SiC Supercharges High-Voltage Inverter Brick for EVs
Automotive supplier Schaeffler has started mass production of a new high-voltage inverter brick equipped with ROHM’s silicon-carbide (SiC) MOSFET bare chips as part of its strategic partnership.
The inverter assembly, also called a “brick,” is the core power building block that controls the electric motor using logic signals. The unit produces the high-frequency currents that set the motor in motion. The traction inverter acts as the bridge between the high-voltage battery and motor. Its primary function is to convert DC from the battery pack into AC used to control the motor’s speed, torque, and other characteristics.
While 400-V battery packs are broadly employed in electric vehicles (EVs) on the road, many car companies are upgrading to battery packs that operate at 800 V or even as high as 1,000 V to enable faster charging rates and higher efficiency.
SiC is becoming integral to traction inverters for EVs because it can handle these high voltages more safely and efficiently than traditional silicon. ROHM said Schaeffler uses SiC MOSFETs to boost the power brick’s performance: Schaeffler increased the brick’s output by raising the maximum possible input voltage from the battery pack to much more than the usual 800 V. At the same time, the unit enables RMS currents of up to 650 A, turning it into a high-density power pack tailored for high-voltage EV platforms.
The companies said the brick is intended for integration by a "major” Chinese car manufacturer. According to Schaeffler, ROHM adjusted the drain-source voltage of the SiC MOSFETs in the brick to meet OEM specifications.
Modular and Scalable Power Brick
As a core building block of the traction inverter, the brick needs to meet high standards for power efficiency, flexibility, and reliability. Its move into mass production underscores both Schaeffler’s system-level design capabilities and the component-level strengths of ROHM’s SiC chips.
By integrating SiC MOSFETs, the frame-mounted sub-module can fit into a compact form factor with high power density. Schaeffler said the modular and scalable architecture allows it to be plugged into a wide range of EV platforms.
“Through our strategic approach of incorporating scalability and modularity into our e-mobility solutions — from individual components to a highly integrated electric axle — we developed the readily integrated inverter brick,” said Thomas Stierle, chief executive of the e-mobility division at Schaeffler. He added that the company leveraged its “generic platform development” approach to move the new product into mass production in only about a year.
The sub-module incorporates several different parts in an “X-in-1 architecture.” These include a power module for generating the pulse-width-modulation (PWM) signals used to control the motor, a DC-link capacitor, a DC link, and a cooling solution for thermal management. The brick also features a DC boost function, which enables cars equipped with an 800-V power architecture to use a 400-V charger to achieve a charging rate equivalent to 800 V.
The Growing Trend Toward SiC Semis
One of the main differences between silicon and SiC is that the latter supports higher thermal conductivity, higher breakdown voltage, and faster switching speeds. Thanks to these features, SiC power devices have reduced conversion losses compared to silicon, which pays dividends for the traction inverters at the heart of EVs. The power savings also improve overall system efficiency, which inevitably increases the EV’s range.
SiC power semiconductors are in the early stages of a global boom, particularly as the 800-V power architecture is one of the prerequisites for faster EV charging rates, according to Yole Group, a technology market research firm.
“SiC is entering a new phase of maturity,” said Poshun Chiu, Principal Analyst at Yole Group, where he covers SiC and other wide bandgap semiconductors. “Despite short-term volatility, long-term growth remains robust, with automotive electrification and industrial diversification as its twin engines.”
ROHM entered the strategic partnership with Schaeffler (previously Vitesco Technologies) in 2020. In 2023, Schaeffler secured a “strategically important” capacity agreement with ROHM, giving it a guaranteed long-term supply of SiC power semiconductors.
The companies said the deal will amount to approximately $1 billion by 2030.
