Improving Energy Efficiency in Industrial Applications with Silicon Carbide
Industrial applications such as server power supplies, uninterruptible power supplies (UPS), and motor
drives consume a significant portion of the world’s power. Thus, any increase in efficiency in industrial
power supplies will substantially reduce a company’s operating costs. Combined with greater power
density and better thermal performance, the demand for high-efficiency power supplies is increasing
exponentially.
Several factors are driving this growth. The first is rising global energy awareness and increasingly
urgency to use energy more wisely and efficiently. The second is the Internet of Things (IoT), which has
resulted in the introduction of new technologies and services of all kinds into industrial applications.
With Smart Industry initiatives such as Industry 4.0, machines, factories, and workplaces are becoming
more intelligent and aware through the connection of devices to achieve greater autonomy, efficiency,
reliability, and safety.
However, industrial automation, such as robotic and motorized production lines, comes with escalating
use and cost of electricity to power these systems. To stay competitive, manufacturers need to be able
to develop new operational practices that keep factory costs down. They also need to make the most of
every square meter of floor space as equipment footprint directly impacts operational costs.
The impact of energy consumption also extends into the data center, which houses the servers that
support industrial applications. Increasing data traffic through automation, artificial intelligence, and
machine learning in turn increases the processing resources required to keep equipment operational.
Thermal performance is also important, given that up to 20% of power consumed in a data center is
used to keep the data centers cool.
The demand for greater efficiency, lower cost
As industrial equipment often runs 24/7, any improvement in efficiency quickly translates to real savings
in terms of significantly reduced energy consumption. The most immediate way to address energy issues
is to increase the energy efficiency of the systems that power these industrial systems. As John Palmour,
one of the founders of Cree | Wolfspeed says, “The least expensive power is the power you don’t use.”
For this reason, there is tremendous pressure from industry, government, and manufacturers to develop
more efficient power supplies. For example, standards like Energy Star and 80 Plus promote efficient
energy use in power supply units (PSU). By meeting these standards, PSU OEMs can easily demonstrate
the efficiency of their systems to a demanding marketplace.
Three characteristics – power density, thermal performance, and conversion efficiency – are among the
biggest challenges for designers of power supplies. In addition, designers need to meet these challenges
while minimizing overall system cost.
Traditional approaches to power supply design will continue to provide some improvement in these
areas, but gains will be limited as developers have been focused on squeezing more from these systems
for years. To achieve significant improvement, new approaches are required.
Silicon Carbide delivers
Silicon carbide (SiC) is a wide bandgap semiconductor base material. It can be used as a bare die
substrate, in discrete components like Schottky diodes and MOSFETs, as well as power modules.
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Historically, silicon (Si) has been used as a semiconductor base for the majority of electronics
applications. However, Si is an inefficient foundation for power supply systems when compared to SiC.
SiC offers many advantages over Si (see Figure 1).
Figure 1
Silicon carbide (SiC) offers many advantages over traditional silicon (Si).
Source: Wolfspeed, A Cree Company
These include:
• SiC-based components have lower leakage currents compared to their Si counterparts. This is
because electron-hole pairs generate slower in SiC than in Si, resulting in lower leakage current
losses when a switch is off.
• SiC has a wide bandgap of 3 electronvolts (eV) and is able to withstand a voltage gradient over
eight times greater than Si without undergoing avalanche breakdown. The increased critical
breakdown strength of SiC enables components to withstand a higher voltage in the same
package as Si. Because of this, SiC-based components like MOSFETs can be created at blocking
voltages about 10X compared to Si. Thus, very high voltage, high power devices can be
fabricated reliably, and designers can work within tighter margins to deliver higher
performance. These devices can be placed very close together, allowing for greater packing
density of components.
• Higher thermal conductivity results in more efficient heat transfer. Furthermore, a lower onstate resistance decreases conducting losses.
• SiC-based components are capable of higher switching frequencies. The higher switching
frequency of SiC enables a peak efficiency of > 98.5%, making it possible for systems to meet the
80 Plus Titanium Standard (see Figure 2).
Figure 2:
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This graph shows of the efficiency of a 20kW SiC AC/DC convertor. As can be seen from these
experimental results, the convertor is able to achieve a peak efficiency of > 98.5%, reaching 80 Plus
Titanium standards.
Source: Wolfspeed
Industrial applications that benefit from SiC
With these characteristics, SiC-based components enable power supplier designers to reach new levels
of efficiency. The impact of SiC can be seen in a number of industrial applications:
Power factor correction (PFC): PFC is a technique that can drastically reduce wasted power by increasing
the power factor of a power supply. Without PFC, power supplies draw current in short, high magnitude
pulses. With PFC, these pulses can be smoothed out to reduce the input root mean square (RMS)
current and apparent input power. This effectively shapes the input current to maximize the power
realized from the supply.
The higher frequency enabled by SiC allows for the use of smaller and more affordable surrounding
components (see Figure 3).
