capacity is, of course, one of the main concerns we have today, not to ourselves. Let’s say the entire market is in the same situation.”
He said he believes that “capacity means investment from the Tier 1, and this means suppliers like onsemi are here to make partnership.”
Regarding efficiency, we have recently seen many developments and advancements in AC/DC converters, a key component in power applications.
“We’ve released several products operating at significantly higher switching frequencies than our competitors,” Drucker said.
As he pointed out, Silanna is taking a very holistic view to development of these products. They are doing reference design development at the same time they are developing and designing the chips. That allows them to have immediate feedback on the design, paying careful attention to board layout, pinout, component selection and filter components.
With its integrated voltage regulator proprietary technology, Empower Semiconductor has introduced a novel type of capacitor, called e-cap. It’s a silicon capacitor technology that integrates multiple discrete capacitances into a single, integrated, solid-state device.
“[The] capacitor is one of the most basic and fundamental components, yet there’s been no innovation in the industry for generations,” Shultis said. “For our integrated voltage regulator, we needed something that was much more stable and compact than MLCC capacitors to enable high switching frequencies. Since it didn’t exist, we developed the e-cap silicon capacitor technology for those reasons.”
In recent years, SiC and GaN have been emerging in the power component market, achieving a growing industry acceptance. The panelists discussed prospects and challenges of wide-bandgap technologies in multiple application contexts, as well as the last barriers to overcome for their widespread adoption, such as large-volume capabilities and prices.
When you want to introduce a new device on the market, a very important aspect to consider concerns the definition of a model capable of reflecting, as faithfully as possible, the static and dynamic behavior of the component. Being very critical, this activity is not free from problems, including temperature.
When designing a new SiC- or GaN-based part, independent parameters accurately incubated into the model are needed. Additionally, to run the system-level simulation, the interface at the temperature-dependent substrate and the cooling material behavior must be defined. For instance, at room temperature, SiC is 3.7× to 4× more thermally conductive than silicon.
“When you approach temperatures as high as 175˚C, the thermal conductivity will significantly go down,” said Dilder Chowdhury, director of strategic marketing for power GaN technology at Nexperia. “We usually start with a simple model, obtaining our alpha samples. We immediately start comparing the performance of the alpha devices with the simulation, and then we fine-tune the temperature-dependent parameters. That’s how we get much closer to real-life behavior.”
SiC and GaN play an essential role in the electrification process of vehicles, especially used in inverters and power converters. The high breakdown voltages of SiC, in particular, are supporting the increasing transition of the EV bus to the 800-V voltage, which can provide faster recharge times and better thermal management.
“Through the acquisition of Microsemi a couple of years ago, Microchip has inherited the power module product line,” said Erich Niklas, senior channel manager of technical marketing for SiC at Microchip Technology. “We strongly believe in silicon carbide modules, and the demand from the market for applications like traction inverters and storage devices, where modules get more and more into the picture, is very clear.”
This year, Microchip released 3.3-kV SiC FETs and diodes (now discrete), he added, “but the key will be to use those devices in various applications as a power module, rather than in a discrete version of it. Module is for sure a key for silicon carbide in the future for higher-power applications.”
Due to their intermittent availability, renewable energies require proper energy-storage solutions. That, in turn, requires efficient power-conversion systems.
“From the standpoint of efficiency, we have done our research in terms of what could be the next things to improve,” Ovi said. “We have seen that the most prominent market to push and look forward is the battery storage market. These kinds of devices are always working, 24/7, and reduction of overall losses can really make a difference.
“We have designed our 10-W to 10-kW–plus power converters for battery-based energy storage providing different capabilities, like single-direction and bidirectional chargers, and CC/CV or custom charge algorithms,” he added.
The panel talk concluded with some considerations on the need and the role of young engineers in the power-electronics industry. The speakers all agreed there is a strong demand for young engineers in the industry, especially in the power arena.
“We’re making so much progress, and yet there’s so much further to go,” Drucker said. “There are a lot of exciting developments, new materials, new devices, new architectures. I think there is a huge and exciting opportunity, and you can really be contributing to the betterment of the planet at the same time.”