3 Next-Gen SiC Semiconductor Applications in Automotive

November 17, 2020 Shannon Flynn

Silicon carbide (SiC) semiconductors have recently risen in popularity as a growing number of engineers choose them over previous semiconductors made from silicon. They can tolerate higher voltage levels and temperatures than silicon semiconductors.

Both of these characteristics and others make them appealing for use in the automotive sector. These semiconductors offer advantages appreciated by car manufacturers and owners alike, such as faster battery charging and better energy-efficiency. Here are three examples of exciting progress in that sector:

1. Less Heat Dissipation While Promoting Higher Switching Frequencies

One compelling application of these semiconductors involves allowing higher switching frequencies for the power electronics that collectively serve as the "command centers" for electric and hybrid vehicles. Starting in June 2018, Bosch laid the plans for an extensive SiC semiconductor manufacturing facility. The brand's process involves creating a chemical bond by introducing additional carbon atoms into the crystalline structure of ultra-pure silicon.

Turning discs of silicon carbide into chips requires advanced manufacturing processes that can last up to 14 weeks. Bosch didn't provide further details about those steps, but it highlighted the advantages of accomplishing them. This approach leads to a 50% reduction in energy lost as heat. That outcome results in more efficient power electronics and energy for the electric motor, meaning drivers get a more extended range.

SiC semiconductors also have better electrical conductivity compared to those made from silicon. That advantage allows for a faster switching frequency associated with the performance of power electronics. Increased switching capacity allows for using smaller supporting components, such as inductors and transformers.

Moreover, the minimized heat dissipation provided by SiC semiconductors allows engineers to spend less on expensive options to keep powertrains cool. This advantage cuts down on a vehicle's size and weight dimensions, plus keeps delicate electronics within the recommended temperature range for good performance and longer life spans.

2. Reduced Consumption of Power Components, Plus More Miniaturization

SiC semiconductors also help automotive engineers cut down on decreases associated with power switching and minimize overall power consumption. Relatedly, these components allow for making cooling systems and peripheral components smaller and simpler.

In one recent example, Mitsubishi Electric released a metal oxide semiconductor field-effect transistor (MOSFET) semiconductor made with junction field-effect transistor (JFET) N-channel doping technology. This approach requires adding donor impurities to achieve a negative current flow of electrons. N-channel JFETs have a greater channel conductivity and lower resistance than their P-channel counterparts.

Mitsubishi said this design led to an 85% reduction in the consumption of power-supply systems compared to results achieved by conventional insulated-gate bipolar transistor (IGBT) semiconductors. Additionally, an accompanying decrease in switching-related power loss allows engineers to shrink and simplify cooling systems and peripheral components. Making them miniaturized and more straightforward reduces the associated sizes and costs.

3. Faster Charges, Less Range Anxiety

Many people who show interest in electric vehicles still worry that those cars might not have a long enough range to support their typical travels. A related concern is the amount of time required to give those cars a full charge. A newly developed inverter equipped with SiC semiconductors promises to halve the time needed to charge an electric vehicle. Additionally, these new inverters have double the previous model's voltage, which gives them more power.

A partnership between Delphi Technologies and Cree uses the first company's inverters combined with Cree's SiC MOSFETs. The inverters feature a patented power switch with a double-sided, thermally conductive cooling design. It reduces the power module's overall temperature while enabling higher power outputs to support a longer range for hybrid and fully electric automobiles. These inverters are also 40% lighter and 30% more compact than competing models.

Delphi Technologies' CEO noted that the faster switching capabilities of SiC enable building faster, lighter, and smaller motors for future cars. Additionally, doubling the voltage allows for more flexibility in features like smaller, less expensive power cables or better harvesting of kinetic energy during braking. Moreover, since the inverter's power switch fits into the same inverter package as a previously available silicon switch, engineering expenses decrease.

A Promising but Imperfect Option

Some of these developments are in the early stages. That means engineers might run into unexpected pitfalls, such as issues with SiC substrate availability or costs that limit the scalability of mass production.

Moreover, most of today's SiC semiconductors sit inside die or wire-bonded packing intended for low-frequency circuits. Those worked well for silicon, but the higher frequencies of these newer options limit the potential of SiC due to parasitic capacitance and inductance. Thus, if automotive brands pursue widespread adoption of SiC semiconductors, that decision may require extensive manufacturing facility revamps.

Even so, the already-identified gains associated with SiC semiconductors mentioned here are arguably impressive. They could open new opportunities for automotive engineers while making future car models more attractive to choosy consumers. In addition, manufacturers are projected to gain 75% in profitability, so updating semiconductor technology could assist in this growth.

Succeeding as an engineer requires maintaining a problem-solving mindset. People working on automotive innovations with improved semiconductors will undoubtedly encounter obstacles but overcoming them could lead to new wisdom and better designs for the cars of the future.


Shannon Flynn is a technology blogger who writes about AI and IT trends. She's also the Managing Editor of ReHack.com and freelances for sites like Re-Work, ChatbotNewsDaily, and other sites. Follow her on Medium or ReHack on Twitter for more tech news!

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