Figure 3:
Dual-Boost Semi-Bridgeless PFC using Si
Hybrid Totem Pole PFC featuring SiC
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The higher frequency enabled by SiC allows for the use of smaller and more affordable surrounding
components. As can be seen, a hybrid approach using SiC MOSFETs requires fewer components, is more
cost effective, and achieves a higher power density.
Source: Wolfspeed
As can be seen, a hybrid approach using SiC MOSFETs requires fewer components, is more cost
effective, and achieves a higher power density. This leads to reduced system size, weight, and cost (see
Figure 4). Furthermore, in addition to reducing overall energy consumption, the higher efficiency
achieved improves thermal performance, leading to additional reductions in the size and weight of the
power supply.
Figure 4:
Silicon carbide (SiC) offers significant advantages over traditional silicon (Si).
Source: Wolfspeed
Electric Vehicle Charging: Electric vehicles, require both efficient and fast charging to minimize vehicle
downtime. Fast charging stations provide significant advantages over vehicle on-board chargers (OBC),
enabling charging times of 30 minutes compared to > 4 hours for OBCs. Charging stations are more
flexible as they support hot-swappable power conversion blocks to maximize up-time. Charging stations
can also be designed in a scalable fashion, enabling faster time-to-market and lower R&D costs. To be
successful, a charging station must provide high efficiency, improved power density, ruggedness,
reliability, and bi-directional energy flow for smart grid enablement.
With 2-3 times faster switching, SiC-based chargers have up to 30% lower loses and require 30% fewer
components. As can be seen in the block diagram for an AC/DC convertor (see Figure 5), the use of SiCbased components results in a design with fewer components, smaller size, and lower system cost while
enabling bi-directional power transfer.
Figure 5:
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As can be seen in this block diagram for an AC/DC convertor, the use of SiC-based components results in
a design with fewer components, smaller size, and lower system cost while enabling bi-directional
power transfer.
Source: Wolfspeed
In addition, the higher efficiency and improved thermal performance of SiC enables higher power
density (typically an increase of 65%). This means each station can deliver more power, translating to
either faster charging time and or more vehicles charged per station. Currently, the ability to charge
more vehicles is typically more important than being able to charge faster. This is because battery
technology is behind today’s power supply capabilities which can deliver energy to EV batteries faster
than they can be safely charged.
Server Power Supplies: Data centers currently use 3% of all power in the US. This figure is estimated to
rise to 15% over the next 7 years. With increasing IoT deployment, data centers – and their associated
energy and operational costs – can be expected to become a key consideration in determining the
efficiency of industrial systems and smart factories. The advantages of SiC will help improve data center
efficiency in many ways over the coming years. For example, SiC-based MOSFETs and diodes utilized in
data centers today improve server thermal performance to yield 40% saving in cooling-related energy
costs alone.
Wolfspeed SiC – a firm foundation for powering tomorrow
Wolfspeed, A Cree Company, is an innovator of SiC-based power and radio frequency (RF)
semiconductors. With more than 30 years of experience in producing and designing with SiC, Wolfspeed
is the world leader in SiC technology. Wolfspeed offers a wide portfolio of SiC-based components to help
optimize industrial system and power supply designs.
The demand for SiC is growing as the need for lighter, more efficient and cooler power devices grows.
Wolfspeed has recently initiated a five-year, $1 billion investment to increase its SiC wafer fabrication
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capacity and SiC materials production by 30X to meet expected market growth by 2024. The wide
bandgap semiconductor components produced will enable dramatic technology shifts currently
underway within the automotive, communications infrastructure, and industrial markets.
Wolfspeed SiC is a field-proven technology with industry-leading reliability. It is used in a great many
applications, including motor drives, server power, telecom, and electric vehicle charging. During the
period from 2010 to 2020, SiC-based power supplies in these applications have logged 6-7 trillion hours
of operation and contributed 620 billion kWh in energy savings. Wolfspeed also has the industry’s
lowest failure in time (FIT) rate (< 5%).
The unique attributes of silicon carbide promise to radically reduce the amount of energy the world
consumes. Wolfspeed SiC provides the industry-leading switching speeds, high performance, and
superior thermal capacity power system designers need to build energy conserving power
infrastructure.
The world runs on power, and Wolfspeed SiC enables a future where the world can do much more with
less.
Author: Dave Skinner, Senior Product Marketing Manager
Dave Skinner is the Senior Product Marketing Manager for the silicon carbide power business at Wolfspeed, a Cree
Company. After earning his MSEE and BSEE degrees from Georgia Tech in Atlanta, GA, he began his career with
another disruptive high-efficiency power technology, designing class D audio amplifier ICs and systems at Texas
Instruments. He has served in a variety of global leadership roles in analog and power semiconductor product
development, product marketing, field applications engineering, and sales. Dave also consults with non-profit and
charitable-giving organizations to evaluate and recommend technology solutions that remove barriers to learning
for people with low vision disabilities.
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