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SiC-based Motor Drives: Manufacturing the Next Generation of Industrial Energy Savings

April 12, 2017

By Kelsey Horowitz, Timothy Remo, and Samantha Reese, CEMAC Analysts

A silicon-carbide wafer reflects light in a rainbow of colors.

Motor driven systems consume a little more than half of all electricity used within the manufacturing sector. In all applications, medium and high power motors—while being much fewer in number than low power systems—constitute the vast majority of total motor energy consumption. Typically, these medium-voltage, medium- to high-power electric motors and drives used in the chemical, resource extraction, and manufacturing industries, which employ relatively inefficient gearboxes and mechanical throttles when the motor speed needs to be adjusted. Replacing these inefficient systems with power-electronics-based variable frequency drives (VFDs) could enable substantial reductions in global energy consumption in the industrial sector. And even greater energy savings could be achieved if the electronics in the new VFDs are constructed not from silicon, but from silicon carbide (SiC). SiC is a wide bandgap semiconductor material that can increase the efficiency of VFDs and enable them to operate efficiently at higher voltages, powers, temperatures, and switching frequencies compared with VFD designs based on silicon. SiC power electronics have reduced cooling requirements, lower part counts, and the possibility of using smaller passive components, reducing their physical footprint and, potentially, the system cost of VFDs.

While the market share of SiC power electronics is currently low, it is expected to grow considerably over the next 5 years in applications that can take advantage of its properties. This presents an opportunity not only for energy savings, but also for the manufacture of components along the value chain for SiC-based drives, which would have spillover effects for other SiC-based electronics applications ranging from vehicles to consumer electronics.

CEMAC's latest report, "A Manufacturing Cost and Supply Chain Analysis of SiC Power Electronics Applicable to Medium-Voltage Motor Drives," breaks down the regional competitiveness issues involved in manufacturing these components. Our analysis, funded by the Department of Energy's Advanced Manufacturing Office, includes bottom-up regional cost models as well as an assessment of the impact of the supply chain, incentives, cost of capital, and other factors on competitiveness.

One interesting finding in our report is that the United States is a global leader in the production of SiC wafers—a key component in SiC power electronics. The figure below shows the estimated cost breakdowns for manufacturing SiC wafers in different countries, assuming that the capability of firms in all countries is equal. In fact, leading firms in the U.S. are currently able to obtain higher yields and manufacture larger area wafers compared to many firms located elsewhere, which could translate to a cost advantage.

A chart compares the minimum sustainable price at which silicon-carbide wafers can be manufactured in Urban China, the United States, Japan, Germany, Sweden, and Taiwan. The minimum sustainable prices are: $2,455 for China, $2,992 for Germany, $2,901 for Japan, $2,917 for Sweden, $2,724 for Taiwan, and $2,733 for the United States.

Breakdown of modeled regional manufacturing costs for 6-inch SiC wafers. These costs include the cost of the substrate as well as a 30μm thick epitaxial layer. In this chart, MSP stands for minimum sustainable price, SG&A stands for sales, general, and administrative costs, and R&D stands for research and development costs. Error bars are driven by variability in the pricing of input materials, as well as in manufacturing processes; for example, different firms have different labor counts and spending on R&D and SG&A, and pricing for materials varies across suppliers.

The report also examines how innovations may contribute to shifts in global dynamics or adoption of more efficient drives. We found that there is a substantial opportunity for research to help reduce the costs of SiC wafers, which are a primary driver of SiC chip and power module costs. For example, increasing the throughput of the SiC crystal and the epitaxial growth processes, or reducing the cost of consumables associated with the crystal growth and wafering, could significantly drive down the cost of SiC power electronics.

For more analysis of the SiC value chain and regional competitiveness, check out the recently released report.