From EVs to solar panels to HVACs, SiC devices are bolstering power density, efficiency, and reliability while shrinking system size and weight.
Nearly a half-decade after Tesla incorporated Silicon Carbide (SiC) MOSFETs in Model 3’s traction inverter, a device that converts the direct current coming out of the battery into the alternating current needed to drive the motor, this wide-bandgap (WBG) technology has come a long way in changing the power dynamic in electric-vehicle designs.
A study from Exawatt forecasts that 70% of passenger EVs will use SiC MOSFETs by 2030. Next, this WBG semiconductor material is expected to transform renewable energy designs spanning from wind turbines to industrial motors to solar panels.
Besides vehicle electrification, a variety of devices like traction inverters constantly translate, manage, and regulate the flow of energy in the electrification of wind farms, solar power, and power grids.
Infineon’s SiC devices were at the heart of a one-year pilot project to reduce motor noise in streetcars in Munich, Germany.
But why are SiC components a better fit in EVs and renewable energy designs like photovoltaic inverters? In power applications serving vehicle electrification as well as renewable energy systems, efficiency, reliability, and power density are constant challenges for design engineers. However, silicon-based components have mostly reached their limits in efficiency improvements and system cost reduction.
On the other hand, designs like traction power units, industrial motor drives, and energy infrastructure solutions require high voltage switching technology to increase efficiency, reduce system size and weight, and enhance reliability. That calls for a new breed of power components that improve efficiency at the system level, enhance power density, reduce electromagnetic interference, and shrink system size and weight. Enter SiC power semiconductors.
Take the case of EVs, in which SiC components have become a key design enabler in traction inverters, on-board chargers (OBCs), DC/DC converters, and e-climate compressors. The following section will delve into how SiC semiconductors improve efficiency and reduce the size of EV drivetrains and chargers.
Why SiC is mainstay in EVs
It’s no wonder that EVs aspire to increase the capacity of the on-board battery to improve the cruising range. Moreover, EVs are using higher-voltage 800-V batteries to meet the demand for shorter charging times. Not surprisingly, therefore, automotive designers urgently need power devices capable of withstanding high voltage with low losses.
SiC components can handle voltage as high as 1,200 V and beyond while offering higher thermal conductivity. Additionally, their robust handling of high frequencies leads to smaller passive components within power systems. That’s how SiC power devices help increase efficiency and lower the vehicle’s weight and cost.
Besides the drivetrain, the part that fetches the energy from the power source (the battery) to the axels to keep vehicles going, the most notable adjacent market is on-board charging for EVs. Here, converter devices are like traction inverters but do the opposite: They convert the AC power from the wall into DC power to suit the battery.
When Lucid, a carmaker in California, was designing its first luxury sedan EV, Lucid Air, it employed SiC MOSFETs in the main on-board charging unit, which integrated a DC/DC converter and the bidirectional OBC to ensure an advanced power-factor–correction circuit capable of operating at high switching frequencies.
Rohm’s SiC MOSFETs powered Lucid Air’s Wunderbox, the main on-board charging unit that integrates a DC/DC converter and the bidirectional OBC.
The incorporation of Rohm’s SCT3040K and SCT3080K SiC MOSFETs also helped Lucid reduce the size of the design and reduce power losses due to high charging efficiency. Rohm has optimized its SiC MOSFETs for automotive powertrain systems such as the main drive inverters.
Then there are electric buses in China launched by Yutong Group; here, the high-efficiency powertrain system for electric buses is based on StarPower modules that incorporate Wolfspeed’s 1,200-V SiC MOSFETs.
Beyond EVs: renewable energy
While SiC is reshaping the functioning of the drivetrain and OBCs in EVs, it has demonstrated the potential to serve electrification applications ranging from heating, ventilation, and air conditioning (HVAC) systems to power grids to industrial motors. In short, the SiC story is quite bigger than EVs.
Case in point: The installed photovoltaic capacity is proliferating worldwide, replacing about 600 medium-sized coal-fired power plants. Solar power systems use plenty of inverters, and here, weight and size are major considerations in installing solar panels. The reduction in the size of an inverter could significantly lower the workforce required to install and maintain solar panels.
Midnite Solar, a producer of alternative energy products based in Arlington, Washington, has employed Rohm’s SiC MOSFETs in solar charge controllers, dual MPPT charge controllers, battery-based chargers/inverters, and 120-/240-V inverters/chargers. While trying to make an inverter work as a charger, wherein it must run bidirectionally, Midnite Solar initially tried an IGBT pair in combination with another diode. But that didn’t quite work, and eventually, SiC solved the design puzzle.
Then there is Delta Energy Systems, which has used Wolfspeed’s SiC MOSFETs in its solar power inverter to bolster power density and energy efficiency while lowering the weight of inverters.
